API Refactor template layer into its own module

Includes the following large-scale changes:
- Impoved barrier between model and view layers
- Improved casting of scalar to relevant DBField types
- Improved capabilities for rendering arbitrary data in templates

_config/view.yml

@@ -0,0 +1,6 @@
+---
+Name: view-config
+---
+SilverStripe\Core\Injector\Injector:
+  SilverStripe\View\TemplateEngine:
+    class: 'SilverStripe\View\SSTemplateEngine'

bin/sake

@@ -2,6 +2,7 @@
 <?php
 
 use SilverStripe\Cli\Sake;
+use SilverStripe\ORM\DB;
 
 // Ensure that people can't access this from a web-server
 if (!in_array(PHP_SAPI, ['cli', 'cgi', 'cgi-fcgi'])) {
@@ -11,5 +12,8 @@ if (!in_array(PHP_SAPI, ['cli', 'cgi', 'cgi-fcgi'])) {
 
 require_once __DIR__ . '/../src/includes/autoload.php';
 
+// CLI scripts must only use the primary database connection and not replicas
+DB::setMustUsePrimary();
+
 $sake = new Sake();
 $sake->run();

src/Control/ContentNegotiator.php

@@ -225,7 +225,7 @@ class ContentNegotiator
         // Fix base tag
         $content = preg_replace(
             '/<base href="([^"]*)" \/>/',
-            '<base href="$1"><!--[if lte IE 6]></base><![endif]-->',
+            '<base href="$1">',
             $content ?? ''
         );
 

src/Control/Controller.php

@@ -3,11 +3,14 @@
 namespace SilverStripe\Control;
 
 use SilverStripe\Core\ClassInfo;
+use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Dev\Debug;
+use SilverStripe\Model\ModelData;
 use SilverStripe\ORM\FieldType\DBHTMLText;
 use SilverStripe\Security\Member;
 use SilverStripe\Security\Security;
 use SilverStripe\View\SSViewer;
+use SilverStripe\View\TemplateEngine;
 use SilverStripe\View\TemplateGlobalProvider;
 
 /**
@@ -88,6 +91,8 @@ class Controller extends RequestHandler implements TemplateGlobalProvider
         'handleIndex',
     ];
 
+    protected ?TemplateEngine $templateEngine = null;
+
     public function __construct()
     {
         parent::__construct();
@@ -401,7 +406,7 @@ class Controller extends RequestHandler implements TemplateGlobalProvider
             $templates = array_unique(array_merge($actionTemplates, $classTemplates));
         }
 
-        return SSViewer::create($templates);
+        return SSViewer::create($templates, $this->getTemplateEngine());
     }
 
     /**
@@ -453,9 +458,10 @@ class Controller extends RequestHandler implements TemplateGlobalProvider
         }
 
         $class = static::class;
-        while ($class != 'SilverStripe\\Control\\RequestHandler') {
+        $engine = $this->getTemplateEngine();
+        while ($class !== RequestHandler::class) {
             $templateName = strtok($class ?? '', '_') . '_' . $action;
-            if (SSViewer::hasTemplate($templateName)) {
+            if ($engine->hasTemplate($templateName)) {
                 return $class;
             }
 
@@ -487,17 +493,25 @@ class Controller extends RequestHandler implements TemplateGlobalProvider
             $parentClass = get_parent_class($parentClass ?? '');
         }
 
-        return SSViewer::hasTemplate($templates);
+        $engine = $this->getTemplateEngine();
+        return $engine->hasTemplate($templates);
+    }
+
+    public function renderWith($template, ModelData|array $customFields = []): DBHTMLText
+    {
+        // Ensure template engine is used, unless the viewer was already explicitly instantiated
+        if (!($template instanceof SSViewer)) {
+            $template = SSViewer::create($template, $this->getTemplateEngine());
+        }
+        return parent::renderWith($template, $customFields);
     }
 
     /**
      * Render the current controller with the templates determined by {@link getViewer()}.
      *
      * @param array $params
-     *
-     * @return string
      */
-    public function render($params = null)
+    public function render($params = null): DBHTMLText
     {
         $template = $this->getViewer($this->getAction());
 
@@ -737,4 +751,12 @@ class Controller extends RequestHandler implements TemplateGlobalProvider
             'CurrentPage' => 'curr',
         ];
     }
+
+    protected function getTemplateEngine(): TemplateEngine
+    {
+        if (!$this->templateEngine) {
+            $this->templateEngine = Injector::inst()->create(TemplateEngine::class);
+        }
+        return $this->templateEngine;
+    }
 }

src/Control/Director.php

@@ -17,6 +17,7 @@ use SilverStripe\Versioned\Versioned;
 use SilverStripe\View\Requirements;
 use SilverStripe\View\Requirements_Backend;
 use SilverStripe\View\TemplateGlobalProvider;
+use SilverStripe\ORM\DB;
 
 /**
  * Director is responsible for processing URLs, and providing environment information.
@@ -84,6 +85,14 @@ class Director implements TemplateGlobalProvider
      */
     private static $default_base_url = '`SS_BASE_URL`';
 
+    /**
+     * List of routing rule patterns that must only use the primary database and not a replica
+     */
+    private static array $rule_patterns_must_use_primary_db = [
+        'dev',
+        'Security',
+    ];
+
     public function __construct()
     {
     }
@@ -296,6 +305,18 @@ class Director implements TemplateGlobalProvider
     {
         Injector::inst()->registerService($request, HTTPRequest::class);
 
+        // Check if primary database must be used based on request rules
+        // Note this check must happend before the rules are processed as
+        // $shiftOnSuccess param is passed as true in `$request->match($pattern, true)` later on in
+        // this method, which modifies `$this->dirParts`, thus affecting `$request->match($rule)` directly below
+        $primaryDbOnlyRules = Director::config()->uninherited('rule_patterns_must_use_primary_db');
+        foreach ($primaryDbOnlyRules as $rule) {
+            if ($request->match($rule)) {
+                DB::setMustUsePrimary();
+                break;
+            }
+        }
+
         $rules = Director::config()->uninherited('rules');
 
         $this->extend('updateRules', $rules);

src/Control/Email/Email.php

@@ -398,16 +398,13 @@ class Email extends SymfonyEmail
         return $this;
     }
 
-    public function getHTMLTemplate(): string
+    public function getHTMLTemplate(): string|array
     {
         if ($this->HTMLTemplate) {
             return $this->HTMLTemplate;
         }
 
-        return ThemeResourceLoader::inst()->findTemplate(
+        return SSViewer::get_templates_by_class(static::class, '', Email::class);
-            SSViewer::get_templates_by_class(static::class, '', Email::class),
-            SSViewer::get_themes()
-        );
     }
 
     /**

src/Control/HTTPResponse.php

@@ -8,11 +8,12 @@ use SilverStripe\Core\Convert;
 use SilverStripe\Core\Injector\Injectable;
 use SilverStripe\Core\Injector\Injector;
 use SilverStripe\View\Requirements;
+use Stringable;
 
 /**
  * Represents a response returned by a controller.
  */
-class HTTPResponse
+class HTTPResponse implements Stringable
 {
     use Injectable;
 
@@ -444,10 +445,8 @@ EOT
 
     /**
      * The HTTP response represented as a raw string
-     *
-     * @return string
      */
-    public function __toString()
+    public function __toString(): string
     {
         $headers = [];
         foreach ($this->getHeaders() as $header => $values) {

src/Control/RSS/RSSFeed_Entry.php

@@ -47,7 +47,7 @@ class RSSFeed_Entry extends ModelData
      */
     public function __construct($entry, $titleField, $descriptionField, $authorField)
     {
-        $this->failover = $entry;
+        $this->setFailover($entry);
         $this->titleField = $titleField;
         $this->descriptionField = $descriptionField;
         $this->authorField = $authorField;
@@ -58,7 +58,7 @@ class RSSFeed_Entry extends ModelData
     /**
      * Get the description of this entry
      *
-     * @return DBField Returns the description of the entry.
+     * @return DBField|null Returns the description of the entry.
      */
     public function Title()
     {
@@ -68,7 +68,7 @@ class RSSFeed_Entry extends ModelData
     /**
      * Get the description of this entry
      *
-     * @return DBField Returns the description of the entry.
+     * @return DBField|null Returns the description of the entry.
      */
     public function Description()
     {
@@ -85,7 +85,7 @@ class RSSFeed_Entry extends ModelData
     /**
      * Get the author of this entry
      *
-     * @return DBField Returns the author of the entry.
+     * @return DBField|null Returns the author of the entry.
      */
     public function Author()
     {
@@ -96,7 +96,7 @@ class RSSFeed_Entry extends ModelData
      * Return the safely casted field
      *
      * @param string $fieldName Name of field
-     * @return DBField
+     * @return DBField|null
      */
     public function rssField($fieldName)
     {

src/Core/ClassInfo.php

@@ -85,7 +85,7 @@ class ClassInfo implements Flushable
     public static function hasTable($tableName)
     {
         $cache = ClassInfo::getCache();
-        $configData = serialize(DB::getConfig());
+        $configData = serialize(DB::getConfig(DB::CONN_PRIMARY));
         $cacheKey = 'tableList_' . md5($configData);
         $tableList = $cache->get($cacheKey) ?? [];
         if (empty($tableList) && DB::is_active()) {

src/Core/CoreKernel.php

@@ -7,12 +7,14 @@ use SilverStripe\Dev\Install\DatabaseAdapterRegistry;
 use SilverStripe\ORM\Connect\NullDatabase;
 use SilverStripe\ORM\DB;
 use Exception;
+use InvalidArgumentException;
 
 /**
  * Simple Kernel container
  */
 class CoreKernel extends BaseKernel
 {
+
     protected bool $bootDatabase = true;
 
     /**
@@ -38,7 +40,7 @@ class CoreKernel extends BaseKernel
         $this->flush = $flush;
 
         if (!$this->bootDatabase) {
-            DB::set_conn(new NullDatabase());
+            DB::set_conn(new NullDatabase(), DB::CONN_PRIMARY);
         }
 
         $this->bootPHP();
@@ -73,7 +75,7 @@ class CoreKernel extends BaseKernel
     }
 
     /**
-     * Load default database configuration from the $database and $databaseConfig globals
+     * Load database configuration from the $database and $databaseConfig globals
      */
     protected function bootDatabaseGlobals()
     {
@@ -84,41 +86,62 @@ class CoreKernel extends BaseKernel
         global $databaseConfig;
         global $database;
 
-        // Case 1: $databaseConfig global exists. Merge $database in as needed
+        // Ensure global database config has prefix and suffix applied
-        if (!empty($databaseConfig)) {
+        if (!empty($databaseConfig) && !empty($database)) {
-            if (!empty($database)) {
             $databaseConfig['database'] = $this->getDatabasePrefix() . $database . $this->getDatabaseSuffix();
         }
 
-            // Only set it if its valid, otherwise ignore $databaseConfig entirely
+        // Set config for primary and any replicas
-            if (!empty($databaseConfig['database'])) {
+        for ($i = 0; $i <= DB::MAX_REPLICAS; $i++) {
-                DB::setConfig($databaseConfig);
+            if ($i === 0) {
+                $name = DB::CONN_PRIMARY;
+            } else {
+                $name = DB::getReplicaConfigKey($i);
+                if (!DB::hasConfig($name)) {
+                    break;
+                }
+            }
 
+            // Case 1: $databaseConfig global exists
+            // Only set it if its valid, otherwise ignore $databaseConfig entirely
+            if (!empty($databaseConfig) && !empty($databaseConfig['database'])) {
+                DB::setConfig($databaseConfig, $name);
                 return;
             }
-        }
 
-        // Case 2: $database merged into existing config
+            // Case 2: $databaseConfig global does not exist
+            // Merge $database global into existing config
             if (!empty($database)) {
-            $existing = DB::getConfig();
+                $dbConfig = DB::getConfig($name);
-            $existing['database'] = $this->getDatabasePrefix() . $database . $this->getDatabaseSuffix();
+                $dbConfig['database'] = $this->getDatabasePrefix() . $database . $this->getDatabaseSuffix();
-
+                DB::setConfig($dbConfig, $name);
-            DB::setConfig($existing);
+            }
         }
     }
 
     /**
-     * Load default database configuration from environment variable
+     * Load database configuration from environment variables
      */
     protected function bootDatabaseEnvVars()
     {
         if (!$this->bootDatabase) {
             return;
         }
-        // Set default database config
+        // Set primary database config
         $databaseConfig = $this->getDatabaseConfig();
         $databaseConfig['database'] = $this->getDatabaseName();
-        DB::setConfig($databaseConfig);
+        DB::setConfig($databaseConfig, DB::CONN_PRIMARY);
+
+        // Set database replicas config
+        for ($i = 1; $i <= DB::MAX_REPLICAS; $i++) {
+            $envKey = $this->getReplicaEnvKey('SS_DATABASE_SERVER', $i);
+            if (!Environment::hasEnv($envKey)) {
+                break;
+            }
+            $replicaDatabaseConfig = $this->getDatabaseReplicaConfig($i);
+            $configKey = DB::getReplicaConfigKey($i);
+            DB::setConfig($replicaDatabaseConfig, $configKey);
+        }
     }
 
     /**
@@ -127,12 +150,72 @@ class CoreKernel extends BaseKernel
      * @return array
      */
     protected function getDatabaseConfig()
+    {
+        return $this->getSingleDataBaseConfig(0);
+    }
+
+    private function getDatabaseReplicaConfig(int $replica)
+    {
+        if ($replica <= 0) {
+            throw new InvalidArgumentException('Replica number must be greater than 0');
+        }
+        return $this->getSingleDataBaseConfig($replica);
+    }
+
+    /**
+     * Convert a database key to a replica key
+     * e.g. SS_DATABASE_SERVER -> SS_DATABASE_SERVER_REPLICA_01
+     *
+     * @param string $key - The key to look up in the environment
+     * @param int $replica - Replica number
+     */
+    private function getReplicaEnvKey(string $key, int $replica): string
+    {
+        if ($replica <= 0) {
+            throw new InvalidArgumentException('Replica number must be greater than 0');
+        }
+        // Do not allow replicas to define keys that could lead to unexpected behaviour if
+        // they do not match the primary database configuration
+        if (in_array($key, ['SS_DATABASE_CLASS', 'SS_DATABASE_NAME', 'SS_DATABASE_CHOOSE_NAME'])) {
+            return $key;
+        }
+        // Left pad replica number with a zeros to match the length of the maximum replica number
+        $len = strlen((string) DB::MAX_REPLICAS);
+        return $key . '_REPLICA_' . str_pad($replica, $len, '0', STR_PAD_LEFT);
+    }
+
+    /**
+     * Reads a single database configuration variable from the environment
+     * For replica databases, it will first attempt to find replica-specific configuration
+     * before falling back to the primary configuration.
+     *
+     * Replicate specific configuration has `_REPLICA_01` appended to the key
+     * where 01 is the replica number.
+     *
+     * @param string $key - The key to look up in the environment
+     * @param int $replica - Replica number. Passing 0 will return the primary database configuration
+     */
+    private function getDatabaseConfigVariable(string $key, int $replica): string
+    {
+        if ($replica > 0) {
+            $key = $this->getReplicaEnvKey($key, $replica);
+        }
+        if (Environment::hasEnv($key)) {
+            return Environment::getEnv($key);
+        }
+        return '';
+    }
+
+    /**
+     * @param int $replica - Replica number. Passing 0 will return the primary database configuration
+     */
+    private function getSingleDataBaseConfig(int $replica): array
     {
         $databaseConfig = [
-            "type" => Environment::getEnv('SS_DATABASE_CLASS') ?: 'MySQLDatabase',
+            "type" => $this->getDatabaseConfigVariable('SS_DATABASE_CLASS', $replica) ?: 'MySQLDatabase',
-            "server" => Environment::getEnv('SS_DATABASE_SERVER') ?: 'localhost',
+            "server" => $this->getDatabaseConfigVariable('SS_DATABASE_SERVER', $replica) ?: 'localhost',
-            "username" => Environment::getEnv('SS_DATABASE_USERNAME') ?: null,
+            "username" => $this->getDatabaseConfigVariable('SS_DATABASE_USERNAME', $replica) ?: null,
-            "password" => Environment::getEnv('SS_DATABASE_PASSWORD') ?: null,
+            "password" => $this->getDatabaseConfigVariable('SS_DATABASE_PASSWORD', $replica) ?: null,
         ];
 
         // Only add SSL keys in the array if there is an actual value associated with them
@@ -143,7 +226,7 @@ class CoreKernel extends BaseKernel
             'ssl_cipher' => 'SS_DATABASE_SSL_CIPHER',
         ];
         foreach ($sslConf as $key => $envVar) {
-            $envValue = Environment::getEnv($envVar);
+            $envValue = $this->getDatabaseConfigVariable($envVar, $replica);
             if ($envValue) {
                 $databaseConfig[$key] = $envValue;
             }
@@ -159,25 +242,25 @@ class CoreKernel extends BaseKernel
         }
 
         // Set the port if called for
-        $dbPort = Environment::getEnv('SS_DATABASE_PORT');
+        $dbPort = $this->getDatabaseConfigVariable('SS_DATABASE_PORT', $replica);
         if ($dbPort) {
             $databaseConfig['port'] = $dbPort;
         }
 
         // Set the timezone if called for
-        $dbTZ = Environment::getEnv('SS_DATABASE_TIMEZONE');
+        $dbTZ = $this->getDatabaseConfigVariable('SS_DATABASE_TIMEZONE', $replica);
         if ($dbTZ) {
             $databaseConfig['timezone'] = $dbTZ;
         }
 
         // For schema enabled drivers:
-        $dbSchema = Environment::getEnv('SS_DATABASE_SCHEMA');
+        $dbSchema = $this->getDatabaseConfigVariable('SS_DATABASE_SCHEMA', $replica);
         if ($dbSchema) {
             $databaseConfig["schema"] = $dbSchema;
         }
 
         // For SQlite3 memory databases (mainly for testing purposes)
-        $dbMemory = Environment::getEnv('SS_DATABASE_MEMORY');
+        $dbMemory = $this->getDatabaseConfigVariable('SS_DATABASE_MEMORY', $replica);
         if ($dbMemory) {
             $databaseConfig["memory"] = $dbMemory;
         }
@@ -205,6 +288,7 @@ class CoreKernel extends BaseKernel
 
     /**
      * Get name of database
+     * Note that any replicas must have the same database name as the primary database
      *
      * @return string
      */

src/Core/Manifest/ModuleResource.php

@@ -5,12 +5,13 @@ namespace SilverStripe\Core\Manifest;
 use InvalidArgumentException;
 use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Core\Path;
+use Stringable;
 
 /**
  * This object represents a single resource file attached to a module, and can be used
  * as a reference to this to be later turned into either a URL or file path.
  */
-class ModuleResource
+class ModuleResource implements Stringable
 {
     /**
      * @var Module
@@ -114,10 +115,8 @@ class ModuleResource
 
     /**
      * Get relative path
-     *
-     * @return string
      */
-    public function __toString()
+    public function __toString(): string
     {
         return $this->getRelativePath();
     }

src/Dev/Backtrace.php

@@ -149,11 +149,11 @@ class Backtrace
         if ($showArgs && isset($item['args'])) {
             $args = [];
             foreach ($item['args'] as $arg) {
-                if (!is_object($arg) || method_exists($arg, '__toString')) {
+                if (is_object($arg)) {
+                    $args[] = get_class($arg);
+                } else {
                     $sarg = is_array($arg) ? 'Array' : strval($arg);
                     $args[] = (strlen($sarg ?? '') > $argCharLimit) ? substr($sarg, 0, $argCharLimit) . '...' : $sarg;
-                } else {
-                    $args[] = get_class($arg);
                 }
             }
 

src/Dev/SapphireTest.php

@@ -48,7 +48,7 @@ use ReflectionClass;
 use SilverStripe\Dev\Exceptions\ExpectedErrorException;
 use SilverStripe\Dev\Exceptions\ExpectedNoticeException;
 use SilverStripe\Dev\Exceptions\ExpectedWarningException;
-use SilverStripe\Dev\Exceptions\UnexpectedErrorException;
+use SilverStripe\ORM\DB;
 
 /**
  * Test case class for the Silverstripe framework.
@@ -434,6 +434,9 @@ abstract class SapphireTest extends TestCase implements TestOnly
      */
     public static function setUpBeforeClass(): void
     {
+        // Disallow the use of DB replicas in tests
+        DB::setMustUsePrimary();
+
         // Start tests
         static::start();
 

src/Dev/TestSession.php

@@ -4,6 +4,7 @@ namespace SilverStripe\Dev;
 
 use Exception;
 use InvalidArgumentException;
+use LogicException;
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\Cookie_Backend;
 use SilverStripe\Control\Director;
@@ -214,7 +215,7 @@ class TestSession
                 $formCrawler = $page->filterXPath("//form[@id='$formID']");
                 $form = $formCrawler->form();
             } catch (InvalidArgumentException $e) {
-                user_error("TestSession::submitForm failed to find the form {$formID}");
+                throw new LogicException("TestSession::submitForm failed to find the form '{$formID}'");
             }
 
             foreach ($data as $fieldName => $value) {
@@ -235,7 +236,7 @@ class TestSession
             if ($button) {
                 $btnXpath = "//button[@name='$button'] | //input[@name='$button'][@type='button' or @type='submit']";
                 if (!$formCrawler->children()->filterXPath($btnXpath)->count()) {
-                    throw new Exception("Can't find button '$button' to submit as part of test.");
+                    throw new LogicException("Can't find button '$button' to submit as part of test.");
                 }
                 $values[$button] = true;
             }

src/Forms/DropdownField.php

@@ -68,7 +68,7 @@ use SilverStripe\Model\ArrayData;
  * DropdownField::create(
  *   'Country',
  *   'Country',
- *   singleton(MyObject::class)->dbObject('Country')->enumValues()
+ *   singleton(MyObject::class)->dbObject('Country')?->enumValues()
  * );
  * </code>
  *

src/Forms/FieldGroup.php

@@ -154,7 +154,7 @@ class FieldGroup extends CompositeField
         /** @var FormField $subfield */
         $messages = [];
         foreach ($dataFields as $subfield) {
-            $message = $subfield->obj('Message')->forTemplate();
+            $message = $subfield->obj('Message')?->forTemplate();
             if ($message) {
                 $messages[] = rtrim($message ?? '', ".");
             }

src/Forms/Form.php

@@ -899,10 +899,10 @@ class Form extends ModelData implements HasRequestHandler
     }
 
     /**
-     * Set the SS template that this form should use
+     * Set the template or template candidates that this form should use
      * to render with. The default is "Form".
      *
-     * @param string|array $template The name of the template (without the .ss extension) or array form
+     * @param string|array $template The name of the template (without the file extension) or array of candidates
      * @return $this
      */
     public function setTemplate($template)

src/Forms/FormField.php

@@ -15,6 +15,7 @@ use SilverStripe\Core\Validation\ValidationResult;
 use SilverStripe\View\AttributesHTML;
 use SilverStripe\View\SSViewer;
 use SilverStripe\Model\ModelData;
+use SilverStripe\ORM\DataObject;
 
 /**
  * Represents a field in a form.
@@ -273,6 +274,8 @@ class FormField extends RequestHandler
         'Title' => 'Text',
         'RightTitle' => 'Text',
         'Description' => 'HTMLFragment',
+        // This is an associative arrays, but we cast to Text so we can get a JSON string representation
+        'SchemaData' => 'Text',
     ];
 
     /**
@@ -458,7 +461,7 @@ class FormField extends RequestHandler
      *
      * By default, makes use of $this->dataValue()
      *
-     * @param ModelData|DataObjectInterface $record Record to save data into
+     * @param DataObjectInterface $record Record to save data into
      */
     public function saveInto(DataObjectInterface $record)
     {
@@ -469,8 +472,10 @@ class FormField extends RequestHandler
         if (($pos = strrpos($this->name ?? '', '.')) !== false) {
             $relation = substr($this->name ?? '', 0, $pos);
             $fieldName = substr($this->name ?? '', $pos + 1);
+            if ($record instanceof DataObject) {
                 $component = $record->relObject($relation);
             }
+        }
 
         if ($fieldName && $component) {
             $component->setCastedField($fieldName, $this->dataValue());
@@ -1027,7 +1032,7 @@ class FormField extends RequestHandler
      */
     protected function _templates($customTemplate = null, $customTemplateSuffix = null)
     {
-        $templates = SSViewer::get_templates_by_class(static::class, $customTemplateSuffix, __CLASS__);
+        $templates = SSViewer::get_templates_by_class(static::class, $customTemplateSuffix ?? '', __CLASS__);
         // Prefer any custom template
         if ($customTemplate) {
             // Prioritise direct template
@@ -1469,12 +1474,12 @@ class FormField extends RequestHandler
             'schemaType' => $this->getSchemaDataType(),
             'component' => $this->getSchemaComponent(),
             'holderId' => $this->HolderID(),
-            'title' => $this->obj('Title')->getSchemaValue(),
+            'title' => $this->obj('Title')?->getSchemaValue(),
             'source' => null,
             'extraClass' => $this->extraClass(),
-            'description' => $this->obj('Description')->getSchemaValue(),
+            'description' => $this->obj('Description')?->getSchemaValue(),
-            'rightTitle' => $this->obj('RightTitle')->getSchemaValue(),
+            'rightTitle' => $this->obj('RightTitle')?->getSchemaValue(),
-            'leftTitle' => $this->obj('LeftTitle')->getSchemaValue(),
+            'leftTitle' => $this->obj('LeftTitle')?->getSchemaValue(),
             'readOnly' => $this->isReadonly(),
             'disabled' => $this->isDisabled(),
             'customValidationMessage' => $this->getCustomValidationMessage(),

src/Forms/FormScaffolder.php

@@ -115,7 +115,7 @@ class FormScaffolder
                 $fieldObject = $this
                     ->obj
                     ->dbObject($fieldName)
-                    ->scaffoldFormField(null, $this->getParamsArray());
+                    ?->scaffoldFormField(null, $this->getParamsArray());
             }
             // Allow fields to opt-out of scaffolding
             if (!$fieldObject) {
@@ -145,7 +145,7 @@ class FormScaffolder
                     $fieldClass = $this->fieldClasses[$fieldName];
                     $hasOneField = new $fieldClass($fieldName);
                 } else {
-                    $hasOneField = $this->obj->dbObject($fieldName)->scaffoldFormField(null, $this->getParamsArray());
+                    $hasOneField = $this->obj->dbObject($fieldName)?->scaffoldFormField(null, $this->getParamsArray());
                 }
                 if (empty($hasOneField)) {
                     continue; // Allow fields to opt out of scaffolding

src/Forms/GridField/GridFieldAddExistingAutocompleter.php

@@ -17,6 +17,9 @@ use SilverStripe\Model\ArrayData;
 use SilverStripe\View\SSViewer;
 use LogicException;
 use SilverStripe\Control\HTTPResponse_Exception;
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\View\TemplateEngine;
+use SilverStripe\View\ViewLayerData;
 
 /**
  * This class is is responsible for adding objects to another object's has_many
@@ -283,12 +286,15 @@ class GridFieldAddExistingAutocompleter extends AbstractGridFieldComponent imple
         $json = [];
         Config::nest();
         SSViewer::config()->set('source_file_comments', false);
-        $viewer = SSViewer::fromString($this->resultsFormat);
+
+        $engine = Injector::inst()->create(TemplateEngine::class);
         foreach ($results as $result) {
             if (!$result->canView()) {
                 continue;
             }
-            $title = Convert::html2raw($viewer->process($result));
+            $title = Convert::html2raw(
+                $engine->renderString($this->resultsFormat, ViewLayerData::create($result), cache: false)
+            );
             $json[] = [
                 'label' => $title,
                 'value' => $title,

src/Forms/GridField/GridFieldDataColumns.php

@@ -222,29 +222,6 @@ class GridFieldDataColumns extends AbstractGridFieldComponent implements GridFie
         ];
     }
 
-    /**
-     * Translate a Object.RelationName.ColumnName $columnName into the value that ColumnName returns
-     *
-     * @param ModelData $record
-     * @param string $columnName
-     * @return string|null - returns null if it could not found a value
-     */
-    protected function getValueFromRelation($record, $columnName)
-    {
-        $fieldNameParts = explode('.', $columnName ?? '');
-        $tmpItem = clone($record);
-        for ($idx = 0; $idx < sizeof($fieldNameParts ?? []); $idx++) {
-            $methodName = $fieldNameParts[$idx];
-            // Last mmethod call from $columnName return what that method is returning
-            if ($idx == sizeof($fieldNameParts ?? []) - 1) {
-                return $tmpItem->XML_val($methodName);
-            }
-            // else get the object from this $methodName
-            $tmpItem = $tmpItem->$methodName();
-        }
-        return null;
-    }
-
     /**
      * Casts a field to a string which is safe to insert into HTML
      *

src/Forms/GridField/GridFieldFilterHeader.php

@@ -49,6 +49,8 @@ class GridFieldFilterHeader extends AbstractGridFieldComponent implements GridFi
      */
     protected ?string $searchField = null;
 
+    private string $placeHolderText = '';
+
     /**
      * @inheritDoc
      */
@@ -245,6 +247,24 @@ class GridFieldFilterHeader extends AbstractGridFieldComponent implements GridFi
         return false;
     }
 
+    /**
+     * Get the text to be used as a placeholder in the search field.
+     * If blank, the placeholder will be generated based on the class held in the GridField.
+     */
+    public function getPlaceHolderText(): string
+    {
+        return $this->placeHolderText;
+    }
+
+    /**
+     * Set the text to be used as a placeholder in the search field.
+     * If blank, this text will be generated based on the class held in the GridField.
+     */
+    public function setPlaceHolderText(string $placeHolderText): static
+    {
+        $this->placeHolderText = $placeHolderText;
+        return $this;
+    }
 
     /**
      * Generate a search context based on the model class of the of the GridField
@@ -318,7 +338,7 @@ class GridFieldFilterHeader extends AbstractGridFieldComponent implements GridFi
         $schema = [
             'formSchemaUrl' => $schemaUrl,
             'name' => $searchField,
-            'placeholder' => _t(__CLASS__ . '.Search', 'Search "{name}"', ['name' => $this->getTitle($gridField, $inst)]),
+            'placeholder' => $this->getPlaceHolder($inst),
             'filters' => $filters ?: new \stdClass, // stdClass maps to empty json object '{}'
             'gridfield' => $gridField->getName(),
             'searchAction' => $searchAction->getAttribute('name'),
@@ -330,19 +350,6 @@ class GridFieldFilterHeader extends AbstractGridFieldComponent implements GridFi
         return json_encode($schema);
     }
 
-    private function getTitle(GridField $gridField, object $inst): string
-    {
-        if ($gridField->Title) {
-            return $gridField->Title;
-        }
-
-        if (ClassInfo::hasMethod($inst, 'i18n_plural_name')) {
-            return $inst->i18n_plural_name();
-        }
-
-        return ClassInfo::shortName($inst);
-    }
-
     /**
      * Returns the search form for the component
      *
@@ -386,7 +393,7 @@ class GridFieldFilterHeader extends AbstractGridFieldComponent implements GridFi
             $field->addExtraClass('stacked no-change-track');
         }
 
-        $name = $this->getTitle($gridField, singleton($gridField->getModelClass()));
+        $name = $this->getTitle(singleton($gridField->getModelClass()));
 
         $this->searchForm = $form = new Form(
             $gridField,
@@ -456,4 +463,32 @@ class GridFieldFilterHeader extends AbstractGridFieldComponent implements GridFi
             )
         ];
     }
+
+    /**
+     * Get the text that will be used as a placeholder in the search field.
+     *
+     * @param object $obj An instance of the class that will be searched against.
+     * If getPlaceHolderText is empty, this object will be used to build the placeholder
+     * e.g. 'Search "My Data Object"'
+     */
+    private function getPlaceHolder(object $obj): string
+    {
+        $placeholder = $this->getPlaceHolderText();
+        if (!empty($placeholder)) {
+            return $placeholder;
+        }
+        if ($obj) {
+            return _t(__CLASS__ . '.Search', 'Search "{name}"', ['name' => $this->getTitle($obj)]);
+        }
+        return _t(__CLASS__ . '.Search_Default', 'Search');
+    }
+
+    private function getTitle(object $inst): string
+    {
+        if (ClassInfo::hasMethod($inst, 'i18n_plural_name')) {
+            return $inst->i18n_plural_name();
+        }
+
+        return ClassInfo::shortName($inst);
+    }
 }

src/Forms/GridField/GridState.php

@@ -5,6 +5,7 @@ namespace SilverStripe\Forms\GridField;
 use SilverStripe\Core\Convert;
 use SilverStripe\Forms\HiddenField;
 use SilverStripe\ORM\DataList;
+use Stringable;
 
 /**
  * This class is a snapshot of the current status of a {@link GridField}.
@@ -14,7 +15,7 @@ use SilverStripe\ORM\DataList;
  *
  * @see GridField
  */
-class GridState extends HiddenField
+class GridState extends HiddenField implements Stringable
 {
 
     /**
@@ -129,11 +130,7 @@ class GridState extends HiddenField
         return Convert::raw2att($this->Value());
     }
 
-    /**
+    public function __toString(): string
-     *
-     * @return string
-     */
-    public function __toString()
     {
         return $this->Value();
     }

src/Forms/GridField/GridState_Data.php

@@ -2,13 +2,15 @@
 
 namespace SilverStripe\Forms\GridField;
 
+use Stringable;
+
 /**
  * Simple set of data, similar to stdClass, but without the notice-level
  * errors.
  *
  * @see GridState
  */
-class GridState_Data
+class GridState_Data implements Stringable
 {
 
     /**
@@ -94,7 +96,7 @@ class GridState_Data
         unset($this->data[$name]);
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         if (!$this->data) {
             return "";

src/Forms/HTMLEditor/HTMLEditorField.php

@@ -5,9 +5,11 @@ namespace SilverStripe\Forms\HTMLEditor;
 use SilverStripe\Assets\Shortcodes\ImageShortcodeProvider;
 use SilverStripe\Forms\FormField;
 use SilverStripe\Forms\TextareaField;
-use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DataObjectInterface;
 use Exception;
+use SilverStripe\Model\ModelData;
+use SilverStripe\ORM\FieldType\DBField;
+use SilverStripe\View\CastingService;
 use SilverStripe\View\Parsers\HTMLValue;
 
 /**
@@ -123,13 +125,9 @@ class HTMLEditorField extends TextareaField
         );
     }
 
-    /**
-     * @param DataObject|DataObjectInterface $record
-     * @throws Exception
-     */
     public function saveInto(DataObjectInterface $record)
     {
-        if ($record->hasField($this->name) && $record->escapeTypeForField($this->name) != 'xml') {
+        if (!$this->usesXmlFriendlyField($record)) {
             throw new Exception(
                 'HTMLEditorField->saveInto(): This field should save into a HTMLText or HTMLVarchar field.'
             );
@@ -225,4 +223,15 @@ class HTMLEditorField extends TextareaField
 
         return $config;
     }
+
+    private function usesXmlFriendlyField(DataObjectInterface $record): bool
+    {
+        if ($record instanceof ModelData && !$record->hasField($this->getName())) {
+            return true;
+        }
+
+        $castingService = CastingService::singleton();
+        $castValue = $castingService->cast($this->Value(), $record, $this->getName());
+        return $castValue instanceof DBField && $castValue::config()->get('escape_type') === 'xml';
+    }
 }

src/Forms/TreeDropdownField.php

@@ -7,6 +7,7 @@ use InvalidArgumentException;
 use SilverStripe\Assets\Folder;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\HTTPResponse;
+use SilverStripe\Model\List\SS_List;
 use SilverStripe\ORM\DataList;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\FieldType\DBDatetime;
@@ -519,13 +520,20 @@ class TreeDropdownField extends FormField implements HasOneRelationFieldInterfac
 
         // Allow to pass values to be selected within the ajax request
         $value = $request->requestVar('forceValue') ?: $this->value;
-        if ($value && ($values = preg_split('/,\s*/', $value ?? ''))) {
+        if ($value instanceof SS_List) {
+            $values = $value;
+        } elseif ($value) {
+            $values = preg_split('/,\s*/', $value ?? '');
+        } else {
+            $values = [];
+        }
+        if (!empty($values)) {
             foreach ($values as $value) {
                 if (!$value || $value == 'unchanged') {
                     continue;
                 }
 
-                $object = $this->objectForKey($value);
+                $object = is_object($value) ? $value : $this->objectForKey($value);
                 if (!$object) {
                     continue;
                 }
@@ -870,14 +878,14 @@ class TreeDropdownField extends FormField implements HasOneRelationFieldInterfac
                 $ancestors = $record->getAncestors(true)->reverse();
 
                 foreach ($ancestors as $parent) {
-                    $title = $parent->obj($this->getTitleField())->getValue();
+                    $title = $parent->obj($this->getTitleField())?->getValue();
                     $titlePath .= $title . '/';
                 }
             }
             $data['data']['valueObject'] = [
-                'id' => $record->obj($this->getKeyField())->getValue(),
+                'id' => $record->obj($this->getKeyField())?->getValue(),
-                'title' => $record->obj($this->getTitleField())->getValue(),
+                'title' => $record->obj($this->getTitleField())?->getValue(),
-                'treetitle' => $record->obj($this->getLabelField())->getSchemaValue(),
+                'treetitle' => $record->obj($this->getLabelField())?->getSchemaValue(),
                 'titlePath' => $titlePath,
             ];
         }

src/Forms/TreeMultiselectField.php

@@ -92,10 +92,10 @@ class TreeMultiselectField extends TreeDropdownField
         foreach ($items as $item) {
             if ($item instanceof DataObject) {
                 $values[] = [
-                    'id' => $item->obj($this->getKeyField())->getValue(),
+                    'id' => $item->obj($this->getKeyField())?->getValue(),
-                    'title' => $item->obj($this->getTitleField())->getValue(),
+                    'title' => $item->obj($this->getTitleField())?->getValue(),
                     'parentid' => $item->ParentID,
-                    'treetitle' => $item->obj($this->getLabelField())->getSchemaValue(),
+                    'treetitle' => $item->obj($this->getLabelField())?->getSchemaValue(),
                 ];
             } else {
                 $values[] = $item;
@@ -212,7 +212,7 @@ class TreeMultiselectField extends TreeDropdownField
             foreach ($items as $item) {
                 $idArray[] = $item->ID;
                 $titleArray[] = ($item instanceof ModelData)
-                    ? $item->obj($this->getLabelField())->forTemplate()
+                    ? $item->obj($this->getLabelField())?->forTemplate()
                     : Convert::raw2xml($item->{$this->getLabelField()});
             }
 

src/Model/ArrayData.php

@@ -4,6 +4,7 @@ namespace SilverStripe\Model;
 
 use SilverStripe\Core\ArrayLib;
 use InvalidArgumentException;
+use JsonSerializable;
 use stdClass;
 
 /**
@@ -16,14 +17,9 @@ use stdClass;
  * ));
  * </code>
  */
-class ArrayData extends ModelData
+class ArrayData extends ModelData implements JsonSerializable
 {
-
+    protected array $array;
-    /**
-     * @var array
-     * @see ArrayData::_construct()
-     */
-    protected $array;
 
     /**
      * @param object|array $value An associative array, or an object with simple properties.
@@ -52,10 +48,8 @@ class ArrayData extends ModelData
 
     /**
      * Get the source array
-     *
-     * @return array
      */
-    public function toMap()
+    public function toMap(): array
     {
         return $this->array;
     }
@@ -87,6 +81,7 @@ class ArrayData extends ModelData
     */
     public function setField(string $fieldName, mixed $value): static
     {
+        $this->objCacheClear();
         $this->array[$fieldName] = $value;
         return $this;
     }
@@ -102,6 +97,16 @@ class ArrayData extends ModelData
         return isset($this->array[$fieldName]);
     }
 
+    public function exists(): bool
+    {
+        return !empty($this->array);
+    }
+
+    public function jsonSerialize(): array
+    {
+        return $this->array;
+    }
+
     /**
      * Converts an associative array to a simple object
      *

src/Model/List/ListDecorator.php

@@ -56,7 +56,9 @@ abstract class ListDecorator extends ModelData implements SS_List, Sortable, Fil
     public function setList(SS_List&Sortable&Filterable&Limitable $list): ListDecorator
     {
         $this->list = $list;
-        $this->failover = $this->list;
+        if ($list instanceof ModelData) {
+            $this->setFailover($list);
+        }
         return $this;
     }
 

src/Model/ModelData.php

@@ -2,7 +2,6 @@
 
 namespace SilverStripe\Model;
 
-use Exception;
 use InvalidArgumentException;
 use LogicException;
 use ReflectionMethod;
@@ -12,14 +11,14 @@ use SilverStripe\Core\Config\Configurable;
 use SilverStripe\Core\Convert;
 use SilverStripe\Core\Extensible;
 use SilverStripe\Core\Injector\Injectable;
-use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Dev\Debug;
 use SilverStripe\Core\ArrayLib;
-use SilverStripe\Model\List\ArrayList;
 use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\ORM\FieldType\DBHTMLText;
 use SilverStripe\Model\ArrayData;
+use SilverStripe\View\CastingService;
 use SilverStripe\View\SSViewer;
+use Stringable;
 use UnexpectedValueException;
 
 /**
@@ -29,7 +28,7 @@ use UnexpectedValueException;
  * is provided and automatically escaped by ModelData. Any class that needs to be available to a view (controllers,
  * {@link DataObject}s, page controls) should inherit from this class.
  */
-class ModelData
+class ModelData implements Stringable
 {
     use Extensible {
         defineMethods as extensibleDefineMethods;
@@ -38,7 +37,7 @@ class ModelData
     use Configurable;
 
     /**
-     * An array of objects to cast certain fields to. This is set up as an array in the format:
+     * An array of DBField classes to cast certain fields to. This is set up as an array in the format:
      *
      * <code>
      * public static $casting = array (
@@ -47,16 +46,18 @@ class ModelData
      * </code>
      */
     private static array $casting = [
-        'CSSClasses' => 'Varchar'
+        'CSSClasses' => 'Varchar',
+        'forTemplate' => 'HTMLText',
     ];
 
     /**
-     * The default object to cast scalar fields to if casting information is not specified, and casting to an object
+     * The default class to cast scalar fields to if casting information is not specified, and casting to an object
      * is required.
+     * This can be any injectable service name but must resolve to a DBField subclass.
+     *
+     * If null, casting will be determined based on the type of value (e.g. integers will be cast to DBInt)
      */
-    private static string $default_cast = 'Text';
+    private static ?string $default_cast = null;
-
-    private static array $casting_cache = [];
 
     /**
      * Acts as a PHP 8.2+ compliant replacement for dynamic properties
@@ -204,6 +205,7 @@ class ModelData
 
     public function setDynamicData(string $field, mixed $value): static
     {
+        $this->objCacheClear();
         $this->dynamicData[$field] = $value;
         return $this;
     }
@@ -251,8 +253,7 @@ class ModelData
     // -----------------------------------------------------------------------------------------------------------------
 
     /**
-     * Add methods from the {@link ModelData::$failover} object, as well as wrapping any methods prefixed with an
+     * Add methods from the {@link ModelData::$failover} object
-     * underscore into a {@link ModelData::cachedCall()}.
      *
      * @throws LogicException
      */
@@ -305,12 +306,18 @@ class ModelData
         return true;
     }
 
-    /**
-     * Return the class name (though subclasses may return something else)
-     */
     public function __toString(): string
     {
-        return static::class;
+        return $this->forTemplate();
+    }
+
+    /**
+     * Return the HTML markup that represents this model when it is directly injected into a template (e.g. using $Me).
+     * By default this attempts to render the model using templates based on the class hierarchy.
+     */
+    public function forTemplate(): string
+    {
+        return $this->renderWith($this->getViewerTemplates());
     }
 
     public function getCustomisedObj(): ?ModelData
@@ -326,14 +333,10 @@ class ModelData
     // CASTING ---------------------------------------------------------------------------------------------------------
 
     /**
-     * Return the "casting helper" (a piece of PHP code that when evaluated creates a casted value object)
+     * Return the "casting helper" (an injectable service name)
      * for a field on this object. This helper will be a subclass of DBField.
-     *
-     * @param bool $useFallback If true, fall back on the default casting helper if there isn't an explicit one.
-     * @return string|null Casting helper As a constructor pattern, and may include arguments.
-     * @throws Exception
      */
-    public function castingHelper(string $field, bool $useFallback = true): ?string
+    public function castingHelper(string $field): ?string
     {
         // Get casting if it has been configured.
         // DB fields and PHP methods are all case insensitive so we normalise casing before checking.
@@ -346,67 +349,15 @@ class ModelData
         // If no specific cast is declared, fall back to failover.
         $failover = $this->getFailover();
         if ($failover) {
-            $cast = $failover->castingHelper($field, $useFallback);
+            $cast = $failover->castingHelper($field);
             if ($cast) {
                 return $cast;
             }
         }
 
-        if ($useFallback) {
-            return $this->defaultCastingHelper($field);
-        }
-
         return null;
     }
 
-    /**
-     * Return the default "casting helper" for use when no explicit casting helper is defined.
-     * This helper will be a subclass of DBField. See castingHelper()
-     */
-    protected function defaultCastingHelper(string $field): string
-    {
-        // If there is a failover, the default_cast will always
-        // be drawn from this object instead of the top level object.
-        $failover = $this->getFailover();
-        if ($failover) {
-            $cast = $failover->defaultCastingHelper($field);
-            if ($cast) {
-                return $cast;
-            }
-        }
-
-        // Fall back to raw default_cast
-        $default = $this->config()->get('default_cast');
-        if (empty($default)) {
-            throw new Exception('No default_cast');
-        }
-        return $default;
-    }
-
-    /**
-     * Get the class name a field on this object will be casted to.
-     */
-    public function castingClass(string $field): string
-    {
-        // Strip arguments
-        $spec = $this->castingHelper($field);
-        return trim(strtok($spec ?? '', '(') ?? '');
-    }
-
-    /**
-     * Return the string-format type for the given field.
-     *
-     * @return string 'xml'|'raw'
-     */
-    public function escapeTypeForField(string $field): string
-    {
-        $class = $this->castingClass($field) ?: $this->config()->get('default_cast');
-
-        /** @var DBField $type */
-        $type = Injector::inst()->get($class, true);
-        return $type->config()->get('escape_type');
-    }
-
     // TEMPLATE ACCESS LAYER -------------------------------------------------------------------------------------------
 
     /**
@@ -417,9 +368,9 @@ class ModelData
      *  - an SSViewer instance
      *
      * @param string|array|SSViewer $template the template to render into
-     * @param ModelData|array|null $customFields fields to customise() the object with before rendering
+     * @param ModelData|array $customFields fields to customise() the object with before rendering
      */
-    public function renderWith($template, ModelData|array|null $customFields = null): DBHTMLText
+    public function renderWith($template, ModelData|array $customFields = []): DBHTMLText
     {
         if (!is_object($template)) {
             $template = SSViewer::create($template);
@@ -429,9 +380,10 @@ class ModelData
 
         if ($customFields instanceof ModelData) {
             $data = $data->customise($customFields);
+            $customFields = [];
         }
         if ($template instanceof SSViewer) {
-            return $template->process($data, is_array($customFields) ? $customFields : null);
+            return $template->process($data, $customFields);
         }
 
         throw new UnexpectedValueException(
@@ -440,27 +392,11 @@ class ModelData
     }
 
     /**
-     * Generate the cache name for a field
+     * Get a cached value from the field cache for a field
-     *
-     * @param string $fieldName Name of field
-     * @param array $arguments List of optional arguments given
-     * @return string
      */
-    protected function objCacheName($fieldName, $arguments)
+    public function objCacheGet(string $fieldName, array $arguments = []): mixed
-    {
-        return $arguments
-            ? $fieldName . ":" . var_export($arguments, true)
-            : $fieldName;
-    }
-
-    /**
-     * Get a cached value from the field cache
-     *
-     * @param string $key Cache key
-     * @return mixed
-     */
-    protected function objCacheGet($key)
     {
+        $key = $this->objCacheName($fieldName, $arguments);
         if (isset($this->objCache[$key])) {
             return $this->objCache[$key];
         }
@@ -468,24 +404,19 @@ class ModelData
     }
 
     /**
-     * Store a value in the field cache
+     * Store a value in the field cache for a field
-     *
-     * @param string $key Cache key
-     * @param mixed $value
-     * @return $this
      */
-    protected function objCacheSet($key, $value)
+    public function objCacheSet(string $fieldName, array $arguments, mixed $value): static
     {
+        $key = $this->objCacheName($fieldName, $arguments);
         $this->objCache[$key] = $value;
         return $this;
     }
 
     /**
      * Clear object cache
-     *
-     * @return $this
      */
-    protected function objCacheClear()
+    public function objCacheClear(): static
     {
         $this->objCache = [];
         return $this;
@@ -497,82 +428,46 @@ class ModelData
      *
      * @return object|DBField|null The specific object representing the field, or null if there is no
      * property, method, or dynamic data available for that field.
-     * Note that if there is a property or method that returns null, a relevant DBField instance will
-     * be returned.
      */
     public function obj(
         string $fieldName,
         array $arguments = [],
-        bool $cache = false,
+        bool $cache = false
-        ?string $cacheName = null
     ): ?object {
-        $hasObj = false;
-        if (!$cacheName && $cache) {
-            $cacheName = $this->objCacheName($fieldName, $arguments);
-        }
-
         // Check pre-cached value
-        $value = $cache ? $this->objCacheGet($cacheName) : null;
+        $value = $cache ? $this->objCacheGet($fieldName, $arguments) : null;
-        if ($value !== null) {
+        if ($value === null) {
-            return $value;
+            $hasObj = false;
-        }
-
             // Load value from record
             if ($this->hasMethod($fieldName)) {
+                // Try methods first - there's a LOT of logic that assumes this will be checked first.
                 $hasObj = true;
                 $value = call_user_func_array([$this, $fieldName], $arguments ?: []);
             } else {
-            $hasObj = $this->hasField($fieldName) || ($this->hasMethod("get{$fieldName}") && $this->isAccessibleMethod("get{$fieldName}"));
+                $getter = "get{$fieldName}";
+                $hasGetter = $this->hasMethod($getter) && $this->isAccessibleMethod($getter);
+                // Try fields and getters if there was no method with that name.
+                $hasObj = $this->hasField($fieldName) || $hasGetter;
+                if ($hasGetter && !empty($arguments)) {
+                    $value = $this->$getter(...$arguments);
+                } else {
                     $value = $this->$fieldName;
                 }
+            }
+
+            // Record in cache
+            if ($value !== null && $cache) {
+                $this->objCacheSet($fieldName, $arguments, $value);
+            }
 
             // Return null early if there's no backing for this field
             // i.e. no poperty, no method, etc - it just doesn't exist on this model.
             if (!$hasObj && $value === null) {
                 return null;
             }
-
-        // Try to cast object if we have an explicit cast set
-        if (!is_object($value)) {
-            $castingHelper = $this->castingHelper($fieldName, false);
-            if ($castingHelper !== null) {
-                $valueObject = Injector::inst()->create($castingHelper, $fieldName);
-                $valueObject->setValue($value, $this);
-                $value = $valueObject;
-            }
         }
 
-        // Wrap list arrays in ModelData so templates can handle them
+        return CastingService::singleton()->cast($value, $this, $fieldName, true);
-        if (is_array($value) && array_is_list($value)) {
-            $value = ArrayList::create($value);
-        }
-
-        // Fallback on default casting
-        if (!is_object($value)) {
-            // Force cast
-            $castingHelper = $this->defaultCastingHelper($fieldName);
-            $valueObject = Injector::inst()->create($castingHelper, $fieldName);
-            $valueObject->setValue($value, $this);
-            $value = $valueObject;
-        }
-
-        // Record in cache
-        if ($cache) {
-            $this->objCacheSet($cacheName, $value);
-        }
-
-        return $value;
-    }
-
-    /**
-     * A simple wrapper around {@link ModelData::obj()} that automatically caches the result so it can be used again
-     * without re-running the method.
-     *
-     * @return Object|DBField
-     */
-    public function cachedCall(string $fieldName, array $arguments = [], ?string $cacheName = null): object
-    {
-        return $this->obj($fieldName, $arguments, true, $cacheName);
     }
 
     /**
@@ -588,36 +483,6 @@ class ModelData
         return (bool) $result;
     }
 
-    /**
-     * Get the string value of a field on this object that has been suitable escaped to be inserted directly into a
-     * template.
-     */
-    public function XML_val(string $field, array $arguments = [], bool $cache = false): string
-    {
-        $result = $this->obj($field, $arguments, $cache);
-        if (!$result) {
-            return '';
-        }
-        // Might contain additional formatting over ->XML(). E.g. parse shortcodes, nl2br()
-        return $result->forTemplate();
-    }
-
-    /**
-     * Get an array of XML-escaped values by field name
-     *
-     * @param array $fields an array of field names
-     */
-    public function getXMLValues(array $fields): array
-    {
-        $result = [];
-
-        foreach ($fields as $field) {
-            $result[$field] = $this->XML_val($field);
-        }
-
-        return $result;
-    }
-
     // UTILITY METHODS -------------------------------------------------------------------------------------------------
 
     /**
@@ -677,4 +542,14 @@ class ModelData
     {
         return ModelDataDebugger::create($this);
     }
+
+    /**
+     * Generate the cache name for a field
+     */
+    private function objCacheName(string $fieldName, array $arguments = []): string
+    {
+        return empty($arguments)
+            ? $fieldName
+            : $fieldName . ":" . var_export($arguments, true);
+    }
 }

src/Model/ModelDataCustomised.php

@@ -49,17 +49,22 @@ class ModelDataCustomised extends ModelData
         return isset($this->customised->$property) || isset($this->original->$property) || parent::__isset($property);
     }
 
+    public function forTemplate(): string
+    {
+        return $this->original->forTemplate();
+    }
+
     public function hasMethod($method)
     {
         return $this->customised->hasMethod($method) || $this->original->hasMethod($method);
     }
 
-    public function cachedCall(string $fieldName, array $arguments = [], ?string $cacheName = null): object
+    public function castingHelper(string $field): ?string
     {
-        if ($this->customisedHas($fieldName)) {
+        if ($this->customisedHas($field)) {
-            return $this->customised->cachedCall($fieldName, $arguments, $cacheName);
+            return $this->customised->castingHelper($field);
         }
-        return $this->original->cachedCall($fieldName, $arguments, $cacheName);
+        return $this->original->castingHelper($field);
     }
 
     public function obj(
@@ -74,10 +79,15 @@ class ModelDataCustomised extends ModelData
         return $this->original->obj($fieldName, $arguments, $cache, $cacheName);
     }
 
-    private function customisedHas(string $fieldName): bool
+    public function customisedHas(string $fieldName): bool
     {
         return property_exists($this->customised, $fieldName) ||
             $this->customised->hasField($fieldName) ||
             $this->customised->hasMethod($fieldName);
     }
+
+    public function getCustomisedModelData(): ?ModelData
+    {
+        return $this->customised;
+    }
 }

src/ORM/Connect/TempDatabase.php

@@ -43,7 +43,7 @@ class TempDatabase
      *
      * @param string $name DB Connection name to use
      */
-    public function __construct($name = 'default')
+    public function __construct($name = DB::CONN_PRIMARY)
     {
         $this->name = $name;
     }

src/ORM/DB.php

@@ -3,6 +3,7 @@
 namespace SilverStripe\ORM;
 
 use InvalidArgumentException;
+use RunTimeException;
 use SilverStripe\Control\Director;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Core\Config\Config;
@@ -21,6 +22,22 @@ use SilverStripe\ORM\Queries\SQLExpression;
  */
 class DB
 {
+    /**
+     * A dynamic connection that will use either a replica connection (if one is
+     * available and not forced to use the 'primary' connection), or the 'primary' connection
+     */
+    public const CONN_DYNAMIC = 'dynamic';
+
+    /**
+     * The 'primary' connection name, which is the main database connection and is used for all write
+     * operations and for read operations when the 'dynamic' connection is forced to use the 'primary' connection
+     */
+    public const CONN_PRIMARY = 'primary';
+
+    /**
+     * The maximum number of replicas databases that can be configured
+     */
+    public const MAX_REPLICAS = 99;
 
     /**
      * This constant was added in SilverStripe 2.4 to indicate that SQL-queries
@@ -58,19 +75,47 @@ class DB
      */
     protected static $configs = [];
 
-
-
     /**
      * The last SQL query run.
      * @var string
      */
     public static $lastQuery;
 
+    /**
+     * The name of the last connection used. This is only used for unit-testing purposes.
+     * @interal
+     */
+    private static string $lastConnectionName = '';
+
     /**
      * Internal flag to keep track of when db connection was attempted.
+     *
+     * @internal
      */
     private static $connection_attempted = false;
 
+    /**
+     * Only use the primary database connection for the rest of the current request
+     *
+     * @internal
+     */
+    private static bool $mustUsePrimary = false;
+
+    /**
+     * Used by DB::withPrimary() to count the number of times it has been called
+     * Uses an int instead of a bool to allow for nested calls
+     *
+     * @internal
+     */
+    private static int $withPrimaryCount = 0;
+
+    /**
+     * The key of the replica config to use for this request
+     *
+     * @internal
+     */
+    private static string $replicaConfigKey = '';
+
     /**
      * Set the global database connection.
      * Pass an object that's a subclass of SS_Database.  This object will be used when {@link DB::query()}
@@ -78,11 +123,11 @@ class DB
      *
      * @param Database $connection The connection object to set as the connection.
      * @param string $name The name to give to this connection.  If you omit this argument, the connection
-     * will be the default one used by the ORM.  However, you can store other named connections to
+     * will be the primary one used by the ORM.  However, you can store other named connections to
      * be accessed through DB::get_conn($name).  This is useful when you have an application that
      * needs to connect to more than one database.
      */
-    public static function set_conn(Database $connection, $name = 'default')
+    public static function set_conn(Database $connection, $name)
     {
         DB::$connections[$name] = $connection;
     }
@@ -92,11 +137,17 @@ class DB
      *
      * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
      * the default connection is returned.
-     * @return Database
+     * @return Database|null
      */
-    public static function get_conn($name = 'default')
+    public static function get_conn($name = DB::CONN_DYNAMIC)
     {
+        // Allow default to connect to replica if configured
+        if ($name === DB::CONN_DYNAMIC) {
+            $name = DB::getDynamicConnectionName();
+        }
+
         if (isset(DB::$connections[$name])) {
+            DB::$lastConnectionName = $name;
             return DB::$connections[$name];
         }
 
@@ -109,14 +160,50 @@ class DB
         return null;
     }
 
+    /**
+     * Whether the primary database connection will be used if the database is used right now
+     */
+    public static function willUsePrimary(): bool
+    {
+        return DB::$mustUsePrimary || DB::$withPrimaryCount > 0 || !DB::hasReplicaConfig();
+    }
+
+    /**
+     * Set to use the primary database connection for rest of the current request
+     * meaning that replia connections will no longer be used
+     *
+     * This intentioally does not have a parameter to set this back to false, as this it to prevent
+     * accidentally attempting writing to a replica, or reading from an out of date replica
+     * after a write
+     */
+    public static function setMustUsePrimary(): void
+    {
+        DB::$mustUsePrimary = true;
+    }
+
+    /**
+     * Only use the primary database connection when calling $callback
+     * Use this when doing non-mutable queries on the primary database where querying
+     * an out of sync replica could cause issues
+     * There's no need to use this with mutable queries, or after calling a mutable query
+     * as the primary database connection will be automatically used
+     */
+    public static function withPrimary(callable $callback): mixed
+    {
+        DB::$withPrimaryCount++;
+        $result = $callback();
+        DB::$withPrimaryCount--;
+        return $result;
+    }
+
     /**
      * Retrieves the schema manager for the current database
      *
-     * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
+     * @param string $name An optional name given to a connection in the DB::setConn() call.
-     * the default connection is returned.
+     * If omitted, a dynamic connection is returned.
-     * @return DBSchemaManager
+     * @return DBSchemaManager|null
      */
-    public static function get_schema($name = 'default')
+    public static function get_schema($name = DB::CONN_DYNAMIC)
     {
         $connection = DB::get_conn($name);
         if ($connection) {
@@ -130,11 +217,11 @@ class DB
      *
      * @param SQLExpression $expression The expression object to build from
      * @param array $parameters Out parameter for the resulting query parameters
-     * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
+     * @param string $name An optional name given to a connection in the DB::setConn() call.
-     * the default connection is returned.
+     * If omitted, a dynamic connection is returned.
-     * @return string The resulting SQL as a string
+     * @return string|null The resulting SQL as a string
      */
-    public static function build_sql(SQLExpression $expression, &$parameters, $name = 'default')
+    public static function build_sql(SQLExpression $expression, &$parameters, $name = DB::CONN_DYNAMIC)
     {
         $connection = DB::get_conn($name);
         if ($connection) {
@@ -148,11 +235,11 @@ class DB
     /**
      * Retrieves the connector object for the current database
      *
-     * @param string $name An optional name given to a connection in the DB::setConn() call.  If omitted,
+     * @param string $name An optional name given to a connection in the DB::setConn() call.
-     * the default connection is returned.
+     * If omitted, a dynamic connection is returned.
-     * @return DBConnector
+     * @return DBConnector|null
      */
-    public static function get_connector($name = 'default')
+    public static function get_connector($name = DB::CONN_DYNAMIC)
     {
         $connection = DB::get_conn($name);
         if ($connection) {
@@ -268,8 +355,13 @@ class DB
      * @param string $label identifier for the connection
      * @return Database
      */
-    public static function connect($databaseConfig, $label = 'default')
+    public static function connect($databaseConfig, $label = DB::CONN_DYNAMIC)
     {
+        // Allow default to connect to replica if configured
+        if ($label === DB::CONN_DYNAMIC) {
+            $label = DB::getDynamicConnectionName();
+        }
+
         // This is used by the "testsession" module to test up a test session using an alternative name
         if ($name = DB::get_alternative_database_name()) {
             $databaseConfig['database'] = $name;
@@ -288,6 +380,7 @@ class DB
         $conn = Injector::inst()->create($dbClass);
         DB::set_conn($conn, $label);
         $conn->connect($databaseConfig);
+        DB::$lastConnectionName = $label;
 
         return $conn;
     }
@@ -298,7 +391,7 @@ class DB
      * @param array $databaseConfig
      * @param string $name
      */
-    public static function setConfig($databaseConfig, $name = 'default')
+    public static function setConfig($databaseConfig, $name = DB::CONN_PRIMARY)
     {
         static::$configs[$name] = $databaseConfig;
     }
@@ -309,13 +402,42 @@ class DB
      * @param string $name
      * @return mixed
      */
-    public static function getConfig($name = 'default')
+    public static function getConfig($name = DB::CONN_PRIMARY)
     {
-        if (isset(static::$configs[$name])) {
+        if (static::hasConfig($name)) {
             return static::$configs[$name];
         }
     }
 
+    /**
+     * Check if a named connection config exists
+     */
+    public static function hasConfig($name = DB::CONN_PRIMARY): bool
+    {
+        return array_key_exists($name, static::$configs);
+    }
+
+    /**
+     * Get a replica database configuration key
+     * e.g. replica_01
+     */
+    public static function getReplicaConfigKey(int $replica): string
+    {
+        $len = strlen((string) DB::MAX_REPLICAS);
+        return 'replica_' . str_pad($replica, $len, '0', STR_PAD_LEFT);
+    }
+
+    /**
+     * Check if there are any replica configurations
+     */
+    public static function hasReplicaConfig(): bool
+    {
+        $configKeys = array_keys(static::$configs);
+        return !empty(array_filter($configKeys, function (string $key) {
+            return (bool) preg_match('#^replica_[0-9]+$#', $key);
+        }));
+    }
+
     /**
      * Returns true if a database connection has been attempted.
      * In particular, it lets the caller know if we're still so early in the execution pipeline that
@@ -335,8 +457,8 @@ class DB
     public static function query($sql, $errorLevel = E_USER_ERROR)
     {
         DB::$lastQuery = $sql;
-
+        $name = DB::getDynamicConnectionName($sql);
-        return DB::get_conn()->query($sql, $errorLevel);
+        return DB::get_conn($name)->query($sql, $errorLevel);
     }
 
     /**
@@ -427,8 +549,8 @@ class DB
     public static function prepared_query($sql, $parameters, $errorLevel = E_USER_ERROR)
     {
         DB::$lastQuery = $sql;
-
+        $name = DB::getDynamicConnectionName($sql);
-        return DB::get_conn()->preparedQuery($sql, $parameters, $errorLevel);
+        return DB::get_conn($name)->preparedQuery($sql, $parameters, $errorLevel);
     }
 
     /**
@@ -680,4 +802,63 @@ class DB
     {
         DB::get_schema()->alterationMessage($message, $type);
     }
+
+    /**
+     * Get the name of the database connection to use for the given SQL query
+     * The 'dynamic' connection can be either the primary or a replica connection if configured
+     */
+    private static function getDynamicConnectionName(string $sql = ''): string
+    {
+        if (DB::willUsePrimary()) {
+            return DB::CONN_PRIMARY;
+        }
+        if (DB::isMutableSql($sql)) {
+            DB::$mustUsePrimary = true;
+            return DB::CONN_PRIMARY;
+        }
+        if (DB::$replicaConfigKey) {
+            return DB::$replicaConfigKey;
+        }
+        $name = DB::getRandomReplicaConfigKey();
+        DB::$replicaConfigKey = $name;
+        return $name;
+    }
+
+    /**
+     * Check if the given SQL query is mutable
+     */
+    private static function isMutableSql(string $sql): bool
+    {
+        $dbClass = DB::getConfig(DB::CONN_PRIMARY)['type'];
+        // This must use getServiceSpec() and not Injector::get/create() followed by
+        // getConnector() as this can remove the dbConn from a different connection
+        // under edge case conditions
+        $dbSpec = Injector::inst()->getServiceSpec($dbClass);
+        $connectorService = $dbSpec['properties']['connector'];
+        $connector = Injector::inst()->convertServiceProperty($connectorService);
+        return $connector->isQueryMutable($sql);
+    }
+
+    /**
+     * Get a random replica database configuration key from the available replica configurations
+     * The replica choosen will be used for the rest of the request, unless the primary connection
+     * is forced
+     */
+    private static function getRandomReplicaConfigKey(): string
+    {
+        $replicaNumbers = [];
+        for ($i = 1; $i <= DB::MAX_REPLICAS; $i++) {
+            $replicaKey = DB::getReplicaConfigKey($i);
+            if (!DB::hasConfig($replicaKey)) {
+                break;
+            }
+            $replicaNumbers[] = $i;
+        }
+        if (count($replicaNumbers) === 0) {
+            throw new RunTimeException('No replica configurations found');
+        }
+        // Choose a random replica
+        $index = rand(0, count($replicaNumbers) - 1);
+        return DB::getReplicaConfigKey($replicaNumbers[$index]);
+    }
 }

src/ORM/DataList.php

@@ -19,6 +19,7 @@ use SilverStripe\Model\List\Limitable;
 use SilverStripe\Model\List\Map;
 use SilverStripe\Model\List\Sortable;
 use SilverStripe\Model\List\SS_List;
+use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\ORM\Filters\SearchFilterable;
 
 /**
@@ -237,7 +238,7 @@ class DataList extends ModelData implements SS_List, Filterable, Sortable, Limit
      */
     public function sql(&$parameters = [])
     {
-        return $this->dataQuery->query()->sql($parameters);
+        return $this->dataQuery->sql($parameters);
     }
 
     /**
@@ -1040,7 +1041,7 @@ class DataList extends ModelData implements SS_List, Filterable, Sortable, Limit
 
     private function executeQuery(): Query
     {
-        $query = $this->dataQuery->query()->execute();
+        $query = $this->dataQuery->execute();
         $this->fetchEagerLoadRelations($query);
         return $query;
     }
@@ -1852,7 +1853,7 @@ class DataList extends ModelData implements SS_List, Filterable, Sortable, Limit
         return $relation;
     }
 
-    public function dbObject($fieldName)
+    public function dbObject(string $fieldName): ?DBField
     {
         return singleton($this->dataClass)->dbObject($fieldName);
     }

src/ORM/DataObject.php

@@ -104,9 +104,6 @@ use stdClass;
  * }
  * </code>
  *
- * If any public method on this class is prefixed with an underscore,
- * the results are cached in memory through {@link cachedCall()}.
- *
  * @property int $ID ID of the DataObject, 0 if the DataObject doesn't exist in database.
  * @property int $OldID ID of object, if deleted
  * @property string $Title
@@ -145,6 +142,14 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
      */
     private static $default_classname = null;
 
+    /**
+     * Whether this DataObject class must only use the primary database and not a read-only replica
+     * Note that this will be only be enforced when using DataQuery::execute() or
+     * another method that uses calls DataQuery::execute() internally e.g. DataObject::get()
+     * This will not be enforced when using low-level ORM functionality to query data e.g. SQLSelect or DB::query()
+     */
+    private static bool $must_use_primary_db = false;
+
     /**
      * Data stored in this objects database record. An array indexed by fieldname.
      *
@@ -1937,6 +1942,7 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
         string $eagerLoadRelation,
         EagerLoadedList|DataObject $eagerLoadedData
     ): void {
+        $this->objCacheClear();
         $this->eagerLoadedData[$eagerLoadRelation] = $eagerLoadedData;
     }
 
@@ -3033,7 +3039,7 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
     /**
      * {@inheritdoc}
      */
-    public function castingHelper(string $field, bool $useFallback = true): ?string
+    public function castingHelper(string $field): ?string
     {
         $fieldSpec = static::getSchema()->fieldSpec(static::class, $field);
         if ($fieldSpec) {
@@ -3051,7 +3057,7 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
             }
         }
 
-        return parent::castingHelper($field, $useFallback);
+        return parent::castingHelper($field);
     }
 
     /**
@@ -3234,11 +3240,11 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
      *   - it still returns an object even when the field has no value.
      *   - it only matches fields and not methods
      *   - it matches foreign keys generated by has_one relationships, eg, "ParentID"
+     *   - if the field exists, the return value is ALWAYS a DBField instance
      *
-     * @param string $fieldName Name of the field
+     * Returns null if the field doesn't exist
-     * @return DBField The field as a DBField object
      */
-    public function dbObject($fieldName)
+    public function dbObject(string $fieldName): ?DBField
     {
         // Check for field in DB
         $schema = static::getSchema();
@@ -3306,7 +3312,7 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
             } elseif ($component instanceof Relation || $component instanceof DataList) {
                 // $relation could either be a field (aggregate), or another relation
                 $singleton = DataObject::singleton($component->dataClass());
-                $component = $singleton->dbObject($relation) ?: $component->relation($relation);
+                $component = $singleton->dbObject($relation) ?? $component->relation($relation);
             } elseif ($component instanceof DataObject && ($dbObject = $component->dbObject($relation))) {
                 $component = $dbObject;
             } elseif ($component instanceof ModelData && $component->hasField($relation)) {
@@ -4399,7 +4405,7 @@ class DataObject extends ModelData implements DataObjectInterface, i18nEntityPro
         // has_one fields should not use dbObject to check if a value is given
         $hasOne = static::getSchema()->hasOneComponent(static::class, $field);
         if (!$hasOne && ($obj = $this->dbObject($field))) {
-            return $obj->exists();
+            return $obj && $obj->exists();
         } else {
             return parent::hasValue($field, $arguments, $cache);
         }

src/ORM/DataQuery.php

@@ -10,6 +10,7 @@ use SilverStripe\ORM\Connect\Query;
 use SilverStripe\ORM\Queries\SQLConditionGroup;
 use SilverStripe\ORM\Queries\SQLSelect;
 use InvalidArgumentException;
+use SilverStripe\Core\Config\Config;
 
 /**
  * An object representing a query of data from the DataObject's supporting database.
@@ -449,7 +450,9 @@ class DataQuery
      */
     public function execute()
     {
-        return $this->getFinalisedQuery()->execute();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->execute()
+        );
     }
 
     /**
@@ -472,7 +475,9 @@ class DataQuery
     public function count()
     {
         $quotedColumn = DataObject::getSchema()->sqlColumnForField($this->dataClass(), 'ID');
-        return $this->getFinalisedQuery()->count("DISTINCT {$quotedColumn}");
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->count("DISTINCT {$quotedColumn}")
+        );
     }
 
     /**
@@ -501,7 +506,9 @@ class DataQuery
 
         // Wrap the whole thing in an "EXISTS"
         $sql = 'SELECT CASE WHEN EXISTS(' . $statement->sql($params) . ') THEN 1 ELSE 0 END';
-        $result = DB::prepared_query($sql, $params);
+        $result = $this->withCorrectDatabase(
+            fn() => DB::prepared_query($sql, $params)
+        );
         $row = $result->record();
         $result = reset($row);
 
@@ -582,7 +589,9 @@ class DataQuery
      */
     public function aggregate($expression)
     {
-        return $this->getFinalisedQuery()->aggregate($expression)->execute()->value();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->aggregate($expression)->execute()->value()
+        );
     }
 
     /**
@@ -593,7 +602,9 @@ class DataQuery
      */
     public function firstRow()
     {
-        return $this->getFinalisedQuery()->firstRow();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->firstRow()
+        );
     }
 
     /**
@@ -604,7 +615,9 @@ class DataQuery
      */
     public function lastRow()
     {
-        return $this->getFinalisedQuery()->lastRow();
+        return $this->withCorrectDatabase(
+            fn() => $this->getFinalisedQuery()->lastRow()
+        );
     }
 
     /**
@@ -1344,7 +1357,9 @@ class DataQuery
         $query->selectField($fieldExpression, $field);
         $this->ensureSelectContainsOrderbyColumns($query, $originalSelect);
 
-        return $query->execute()->column($field);
+        return $this->withCorrectDatabase(
+            fn() => $query->execute()->column($field)
+        );
     }
 
     /**
@@ -1495,4 +1510,16 @@ class DataQuery
 
         return $updated;
     }
+
+    /**
+     * Calls a callback on either the primary database or a replica, with respect to the configured
+     * value of `must_use_primary_db` on the current dataClass
+     */
+    private function withCorrectDatabase(callable $callback): mixed
+    {
+        if (Config::inst()->get($this->dataClass(), 'must_use_primary_db')) {
+            return DB::withPrimary($callback);
+        }
+        return $callback();
+    }
 }

src/ORM/EagerLoadedList.php

@@ -171,7 +171,7 @@ class EagerLoadedList extends ModelData implements Relation, SS_List, Filterable
         return $this->dataClass;
     }
 
-    public function dbObject($fieldName): ?DBField
+    public function dbObject(string $fieldName): ?DBField
     {
         return singleton($this->dataClass)->dbObject($fieldName);
     }

src/ORM/FieldType/DBComposite.php

@@ -73,7 +73,7 @@ abstract class DBComposite extends DBField
         foreach ($this->compositeDatabaseFields() as $field => $spec) {
             // Write sub-manipulation
             $fieldObject = $this->dbObject($field);
-            $fieldObject->writeToManipulation($manipulation);
+            $fieldObject?->writeToManipulation($manipulation);
         }
     }
 
@@ -137,7 +137,7 @@ abstract class DBComposite extends DBField
         // By default all fields
         foreach ($this->compositeDatabaseFields() as $field => $spec) {
             $fieldObject = $this->dbObject($field);
-            if (!$fieldObject->exists()) {
+            if (!$fieldObject?->exists()) {
                 return false;
             }
         }

src/ORM/FieldType/DBField.php

@@ -520,11 +520,6 @@ abstract class DBField extends ModelData implements DBIndexable
 DBG;
     }
 
-    public function __toString(): string
-    {
-        return (string)$this->forTemplate();
-    }
-
     public function getArrayValue()
     {
         return $this->arrayValue;

src/ORM/FieldType/DBVarchar.php

@@ -47,7 +47,7 @@ class DBVarchar extends DBString
      * can be useful if you want to have text fields with a length limit that
      * is dictated by the DB field.
      *
-     * TextField::create('Title')->setMaxLength(singleton('SiteTree')->dbObject('Title')->getSize())
+     * TextField::create('Title')->setMaxLength(singleton('SiteTree')->dbObject('Title')?->getSize())
      *
      * @return int The size of the field
      */

src/ORM/Filters/SearchFilter.php

@@ -339,7 +339,7 @@ abstract class SearchFilter
 
         /** @var DBField $dbField */
         $dbField = singleton($this->model)->dbObject($this->name);
-        $dbField->setValue($this->value);
+        $dbField?->setValue($this->value);
         return $dbField->RAW();
     }
 

src/ORM/Queries/SQLExpression.php

@@ -6,12 +6,13 @@ use SilverStripe\Core\Convert;
 use SilverStripe\ORM\Connect\Query;
 use SilverStripe\ORM\DB;
 use Exception;
+use Stringable;
 
 /**
  * Abstract base class for an object representing an SQL query.
  * The various parts of the SQL query can be manipulated individually.
  */
-abstract class SQLExpression
+abstract class SQLExpression implements Stringable
 {
 
     /**
@@ -44,10 +45,8 @@ abstract class SQLExpression
 
     /**
      * Return the generated SQL string for this query
-     *
-     * @return string
      */
-    public function __toString()
+    public function __toString(): string
     {
         try {
             $sql = $this->sql($parameters);

src/ORM/Relation.php

@@ -45,9 +45,6 @@ interface Relation extends SS_List, Filterable, Sortable, Limitable
 
     /**
      * Return the DBField object that represents the given field on the related class.
-     *
-     * @param string $fieldName Name of the field
-     * @return DBField The field as a DBField object
      */
-    public function dbObject($fieldName);
+    public function dbObject(string $fieldName): ?DBField;
 }

src/ORM/UnsavedRelationList.php

@@ -307,11 +307,8 @@ class UnsavedRelationList extends ArrayList implements Relation
 
     /**
      * Return the DBField object that represents the given field on the related class.
-     *
-     * @param string $fieldName Name of the field
-     * @return DBField The field as a DBField object
      */
-    public function dbObject($fieldName)
+    public function dbObject(string $fieldName): ?DBField
     {
         return DataObject::singleton($this->dataClass)->dbObject($fieldName);
     }

src/PolyExecution/PolyOutput.php

@@ -226,9 +226,6 @@ class PolyOutput extends Output
     {
         $listInfo = $this->listTypeStack[array_key_last($this->listTypeStack)];
         $listType = $listInfo['type'];
-        if ($listType === PolyOutput::LIST_ORDERED) {
-            echo '';
-        }
         if ($options === null) {
             $options = $listInfo['options'];
         }

src/Security/Group.php

@@ -88,6 +88,8 @@ class Group extends DataObject
 
     private static $table_name = "Group";
 
+    private static bool $must_use_primary_db = true;
+
     private static $indexes = [
         'Title' => true,
         'Code' => true,

src/Security/LoginAttempt.php

@@ -50,6 +50,8 @@ class LoginAttempt extends DataObject
 
     private static $table_name = "LoginAttempt";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * @param bool $includerelations Indicate if the labels returned include relation fields
      * @return array

src/Security/Member.php

@@ -105,6 +105,8 @@ class Member extends DataObject
 
     private static $table_name = "Member";
 
+    private static bool $must_use_primary_db = true;
+
     private static $default_sort = '"Surname", "FirstName"';
 
     private static $indexes = [
@@ -343,7 +345,7 @@ class Member extends DataObject
     {
         /** @var DBDatetime $lockedOutUntilObj */
         $lockedOutUntilObj = $this->dbObject('LockedOutUntil');
-        if ($lockedOutUntilObj->InFuture()) {
+        if ($lockedOutUntilObj?->InFuture()) {
             return true;
         }
 
@@ -370,7 +372,7 @@ class Member extends DataObject
         /** @var DBDatetime $firstFailureDate */
         $firstFailureDate = $attempts->first()->dbObject('Created');
         $maxAgeSeconds = $this->config()->get('lock_out_delay_mins') * 60;
-        $lockedOutUntil = $firstFailureDate->getTimestamp() + $maxAgeSeconds;
+        $lockedOutUntil = $firstFailureDate?->getTimestamp() + $maxAgeSeconds;
         $now = DBDatetime::now()->getTimestamp();
         if ($now < $lockedOutUntil) {
             return true;
@@ -426,7 +428,7 @@ class Member extends DataObject
         $currentValue = $this->PasswordExpiry;
         $currentDate = $this->dbObject('PasswordExpiry');
 
-        if ($dataValue && (!$currentValue || $currentDate->inFuture())) {
+        if ($dataValue && (!$currentValue || $currentDate?->inFuture())) {
             // Only alter future expiries - this way an admin could see how long ago a password expired still
             $this->PasswordExpiry = DBDatetime::now()->Rfc2822();
         } elseif (!$dataValue && $this->isPasswordExpired()) {

src/Security/MemberPassword.php

@@ -27,6 +27,8 @@ class MemberPassword extends DataObject
 
     private static $table_name = "MemberPassword";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * Log a password change from the given member.
      * Call MemberPassword::log($this) from within Member whenever the password is changed.

src/Security/Permission.php

@@ -46,6 +46,8 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
 
     private static $table_name = "Permission";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * This is the value to use for the "Type" field if a permission should be
      * granted.
@@ -233,7 +235,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
         }
 
         // Raw SQL for efficiency
-        $permission = DB::prepared_query(
+        $permission = DB::withPrimary(fn() => DB::prepared_query(
             "SELECT \"ID\"
             FROM \"Permission\"
             WHERE (
@@ -249,7 +251,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                 $groupParams,
                 $argParams
             )
-        )->value();
+        )->value());
 
         if ($permission) {
             return $permission;
@@ -257,7 +259,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
 
         // Strict checking disabled?
         if (!static::config()->strict_checking || !$strict) {
-            $hasPermission = DB::prepared_query(
+            $hasPermission = DB::withPrimary(fn() => DB::prepared_query(
                 "SELECT COUNT(*)
                 FROM \"Permission\"
                 WHERE (
@@ -265,7 +267,7 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                     \"Type\" = ?
                 )",
                 array_merge($codeParams, [Permission::GRANT_PERMISSION])
-            )->value();
+            )->value());
 
             if (!$hasPermission) {
                 return false;
@@ -288,7 +290,8 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
         if ($groupList) {
             $groupCSV = implode(", ", $groupList);
 
-            $allowed = array_unique(DB::query("
+            $allowed = array_unique(
+                DB::withPrimary(fn() => DB::query("
                     SELECT \"Code\"
                     FROM \"Permission\"
                     WHERE \"Type\" = " . Permission::GRANT_PERMISSION . " AND \"GroupID\" IN ($groupCSV)
@@ -300,13 +303,16 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                     INNER JOIN \"PermissionRole\" PR ON PRC.\"RoleID\" = PR.\"ID\"
                     INNER JOIN \"Group_Roles\" GR ON GR.\"PermissionRoleID\" = PR.\"ID\"
                     WHERE \"GroupID\" IN ($groupCSV)
-			")->column() ?? []);
+                "))->column() ?? []
+            );
 
-            $denied = array_unique(DB::query("
+            $denied = array_unique(
+                DB::withPrimary(fn() => DB::query("
                     SELECT \"Code\"
                     FROM \"Permission\"
                     WHERE \"Type\" = " . Permission::DENY_PERMISSION . " AND \"GroupID\" IN ($groupCSV)
-			")->column() ?? []);
+                "))->column() ?? []
+            );
 
             return array_diff($allowed ?? [], $denied);
         }
@@ -584,7 +590,9 @@ class Permission extends DataObject implements TemplateGlobalProvider, Resettabl
                 $flatCodeArray[] = $code;
             }
         }
-        $otherPerms = DB::query("SELECT DISTINCT \"Code\" From \"Permission\" WHERE \"Code\" != ''")->column();
+        $otherPerms = DB::withPrimary(
+            fn() => DB::query("SELECT DISTINCT \"Code\" From \"Permission\" WHERE \"Code\" != ''")->column()
+        );
 
         if ($otherPerms) {
             foreach ($otherPerms as $otherPerm) {

src/Security/PermissionCheckboxSetField.php

@@ -117,7 +117,7 @@ class PermissionCheckboxSetField extends FormField
                 $uninheritedCodes[$permission->Code][] = _t(
                     'SilverStripe\\Security\\PermissionCheckboxSetField.AssignedTo',
                     'assigned to "{title}"',
-                    ['title' => $record->dbObject('Title')->forTemplate()]
+                    ['title' => $record->dbObject('Title')?->forTemplate()]
                 );
             }
 
@@ -135,7 +135,7 @@ class PermissionCheckboxSetField extends FormField
                                 'SilverStripe\\Security\\PermissionCheckboxSetField.FromRole',
                                 'inherited from role "{title}"',
                                 'A permission inherited from a certain permission role',
-                                ['title' => $role->dbObject('Title')->forTemplate()]
+                                ['title' => $role->dbObject('Title')?->forTemplate()]
                             );
                         }
                     }
@@ -159,8 +159,8 @@ class PermissionCheckboxSetField extends FormField
                                         'inherited from role "{roletitle}" on group "{grouptitle}"',
                                         'A permission inherited from a role on a certain group',
                                         [
-                                            'roletitle' => $role->dbObject('Title')->forTemplate(),
+                                            'roletitle' => $role->dbObject('Title')?->forTemplate(),
-                                            'grouptitle' => $parent->dbObject('Title')->forTemplate()
+                                            'grouptitle' => $parent->dbObject('Title')?->forTemplate()
                                         ]
                                     );
                                 }
@@ -176,7 +176,7 @@ class PermissionCheckboxSetField extends FormField
                                     'SilverStripe\\Security\\PermissionCheckboxSetField.FromGroup',
                                     'inherited from group "{title}"',
                                     'A permission inherited from a certain group',
-                                    ['title' => $parent->dbObject('Title')->forTemplate()]
+                                    ['title' => $parent->dbObject('Title')?->forTemplate()]
                                 );
                             }
                         }

src/Security/PermissionRole.php

@@ -40,6 +40,8 @@ class PermissionRole extends DataObject
 
     private static $table_name = "PermissionRole";
 
+    private static bool $must_use_primary_db = true;
+
     private static $default_sort = '"Title"';
 
     private static $singular_name = 'Role';

src/Security/PermissionRoleCode.php

@@ -24,6 +24,8 @@ class PermissionRoleCode extends DataObject
 
     private static $table_name = "PermissionRoleCode";
 
+    private static bool $must_use_primary_db = true;
+    
     private static $indexes = [
         "Code" => true,
     ];

src/Security/RememberLoginHash.php

@@ -44,6 +44,8 @@ class RememberLoginHash extends DataObject
 
     private static $table_name = "RememberLoginHash";
 
+    private static bool $must_use_primary_db = true;
+
     /**
      * Determines if logging out on one device also clears existing login tokens
      * on all other devices owned by the member.

src/Security/Security.php

@@ -437,6 +437,12 @@ class Security extends Controller implements TemplateGlobalProvider
      */
     public static function setCurrentUser($currentUser = null)
     {
+        // Always use the primary database and not a replica if a CMS user is logged in
+        // This is to ensure that when viewing content on the frontend it is always
+        // up to date i.e. not from an unsynced replica
+        if ($currentUser && Permission::checkMember($currentUser, 'CMS_ACCESS')) {
+            DB::setMustUsePrimary();
+        }
         Security::$currentUser = $currentUser;
     }
 

src/View/CastingService.php

@@ -0,0 +1,100 @@
+<?php
+
+namespace SilverStripe\View;
+
+use LogicException;
+use SilverStripe\Core\ClassInfo;
+use SilverStripe\Core\Injector\Injectable;
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Model\ArrayData;
+use SilverStripe\Model\List\ArrayList;
+use SilverStripe\Model\ModelData;
+use SilverStripe\ORM\FieldType\DBBoolean;
+use SilverStripe\ORM\FieldType\DBFloat;
+use SilverStripe\ORM\FieldType\DBInt;
+use SilverStripe\ORM\FieldType\DBText;
+
+class CastingService
+{
+    use Injectable;
+
+    /**
+     * Cast a value to the relevant object (usually a DBField instance) for use in the view layer.
+     *
+     * @param null|array|ModelData $source Where the data originates from. This is used both to check for casting helpers
+     * and to help set the value in cast DBField instances.
+     * @param bool $strict If true, an object will be returned even if $data is null.
+     */
+    public function cast(mixed $data, null|array|ModelData $source = null, string $fieldName = '', bool $strict = false): ?object
+    {
+        // null is null - we shouldn't cast it to an object, because that makes it harder
+        // for downstream checks to know there's "no value".
+        if (!$strict && $data === null) {
+            return null;
+        }
+
+        // Assume anything that's an object is intentionally using whatever class it's using
+        // and don't cast it.
+        if (is_object($data)) {
+            return $data;
+        }
+
+        $service = null;
+        if ($source instanceof ModelData) {
+            $service = $source->castingHelper($fieldName);
+        }
+
+        // Cast to object if there's an explicit casting for this field
+        // Explicit casts take precedence over array casting
+        if ($service) {
+            $castObject = Injector::inst()->create($service, $fieldName);
+            if (!ClassInfo::hasMethod($castObject, 'setValue')) {
+                throw new LogicException('Explicit casting service must have a setValue method.');
+            }
+            $castObject->setValue($data, $source);
+            return $castObject;
+        }
+
+        // Wrap arrays in ModelData so templates can handle them
+        if (is_array($data)) {
+            return array_is_list($data) ? ArrayList::create($data) : ArrayData::create($data);
+        }
+
+        // Fall back to default casting
+        $service = $this->defaultService($data, $source, $fieldName);
+        $castObject = Injector::inst()->create($service, $fieldName);
+        if (!ClassInfo::hasMethod($castObject, 'setValue')) {
+            throw new LogicException('Default service must have a setValue method.');
+        }
+        $castObject->setValue($data, $source);
+        return $castObject;
+    }
+
+    /**
+     * Get the default service to use if no explicit service is declared for this field on the source model.
+     */
+    private function defaultService(mixed $data, mixed $source = null, string $fieldName = ''): ?string
+    {
+        $default = null;
+        if ($source instanceof ModelData) {
+            $default = $source::config()->get('default_cast');
+            if ($default === null) {
+                $failover = $source->getFailover();
+                if ($failover) {
+                    $default = $this->defaultService($data, $failover, $fieldName);
+                }
+            }
+        }
+        if ($default !== null) {
+            return $default;
+        }
+
+        return match (gettype($data)) {
+            'boolean' => DBBoolean::class,
+            'string' => DBText::class,
+            'double' => DBFloat::class,
+            'integer' => DBInt::class,
+            default => DBText::class,
+        };
+    }
+}

src/View/Dev/SSViewerTestState.php

@@ -11,7 +11,7 @@ class SSViewerTestState implements TestState
 {
     public function setUp(SapphireTest $test)
     {
-        SSViewer::set_themes(null);
+        SSViewer::set_themes([]);
         SSViewer::setRewriteHashLinksDefault(null);
         ContentNegotiator::setEnabled(null);
     }

src/View/Exception/MissingTemplateException.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace SilverStripe\View\Exception;
+
+use LogicException;
+
+/**
+ * Exception that indicates a template was not found when attemping to use a template engine
+ */
+class MissingTemplateException extends LogicException
+{}

src/View/SSTemplateEngine.php

@@ -0,0 +1,467 @@
+<?php
+
+namespace SilverStripe\View;
+
+use InvalidArgumentException;
+use Psr\SimpleCache\CacheInterface;
+use SilverStripe\Control\Director;
+use SilverStripe\Core\Config\Configurable;
+use SilverStripe\Core\Flushable;
+use SilverStripe\Core\Injector\Injectable;
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Core\Path;
+use SilverStripe\ORM\FieldType\DBHTMLText;
+use SilverStripe\Security\Permission;
+use SilverStripe\View\Exception\MissingTemplateException;
+
+/**
+ * Parses template files with an *.ss file extension, or strings representing templates in that format.
+ *
+ * In addition to a full template in the templates/ folder, a template in
+ * templates/Content or templates/Layout will be rendered into `$Content` and
+ * `$Layout`, respectively.
+ *
+ * A single template can be parsed by multiple nested SSTemplateEngine instances
+ * through `$Layout`/`$Content` placeholders, as well as `<% include MyTemplateFile %>` template commands.
+ *
+ * <b>Caching</b>
+ *
+ * Compiled templates are cached, usually on the filesystem.
+ * If you put ?flush=1 on your URL, it will force the template to be recompiled.
+ *
+ */
+class SSTemplateEngine implements TemplateEngine, Flushable
+{
+    use Injectable;
+    use Configurable;
+
+    /**
+     * Default prepended cache key for partial caching
+     */
+    private static string $global_key = '$CurrentReadingMode, $CurrentUser.ID';
+
+    /**
+     * List of models being processed
+     */
+    protected static array $topLevel = [];
+
+    /**
+     * @internal
+     */
+    private static bool $template_cache_flushed = false;
+
+    /**
+     * @internal
+     */
+    private static bool $cacheblock_cache_flushed = false;
+
+    private ?CacheInterface $partialCacheStore = null;
+
+    private ?TemplateParser $parser = null;
+
+    /**
+     * A template or pool of candidate templates to choose from.
+     */
+    private string|array $templateCandidates = [];
+
+    /**
+     * Absolute path to chosen template file which will be used in the call to render()
+     */
+    private ?string $chosen = null;
+
+    /**
+     * Templates to use when looking up 'Layout' or 'Content'
+     */
+    private array $subTemplates = [];
+
+    public function __construct(string|array $templateCandidates = [])
+    {
+        if (!empty($templateCandidates)) {
+            $this->setTemplate($templateCandidates);
+        }
+    }
+
+    /**
+     * Execute the given template, passing it the given data.
+     * Used by the <% include %> template tag to process included templates.
+     *
+     * @param array $overlay Associative array of fields (e.g. args into an include template) to inject into the
+     * template as properties. These override properties and methods with the same name from $data and from global
+     * template providers.
+     */
+    public static function execute_template(array|string $template, ViewLayerData $data, array $overlay = [], ?SSViewer_Scope $scope = null): string
+    {
+        $engine = static::create($template);
+        return $engine->render($data, $overlay, $scope);
+    }
+
+    /**
+     * Triggered early in the request when someone requests a flush.
+     */
+    public static function flush(): void
+    {
+        SSTemplateEngine::flushTemplateCache(true);
+        SSTemplateEngine::flushCacheBlockCache(true);
+    }
+
+    /**
+     * Clears all parsed template files in the cache folder.
+     *
+     * @param bool $force Set this to true to force a re-flush. If left to false, flushing
+     * will only be performed once a request.
+     */
+    public static function flushTemplateCache(bool $force = false): void
+    {
+        if (!SSTemplateEngine::$template_cache_flushed || $force) {
+            $dir = dir(TEMP_PATH);
+            while (false !== ($file = $dir->read())) {
+                if (strstr($file ?? '', '.cache')) {
+                    unlink(TEMP_PATH . DIRECTORY_SEPARATOR . $file);
+                }
+            }
+            SSTemplateEngine::$template_cache_flushed = true;
+        }
+    }
+
+    /**
+     * Clears all partial cache blocks.
+     *
+     * @param bool $force Set this to true to force a re-flush. If left to false, flushing
+     * will only be performed once a request.
+     */
+    public static function flushCacheBlockCache(bool $force = false): void
+    {
+        if (!SSTemplateEngine::$cacheblock_cache_flushed || $force) {
+            $cache = Injector::inst()->get(CacheInterface::class . '.cacheblock');
+            $cache->clear();
+            SSTemplateEngine::$cacheblock_cache_flushed = true;
+        }
+    }
+
+    public function hasTemplate(array|string $templateCandidates): bool
+    {
+        return (bool) $this->findTemplate($templateCandidates);
+    }
+
+    public function renderString(string $template, ViewLayerData $model, array $overlay = [], bool $cache = true): string
+    {
+        $hash = sha1($template);
+        $cacheFile = TEMP_PATH . DIRECTORY_SEPARATOR . ".cache.$hash";
+
+        // Generate a file whether we're caching or not.
+        // This is an inefficiency that's required due to the way rendered templates get processed.
+        if (!file_exists($cacheFile ?? '') || isset($_GET['flush'])) {
+            $content = $this->parseTemplateContent($template, "string sha1=$hash");
+            $fh = fopen($cacheFile ?? '', 'w');
+            fwrite($fh, $content ?? '');
+            fclose($fh);
+        }
+
+        $output = $this->includeGeneratedTemplate($cacheFile, $model, $overlay, []);
+
+        if (!$cache) {
+            unlink($cacheFile ?? '');
+        }
+
+        return $output;
+    }
+
+    public function render(ViewLayerData $model, array $overlay = [], ?SSViewer_Scope $scope = null): string
+    {
+        SSTemplateEngine::$topLevel[] = $model;
+        $template = $this->chosen;
+
+        // If there's no template, throw an exception
+        if (!$template) {
+            if (empty($this->templateCandidates)) {
+                throw new MissingTemplateException(
+                    'No template to render. '
+                    . 'Try calling setTemplate() or passing template candidates into the constructor.'
+                );
+            }
+            $message = 'None of the following templates could be found: ';
+            $message .= print_r($this->templateCandidates, true);
+            $themes = SSViewer::get_themes();
+            if (!$themes) {
+                $message .= ' (no theme in use)';
+            } else {
+                $message .= ' in themes "' . print_r($themes, true) . '"';
+            }
+            throw new MissingTemplateException($message);
+        }
+
+        $cacheFile = TEMP_PATH . DIRECTORY_SEPARATOR . '.cache'
+            . str_replace(['\\','/',':'], '.', Director::makeRelative(realpath($template ?? '')) ?? '');
+        $lastEdited = filemtime($template ?? '');
+
+        if (!file_exists($cacheFile ?? '') || filemtime($cacheFile ?? '') < $lastEdited) {
+            $content = file_get_contents($template ?? '');
+            $content = $this->parseTemplateContent($content, $template);
+
+            $fh = fopen($cacheFile ?? '', 'w');
+            fwrite($fh, $content ?? '');
+            fclose($fh);
+        }
+
+        $underlay = ['I18NNamespace' => basename($template ?? '')];
+
+        // Makes the rendered sub-templates available on the parent model,
+        // through $Content and $Layout placeholders.
+        foreach (['Content', 'Layout'] as $subtemplate) {
+            // Detect sub-template to use
+            $sub = $this->getSubtemplateFor($subtemplate);
+            if (!$sub) {
+                continue;
+            }
+
+            // Create lazy-evaluated underlay for this subtemplate
+            $underlay[$subtemplate] = function () use ($model, $overlay, $sub) {
+                $subtemplateViewer = clone $this;
+                // Select the right template and render if the template exists
+                $subtemplateViewer->setTemplate($sub);
+                // If there's no template for that underlay, just don't render anything.
+                // This mirrors how SSViewer_Scope handles null values.
+                if (!$subtemplateViewer->chosen) {
+                    return null;
+                }
+                // Render and wrap in DBHTMLText so it doesn't get escaped
+                return DBHTMLText::create()->setValue($subtemplateViewer->render($model, $overlay));
+            };
+        }
+
+        $output = $this->includeGeneratedTemplate($cacheFile, $model, $overlay, $underlay, $scope);
+
+        array_pop(SSTemplateEngine::$topLevel);
+
+        return $output;
+    }
+
+    public function setTemplate(string|array $templateCandidates): static
+    {
+        $this->templateCandidates = $templateCandidates;
+        $this->chosen = $this->findTemplate($templateCandidates);
+        $this->subTemplates = [];
+        return $this;
+    }
+
+    /**
+     * Set the template parser that will be used in template generation
+     */
+    public function setParser(TemplateParser $parser): static
+    {
+        $this->parser = $parser;
+        return $this;
+    }
+
+    /**
+     * Returns the parser that is set for template generation
+     */
+    public function getParser(): TemplateParser
+    {
+        if (!$this->parser) {
+            $this->setParser(Injector::inst()->get(SSTemplateParser::class));
+        }
+        return $this->parser;
+    }
+
+    /**
+     * Set the cache object to use when storing / retrieving partial cache blocks.
+     */
+    public function setPartialCacheStore(CacheInterface $cache): static
+    {
+        $this->partialCacheStore = $cache;
+        return $this;
+    }
+
+    /**
+     * Get the cache object to use when storing / retrieving partial cache blocks.
+     */
+    public function getPartialCacheStore(): CacheInterface
+    {
+        if (!$this->partialCacheStore) {
+            $this->partialCacheStore = Injector::inst()->get(CacheInterface::class . '.cacheblock');
+        }
+        return $this->partialCacheStore;
+    }
+
+    /**
+     * An internal utility function to set up variables in preparation for including a compiled
+     * template, then do the include
+     *
+     * @param string $cacheFile The path to the file that contains the template compiled to PHP
+     * @param ViewLayerData $model The model to use as the root scope for the template
+     * @param array $overlay Any variables to layer on top of the scope
+     * @param array $underlay Any variables to layer underneath the scope
+     * @param SSViewer_Scope|null $inheritedScope The current scope of a parent template including a sub-template
+     */
+    protected function includeGeneratedTemplate(
+        string $cacheFile,
+        ViewLayerData $model,
+        array $overlay,
+        array $underlay,
+        ?SSViewer_Scope $inheritedScope = null
+    ): string {
+        if (isset($_GET['showtemplate']) && $_GET['showtemplate'] && Permission::check('ADMIN')) {
+            $lines = file($cacheFile ?? '');
+            echo "<h2>Template: $cacheFile</h2>";
+            echo '<pre>';
+            foreach ($lines as $num => $line) {
+                echo str_pad($num+1, 5) . htmlentities($line, ENT_COMPAT, 'UTF-8');
+            }
+            echo '</pre>';
+        }
+
+        $cache = $this->getPartialCacheStore();
+        $scope = new SSViewer_Scope($model, $overlay, $underlay, $inheritedScope);
+        $val = '';
+
+        // Placeholder for values exposed to $cacheFile
+        [$cache, $scope, $val];
+        include($cacheFile);
+
+        return $val;
+    }
+
+    /**
+     * Get the appropriate template to use for the named sub-template, or null if none are appropriate
+     */
+    protected function getSubtemplateFor(string $subtemplate): ?array
+    {
+        // Get explicit subtemplate name
+        if (isset($this->subTemplates[$subtemplate])) {
+            return $this->subTemplates[$subtemplate];
+        }
+
+        // Don't apply sub-templates if type is already specified (e.g. 'Includes')
+        if (isset($this->templateCandidates['type'])) {
+            return null;
+        }
+
+        // Filter out any other typed templates as we can only add, not change type
+        $templates = array_filter(
+            (array) $this->templateCandidates,
+            function ($template) {
+                return !isset($template['type']);
+            }
+        );
+        if (empty($templates)) {
+            return null;
+        }
+
+        // Set type to subtemplate
+        $templates['type'] = $subtemplate;
+        return $templates;
+    }
+
+    /**
+     * Parse given template contents
+     *
+     * @param string $content The template contents
+     * @param string $template The template file name
+     */
+    protected function parseTemplateContent(string $content, string $template = ""): string
+    {
+        return $this->getParser()->compileString(
+            $content,
+            $template,
+            Director::isDev() && SSViewer::config()->uninherited('source_file_comments')
+        );
+    }
+
+    /**
+     * Attempts to find possible candidate templates from a set of template
+     * names from modules, current theme directory and finally the application
+     * folder.
+     *
+     * The template names can be passed in as plain strings, or be in the
+     * format "type/name", where type is the type of template to search for
+     * (e.g. Includes, Layout).
+     *
+     * The results of this method will be cached for future use.
+     *
+     * @param string|array $template Template name, or template spec in array format with the keys
+     * 'type' (type string) and 'templates' (template hierarchy in order of precedence).
+     * If 'templates' is omitted then any other item in the array will be treated as the template
+     * list, or list of templates each in the array spec given.
+     * Templates with an .ss extension will be treated as file paths, and will bypass
+     * theme-coupled resolution.
+     * @param array $themes List of themes to use to resolve themes. Defaults to {@see SSViewer::get_themes()}
+     * @return string Absolute path to resolved template file, or null if not resolved.
+     * File location will be in the format themes/<theme>/templates/<directories>/<type>/<basename>.ss
+     * Note that type (e.g. 'Layout') is not the root level directory under 'templates'.
+     * Returns null if no template was found.
+     */
+    private function findTemplate(string|array $template, array $themes = []): ?string
+    {
+        if (empty($themes)) {
+            $themes = SSViewer::get_themes();
+        }
+
+        $cacheAdapter = ThemeResourceLoader::inst()->getCache();
+        $cacheKey = 'findTemplate_' . md5(json_encode($template) . json_encode($themes));
+
+        // Look for a cached result for this data set
+        if ($cacheAdapter->has($cacheKey)) {
+            return $cacheAdapter->get($cacheKey);
+        }
+
+        $type = '';
+        if (is_array($template)) {
+            // Check if templates has type specified
+            if (array_key_exists('type', $template ?? [])) {
+                $type = $template['type'];
+                unset($template['type']);
+            }
+            // Templates are either nested in 'templates' or just the rest of the list
+            $templateList = array_key_exists('templates', $template ?? []) ? $template['templates'] : $template;
+        } else {
+            $templateList = [$template];
+        }
+
+        $themePaths = ThemeResourceLoader::inst()->getThemePaths($themes);
+        $baseDir = ThemeResourceLoader::inst()->getBase();
+        foreach ($templateList as $i => $template) {
+            // Check if passed list of templates in array format
+            if (is_array($template)) {
+                $path = $this->findTemplate($template, $themes);
+                if ($path) {
+                    $cacheAdapter->set($cacheKey, $path);
+                    return $path;
+                }
+                continue;
+            }
+
+            // If we have an .ss extension, this is a path, not a template name. We should
+            // pass in templates without extensions in order for template manifest to find
+            // files dynamically.
+            if (substr($template ?? '', -3) == '.ss' && file_exists($template ?? '')) {
+                $cacheAdapter->set($cacheKey, $template);
+                return $template;
+            }
+
+            // Check string template identifier
+            $template = str_replace('\\', '/', $template ?? '');
+            $parts = explode('/', $template ?? '');
+
+            $tail = array_pop($parts);
+            $head = implode('/', $parts);
+            foreach ($themePaths as $themePath) {
+                // Join path
+                $pathParts = [ $baseDir, $themePath, 'templates', $head, $type, $tail ];
+                try {
+                    $path = Path::join($pathParts) . '.ss';
+                    if (file_exists($path ?? '')) {
+                        $cacheAdapter->set($cacheKey, $path);
+                        return $path;
+                    }
+                } catch (InvalidArgumentException $e) {
+                    // No-op
+                }
+            }
+        }
+
+        // No template found
+        $cacheAdapter->set($cacheKey, null);
+        return null;
+    }
+}

src/View/SSTemplateParser.peg

@@ -16,15 +16,6 @@ this is: framework/src/View):
 
 See the php-peg docs for more information on the parser format, and how to convert this file into SSTemplateParser.php
 
-TODO:
-    Template comments - <%-- --%>
-    $Iteration
-    Partial cache blocks
-    i18n - we dont support then deprecated _t() or sprintf(_t()) methods; or the new <% t %> block yet
-    Add with and loop blocks
-    Add Up and Top
-    More error detection?
-
 This comment will not appear in the output
 */
 
@@ -247,7 +238,7 @@ class SSTemplateParser extends Parser implements TemplateParser
         }
 
         $res['php'] .= ($sub['ArgumentMode'] == 'default') ? $sub['string_php'] :
-            str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '');
+            str_replace('$$FINAL', 'getValueAsArgument', $sub['php'] ?? '');
     }
 
     /*!*
@@ -274,8 +265,8 @@ class SSTemplateParser extends Parser implements TemplateParser
     }
 
     /**
-     * The basic generated PHP of LookupStep and LastLookupStep is the same, except that LookupStep calls 'obj' to
+     * The basic generated PHP of LookupStep and LastLookupStep is the same, except that LookupStep calls 'scopeToIntermediateValue' to
-     * get the next ModelData in the sequence, and LastLookupStep calls different methods (XML_val, hasValue, obj)
+     * get the next ModelData in the sequence, and LastLookupStep calls different methods (getOutputValue, hasValue, scopeToIntermediateValue)
      * depending on the context the lookup is used in.
      */
     function Lookup_AddLookupStep(&$res, $sub, $method)
@@ -286,15 +277,17 @@ class SSTemplateParser extends Parser implements TemplateParser
 
         if (isset($sub['Call']['CallArguments']) && isset($sub['Call']['CallArguments']['php'])) {
             $arguments = $sub['Call']['CallArguments']['php'];
-            $res['php'] .= "->$method('$property', [$arguments], true)";
+            $type = ViewLayerData::TYPE_METHOD;
+            $res['php'] .= "->$method('$property', [$arguments], '$type')";
         } else {
-            $res['php'] .= "->$method('$property', [], true)";
+            $type = ViewLayerData::TYPE_PROPERTY;
+            $res['php'] .= "->$method('$property', [], '$type')";
         }
     }
 
     function Lookup_LookupStep(&$res, $sub)
     {
-        $this->Lookup_AddLookupStep($res, $sub, 'obj');
+        $this->Lookup_AddLookupStep($res, $sub, 'scopeToIntermediateValue');
     }
 
     function Lookup_LastLookupStep(&$res, $sub)
@@ -357,7 +350,7 @@ class SSTemplateParser extends Parser implements TemplateParser
 
     function InjectionVariables_Argument(&$res, $sub)
     {
-        $res['php'] .= str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '') . ',';
+        $res['php'] .= str_replace('$$FINAL', 'getOutputValue', $sub['php'] ?? '') . ',';
     }
 
     function InjectionVariables__finalise(&$res)
@@ -392,7 +385,7 @@ class SSTemplateParser extends Parser implements TemplateParser
     */
     function Injection_STR(&$res, $sub)
     {
-        $res['php'] = '$val .= '. str_replace('$$FINAL', 'XML_val', $sub['Lookup']['php'] ?? '') . ';';
+        $res['php'] = '$val .= '. str_replace('$$FINAL', 'getOutputValue', $sub['Lookup']['php'] ?? '') . ';';
     }
 
     /*!*
@@ -535,10 +528,10 @@ class SSTemplateParser extends Parser implements TemplateParser
             if (!empty($res['php'])) {
                 $res['php'] .= $sub['string_php'];
             } else {
-                $res['php'] = str_replace('$$FINAL', 'XML_val', $sub['lookup_php'] ?? '');
+                $res['php'] = str_replace('$$FINAL', 'getOutputValue', $sub['lookup_php'] ?? '');
             }
         } else {
-            $res['php'] .= str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '');
+            $res['php'] .= str_replace('$$FINAL', 'getOutputValue', $sub['php'] ?? '');
         }
     }
 
@@ -566,8 +559,6 @@ class SSTemplateParser extends Parser implements TemplateParser
             $res['php'] .= '((bool)'.$sub['php'].')';
         } else {
             $php = ($sub['ArgumentMode'] == 'default' ? $sub['lookup_php'] : $sub['php']);
-            // TODO: kinda hacky - maybe we need a way to pass state down the parse chain so
-            // Lookup_LastLookupStep and Argument_BareWord can produce hasValue instead of XML_val
             $res['php'] .= str_replace('$$FINAL', 'hasValue', $php ?? '');
         }
     }
@@ -697,7 +688,7 @@ class SSTemplateParser extends Parser implements TemplateParser
             $res['php'] = '';
         }
 
-        $res['php'] .= str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '');
+        $res['php'] .= str_replace('$$FINAL', 'getOutputValue', $sub['php'] ?? '');
     }
 
     /*!*
@@ -779,7 +770,7 @@ class SSTemplateParser extends Parser implements TemplateParser
         // the passed cache key, the block index, and the sha hash of the template.
         $res['php'] .= '$keyExpression = function() use ($scope, $cache) {' . PHP_EOL;
         $res['php'] .= '$val = \'\';' . PHP_EOL;
-        if ($globalKey = SSViewer::config()->get('global_key')) {
+        if ($globalKey = SSTemplateEngine::config()->get('global_key')) {
             // Embed the code necessary to evaluate the globalKey directly into the template,
             // so that SSTemplateParser only needs to be called during template regeneration.
             // Warning: If the global key is changed, it's necessary to flush the template cache.
@@ -827,7 +818,7 @@ class SSTemplateParser extends Parser implements TemplateParser
     {
         $entity = $sub['String']['text'];
         if (strpos($entity ?? '', '.') === false) {
-            $res['php'] .= "\$scope->XML_val('I18NNamespace').'.$entity'";
+            $res['php'] .= "\$scope->getOutputValue('I18NNamespace').'.$entity'";
         } else {
             $res['php'] .= "'$entity'";
         }
@@ -915,7 +906,7 @@ class SSTemplateParser extends Parser implements TemplateParser
                 break;
 
             default:
-                $res['php'] .= str_replace('$$FINAL', 'obj', $sub['php'] ?? '') . '->self()';
+                $res['php'] .= str_replace('$$FINAL', 'scopeToIntermediateValue', $sub['php'] ?? '') . '->self()';
                 break;
         }
     }
@@ -947,8 +938,8 @@ class SSTemplateParser extends Parser implements TemplateParser
         $template = $res['template'];
         $arguments = $res['arguments'];
 
-        // Note: 'type' here is important to disable subTemplates in SSViewer::getSubtemplateFor()
+        // Note: 'type' here is important to disable subTemplates in SSTemplateEngine::getSubtemplateFor()
-        $res['php'] = '$val .= \\SilverStripe\\View\\SSViewer::execute_template([["type" => "Includes", '.$template.'], '.$template.'], $scope->getItem(), [' .
+        $res['php'] = '$val .= \\SilverStripe\\View\\SSTemplateEngine::execute_template([["type" => "Includes", '.$template.'], '.$template.'], $scope->getCurrentItem(), [' .
             implode(',', $arguments)."], \$scope, true);\n";
 
         if ($this->includeDebuggingComments) { // Add include filename comments on dev sites
@@ -1037,7 +1028,7 @@ class SSTemplateParser extends Parser implements TemplateParser
 
         // loop without arguments loops on the current scope
         if ($res['ArgumentCount'] == 0) {
-            $on = '$scope->locally()->obj(\'Me\', [], true)';
+            $on = '$scope->locally()->self()';
         } else {    //loop in the normal way
             $arg = $res['Arguments'][0];
             if ($arg['ArgumentMode'] == 'string') {
@@ -1045,13 +1036,13 @@ class SSTemplateParser extends Parser implements TemplateParser
             }
             $on = str_replace(
                 '$$FINAL',
-                'obj',
+                'scopeToIntermediateValue',
                 ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php']
             );
         }
 
         return
-            $on . '; $scope->pushScope(); while (($key = $scope->next()) !== false) {' . PHP_EOL .
+            $on . '; $scope->pushScope(); while ($scope->next() !== false) {' . PHP_EOL .
                 $res['Template']['php'] . PHP_EOL .
             '}; $scope->popScope(); ';
     }
@@ -1071,7 +1062,7 @@ class SSTemplateParser extends Parser implements TemplateParser
             throw new SSTemplateParseException('Control block cant take string as argument.', $this);
         }
 
-        $on = str_replace('$$FINAL', 'obj', ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php']);
+        $on = str_replace('$$FINAL', 'scopeToIntermediateValue', ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php']);
         return
             $on . '; $scope->pushScope();' . PHP_EOL .
                 $res['Template']['php'] . PHP_EOL .
@@ -1116,27 +1107,6 @@ class SSTemplateParser extends Parser implements TemplateParser
         }
     }
 
-    /**
-     * This is an open block handler, for the <% debug %> utility tag
-     */
-    function OpenBlock_Handle_Debug(&$res)
-    {
-        if ($res['ArgumentCount'] == 0) {
-            return '$scope->debug();';
-        } elseif ($res['ArgumentCount'] == 1) {
-            $arg = $res['Arguments'][0];
-
-            if ($arg['ArgumentMode'] == 'string') {
-                return 'Debug::show('.$arg['php'].');';
-            }
-
-            $php = ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php'];
-            return '$val .= Debug::show('.str_replace('FINALGET!', 'cachedCall', $php ?? '').');';
-        } else {
-            throw new SSTemplateParseException('Debug takes 0 or 1 argument only.', $this);
-        }
-    }
-
     /**
      * This is an open block handler, for the <% base_tag %> tag
      */
@@ -1145,7 +1115,9 @@ class SSTemplateParser extends Parser implements TemplateParser
         if ($res['ArgumentCount'] != 0) {
             throw new SSTemplateParseException('Base_tag takes no arguments', $this);
         }
-        return '$val .= \\SilverStripe\\View\\SSViewer::get_base_tag($val);';
+        $code = '$isXhtml = preg_match(\'/<!DOCTYPE[^>]+xhtml/i\', $val);';
+        $code .= PHP_EOL . '$val .= \\SilverStripe\\View\\SSViewer::getBaseTag($isXhtml);';
+        return $code;
     }
 
     /**
@@ -1297,9 +1269,9 @@ EOC;
      * @param string $templateName The name of the template, normally the filename the template source was loaded from
      * @param bool $includeDebuggingComments True is debugging comments should be included in the output
      * @param bool $topTemplate True if this is a top template, false if it's just a template
-     * @return mixed|string The php that, when executed (via include or exec) will behave as per the template source
+     * @return string The php that, when executed (via include or exec) will behave as per the template source
      */
-    public function compileString($string, $templateName = "", $includeDebuggingComments = false, $topTemplate = true)
+    public function compileString(string $string, string $templateName = "", bool $includeDebuggingComments = false, bool $topTemplate = true): string
     {
         if (!trim($string ?? '')) {
             $code = '';
@@ -1308,8 +1280,7 @@ EOC;
 
             $this->includeDebuggingComments = $includeDebuggingComments;
 
-            // Ignore UTF8 BOM at beginning of string. TODO: Confirm this is needed, make sure SSViewer handles UTF
+            // Ignore UTF8 BOM at beginning of string.
-            // (and other encodings) properly
             if (substr($string ?? '', 0, 3) == pack("CCC", 0xef, 0xbb, 0xbf)) {
                 $this->pos = 3;
             }
@@ -1341,7 +1312,7 @@ EOC;
      * @param string $templateName
      * @return string $code
      */
-    protected function includeDebuggingComments($code, $templateName)
+    protected function includeDebuggingComments(string $code, string $templateName): string
     {
         // If this template contains a doctype, put it right after it,
         // if not, put it after the <html> tag to avoid IE glitches
@@ -1375,11 +1346,10 @@ EOC;
      * Compiles some file that contains template source code, and returns the php code that will execute as per that
      * source
      *
-     * @static
+     * @param string $template - A file path that contains template source code
-     * @param  $template - A file path that contains template source code
+     * @return string - The php that, when executed (via include or exec) will behave as per the template source
-     * @return mixed|string - The php that, when executed (via include or exec) will behave as per the template source
      */
-    public function compileFile($template)
+    public function compileFile(string $template): string
     {
         return $this->compileString(file_get_contents($template ?? ''), $template);
     }

src/View/SSTemplateParser.php

@@ -572,7 +572,7 @@ class SSTemplateParser extends Parser implements TemplateParser
         }
 
         $res['php'] .= ($sub['ArgumentMode'] == 'default') ? $sub['string_php'] :
-            str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '');
+            str_replace('$$FINAL', 'getValueAsArgument', $sub['php'] ?? '');
     }
 
     /* Call: Method:Word ( "(" < :CallArguments? > ")" )? */
@@ -765,8 +765,8 @@ class SSTemplateParser extends Parser implements TemplateParser
     }
 
     /**
-     * The basic generated PHP of LookupStep and LastLookupStep is the same, except that LookupStep calls 'obj' to
+     * The basic generated PHP of LookupStep and LastLookupStep is the same, except that LookupStep calls 'scopeToIntermediateValue' to
-     * get the next ModelData in the sequence, and LastLookupStep calls different methods (XML_val, hasValue, obj)
+     * get the next ModelData in the sequence, and LastLookupStep calls different methods (getOutputValue, hasValue, scopeToIntermediateValue)
      * depending on the context the lookup is used in.
      */
     function Lookup_AddLookupStep(&$res, $sub, $method)
@@ -777,15 +777,17 @@ class SSTemplateParser extends Parser implements TemplateParser
 
         if (isset($sub['Call']['CallArguments']) && isset($sub['Call']['CallArguments']['php'])) {
             $arguments = $sub['Call']['CallArguments']['php'];
-            $res['php'] .= "->$method('$property', [$arguments], true)";
+            $type = ViewLayerData::TYPE_METHOD;
+            $res['php'] .= "->$method('$property', [$arguments], '$type')";
         } else {
-            $res['php'] .= "->$method('$property', [], true)";
+            $type = ViewLayerData::TYPE_PROPERTY;
+            $res['php'] .= "->$method('$property', [], '$type')";
         }
     }
 
     function Lookup_LookupStep(&$res, $sub)
     {
-        $this->Lookup_AddLookupStep($res, $sub, 'obj');
+        $this->Lookup_AddLookupStep($res, $sub, 'scopeToIntermediateValue');
     }
 
     function Lookup_LastLookupStep(&$res, $sub)
@@ -1009,7 +1011,7 @@ class SSTemplateParser extends Parser implements TemplateParser
 
     function InjectionVariables_Argument(&$res, $sub)
     {
-        $res['php'] .= str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '') . ',';
+        $res['php'] .= str_replace('$$FINAL', 'getOutputValue', $sub['php'] ?? '') . ',';
     }
 
     function InjectionVariables__finalise(&$res)
@@ -1158,7 +1160,7 @@ class SSTemplateParser extends Parser implements TemplateParser
 
     function Injection_STR(&$res, $sub)
     {
-        $res['php'] = '$val .= '. str_replace('$$FINAL', 'XML_val', $sub['Lookup']['php'] ?? '') . ';';
+        $res['php'] = '$val .= '. str_replace('$$FINAL', 'getOutputValue', $sub['Lookup']['php'] ?? '') . ';';
     }
 
     /* DollarMarkedLookup: SimpleInjection */
@@ -1818,10 +1820,10 @@ class SSTemplateParser extends Parser implements TemplateParser
             if (!empty($res['php'])) {
                 $res['php'] .= $sub['string_php'];
             } else {
-                $res['php'] = str_replace('$$FINAL', 'XML_val', $sub['lookup_php'] ?? '');
+                $res['php'] = str_replace('$$FINAL', 'getOutputValue', $sub['lookup_php'] ?? '');
             }
         } else {
-            $res['php'] .= str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '');
+            $res['php'] .= str_replace('$$FINAL', 'getOutputValue', $sub['php'] ?? '');
         }
     }
 
@@ -1886,8 +1888,6 @@ class SSTemplateParser extends Parser implements TemplateParser
             $res['php'] .= '((bool)'.$sub['php'].')';
         } else {
             $php = ($sub['ArgumentMode'] == 'default' ? $sub['lookup_php'] : $sub['php']);
-            // TODO: kinda hacky - maybe we need a way to pass state down the parse chain so
-            // Lookup_LastLookupStep and Argument_BareWord can produce hasValue instead of XML_val
             $res['php'] .= str_replace('$$FINAL', 'hasValue', $php ?? '');
         }
     }
@@ -2470,7 +2470,7 @@ class SSTemplateParser extends Parser implements TemplateParser
             $res['php'] = '';
         }
 
-        $res['php'] .= str_replace('$$FINAL', 'XML_val', $sub['php'] ?? '');
+        $res['php'] .= str_replace('$$FINAL', 'getOutputValue', $sub['php'] ?? '');
     }
 
     /* CacheBlockTemplate: (Comment | Translate | If | Require |    OldI18NTag | Include | ClosedBlock |
@@ -3428,7 +3428,7 @@ class SSTemplateParser extends Parser implements TemplateParser
         // the passed cache key, the block index, and the sha hash of the template.
         $res['php'] .= '$keyExpression = function() use ($scope, $cache) {' . PHP_EOL;
         $res['php'] .= '$val = \'\';' . PHP_EOL;
-        if ($globalKey = SSViewer::config()->get('global_key')) {
+        if ($globalKey = SSTemplateEngine::config()->get('global_key')) {
             // Embed the code necessary to evaluate the globalKey directly into the template,
             // so that SSTemplateParser only needs to be called during template regeneration.
             // Warning: If the global key is changed, it's necessary to flush the template cache.
@@ -3587,7 +3587,7 @@ class SSTemplateParser extends Parser implements TemplateParser
     {
         $entity = $sub['String']['text'];
         if (strpos($entity ?? '', '.') === false) {
-            $res['php'] .= "\$scope->XML_val('I18NNamespace').'.$entity'";
+            $res['php'] .= "\$scope->getOutputValue('I18NNamespace').'.$entity'";
         } else {
             $res['php'] .= "'$entity'";
         }
@@ -3792,7 +3792,7 @@ class SSTemplateParser extends Parser implements TemplateParser
                 break;
 
             default:
-                $res['php'] .= str_replace('$$FINAL', 'obj', $sub['php'] ?? '') . '->self()';
+                $res['php'] .= str_replace('$$FINAL', 'scopeToIntermediateValue', $sub['php'] ?? '') . '->self()';
                 break;
         }
     }
@@ -3896,8 +3896,8 @@ class SSTemplateParser extends Parser implements TemplateParser
         $template = $res['template'];
         $arguments = $res['arguments'];
 
-        // Note: 'type' here is important to disable subTemplates in SSViewer::getSubtemplateFor()
+        // Note: 'type' here is important to disable subTemplates in SSTemplateEngine::getSubtemplateFor()
-        $res['php'] = '$val .= \\SilverStripe\\View\\SSViewer::execute_template([["type" => "Includes", '.$template.'], '.$template.'], $scope->getItem(), [' .
+        $res['php'] = '$val .= \\SilverStripe\\View\\SSTemplateEngine::execute_template([["type" => "Includes", '.$template.'], '.$template.'], $scope->getCurrentItem(), [' .
             implode(',', $arguments)."], \$scope, true);\n";
 
         if ($this->includeDebuggingComments) { // Add include filename comments on dev sites
@@ -4265,7 +4265,7 @@ class SSTemplateParser extends Parser implements TemplateParser
 
         // loop without arguments loops on the current scope
         if ($res['ArgumentCount'] == 0) {
-            $on = '$scope->locally()->obj(\'Me\', [], true)';
+            $on = '$scope->locally()->self()';
         } else {    //loop in the normal way
             $arg = $res['Arguments'][0];
             if ($arg['ArgumentMode'] == 'string') {
@@ -4273,13 +4273,13 @@ class SSTemplateParser extends Parser implements TemplateParser
             }
             $on = str_replace(
                 '$$FINAL',
-                'obj',
+                'scopeToIntermediateValue',
                 ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php']
             );
         }
 
         return
-            $on . '; $scope->pushScope(); while (($key = $scope->next()) !== false) {' . PHP_EOL .
+            $on . '; $scope->pushScope(); while ($scope->next() !== false) {' . PHP_EOL .
                 $res['Template']['php'] . PHP_EOL .
             '}; $scope->popScope(); ';
     }
@@ -4299,7 +4299,7 @@ class SSTemplateParser extends Parser implements TemplateParser
             throw new SSTemplateParseException('Control block cant take string as argument.', $this);
         }
 
-        $on = str_replace('$$FINAL', 'obj', ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php']);
+        $on = str_replace('$$FINAL', 'scopeToIntermediateValue', ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php']);
         return
             $on . '; $scope->pushScope();' . PHP_EOL .
                 $res['Template']['php'] . PHP_EOL .
@@ -4401,27 +4401,6 @@ class SSTemplateParser extends Parser implements TemplateParser
         }
     }
 
-    /**
-     * This is an open block handler, for the <% debug %> utility tag
-     */
-    function OpenBlock_Handle_Debug(&$res)
-    {
-        if ($res['ArgumentCount'] == 0) {
-            return '$scope->debug();';
-        } elseif ($res['ArgumentCount'] == 1) {
-            $arg = $res['Arguments'][0];
-
-            if ($arg['ArgumentMode'] == 'string') {
-                return 'Debug::show('.$arg['php'].');';
-            }
-
-            $php = ($arg['ArgumentMode'] == 'default') ? $arg['lookup_php'] : $arg['php'];
-            return '$val .= Debug::show('.str_replace('FINALGET!', 'cachedCall', $php ?? '').');';
-        } else {
-            throw new SSTemplateParseException('Debug takes 0 or 1 argument only.', $this);
-        }
-    }
-
     /**
      * This is an open block handler, for the <% base_tag %> tag
      */
@@ -4430,7 +4409,9 @@ class SSTemplateParser extends Parser implements TemplateParser
         if ($res['ArgumentCount'] != 0) {
             throw new SSTemplateParseException('Base_tag takes no arguments', $this);
         }
-        return '$val .= \\SilverStripe\\View\\SSViewer::get_base_tag($val);';
+        $code = '$isXhtml = preg_match(\'/<!DOCTYPE[^>]+xhtml/i\', $val);';
+        $code .= PHP_EOL . '$val .= \\SilverStripe\\View\\SSViewer::getBaseTag($isXhtml);';
+        return $code;
     }
 
     /**
@@ -5321,9 +5302,9 @@ EOC;
      * @param string $templateName The name of the template, normally the filename the template source was loaded from
      * @param bool $includeDebuggingComments True is debugging comments should be included in the output
      * @param bool $topTemplate True if this is a top template, false if it's just a template
-     * @return mixed|string The php that, when executed (via include or exec) will behave as per the template source
+     * @return string The php that, when executed (via include or exec) will behave as per the template source
      */
-    public function compileString($string, $templateName = "", $includeDebuggingComments = false, $topTemplate = true)
+    public function compileString(string $string, string $templateName = "", bool $includeDebuggingComments = false, bool $topTemplate = true): string
     {
         if (!trim($string ?? '')) {
             $code = '';
@@ -5332,8 +5313,7 @@ EOC;
 
             $this->includeDebuggingComments = $includeDebuggingComments;
 
-            // Ignore UTF8 BOM at beginning of string. TODO: Confirm this is needed, make sure SSViewer handles UTF
+            // Ignore UTF8 BOM at beginning of string.
-            // (and other encodings) properly
             if (substr($string ?? '', 0, 3) == pack("CCC", 0xef, 0xbb, 0xbf)) {
                 $this->pos = 3;
             }
@@ -5365,7 +5345,7 @@ EOC;
      * @param string $templateName
      * @return string $code
      */
-    protected function includeDebuggingComments($code, $templateName)
+    protected function includeDebuggingComments(string $code, string $templateName): string
     {
         // If this template contains a doctype, put it right after it,
         // if not, put it after the <html> tag to avoid IE glitches
@@ -5399,11 +5379,10 @@ EOC;
      * Compiles some file that contains template source code, and returns the php code that will execute as per that
      * source
      *
-     * @static
+     * @param string $template - A file path that contains template source code
-     * @param  $template - A file path that contains template source code
+     * @return string - The php that, when executed (via include or exec) will behave as per the template source
-     * @return mixed|string - The php that, when executed (via include or exec) will behave as per the template source
      */
-    public function compileFile($template)
+    public function compileFile(string $template): string
     {
         return $this->compileString(file_get_contents($template ?? ''), $template);
     }

src/View/SSViewer.php

@@ -5,41 +5,20 @@ namespace SilverStripe\View;
 use SilverStripe\Core\Config\Config;
 use SilverStripe\Core\Config\Configurable;
 use SilverStripe\Core\ClassInfo;
-use Psr\SimpleCache\CacheInterface;
 use SilverStripe\Core\Convert;
-use SilverStripe\Core\Flushable;
-use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Core\Injector\Injectable;
 use SilverStripe\Control\Director;
 use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\ORM\FieldType\DBHTMLText;
-use SilverStripe\Security\Permission;
 use InvalidArgumentException;
-use SilverStripe\Model\ModelData;
+use SilverStripe\Core\Injector\Injector;
 
 /**
- * Parses a template file with an *.ss file extension.
+ * Class that manages themes and interacts with TemplateEngine classes to render templates.
  *
- * In addition to a full template in the templates/ folder, a template in
+ * Ensures rendered templates are normalised, e.g have appropriate resources from the Requirements API.
- * templates/Content or templates/Layout will be rendered into $Content and
- * $Layout, respectively.
- *
- * A single template can be parsed by multiple nested {@link SSViewer} instances
- * through $Layout/$Content placeholders, as well as <% include MyTemplateFile %> template commands.
- *
- * <b>Themes</b>
- *
- * See http://doc.silverstripe.org/themes and http://doc.silverstripe.org/themes:developing
- *
- * <b>Caching</b>
- *
- * Compiled templates are cached via {@link Cache}, usually on the filesystem.
- * If you put ?flush=1 on your URL, it will force the template to be recompiled.
- *
- * @see http://doc.silverstripe.org/themes
- * @see http://doc.silverstripe.org/themes:developing
  */
-class SSViewer implements Flushable
+class SSViewer
 {
     use Configurable;
     use Injectable;
@@ -57,18 +36,8 @@ class SSViewer implements Flushable
     /**
      * A list (highest priority first) of themes to use
      * Only used when {@link $theme_enabled} is set to TRUE.
-     *
-     * @config
-     * @var string
      */
-    private static $themes = [];
+    private static array $themes = [];
-
-    /**
-     * Overridden value of $themes config
-     *
-     * @var array
-     */
-    protected static $current_themes = null;
 
     /**
      * Use the theme. Set to FALSE in order to disable themes,
@@ -76,103 +45,46 @@ class SSViewer implements Flushable
      * such as an administrative interface separate from the website theme.
      * It retains the theme settings to be re-enabled, for example when a website content
      * needs to be rendered from within this administrative interface.
-     *
-     * @config
-     * @var bool
      */
-    private static $theme_enabled = true;
+    private static bool $theme_enabled = true;
 
     /**
-     * Default prepended cache key for partial caching
+     * If true, rendered templates will include comments indicating which template file was used.
-     *
+     * May not be supported for some rendering engines.
-     * @config
-     * @var string
      */
-    private static $global_key = '$CurrentReadingMode, $CurrentUser.ID';
+    private static bool $source_file_comments = false;
-
-    /**
-     * @config
-     * @var bool
-     */
-    private static $source_file_comments = false;
 
     /**
      * Set if hash links should be rewritten
-     *
-     * @config
-     * @var bool
      */
-    private static $rewrite_hash_links = true;
+    private static bool $rewrite_hash_links = true;
+
+    /**
+     * Overridden value of $themes config
+     */
+    protected static array $current_themes = [];
 
     /**
      * Overridden value of rewrite_hash_links config
      *
-     * @var bool
+     * Can be set to "php" to rewrite hash links with PHP executable code.
      */
-    protected static $current_rewrite_hash_links = null;
+    protected static null|bool|string $current_rewrite_hash_links = null;
 
     /**
      * Instance variable to disable rewrite_hash_links (overrides global default)
      * Leave null to use global state.
      *
-     * @var bool|null
+     * Can be set to "php" to rewrite hash links with PHP executable code.
      */
-    protected $rewriteHashlinks = null;
+    protected null|bool|string $rewriteHashlinks = null;
 
     /**
-     * @internal
+     * Determines whether resources from the Requirements API are included in a processed result.
-     * @ignore
      */
-    private static $template_cache_flushed = false;
+    protected bool $includeRequirements = true;
 
-    /**
+    private TemplateEngine $templateEngine;
-     * @internal
-     * @ignore
-     */
-    private static $cacheblock_cache_flushed = false;
-
-    /**
-     * List of items being processed
-     *
-     * @var array
-     */
-    protected static $topLevel = [];
-
-    /**
-     * List of templates to select from
-     *
-     * @var array
-     */
-    protected $templates = null;
-
-    /**
-     * Absolute path to chosen template file
-     *
-     * @var string
-     */
-    protected $chosen = null;
-
-    /**
-     * Templates to use when looking up 'Layout' or 'Content'
-     *
-     * @var array
-     */
-    protected $subTemplates = [];
-
-    /**
-     * @var bool
-     */
-    protected $includeRequirements = true;
-
-    /**
-     * @var TemplateParser
-     */
-    protected $parser;
-
-    /**
-     * @var CacheInterface
-     */
-    protected $partialCacheStore = null;
 
     /**
      * @param string|array $templates If passed as a string with .ss extension, used as the "main" template.
@@ -181,86 +93,41 @@ class SSViewer implements Flushable
      *  <code>
      *  array('MySpecificPage', 'MyPage', 'Page')
      *  </code>
-     * @param TemplateParser $parser
      */
-    public function __construct($templates, TemplateParser $parser = null)
+    public function __construct(string|array $templates, ?TemplateEngine $templateEngine = null)
     {
-        if ($parser) {
+        if ($templateEngine) {
-            $this->setParser($parser);
+            $templateEngine->setTemplate($templates);
-        }
-
-        $this->setTemplate($templates);
-
-        if (!$this->chosen) {
-            $message = 'None of the following templates could be found: ';
-            $message .= print_r($templates, true);
-
-            $themes = SSViewer::get_themes();
-            if (!$themes) {
-                $message .= ' (no theme in use)';
         } else {
-                $message .= ' in themes "' . print_r($themes, true) . '"';
+            $templateEngine = Injector::inst()->create(TemplateEngine::class, $templates);
         }
-
+        $this->setTemplateEngine($templateEngine);
-            user_error($message ?? '', E_USER_WARNING);
-        }
-    }
-
-    /**
-     * Triggered early in the request when someone requests a flush.
-     */
-    public static function flush()
-    {
-        SSViewer::flush_template_cache(true);
-        SSViewer::flush_cacheblock_cache(true);
-    }
-
-    /**
-     * Create a template from a string instead of a .ss file
-     *
-     * @param string $content The template content
-     * @param bool|void $cacheTemplate Whether or not to cache the template from string
-     * @return SSViewer
-     */
-    public static function fromString($content, $cacheTemplate = null)
-    {
-        $viewer = SSViewer_FromString::create($content);
-        if ($cacheTemplate !== null) {
-            $viewer->setCacheTemplate($cacheTemplate);
-        }
-        return $viewer;
     }
 
     /**
      * Assign the list of active themes to apply.
      * If default themes should be included add $default as the last entry.
-     *
-     * @param array $themes
      */
-    public static function set_themes($themes = [])
+    public static function set_themes(array $themes): void
     {
         static::$current_themes = $themes;
     }
 
     /**
      * Add to the list of active themes to apply
-     *
-     * @param array $themes
      */
-    public static function add_themes($themes = [])
+    public static function add_themes(array $themes)
     {
         $currentThemes = SSViewer::get_themes();
         $finalThemes = array_merge($themes, $currentThemes);
         // array_values is used to ensure sequential array keys as array_unique can leave gaps
-        static::set_themes(array_values(array_unique($finalThemes ?? [])));
+        static::set_themes(array_values(array_unique($finalThemes)));
     }
 
     /**
      * Get the list of active themes
-     *
-     * @return array
      */
-    public static function get_themes()
+    public static function get_themes(): array
     {
         $default = [SSViewer::PUBLIC_THEME, SSViewer::DEFAULT_THEME];
 
@@ -270,7 +137,7 @@ class SSViewer implements Flushable
 
         // Explicit list is assigned
         $themes = static::$current_themes;
-        if (!isset($themes)) {
+        if (empty($themes)) {
             $themes = SSViewer::config()->uninherited('themes');
         }
         if ($themes) {
@@ -282,23 +149,26 @@ class SSViewer implements Flushable
 
     /**
      * Traverses the given the given class context looking for candidate template names
-     * which match each item in the class hierarchy. The resulting list of template candidates
+     * which match each item in the class hierarchy.
-     * may or may not exist, but you can invoke {@see SSViewer::chooseTemplate} on any list
+     *
-     * to determine the best candidate based on the current themes.
+     * This method does NOT check the filesystem, so the resulting list of template candidates
+     * may or may not exist - but you can pass these template candidates into the SSViewer
+     * constructor or into a TemplateEngine.
+     *
+     * If you really need know if a template file exists, you can call hasTemplate() on a TemplateEngine.
      *
      * @param string|object $classOrObject Valid class name, or object
-     * @param string $suffix
      * @param string $baseClass Class to halt ancestry search at
-     * @return array
      */
-    public static function get_templates_by_class($classOrObject, $suffix = '', $baseClass = null)
+    public static function get_templates_by_class(
-    {
+        string|object $classOrObject,
+        string $suffix = '',
+        ?string $baseClass = null
+    ): array {
         // Figure out the class name from the supplied context.
-        if (!is_object($classOrObject) && !(
+        if (is_string($classOrObject) && !class_exists($classOrObject ?? '')) {
-            is_string($classOrObject) && class_exists($classOrObject ?? '')
-        )) {
             throw new InvalidArgumentException(
-                'SSViewer::get_templates_by_class() expects a valid class name as its first parameter.'
+                'SSViewer::get_templates_by_class() expects a valid class name or instantiated object as its first parameter.'
             );
         }
 
@@ -314,7 +184,7 @@ class SSViewer implements Flushable
                 $templates[] = $matches['name'] . $suffix;
             }
 
-            if ($baseClass && $class == $baseClass) {
+            if ($baseClass && $class === $baseClass) {
                 break;
             }
         }
@@ -323,26 +193,66 @@ class SSViewer implements Flushable
     }
 
     /**
-     * Get the current item being processed
+     * Get an associative array of names to information about callable template provider methods.
      *
-     * @return ModelData
+     * @var boolean $createObject If true, methods will be called on instantiated objects rather than statically on the class.
      */
-    public static function topLevel()
+    public static function getMethodsFromProvider(string $providerInterface, $methodName, bool $createObject = false): array
     {
-        if (SSViewer::$topLevel) {
+        $implementors = ClassInfo::implementorsOf($providerInterface);
-            return SSViewer::$topLevel[sizeof(SSViewer::$topLevel)-1];
+        if ($implementors) {
+            foreach ($implementors as $implementor) {
+                // Create a new instance of the object for method calls
+                if ($createObject) {
+                    $implementor = new $implementor();
+                    $exposedVariables = $implementor->$methodName();
+                } else {
+                    $exposedVariables = $implementor::$methodName();
                 }
-        return null;
+
+                foreach ($exposedVariables as $varName => $details) {
+                    if (!is_array($details)) {
+                        $details = ['method' => $details];
+                    }
+
+                    // If just a value (and not a key => value pair), use method name for both key and value
+                    if (is_numeric($varName)) {
+                        $varName = $details['method'];
+                    }
+
+                    // Add in a reference to the implementing class (might be a string class name or an instance)
+                    $details['implementor'] = $implementor;
+
+                    // And a callable array
+                    if (isset($details['method'])) {
+                        $details['callable'] = [$implementor, $details['method']];
+                    }
+
+                    // Save with both uppercase & lowercase first letter, so either works
+                    $lcFirst = strtolower($varName[0] ?? '') . substr($varName ?? '', 1);
+                    $result[$lcFirst] = $details;
+                    $result[ucfirst($varName)] = $details;
+                }
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * Get the template engine used to render templates for this viewer
+     */
+    public function getTemplateEngine(): TemplateEngine
+    {
+        return $this->templateEngine;
     }
 
     /**
      * Check if rewrite hash links are enabled on this instance
-     *
-     * @return bool
      */
-    public function getRewriteHashLinks()
+    public function getRewriteHashLinks(): null|bool|string
     {
-        if (isset($this->rewriteHashlinks)) {
+        if ($this->rewriteHashlinks !== null) {
             return $this->rewriteHashlinks;
         }
         return static::getRewriteHashLinksDefault();
@@ -350,11 +260,8 @@ class SSViewer implements Flushable
 
     /**
      * Set if hash links are rewritten for this instance
-     *
-     * @param bool $rewrite
-     * @return $this
      */
-    public function setRewriteHashLinks($rewrite)
+    public function setRewriteHashLinks(null|bool|string $rewrite): static
     {
         $this->rewriteHashlinks = $rewrite;
         return $this;
@@ -362,13 +269,11 @@ class SSViewer implements Flushable
 
     /**
      * Get default value for rewrite hash links for all modules
-     *
-     * @return bool
      */
-    public static function getRewriteHashLinksDefault()
+    public static function getRewriteHashLinksDefault(): null|bool|string
     {
         // Check if config overridden
-        if (isset(static::$current_rewrite_hash_links)) {
+        if (static::$current_rewrite_hash_links !== null) {
             return static::$current_rewrite_hash_links;
         }
         return Config::inst()->get(static::class, 'rewrite_hash_links');
@@ -376,209 +281,29 @@ class SSViewer implements Flushable
 
     /**
      * Set default rewrite hash links
-     *
-     * @param bool $rewrite
      */
-    public static function setRewriteHashLinksDefault($rewrite)
+    public static function setRewriteHashLinksDefault(null|bool|string $rewrite)
     {
         static::$current_rewrite_hash_links = $rewrite;
     }
 
-    /**
-     * @param string|array $templates
-     */
-    public function setTemplate($templates)
-    {
-        $this->templates = $templates;
-        $this->chosen = $this->chooseTemplate($templates);
-        $this->subTemplates = [];
-    }
-
-    /**
-     * Find the template to use for a given list
-     *
-     * @param array|string $templates
-     * @return string
-     */
-    public static function chooseTemplate($templates)
-    {
-        return ThemeResourceLoader::inst()->findTemplate($templates, SSViewer::get_themes());
-    }
-
-    /**
-     * Set the template parser that will be used in template generation
-     *
-     * @param TemplateParser $parser
-     */
-    public function setParser(TemplateParser $parser)
-    {
-        $this->parser = $parser;
-    }
-
-    /**
-     * Returns the parser that is set for template generation
-     *
-     * @return TemplateParser
-     */
-    public function getParser()
-    {
-        if (!$this->parser) {
-            $this->setParser(Injector::inst()->get('SilverStripe\\View\\SSTemplateParser'));
-        }
-        return $this->parser;
-    }
-
-    /**
-     * Returns true if at least one of the listed templates exists.
-     *
-     * @param array|string $templates
-     *
-     * @return bool
-     */
-    public static function hasTemplate($templates)
-    {
-        return (bool)ThemeResourceLoader::inst()->findTemplate($templates, SSViewer::get_themes());
-    }
-
     /**
      * Call this to disable rewriting of <a href="#xxx"> links.  This is useful in Ajax applications.
      * It returns the SSViewer objects, so that you can call new SSViewer("X")->dontRewriteHashlinks()->process();
-     *
-     * @return $this
      */
-    public function dontRewriteHashlinks()
+    public function dontRewriteHashlinks(): static
     {
         return $this->setRewriteHashLinks(false);
     }
 
-    /**
-     * @return string
-     */
-    public function exists()
-    {
-        return $this->chosen;
-    }
-
-    /**
-     * @param string $identifier A template name without '.ss' extension or path
-     * @param string $type The template type, either "main", "Includes" or "Layout"
-     * @return string Full system path to a template file
-     */
-    public static function getTemplateFileByType($identifier, $type = null)
-    {
-        return ThemeResourceLoader::inst()->findTemplate(['type' => $type, $identifier], SSViewer::get_themes());
-    }
-
-    /**
-     * Clears all parsed template files in the cache folder.
-     *
-     * Can only be called once per request (there may be multiple SSViewer instances).
-     *
-     * @param bool $force Set this to true to force a re-flush. If left to false, flushing
-     * may only be performed once a request.
-     */
-    public static function flush_template_cache($force = false)
-    {
-        if (!SSViewer::$template_cache_flushed || $force) {
-            $dir = dir(TEMP_PATH);
-            while (false !== ($file = $dir->read())) {
-                if (strstr($file ?? '', '.cache')) {
-                    unlink(TEMP_PATH . DIRECTORY_SEPARATOR . $file);
-                }
-            }
-            SSViewer::$template_cache_flushed = true;
-        }
-    }
-
-    /**
-     * Clears all partial cache blocks.
-     *
-     * Can only be called once per request (there may be multiple SSViewer instances).
-     *
-     * @param bool $force Set this to true to force a re-flush. If left to false, flushing
-     * may only be performed once a request.
-     */
-    public static function flush_cacheblock_cache($force = false)
-    {
-        if (!SSViewer::$cacheblock_cache_flushed || $force) {
-            $cache = Injector::inst()->get(CacheInterface::class . '.cacheblock');
-            $cache->clear();
-
-
-            SSViewer::$cacheblock_cache_flushed = true;
-        }
-    }
-
-    /**
-     * Set the cache object to use when storing / retrieving partial cache blocks.
-     *
-     * @param CacheInterface $cache
-     */
-    public function setPartialCacheStore($cache)
-    {
-        $this->partialCacheStore = $cache;
-    }
-
-    /**
-     * Get the cache object to use when storing / retrieving partial cache blocks.
-     *
-     * @return CacheInterface
-     */
-    public function getPartialCacheStore()
-    {
-        if ($this->partialCacheStore) {
-            return $this->partialCacheStore;
-        }
-
-        return Injector::inst()->get(CacheInterface::class . '.cacheblock');
-    }
-
     /**
      * Flag whether to include the requirements in this response.
-     *
-     * @param bool $incl
      */
-    public function includeRequirements($incl = true)
+    public function includeRequirements(bool $incl = true)
     {
         $this->includeRequirements = $incl;
     }
 
-    /**
-     * An internal utility function to set up variables in preparation for including a compiled
-     * template, then do the include
-     *
-     * Effectively this is the common code that both SSViewer#process and SSViewer_FromString#process call
-     *
-     * @param string $cacheFile The path to the file that contains the template compiled to PHP
-     * @param ModelData $item The item to use as the root scope for the template
-     * @param array $overlay Any variables to layer on top of the scope
-     * @param array $underlay Any variables to layer underneath the scope
-     * @param ModelData $inheritedScope The current scope of a parent template including a sub-template
-     * @return string The result of executing the template
-     */
-    protected function includeGeneratedTemplate($cacheFile, $item, $overlay, $underlay, $inheritedScope = null)
-    {
-        if (isset($_GET['showtemplate']) && $_GET['showtemplate'] && Permission::check('ADMIN')) {
-            $lines = file($cacheFile ?? '');
-            echo "<h2>Template: $cacheFile</h2>";
-            echo "<pre>";
-            foreach ($lines as $num => $line) {
-                echo str_pad($num+1, 5) . htmlentities($line, ENT_COMPAT, 'UTF-8');
-            }
-            echo "</pre>";
-        }
-
-        $cache = $this->getPartialCacheStore();
-        $scope = new SSViewer_DataPresenter($item, $overlay, $underlay, $inheritedScope);
-        $val = '';
-
-        // Placeholder for values exposed to $cacheFile
-        [$cache, $scope, $val];
-        include($cacheFile);
-
-        return $val;
-    }
-
     /**
      * The process() method handles the "meat" of the template processing.
      *
@@ -590,70 +315,25 @@ class SSViewer implements Flushable
      *
      * Note: You can call this method indirectly by {@link ModelData->renderWith()}.
      *
-     * @param ModelData $item
+     * @param array $overlay Associative array of fields for use in the template.
-     * @param array|null $arguments Arguments to an included template
+     * These will override properties and methods with the same name from $data and from global
-     * @param ModelData $inheritedScope The current scope of a parent template including a sub-template
+     * template providers.
-     * @return DBHTMLText Parsed template output.
      */
-    public function process($item, $arguments = null, $inheritedScope = null)
+    public function process(mixed $item, array $overlay = []): DBHTMLText
     {
+        $item = ViewLayerData::create($item);
         // Set hashlinks and temporarily modify global state
         $rewrite = $this->getRewriteHashLinks();
         $origRewriteDefault = static::getRewriteHashLinksDefault();
         static::setRewriteHashLinksDefault($rewrite);
 
-        SSViewer::$topLevel[] = $item;
+        // Actually render the template
-
+        $output = $this->getTemplateEngine()->render($item, $overlay);
-        $template = $this->chosen;
-
-        $cacheFile = TEMP_PATH . DIRECTORY_SEPARATOR . '.cache'
-            . str_replace(['\\','/',':'], '.', Director::makeRelative(realpath($template ?? '')) ?? '');
-        $lastEdited = filemtime($template ?? '');
-
-        if (!file_exists($cacheFile ?? '') || filemtime($cacheFile ?? '') < $lastEdited) {
-            $content = file_get_contents($template ?? '');
-            $content = $this->parseTemplateContent($content, $template);
-
-            $fh = fopen($cacheFile ?? '', 'w');
-            fwrite($fh, $content ?? '');
-            fclose($fh);
-        }
-
-        $underlay = ['I18NNamespace' => basename($template ?? '')];
-
-        // Makes the rendered sub-templates available on the parent item,
-        // through $Content and $Layout placeholders.
-        foreach (['Content', 'Layout'] as $subtemplate) {
-            // Detect sub-template to use
-            $sub = $this->getSubtemplateFor($subtemplate);
-            if (!$sub) {
-                continue;
-            }
-
-            // Create lazy-evaluated underlay for this subtemplate
-            $underlay[$subtemplate] = function () use ($item, $arguments, $sub) {
-                $subtemplateViewer = clone $this;
-                // Disable requirements - this will be handled by the parent template
-                $subtemplateViewer->includeRequirements(false);
-                // Select the right template
-                $subtemplateViewer->setTemplate($sub);
-
-                // Render if available
-                if ($subtemplateViewer->exists()) {
-                    return $subtemplateViewer->process($item, $arguments);
-                }
-                return null;
-            };
-        }
-
-        $output = $this->includeGeneratedTemplate($cacheFile, $item, $arguments, $underlay, $inheritedScope);
 
         if ($this->includeRequirements) {
             $output = Requirements::includeInHTML($output);
         }
 
-        array_pop(SSViewer::$topLevel);
-
         // If we have our crazy base tag, then fix # links referencing the current page.
         if ($rewrite) {
             if (strpos($output ?? '', '<base') !== false) {
@@ -669,6 +349,8 @@ PHP;
             }
         }
 
+        // Wrap the HTML in a `DBHTMLText`. We use `HTMLFragment` here because shortcodes should
+        // already have been processed, so this avoids unnecessarily trying to process them again
         /** @var DBHTMLText $html */
         $html = DBField::create_field('HTMLFragment', $output);
 
@@ -677,163 +359,31 @@ PHP;
         return $html;
     }
 
-    /**
-     * Get the appropriate template to use for the named sub-template, or null if none are appropriate
-     *
-     * @param string $subtemplate Sub-template to use
-     *
-     * @return array|null
-     */
-    protected function getSubtemplateFor($subtemplate)
-    {
-        // Get explicit subtemplate name
-        if (isset($this->subTemplates[$subtemplate])) {
-            return $this->subTemplates[$subtemplate];
-        }
-
-        // Don't apply sub-templates if type is already specified (e.g. 'Includes')
-        if (isset($this->templates['type'])) {
-            return null;
-        }
-
-        // Filter out any other typed templates as we can only add, not change type
-        $templates = array_filter(
-            (array)$this->templates,
-            function ($template) {
-                return !isset($template['type']);
-            }
-        );
-        if (empty($templates)) {
-            return null;
-        }
-
-        // Set type to subtemplate
-        $templates['type'] = $subtemplate;
-        return $templates;
-    }
-
-    /**
-     * Execute the given template, passing it the given data.
-     * Used by the <% include %> template tag to process templates.
-     *
-     * @param string $template Template name
-     * @param mixed $data Data context
-     * @param array $arguments Additional arguments
-     * @param Object $scope
-     * @param bool $globalRequirements
-     *
-     * @return string Evaluated result
-     */
-    public static function execute_template($template, $data, $arguments = null, $scope = null, $globalRequirements = false)
-    {
-        $v = SSViewer::create($template);
-
-        if ($globalRequirements) {
-            $v->includeRequirements(false);
-        } else {
-            //nest a requirements backend for our template rendering
-            $origBackend = Requirements::backend();
-            Requirements::set_backend(Requirements_Backend::create());
-        }
-        try {
-            return $v->process($data, $arguments, $scope);
-        } finally {
-            if (!$globalRequirements) {
-                Requirements::set_backend($origBackend);
-            }
-        }
-    }
-
-    /**
-     * Execute the evaluated string, passing it the given data.
-     * Used by partial caching to evaluate custom cache keys expressed using
-     * template expressions
-     *
-     * @param string $content Input string
-     * @param mixed $data Data context
-     * @param array $arguments Additional arguments
-     * @param bool $globalRequirements
-     *
-     * @return string Evaluated result
-     */
-    public static function execute_string($content, $data, $arguments = null, $globalRequirements = false)
-    {
-        $v = SSViewer::fromString($content);
-
-        if ($globalRequirements) {
-            $v->includeRequirements(false);
-        } else {
-            //nest a requirements backend for our template rendering
-            $origBackend = Requirements::backend();
-            Requirements::set_backend(Requirements_Backend::create());
-        }
-        try {
-            return $v->process($data, $arguments);
-        } finally {
-            if (!$globalRequirements) {
-                Requirements::set_backend($origBackend);
-            }
-        }
-    }
-
-    /**
-     * Parse given template contents
-     *
-     * @param string $content The template contents
-     * @param string $template The template file name
-     * @return string
-     */
-    public function parseTemplateContent($content, $template = "")
-    {
-        return $this->getParser()->compileString(
-            $content,
-            $template,
-            Director::isDev() && SSViewer::config()->uninherited('source_file_comments')
-        );
-    }
-
-    /**
-     * Returns the filenames of the template that will be rendered.  It is a map that may contain
-     * 'Content' & 'Layout', and will have to contain 'main'
-     *
-     * @return array
-     */
-    public function templates()
-    {
-        return array_merge(['main' => $this->chosen], $this->subTemplates);
-    }
-
-    /**
-     * @param string $type "Layout" or "main"
-     * @param string $file Full system path to the template file
-     */
-    public function setTemplateFile($type, $file)
-    {
-        if (!$type || $type == 'main') {
-            $this->chosen = $file;
-        } else {
-            $this->subTemplates[$type] = $file;
-        }
-    }
-
     /**
      * Return an appropriate base tag for the given template.
      * It will be closed on an XHTML document, and unclosed on an HTML document.
      *
-     * @param string $contentGeneratedSoFar The content of the template generated so far; it should contain
+     * @param bool $isXhtml Whether the DOCTYPE is xhtml or not.
-     * the DOCTYPE declaration.
-     * @return string
      */
-    public static function get_base_tag($contentGeneratedSoFar)
+    public static function getBaseTag(bool $isXhtml = false): string
     {
         // Base href should always have a trailing slash
         $base = rtrim(Director::absoluteBaseURL(), '/') . '/';
 
-        // Is the document XHTML?
+        if ($isXhtml) {
-        if (preg_match('/<!DOCTYPE[^>]+xhtml/i', $contentGeneratedSoFar ?? '')) {
             return "<base href=\"$base\" />";
         } else {
-            return "<base href=\"$base\"><!--[if lte IE 6]></base><![endif]-->";
+            return "<base href=\"$base\">";
         }
     }
+
+    /**
+     * Get the engine used to render templates for this viewer.
+     * Note that this is intentionally not public to avoid the engine being set after instantiation.
+     */
+    protected function setTemplateEngine(TemplateEngine $engine): static
+    {
+        $this->templateEngine = $engine;
+        return $this;
+    }
 }

src/View/SSViewer_DataPresenter.php

@@ -1,449 +0,0 @@
-<?php
-
-namespace SilverStripe\View;
-
-use InvalidArgumentException;
-use SilverStripe\Core\ClassInfo;
-use SilverStripe\Model\ModelData;
-use SilverStripe\Model\List\ArrayList;
-use SilverStripe\ORM\FieldType\DBField;
-
-/**
- * This extends SSViewer_Scope to mix in data on top of what the item provides. This can be "global"
- * data that is scope-independant (like BaseURL), or type-specific data that is layered on top cross-cut like
- * (like $FirstLast etc).
- *
- * It's separate from SSViewer_Scope to keep that fairly complex code as clean as possible.
- */
-class SSViewer_DataPresenter extends SSViewer_Scope
-{
-    /**
-     * List of global property providers
-     *
-     * @internal
-     * @var TemplateGlobalProvider[]|null
-     */
-    private static $globalProperties = null;
-
-    /**
-     * List of global iterator providers
-     *
-     * @internal
-     * @var TemplateIteratorProvider[]|null
-     */
-    private static $iteratorProperties = null;
-
-    /**
-     * Overlay variables. Take precedence over anything from the current scope
-     *
-     * @var array|null
-     */
-    protected $overlay;
-
-    /**
-     * Flag for whether overlay should be preserved when pushing a new scope
-     *
-     * @see SSViewer_DataPresenter::pushScope()
-     * @var bool
-     */
-    protected $preserveOverlay = false;
-
-    /**
-     * Underlay variables. Concede precedence to overlay variables or anything from the current scope
-     *
-     * @var array
-     */
-    protected $underlay;
-
-    /**
-     * @var object $item
-     * @var array $overlay
-     * @var array $underlay
-     * @var SSViewer_Scope $inheritedScope
-     */
-    public function __construct(
-        $item,
-        array $overlay = null,
-        array $underlay = null,
-        SSViewer_Scope $inheritedScope = null
-    ) {
-        parent::__construct($item, $inheritedScope);
-
-        $this->overlay = $overlay ?: [];
-        $this->underlay = $underlay ?: [];
-
-        $this->cacheGlobalProperties();
-        $this->cacheIteratorProperties();
-    }
-
-    /**
-     * Build cache of global properties
-     */
-    protected function cacheGlobalProperties()
-    {
-        if (SSViewer_DataPresenter::$globalProperties !== null) {
-            return;
-        }
-
-        SSViewer_DataPresenter::$globalProperties = $this->getPropertiesFromProvider(
-            TemplateGlobalProvider::class,
-            'get_template_global_variables'
-        );
-    }
-
-    /**
-     * Build cache of global iterator properties
-     */
-    protected function cacheIteratorProperties()
-    {
-        if (SSViewer_DataPresenter::$iteratorProperties !== null) {
-            return;
-        }
-
-        SSViewer_DataPresenter::$iteratorProperties = $this->getPropertiesFromProvider(
-            TemplateIteratorProvider::class,
-            'get_template_iterator_variables',
-            true // Call non-statically
-        );
-    }
-
-    /**
-     * @var string $interfaceToQuery
-     * @var string $variableMethod
-     * @var boolean $createObject
-     * @return array
-     */
-    protected function getPropertiesFromProvider($interfaceToQuery, $variableMethod, $createObject = false)
-    {
-        $methods = [];
-
-        $implementors = ClassInfo::implementorsOf($interfaceToQuery);
-        if ($implementors) {
-            foreach ($implementors as $implementor) {
-                // Create a new instance of the object for method calls
-                if ($createObject) {
-                    $implementor = new $implementor();
-                    $exposedVariables = $implementor->$variableMethod();
-                } else {
-                    $exposedVariables = $implementor::$variableMethod();
-                }
-
-                foreach ($exposedVariables as $varName => $details) {
-                    if (!is_array($details)) {
-                        $details = [
-                            'method' => $details,
-                            'casting' => ModelData::config()->uninherited('default_cast')
-                        ];
-                    }
-
-                    // If just a value (and not a key => value pair), use method name for both key and value
-                    if (is_numeric($varName)) {
-                        $varName = $details['method'];
-                    }
-
-                    // Add in a reference to the implementing class (might be a string class name or an instance)
-                    $details['implementor'] = $implementor;
-
-                    // And a callable array
-                    if (isset($details['method'])) {
-                        $details['callable'] = [$implementor, $details['method']];
-                    }
-
-                    // Save with both uppercase & lowercase first letter, so either works
-                    $lcFirst = strtolower($varName[0] ?? '') . substr($varName ?? '', 1);
-                    $result[$lcFirst] = $details;
-                    $result[ucfirst($varName)] = $details;
-                }
-            }
-        }
-
-        return $result;
-    }
-
-    /**
-     * Look up injected value - it may be part of an "overlay" (arguments passed to <% include %>),
-     * set on the current item, part of an "underlay" ($Layout or $Content), or an iterator/global property
-     *
-     * @param string $property Name of property
-     * @param array $params
-     * @param bool $cast If true, an object is always returned even if not an object.
-     * @return array|null
-     */
-    public function getInjectedValue($property, array $params, $cast = true)
-    {
-        // Get source for this value
-        $result = $this->getValueSource($property);
-        if (!array_key_exists('source', $result)) {
-            return null;
-        }
-
-        // Look up the value - either from a callable, or from a directly provided value
-        $source = $result['source'];
-        $res = [];
-        if (isset($source['callable'])) {
-            $res['value'] = $source['callable'](...$params);
-        } elseif (array_key_exists('value', $source)) {
-            $res['value'] = $source['value'];
-        } else {
-            throw new InvalidArgumentException(
-                "Injected property $property doesn't have a value or callable value source provided"
-            );
-        }
-
-        // If we want to provide a casted object, look up what type object to use
-        if ($cast) {
-            $res['obj'] = $this->castValue($res['value'], $source);
-        }
-
-        return $res;
-    }
-
-    /**
-     * Store the current overlay (as it doesn't directly apply to the new scope
-     * that's being pushed). We want to store the overlay against the next item
-     * "up" in the stack (hence upIndex), rather than the current item, because
-     * SSViewer_Scope::obj() has already been called and pushed the new item to
-     * the stack by this point
-     *
-     * @return SSViewer_Scope
-     */
-    public function pushScope()
-    {
-        $scope = parent::pushScope();
-        $upIndex = $this->getUpIndex() ?: 0;
-
-        $itemStack = $this->getItemStack();
-        $itemStack[$upIndex][SSViewer_Scope::ITEM_OVERLAY] = $this->overlay;
-        $this->setItemStack($itemStack);
-
-        // Remove the overlay when we're changing to a new scope, as values in
-        // that scope take priority. The exceptions that set this flag are $Up
-        // and $Top as they require that the new scope inherits the overlay
-        if (!$this->preserveOverlay) {
-            $this->overlay = [];
-        }
-
-        return $scope;
-    }
-
-    /**
-     * Now that we're going to jump up an item in the item stack, we need to
-     * restore the overlay that was previously stored against the next item "up"
-     * in the stack from the current one
-     *
-     * @return SSViewer_Scope
-     */
-    public function popScope()
-    {
-        $upIndex = $this->getUpIndex();
-
-        if ($upIndex !== null) {
-            $itemStack = $this->getItemStack();
-            $this->overlay = $itemStack[$upIndex][SSViewer_Scope::ITEM_OVERLAY];
-        }
-
-        return parent::popScope();
-    }
-
-    /**
-     * $Up and $Top need to restore the overlay from the parent and top-level
-     * scope respectively.
-     *
-     * @param string $name
-     * @param array $arguments
-     * @param bool $cache
-     * @param string $cacheName
-     * @return $this
-     */
-    public function obj($name, $arguments = [], $cache = false, $cacheName = null)
-    {
-        $overlayIndex = false;
-
-        switch ($name) {
-            case 'Up':
-                $upIndex = $this->getUpIndex();
-                if ($upIndex === null) {
-                    throw new \LogicException('Up called when we\'re already at the top of the scope');
-                }
-                $overlayIndex = $upIndex; // Parent scope
-                $this->preserveOverlay = true; // Preserve overlay
-                break;
-            case 'Top':
-                $overlayIndex = 0; // Top-level scope
-                $this->preserveOverlay = true; // Preserve overlay
-                break;
-            default:
-                $this->preserveOverlay = false;
-                break;
-        }
-
-        if ($overlayIndex !== false) {
-            $itemStack = $this->getItemStack();
-            if (!$this->overlay && isset($itemStack[$overlayIndex][SSViewer_Scope::ITEM_OVERLAY])) {
-                $this->overlay = $itemStack[$overlayIndex][SSViewer_Scope::ITEM_OVERLAY];
-            }
-        }
-
-        parent::obj($name, $arguments, $cache, $cacheName);
-        return $this;
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function getObj($name, $arguments = [], $cache = false, $cacheName = null)
-    {
-        $result = $this->getInjectedValue($name, (array)$arguments);
-        if ($result) {
-            return $result['obj'];
-        }
-        return parent::getObj($name, $arguments, $cache, $cacheName);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function __call($name, $arguments)
-    {
-        // Extract the method name and parameters
-        $property = $arguments[0];  // The name of the public function being called
-
-        // The public function parameters in an array
-        $params = (isset($arguments[1])) ? (array)$arguments[1] : [];
-
-        $val = $this->getInjectedValue($property, $params);
-        if ($val) {
-            $obj = $val['obj'];
-            if ($name === 'hasValue') {
-                $result = ($obj instanceof ModelData) ? $obj->exists() : (bool)$obj;
-            } elseif (is_null($obj) || (is_scalar($obj) && !is_string($obj))) {
-                $result = $obj; // Nulls and non-string scalars don't need casting
-            } else {
-                $result = $obj->forTemplate(); // XML_val
-            }
-
-            $this->resetLocalScope();
-            return $result;
-        }
-
-        return parent::__call($name, $arguments);
-    }
-
-    /**
-     * Evaluate a template override. Returns an array where the presence of
-     * a 'value' key indiciates whether an override was successfully found,
-     * as null is a valid override value
-     *
-     * @param string $property Name of override requested
-     * @param array $overrides List of overrides available
-     * @return array An array with a 'value' key if a value has been found, or empty if not
-     */
-    protected function processTemplateOverride($property, $overrides)
-    {
-        if (!array_key_exists($property, $overrides)) {
-            return [];
-        }
-
-        // Detect override type
-        $override = $overrides[$property];
-
-        // Late-evaluate this value
-        if (!is_string($override) && is_callable($override)) {
-            $override = $override();
-
-            // Late override may yet return null
-            if (!isset($override)) {
-                return [];
-            }
-        }
-
-        return ['value' => $override];
-    }
-
-    /**
-     * Determine source to use for getInjectedValue. Returns an array where the presence of
-     * a 'source' key indiciates whether a value source was successfully found, as a source
-     * may be a null value returned from an override
-     *
-     * @param string $property
-     * @return array An array with a 'source' key if a value source has been found, or empty if not
-     */
-    protected function getValueSource($property)
-    {
-        // Check for a presenter-specific override
-        $result = $this->processTemplateOverride($property, $this->overlay);
-        if (array_key_exists('value', $result)) {
-            return ['source' => $result];
-        }
-
-        // Check if the method to-be-called exists on the target object - if so, don't check any further
-        // injection locations
-        $on = $this->getItem();
-        if (is_object($on) && (isset($on->$property) || method_exists($on, $property ?? ''))) {
-            return [];
-        }
-
-        // Check for a presenter-specific override
-        $result = $this->processTemplateOverride($property, $this->underlay);
-        if (array_key_exists('value', $result)) {
-            return ['source' => $result];
-        }
-
-        // Then for iterator-specific overrides
-        if (array_key_exists($property, SSViewer_DataPresenter::$iteratorProperties)) {
-            $source = SSViewer_DataPresenter::$iteratorProperties[$property];
-            /** @var TemplateIteratorProvider $implementor */
-            $implementor = $source['implementor'];
-            if ($this->itemIterator) {
-                // Set the current iterator position and total (the object instance is the first item in
-                // the callable array)
-                $implementor->iteratorProperties(
-                    $this->itemIterator->key(),
-                    $this->itemIteratorTotal
-                );
-            } else {
-                // If we don't actually have an iterator at the moment, act like a list of length 1
-                $implementor->iteratorProperties(0, 1);
-            }
-
-            return ($source) ? ['source' => $source] : [];
-        }
-
-        // And finally for global overrides
-        if (array_key_exists($property, SSViewer_DataPresenter::$globalProperties)) {
-            return [
-                'source' => SSViewer_DataPresenter::$globalProperties[$property] // get the method call
-            ];
-        }
-
-        // No value
-        return [];
-    }
-
-    /**
-     * Ensure the value is cast safely
-     *
-     * @param mixed $value
-     * @param array $source
-     * @return DBField
-     */
-    protected function castValue($value, $source)
-    {
-        // If the value has already been cast, is null, or is a non-string scalar
-        if (is_object($value) || is_null($value) || (is_scalar($value) && !is_string($value))) {
-            return $value;
-        }
-
-        // Wrap list arrays in ModelData so templates can handle them
-        if (is_array($value) && array_is_list($value)) {
-            return ArrayList::create($value);
-        }
-
-        // Get provided or default cast
-        $casting = empty($source['casting'])
-            ? ModelData::config()->uninherited('default_cast')
-            : $source['casting'];
-
-        return DBField::create_field($casting, $value);
-    }
-}

src/View/SSViewer_FromString.php

@@ -1,95 +0,0 @@
-<?php
-
-namespace SilverStripe\View;
-
-use SilverStripe\Core\Config\Config;
-use SilverStripe\ORM\FieldType\DBField;
-
-/**
- * Special SSViewer that will process a template passed as a string, rather than a filename.
- */
-class SSViewer_FromString extends SSViewer
-{
-    /**
-     * The global template caching behaviour if no instance override is specified
-     *
-     * @config
-     * @var bool
-     */
-    private static $cache_template = true;
-
-    /**
-     * The template to use
-     *
-     * @var string
-     */
-    protected $content;
-
-    /**
-     * Indicates whether templates should be cached
-     *
-     * @var bool
-     */
-    protected $cacheTemplate;
-
-    /**
-     * @param string $content
-     * @param TemplateParser $parser
-     */
-    public function __construct($content, TemplateParser $parser = null)
-    {
-        if ($parser) {
-            $this->setParser($parser);
-        }
-
-        $this->content = $content;
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function process($item, $arguments = null, $scope = null)
-    {
-        $hash = sha1($this->content ?? '');
-        $cacheFile = TEMP_PATH . DIRECTORY_SEPARATOR . ".cache.$hash";
-
-        if (!file_exists($cacheFile ?? '') || isset($_GET['flush'])) {
-            $content = $this->parseTemplateContent($this->content, "string sha1=$hash");
-            $fh = fopen($cacheFile ?? '', 'w');
-            fwrite($fh, $content ?? '');
-            fclose($fh);
-        }
-
-        $val = $this->includeGeneratedTemplate($cacheFile, $item, $arguments, null, $scope);
-
-        if ($this->cacheTemplate !== null) {
-            $cacheTemplate = $this->cacheTemplate;
-        } else {
-            $cacheTemplate = static::config()->get('cache_template');
-        }
-
-        if (!$cacheTemplate) {
-            unlink($cacheFile ?? '');
-        }
-
-        $html = DBField::create_field('HTMLFragment', $val);
-
-        return $html;
-    }
-
-    /**
-     * @param boolean $cacheTemplate
-     */
-    public function setCacheTemplate($cacheTemplate)
-    {
-        $this->cacheTemplate = (bool)$cacheTemplate;
-    }
-
-    /**
-     * @return boolean
-     */
-    public function getCacheTemplate()
-    {
-        return $this->cacheTemplate;
-    }
-}

src/View/SSViewer_Scope.php

@@ -2,15 +2,11 @@
 
 namespace SilverStripe\View;
 
-use ArrayIterator;
+use InvalidArgumentException;
-use Countable;
 use Iterator;
-use SilverStripe\Model\List\ArrayList;
+use LogicException;
-use SilverStripe\ORM\FieldType\DBBoolean;
+use SilverStripe\Core\ClassInfo;
-use SilverStripe\ORM\FieldType\DBText;
+use SilverStripe\Core\Injector\Injector;
-use SilverStripe\ORM\FieldType\DBFloat;
-use SilverStripe\ORM\FieldType\DBInt;
-use SilverStripe\ORM\FieldType\DBField;
 
 /**
  * This tracks the current scope for an SSViewer instance. It has three goals:
@@ -18,6 +14,10 @@ use SilverStripe\ORM\FieldType\DBField;
  *   - Track Up and Top
  *   - (As a side effect) Inject data that needs to be available globally (used to live in ModelData)
  *
+ * It is also responsible for mixing in data on top of what the item provides. This can be "global"
+ * data that is scope-independant (like BaseURL), or type-specific data that is layered on top cross-cut like
+ * (like $FirstLast etc).
+ *
  * In order to handle up, rather than tracking it using a tree, which would involve constructing new objects
  * for each step, we use indexes into the itemStack (which already has to exist).
  *
@@ -44,100 +44,107 @@ class SSViewer_Scope
     /**
      * The stack of previous items ("scopes") - an indexed array of: item, item iterator, item iterator total,
      * pop index, up index, current index & parent overlay
-     *
-     * @var array
      */
-    private $itemStack = [];
+    private array $itemStack = [];
 
     /**
      * The current "global" item (the one any lookup starts from)
-     *
-     * @var object
      */
-    protected $item;
+    protected ?ViewLayerData $item;
 
     /**
      * If we're looping over the current "global" item, here's the iterator that tracks with item we're up to
-     *
-     * @var Iterator
      */
-    protected $itemIterator;
+    protected ?Iterator $itemIterator;
 
     /**
      * Total number of items in the iterator
-     *
-     * @var int
      */
-    protected $itemIteratorTotal;
+    protected int $itemIteratorTotal;
 
     /**
      * A pointer into the item stack for the item that will become the active scope on the next pop call
-     *
-     * @var int
      */
-    private $popIndex;
+    private ?int $popIndex;
 
     /**
      * A pointer into the item stack for which item is "up" from this one
-     *
-     * @var int
      */
-    private $upIndex;
+    private ?int $upIndex;
 
     /**
      * A pointer into the item stack for which the active item (or null if not in stack yet)
-     *
-     * @var int
      */
-    private $currentIndex;
+    private int $currentIndex;
 
     /**
      * A store of copies of the main item stack, so it's preserved during a lookup from local scope
      * (which may push/pop items to/from the main item stack)
-     *
-     * @var array
      */
-    private $localStack = [];
+    private array $localStack = [];
 
     /**
      * The index of the current item in the main item stack, so we know where to restore the scope
      * stored in $localStack.
-     *
-     * @var int
      */
-    private $localIndex = 0;
+    private int $localIndex = 0;
 
     /**
-     * @var object $item
+     * List of global property providers
-     * @var SSViewer_Scope $inheritedScope
+     *
+     * @internal
+     * @var TemplateGlobalProvider[]|null
      */
-    public function __construct($item, SSViewer_Scope $inheritedScope = null)
+    private static $globalProperties = null;
-    {
+
+    /**
+     * List of global iterator providers
+     *
+     * @internal
+     * @var TemplateIteratorProvider[]|null
+     */
+    private static $iteratorProperties = null;
+
+    /**
+     * Overlay variables. Take precedence over anything from the current scope
+     */
+    protected array $overlay;
+
+    /**
+     * Flag for whether overlay should be preserved when pushing a new scope
+     */
+    protected bool $preserveOverlay = false;
+
+    /**
+     * Underlay variables. Concede precedence to overlay variables or anything from the current scope
+     */
+    protected array $underlay;
+
+    public function __construct(
+        ?ViewLayerData $item,
+        array $overlay = [],
+        array $underlay = [],
+        ?SSViewer_Scope $inheritedScope = null
+    ) {
         $this->item = $item;
 
         $this->itemIterator = ($inheritedScope) ? $inheritedScope->itemIterator : null;
         $this->itemIteratorTotal = ($inheritedScope) ? $inheritedScope->itemIteratorTotal : 0;
         $this->itemStack[] = [$this->item, $this->itemIterator, $this->itemIteratorTotal, null, null, 0];
+
+        $this->overlay = $overlay;
+        $this->underlay = $underlay;
+
+        $this->cacheGlobalProperties();
+        $this->cacheIteratorProperties();
     }
 
     /**
-     * Returns the current "active" item
+     * Returns the current "current" item in scope
-     *
-     * @return object
      */
-    public function getItem()
+    public function getCurrentItem(): ?ViewLayerData
     {
-        $item = $this->itemIterator ? $this->itemIterator->current() : $this->item;
+        return $this->itemIterator ? $this->itemIterator->current() : $this->item;
-        if (is_scalar($item)) {
-            $item = $this->convertScalarToDBField($item);
-        }
-
-        // Wrap list arrays in ModelData so templates can handle them
-        if (is_array($item) && array_is_list($item)) {
-            $item = ArrayList::create($item);
-        }
-
-        return $item;
     }
 
     /**
@@ -164,56 +171,21 @@ class SSViewer_Scope
     }
 
     /**
-     * Reset the local scope - restores saved state to the "global" item stack. Typically called after
+     * Set scope to an intermediate value, which will be used for getting output later on.
-     * a lookup chain has been completed
      */
-    public function resetLocalScope()
+    public function scopeToIntermediateValue(string $name, array $arguments, string $type): static
     {
-        // Restore previous un-completed lookup chain if set
+        $overlayIndex = false;
-        $previousLocalState = $this->localStack ? array_pop($this->localStack) : null;
-        array_splice($this->itemStack, $this->localIndex + 1, count($this->itemStack ?? []), $previousLocalState);
 
-        list(
+        // $Up and $Top need to restore the overlay from the parent and top-level scope respectively.
-            $this->item,
-            $this->itemIterator,
-            $this->itemIteratorTotal,
-            $this->popIndex,
-            $this->upIndex,
-            $this->currentIndex
-        ) = end($this->itemStack);
-    }
-
-    /**
-     * @param string $name
-     * @param array $arguments
-     * @param bool $cache
-     * @param string $cacheName
-     * @return mixed
-     */
-    public function getObj($name, $arguments = [], $cache = false, $cacheName = null)
-    {
-        $on = $this->getItem();
-        if ($on === null) {
-            return null;
-        }
-        return $on->obj($name, $arguments, $cache, $cacheName);
-    }
-
-    /**
-     * @param string $name
-     * @param array $arguments
-     * @param bool $cache
-     * @param string $cacheName
-     * @return $this
-     */
-    public function obj($name, $arguments = [], $cache = false, $cacheName = null)
-    {
         switch ($name) {
             case 'Up':
-                if ($this->upIndex === null) {
+                $upIndex = $this->getUpIndex();
+                if ($upIndex === null) {
                     throw new \LogicException('Up called when we\'re already at the top of the scope');
                 }
-
+                $overlayIndex = $upIndex; // Parent scope
+                $this->preserveOverlay = true; // Preserve overlay
                 list(
                     $this->item,
                     $this->itemIterator,
@@ -224,6 +196,8 @@ class SSViewer_Scope
                 ) = $this->itemStack[$this->upIndex];
                 break;
             case 'Top':
+                $overlayIndex = 0; // Top-level scope
+                $this->preserveOverlay = true; // Preserve overlay
                 list(
                     $this->item,
                     $this->itemIterator,
@@ -234,13 +208,21 @@ class SSViewer_Scope
                 ) = $this->itemStack[0];
                 break;
             default:
-                $this->item = $this->getObj($name, $arguments, $cache, $cacheName);
+                $this->preserveOverlay = false;
+                $this->item = $this->getObj($name, $arguments, $type);
                 $this->itemIterator = null;
                 $this->upIndex = $this->currentIndex ? $this->currentIndex : count($this->itemStack) - 1;
                 $this->currentIndex = count($this->itemStack);
                 break;
         }
 
+        if ($overlayIndex !== false) {
+            $itemStack = $this->getItemStack();
+            if (!$this->overlay && isset($itemStack[$overlayIndex][SSViewer_Scope::ITEM_OVERLAY])) {
+                $this->overlay = $itemStack[$overlayIndex][SSViewer_Scope::ITEM_OVERLAY];
+            }
+        }
+
         $this->itemStack[] = [
             $this->item,
             $this->itemIterator,
@@ -254,12 +236,10 @@ class SSViewer_Scope
 
     /**
      * Gets the current object and resets the scope.
-     *
-     * @return object
      */
-    public function self()
+    public function self(): ?ViewLayerData
     {
-        $result = $this->getItem();
+        $result = $this->getCurrentItem();
         $this->resetLocalScope();
 
         return $result;
@@ -268,9 +248,13 @@ class SSViewer_Scope
     /**
      * Jump to the last item in the stack, called when a new item is added before a loop/with
      *
-     * @return SSViewer_Scope
+     * Store the current overlay (as it doesn't directly apply to the new scope
+     * that's being pushed). We want to store the overlay against the next item
+     * "up" in the stack (hence upIndex), rather than the current item, because
+     * SSViewer_Scope::obj() has already been called and pushed the new item to
+     * the stack by this point
      */
-    public function pushScope()
+    public function pushScope(): static
     {
         $newLocalIndex = count($this->itemStack ?? []) - 1;
 
@@ -284,16 +268,38 @@ class SSViewer_Scope
         // once we enter a new global scope, we need to make sure we use a new one
         $this->itemIterator = $this->itemStack[$newLocalIndex][SSViewer_Scope::ITEM_ITERATOR] = null;
 
+        $upIndex = $this->getUpIndex() ?: 0;
+
+        $itemStack = $this->getItemStack();
+        $itemStack[$upIndex][SSViewer_Scope::ITEM_OVERLAY] = $this->overlay;
+        $this->setItemStack($itemStack);
+
+        // Remove the overlay when we're changing to a new scope, as values in
+        // that scope take priority. The exceptions that set this flag are $Up
+        // and $Top as they require that the new scope inherits the overlay
+        if (!$this->preserveOverlay) {
+            $this->overlay = [];
+        }
+
         return $this;
     }
 
     /**
      * Jump back to "previous" item in the stack, called after a loop/with block
      *
-     * @return SSViewer_Scope
+     * Now that we're going to jump up an item in the item stack, we need to
+     * restore the overlay that was previously stored against the next item "up"
+     * in the stack from the current one
      */
-    public function popScope()
+    public function popScope(): static
     {
+        $upIndex = $this->getUpIndex();
+
+        if ($upIndex !== null) {
+            $itemStack = $this->getItemStack();
+            $this->overlay = $itemStack[$upIndex][SSViewer_Scope::ITEM_OVERLAY];
+        }
+
         $this->localIndex = $this->popIndex;
         $this->resetLocalScope();
 
@@ -301,11 +307,10 @@ class SSViewer_Scope
     }
 
     /**
-     * Fast-forwards the current iterator to the next item
+     * Fast-forwards the current iterator to the next item.
-     *
+     * @return bool True if there's an item, false if not.
-     * @return mixed
      */
-    public function next()
+    public function next(): bool
     {
         if (!$this->item) {
             return false;
@@ -313,29 +318,18 @@ class SSViewer_Scope
 
         if (!$this->itemIterator) {
             // Note: it is important that getIterator() is called before count() as implemenations may rely on
-            // this to efficiency get both the number of records and an iterator (e.g. DataList does this)
+            // this to efficiently get both the number of records and an iterator (e.g. DataList does this)
-
-            // Item may be an array or a regular IteratorAggregate
-            if (is_array($this->item)) {
-                $this->itemIterator = new ArrayIterator($this->item);
-            } elseif ($this->item instanceof Iterator) {
-                $this->itemIterator = $this->item;
-            } else {
             $this->itemIterator = $this->item->getIterator();
 
             // This will execute code in a generator up to the first yield. For example, this ensures that
-                // DataList::getIterator() is called before Datalist::count()
+            // DataList::getIterator() is called before Datalist::count() which means we only run the query once
+            // instead of running a separate explicit count() query
             $this->itemIterator->rewind();
-            }
 
-            // If the item implements Countable, use that to fetch the count, otherwise we have to inspect the
+            // Get the number of items in the iterator.
-            // iterator and then rewind it.
+            // Don't just use iterator_count because that results in running through the list
-            if ($this->item instanceof Countable) {
+            // which causes some iterators to no longer be iterable for some reason
-                $this->itemIteratorTotal = count($this->item);
+            $this->itemIteratorTotal = $this->item->getIteratorCount();
-            } else {
-                $this->itemIteratorTotal = iterator_count($this->itemIterator);
-                $this->itemIterator->rewind();
-            }
 
             $this->itemStack[$this->localIndex][SSViewer_Scope::ITEM_ITERATOR] = $this->itemIterator;
             $this->itemStack[$this->localIndex][SSViewer_Scope::ITEM_ITERATOR_TOTAL] = $this->itemIteratorTotal;
@@ -349,23 +343,90 @@ class SSViewer_Scope
             return false;
         }
 
-        return $this->itemIterator->key();
+        return true;
     }
 
     /**
-     * @param string $name
+     * Get the value that will be directly rendered in the template.
-     * @param array $arguments
-     * @return mixed
      */
-    public function __call($name, $arguments)
+    public function getOutputValue(string $name, array $arguments, string $type): string
     {
-        $on = $this->getItem();
+        $retval = $this->getObj($name, $arguments, $type);
-        $retval = $on ? $on->$name(...$arguments) : null;
+        $this->resetLocalScope();
+        return $retval === null ? '' : $retval->__toString();
+    }
+
+    /**
+     * Get the value to pass as an argument to a method.
+     */
+    public function getValueAsArgument(string $name, array $arguments, string $type): mixed
+    {
+        $retval = null;
+
+        if ($this->hasOverlay($name)) {
+            $retval = $this->getOverlay($name, $arguments, true);
+        } else {
+            $on = $this->getCurrentItem();
+            if ($on && isset($on->$name)) {
+                $retval = $on->getRawDataValue($name, $arguments, $type);
+            }
+
+            if ($retval === null) {
+                $retval = $this->getUnderlay($name, $arguments, true);
+            }
+        }
 
         $this->resetLocalScope();
         return $retval;
     }
 
+    /**
+     * Check if the current item in scope has a value for the named field.
+     */
+    public function hasValue(string $name, array $arguments, string $type): bool
+    {
+        $retval = null;
+        $overlay = $this->getOverlay($name, $arguments);
+        if ($overlay && $overlay->hasDataValue()) {
+            $retval = true;
+        }
+
+        if ($retval === null) {
+            $on = $this->getCurrentItem();
+            if ($on) {
+                $retval = $on->hasDataValue($name, $arguments, $type);
+            }
+        }
+
+        if (!$retval) {
+            $underlay = $this->getUnderlay($name, $arguments);
+            $retval = $underlay && $underlay->hasDataValue();
+        }
+
+        $this->resetLocalScope();
+        return $retval;
+    }
+
+    /**
+     * Reset the local scope - restores saved state to the "global" item stack. Typically called after
+     * a lookup chain has been completed
+     */
+    protected function resetLocalScope()
+    {
+        // Restore previous un-completed lookup chain if set
+        $previousLocalState = $this->localStack ? array_pop($this->localStack) : null;
+        array_splice($this->itemStack, $this->localIndex + 1, count($this->itemStack ?? []), $previousLocalState);
+
+        list(
+            $this->item,
+            $this->itemIterator,
+            $this->itemIteratorTotal,
+            $this->popIndex,
+            $this->upIndex,
+            $this->currentIndex
+        ) = end($this->itemStack);
+    }
+
     /**
      * @return array
      */
@@ -390,13 +451,174 @@ class SSViewer_Scope
         return $this->upIndex;
     }
 
-    private function convertScalarToDBField(bool|string|float|int $value): DBField
+    /**
+     * Evaluate a template override. Returns an array where the presence of
+     * a 'value' key indiciates whether an override was successfully found,
+     * as null is a valid override value
+     *
+     * @param string $property Name of override requested
+     * @param array $overrides List of overrides available
+     * @return array An array with a 'value' key if a value has been found, or empty if not
+     */
+    protected function processTemplateOverride($property, $overrides)
     {
-        return match (gettype($value)) {
+        if (!array_key_exists($property, $overrides)) {
-            'boolean' => DBBoolean::create()->setValue($value),
+            return [];
-            'string' => DBText::create()->setValue($value),
+        }
-            'double' => DBFloat::create()->setValue($value),
+
-            'integer' => DBInt::create()->setValue($value),
+        // Detect override type
-        };
+        $override = $overrides[$property];
+
+        // Late-evaluate this value
+        if (!is_string($override) && is_callable($override)) {
+            $override = $override();
+
+            // Late override may yet return null
+            if (!isset($override)) {
+                return [];
+            }
+        }
+
+        return ['value' => $override];
+    }
+
+    /**
+     * Build cache of global properties
+     */
+    protected function cacheGlobalProperties()
+    {
+        if (SSViewer_Scope::$globalProperties !== null) {
+            return;
+        }
+
+        SSViewer_Scope::$globalProperties = SSViewer::getMethodsFromProvider(
+            TemplateGlobalProvider::class,
+            'get_template_global_variables'
+        );
+    }
+
+    /**
+     * Build cache of global iterator properties
+     */
+    protected function cacheIteratorProperties()
+    {
+        if (SSViewer_Scope::$iteratorProperties !== null) {
+            return;
+        }
+
+        SSViewer_Scope::$iteratorProperties = SSViewer::getMethodsFromProvider(
+            TemplateIteratorProvider::class,
+            'get_template_iterator_variables',
+            true // Call non-statically
+        );
+    }
+
+    protected function getObj(string $name, array $arguments, string $type): ?ViewLayerData
+    {
+        if ($this->hasOverlay($name)) {
+            return $this->getOverlay($name, $arguments);
+        }
+
+        $on = $this->getCurrentItem();
+        if ($on && isset($on->$name)) {
+            if ($type === ViewLayerData::TYPE_METHOD) {
+                return $on->$name(...$arguments);
+            }
+            // property
+            return $on->$name;
+        }
+
+        return $this->getUnderlay($name, $arguments);
+    }
+
+    protected function hasOverlay(string $property): bool
+    {
+        $result = $this->processTemplateOverride($property, $this->overlay);
+        return array_key_exists('value', $result);
+    }
+
+    protected function getOverlay(string $property, array $args, bool $getRaw = false): mixed
+    {
+        $result = $this->processTemplateOverride($property, $this->overlay);
+        if (array_key_exists('value', $result)) {
+            return $this->getInjectedValue($result, $property, $args, $getRaw);
+        }
+        return null;
+    }
+
+    protected function getUnderlay(string $property, array $args, bool $getRaw = false): mixed
+    {
+        // Check for a presenter-specific override
+        $result = $this->processTemplateOverride($property, $this->underlay);
+        if (array_key_exists('value', $result)) {
+            return $this->getInjectedValue($result, $property, $args, $getRaw);
+        }
+
+        // Then for iterator-specific overrides
+        if (array_key_exists($property, SSViewer_Scope::$iteratorProperties)) {
+            $source = SSViewer_Scope::$iteratorProperties[$property];
+            /** @var TemplateIteratorProvider $implementor */
+            $implementor = $source['implementor'];
+            if ($this->itemIterator) {
+                // Set the current iterator position and total (the object instance is the first item in
+                // the callable array)
+                $implementor->iteratorProperties(
+                    $this->itemIterator->key(),
+                    $this->itemIteratorTotal
+                );
+            } else {
+                // If we don't actually have an iterator at the moment, act like a list of length 1
+                $implementor->iteratorProperties(0, 1);
+            }
+
+            return $this->getInjectedValue($source, $property, $args, $getRaw);
+        }
+
+        // And finally for global overrides
+        if (array_key_exists($property, SSViewer_Scope::$globalProperties)) {
+            return $this->getInjectedValue(
+                SSViewer_Scope::$globalProperties[$property],
+                $property,
+                $args,
+                $getRaw
+            );
+        }
+
+        return null;
+    }
+
+    protected function getInjectedValue(
+        array|TemplateGlobalProvider|TemplateIteratorProvider $source,
+        string $property,
+        array $params,
+        bool $getRaw = false
+    ) {
+        // Look up the value - either from a callable, or from a directly provided value
+        $value = null;
+        if (isset($source['callable'])) {
+            $value = $source['callable'](...$params);
+        } elseif (array_key_exists('value', $source)) {
+            $value = $source['value'];
+        } else {
+            throw new InvalidArgumentException(
+                "Injected property $property doesn't have a value or callable value source provided"
+            );
+        }
+
+        if ($value === null) {
+            return null;
+        }
+
+        // TemplateGlobalProviders can provide an explicit service to cast to which works outside of the regular cast flow
+        if (!$getRaw && isset($source['casting'])) {
+            $castObject = Injector::inst()->create($source['casting'], $property);
+            if (!ClassInfo::hasMethod($castObject, 'setValue')) {
+                throw new LogicException('Explicit cast from template global provider must have a setValue method.');
+            }
+            $castObject->setValue($value);
+            $value = $castObject;
+        }
+
+        return $getRaw ? $value : ViewLayerData::create($value);
     }
 }

src/View/TemplateEngine.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace SilverStripe\View;
+
+use SilverStripe\View\Exception\MissingTemplateException;
+
+/**
+ * Interface for template rendering engines such as twig or ss templates.
+ */
+interface TemplateEngine
+{
+    /**
+     * Instantiate a TemplateEngine
+     *
+     * @param string|array $templateCandidates A template or pool of candidate templates to choose from.
+     * The template engine will check the currently set themes from SSViewer for template files it can handle
+     * from the candidates.
+     */
+    public function __construct(string|array $templateCandidates = []);
+
+    /**
+     * Set the template which will be used in the call to render()
+     *
+     * @param string|array $templateCandidates A template or pool of candidate templates to choose from.
+     * The template engine will check the currently set themes from SSViewer for template files it can handle
+     * from the candidates.
+     */
+    public function setTemplate(string|array $templateCandidates): static;
+
+    /**
+     * Check if there is a template amongst the template candidates that this rendering engine can use.
+     */
+    public function hasTemplate(string|array $templateCandidates): bool;
+
+    /**
+     * Render the template string.
+     *
+     * Doesn't include normalisation such as inserting js/css from Requirements API - that's handled by SSViewer.
+     *
+     * @param ViewLayerData $model The model to get data from when rendering the template.
+     * @param array $overlay Associative array of fields (e.g. args into an include template) to inject into the
+     * template as properties. These override properties and methods with the same name from $data and from global
+     * template providers.
+     */
+    public function renderString(string $template, ViewLayerData $model, array $overlay = [], bool $cache = true): string;
+
+    /**
+     * Render the template which was selected during instantiation or which was set via setTemplate().
+     *
+     * Doesn't include normalisation such as inserting js/css from Requirements API - that's handled by SSViewer.
+     *
+     * @param ViewLayerData $model The model to get data from when rendering the template.
+     * @param array $overlay Associative array of fields (e.g. args into an include template) to inject into the
+     * template as properties. These override properties and methods with the same name from $data and from global
+     * template providers.
+     *
+     * @throws MissingTemplateException if no template file has been set, or there was no valid template file found from the
+     * template candidates
+     */
+    public function render(ViewLayerData $model, array $overlay = []): string;
+}

src/View/TemplateParser.php

@@ -16,5 +16,5 @@ interface TemplateParser
      * @param bool $includeDebuggingComments True is debugging comments should be included in the output
      * @return string The php that, when executed (via include or exec) will behave as per the template source
      */
-    public function compileString($string, $templateName = "", $includeDebuggingComments = false);
+    public function compileString(string $string, string $templateName = "", bool $includeDebuggingComments = false): string;
 }

src/View/ThemeResourceLoader.php

@@ -89,6 +89,14 @@ class ThemeResourceLoader implements Flushable, TemplateGlobalProvider
         return null;
     }
 
+    /**
+     * Get the base path of the application according to the resource loader
+     */
+    public function getBase(): string
+    {
+        return $this->base;
+    }
+
     /**
      * Given a theme identifier, determine the path from the root directory
      *
@@ -161,99 +169,6 @@ class ThemeResourceLoader implements Flushable, TemplateGlobalProvider
         return Path::normalise($modulePath . $subpath, true);
     }
 
-    /**
-     * Attempts to find possible candidate templates from a set of template
-     * names from modules, current theme directory and finally the application
-     * folder.
-     *
-     * The template names can be passed in as plain strings, or be in the
-     * format "type/name", where type is the type of template to search for
-     * (e.g. Includes, Layout).
-     *
-     * The results of this method will be cached for future use.
-     *
-     * @param string|array $template Template name, or template spec in array format with the keys
-     * 'type' (type string) and 'templates' (template hierarchy in order of precedence).
-     * If 'templates' is omitted then any other item in the array will be treated as the template
-     * list, or list of templates each in the array spec given.
-     * Templates with an .ss extension will be treated as file paths, and will bypass
-     * theme-coupled resolution.
-     * @param array $themes List of themes to use to resolve themes. Defaults to {@see SSViewer::get_themes()}
-     * @return string Absolute path to resolved template file, or null if not resolved.
-     * File location will be in the format themes/<theme>/templates/<directories>/<type>/<basename>.ss
-     * Note that type (e.g. 'Layout') is not the root level directory under 'templates'.
-     */
-    public function findTemplate($template, $themes = null)
-    {
-        if ($themes === null) {
-            $themes = SSViewer::get_themes();
-        }
-
-        // Look for a cached result for this data set
-        $cacheKey = md5(json_encode($template) . json_encode($themes));
-        if ($this->getCache()->has($cacheKey)) {
-            return $this->getCache()->get($cacheKey);
-        }
-
-        $type = '';
-        if (is_array($template)) {
-            // Check if templates has type specified
-            if (array_key_exists('type', $template ?? [])) {
-                $type = $template['type'];
-                unset($template['type']);
-            }
-            // Templates are either nested in 'templates' or just the rest of the list
-            $templateList = array_key_exists('templates', $template ?? []) ? $template['templates'] : $template;
-        } else {
-            $templateList = [$template];
-        }
-
-        foreach ($templateList as $i => $template) {
-            // Check if passed list of templates in array format
-            if (is_array($template)) {
-                $path = $this->findTemplate($template, $themes);
-                if ($path) {
-                    $this->getCache()->set($cacheKey, $path);
-                    return $path;
-                }
-                continue;
-            }
-
-            // If we have an .ss extension, this is a path, not a template name. We should
-            // pass in templates without extensions in order for template manifest to find
-            // files dynamically.
-            if (substr($template ?? '', -3) == '.ss' && file_exists($template ?? '')) {
-                $this->getCache()->set($cacheKey, $template);
-                return $template;
-            }
-
-            // Check string template identifier
-            $template = str_replace('\\', '/', $template ?? '');
-            $parts = explode('/', $template ?? '');
-
-            $tail = array_pop($parts);
-            $head = implode('/', $parts);
-            $themePaths = $this->getThemePaths($themes);
-            foreach ($themePaths as $themePath) {
-                // Join path
-                $pathParts = [ $this->base, $themePath, 'templates', $head, $type, $tail ];
-                try {
-                    $path = Path::join($pathParts) . '.ss';
-                    if (file_exists($path ?? '')) {
-                        $this->getCache()->set($cacheKey, $path);
-                        return $path;
-                    }
-                } catch (InvalidArgumentException $e) {
-                    // No-op
-                }
-            }
-        }
-
-        // No template found
-        $this->getCache()->set($cacheKey, null);
-        return null;
-    }
-
     /**
      * Resolve themed CSS path
      *

src/View/ViewLayerData.php

@@ -0,0 +1,254 @@
+<?php
+
+namespace SilverStripe\View;
+
+use BadMethodCallException;
+use InvalidArgumentException;
+use IteratorAggregate;
+use SilverStripe\Core\ClassInfo;
+use SilverStripe\Core\Injector\Injectable;
+use SilverStripe\Model\ModelData;
+use SilverStripe\Model\ModelDataCustomised;
+use SilverStripe\ORM\FieldType\DBClassName;
+use Stringable;
+use Traversable;
+
+class ViewLayerData implements IteratorAggregate, Stringable
+{
+    use Injectable;
+
+    public const TYPE_PROPERTY = 'property';
+
+    public const TYPE_METHOD = 'method';
+
+    public const TYPE_ANY = 'any';
+
+    /**
+     * Special variable names that can be used to get metadata about values
+     */
+    public const META_DATA_NAMES = [
+        // Gets a DBClassName with the class name of $this->data
+        'ClassName',
+        // Returns $this->data
+        'Me',
+    ];
+
+    private object $data;
+
+    public function __construct(mixed $data, mixed $source = null, string $name = '')
+    {
+        if ($data === null) {
+            throw new InvalidArgumentException('$data must not be null');
+        }
+        if ($data instanceof ViewLayerData) {
+            $data = $data->data;
+        } else {
+            $source = $source instanceof ModelData ? $source : null;
+            $data = CastingService::singleton()->cast($data, $source, $name);
+        }
+        $this->data = $data;
+    }
+
+    /**
+     * Needed so we can rewind in SSViewer_Scope::next() after getting itemIteratorTotal without throwing an exception.
+     */
+    public function getIteratorCount(): int
+    {
+        $count = $this->getRawDataValue('count');
+        if (is_numeric($count)) {
+            return $count;
+        }
+        if (is_countable($this->data)) {
+            return count($this->data);
+        }
+        if (ClassInfo::hasMethod($this->data, 'getIterator')) {
+            return iterator_count($this->data->getIterator());
+        }
+        return 0;
+    }
+
+    public function getIterator(): Traversable
+    {
+        if (!is_iterable($this->data) && !ClassInfo::hasMethod($this->data, 'getIterator')) {
+            $type = get_class($this->data);
+            throw new BadMethodCallException("$type is not iterable.");
+        }
+
+        $iterator = $this->data;
+        if (!is_iterable($iterator)) {
+            $iterator = $this->data->getIterator();
+        }
+        $source = $this->data instanceof ModelData ? $this->data : null;
+        foreach ($iterator as $item) {
+            yield $item === null ? null : ViewLayerData::create($item, $source);
+        }
+    }
+
+    /**
+     * Checks if a field is set, or if a getter or a method of that name exists.
+     * We need to check each of these, because we don't currently distinguish between a property, a getter, and a method
+     * which means if any of those exists we have to say the field is "set", otherwise template engines may skip fetching the data.
+     */
+    public function __isset(string $name): bool
+    {
+        // Note we explicitly DO NOT call count() or exists() on the data here because that would
+        // require fetching the data prematurely which could cause performance issues in extreme cases
+        return in_array($name, ViewLayerData::META_DATA_NAMES)
+            || isset($this->data->$name)
+            || ClassInfo::hasMethod($this->data, "get$name")
+            || ClassInfo::hasMethod($this->data, $name);
+    }
+
+    public function __get(string $name): ?ViewLayerData
+    {
+        $value = $this->getRawDataValue($name, type: ViewLayerData::TYPE_PROPERTY);
+        if ($value === null) {
+            return null;
+        }
+        $source = $this->data instanceof ModelData ? $this->data : null;
+        return ViewLayerData::create($value, $source, $name);
+    }
+
+    public function __call(string $name, array $arguments = []): ?ViewLayerData
+    {
+        $value = $this->getRawDataValue($name, $arguments, ViewLayerData::TYPE_METHOD);
+        if ($value === null) {
+            return null;
+        }
+        $source = $this->data instanceof ModelData ? $this->data : null;
+        return ViewLayerData::create($value, $source, $name);
+    }
+
+    public function __toString(): string
+    {
+        if (ClassInfo::hasMethod($this->data, 'forTemplate')) {
+            return $this->data->forTemplate();
+        }
+        return (string) $this->data;
+    }
+
+    /**
+     * Check if there is a truthy value or (for ModelData) if the data exists().
+     */
+    public function hasDataValue(?string $name = null, array $arguments = [], string $type = ViewLayerData::TYPE_ANY): bool
+    {
+        if ($name) {
+            // Ask the model if it has a value for that field
+            if ($this->data instanceof ModelData) {
+                return $this->data->hasValue($name, $arguments);
+            }
+            // Check for ourselves if there's a value for that field
+            // This mimics what ModelData does, which provides consistency
+            $value = $this->getRawDataValue($name, $arguments, $type);
+            if ($value === null) {
+                return false;
+            }
+            $source = $this->data instanceof ModelData ? $this->data : null;
+            return ViewLayerData::create($value, $source, $name)->hasDataValue();
+        }
+        // Ask the model if it "exists"
+        if ($this->data instanceof ModelData) {
+            return $this->data->exists();
+        }
+        // Mimics ModelData checks on lists
+        if (is_countable($this->data)) {
+            return count($this->data) > 0;
+        }
+        // Check for truthiness (which is effectively `return true` since data is an object)
+        // We do this to mimic ModelData->hasValue() for consistency
+        return (bool) $this->data;
+    }
+
+    /**
+     * Get the raw value of some field/property/method on the data, without wrapping it in ViewLayerData.
+     */
+    public function getRawDataValue(string $name, array $arguments = [], string $type = ViewLayerData::TYPE_ANY): mixed
+    {
+        if ($type !== ViewLayerData::TYPE_ANY && $type !== ViewLayerData::TYPE_METHOD && $type !== ViewLayerData::TYPE_PROPERTY) {
+            throw new InvalidArgumentException('$type must be one of the TYPE_* constant values');
+        }
+
+        $data = $this->data;
+        if ($data instanceof ModelDataCustomised && $data->customisedHas($name)) {
+            $data = $data->getCustomisedModelData();
+        }
+
+        // We don't currently use the $type, but could in a future enhancement if we find that distinction useful.
+        $value = $this->getValueFromData($data, $name, $arguments);
+
+        return $value;
+    }
+
+    private function getValueFromData(object $data, string $name, array $arguments): mixed
+    {
+        // Values from ModelData can be cached
+        if ($data instanceof ModelData) {
+            $cached = $data->objCacheGet($name, $arguments);
+            if ($cached !== null) {
+                return $cached;
+            }
+        }
+
+        $value = null;
+        // Keep track of whether we've already fetched a value (allowing null to be the correct value)
+        $fetchedValue = false;
+
+        // Try calling a method even if we're fetching as a property
+        // This matches historical behaviour that a LOT of logic in core modules expects
+        $value = $this->callDataMethod($data, $name, $arguments, $fetchedValue);
+
+        // Try to get a property even if we aren't explicitly trying to call a method, if the method didn't exist.
+        // This matches historical behaviour and allows e.g. `$MyProperty(some-arg)` with a `getMyProperty($arg)` method.
+        if (!$fetchedValue) {
+            // Try an explicit getter
+            // This matches the "magic" getter behaviour of ModelData across the board for consistent results
+            $getter = "get{$name}";
+            $value = $this->callDataMethod($data, $getter, $arguments, $fetchedValue);
+            if (!$fetchedValue && isset($data->$name)) {
+                $value = $data->$name;
+                $fetchedValue = true;
+            }
+        }
+
+        // Caching for modeldata
+        if ($data instanceof ModelData) {
+            $data->objCacheSet($name, $arguments, $value);
+        }
+
+        if ($value === null && in_array($name, ViewLayerData::META_DATA_NAMES)) {
+            $value = $this->getMetaData($data, $name);
+        }
+
+        return $value;
+    }
+
+    private function getMetaData(object $data, string $name): mixed
+    {
+        return match ($name) {
+            'Me' => $data,
+            'ClassName' => DBClassName::create()->setValue(get_class($data)),
+            default => null
+        };
+    }
+
+    private function callDataMethod(object $data, string $name, array $arguments, bool &$fetchedValue = false): mixed
+    {
+        $hasDynamicMethods = method_exists($data, '__call');
+        $hasMethod = ClassInfo::hasMethod($data, $name);
+        if ($hasMethod || $hasDynamicMethods) {
+            try {
+                $value = $data->$name(...$arguments);
+                $fetchedValue = true;
+                return $value;
+            } catch (BadMethodCallException $e) {
+                // Only throw the exception if we weren't relying on __call
+                // It's common for __call to throw BadMethodCallException for methods that aren't "implemented"
+                // so we just want to return null in those cases.
+                if (!$hasDynamicMethods) {
+                    throw $e;
+                }
+            }
+        }
+        return null;
+    }
+}

src/i18n/Messages/Symfony/FlushInvalidatedResource.php

@@ -3,6 +3,7 @@
 namespace SilverStripe\i18n\Messages\Symfony;
 
 use SilverStripe\Core\Flushable;
+use Stringable;
 use Symfony\Component\Config\Resource\SelfCheckingResourceInterface;
 
 /**
@@ -12,10 +13,9 @@ use Symfony\Component\Config\Resource\SelfCheckingResourceInterface;
  * @link https://media.giphy.com/media/fRRD3T37DeY6Y/giphy.gif for use case
  * @see DirectoryResource
  */
-class FlushInvalidatedResource implements SelfCheckingResourceInterface, Flushable
+class FlushInvalidatedResource implements SelfCheckingResourceInterface, Flushable, Stringable
 {
-
+    public function __toString(): string
-    public function __toString()
     {
         return md5(__CLASS__);
     }

tests/php/Control/ControllerTest.php

@@ -19,6 +19,8 @@ use SilverStripe\Dev\FunctionalTest;
 use SilverStripe\Security\Member;
 use SilverStripe\View\SSViewer;
 use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Control\Tests\ControllerTest\ControllerWithDummyEngine;
+use SilverStripe\Control\Tests\ControllerTest\DummyTemplateEngine;
 
 class ControllerTest extends FunctionalTest
 {
@@ -858,4 +860,12 @@ class ControllerTest extends FunctionalTest
         $response = $this->post('HTTPMethodTestController', ['dummy' => 'example']);
         $this->assertEquals('Routed to postLegacyRoot', $response->getBody());
     }
+
+    public function testTemplateEngineUsed()
+    {
+        $controller = new ControllerWithDummyEngine();
+        $this->assertSame('This is my controller', $controller->render()->getValue());
+        $this->assertSame('This is my controller', $controller->renderWith('literally-any-template')->getValue());
+        $this->assertInstanceOf(DummyTemplateEngine::class, $controller->getViewer('')->getTemplateEngine());
+    }
 }

tests/php/Control/ControllerTest/ControllerWithDummyEngine.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace SilverStripe\Control\Tests\ControllerTest;
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\View\TemplateEngine;
+
+class ControllerWithDummyEngine extends Controller implements TestOnly
+{
+    protected function getTemplateEngine(): TemplateEngine
+    {
+        return new DummyTemplateEngine();
+    }
+}

tests/php/Control/ControllerTest/DummyTemplateEngine.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace SilverStripe\Control\Tests\ControllerTest;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\View\TemplateEngine;
+use SilverStripe\View\ViewLayerData;
+
+/**
+ * A dummy template renderer that doesn't actually render any templates.
+ */
+class DummyTemplateEngine implements TemplateEngine, TestOnly
+{
+    private string $output = 'This is my controller';
+
+    public function __construct(string|array $templateCandidates = [])
+    {
+        // no-op
+    }
+
+    public function setTemplate(string|array $templateCandidates): static
+    {
+        return $this;
+    }
+
+    public function hasTemplate(string|array $templateCandidates): bool
+    {
+        return true;
+    }
+
+    public function renderString(string $template, ViewLayerData $model, array $overlay = [], bool $cache = true): string
+    {
+        return $this->output;
+    }
+
+    public function render(ViewLayerData $model, array $overlay = []): string
+    {
+        return $this->output;
+    }
+}

tests/php/Control/Email/EmailTest.php

@@ -416,27 +416,14 @@ class EmailTest extends SapphireTest
 
     public function testHTMLTemplate(): void
     {
-        // Find template on disk
-        $emailTemplate = ModuleResourceLoader::singleton()->resolveResource(
-            'silverstripe/framework:templates/SilverStripe/Control/Email/Email.ss'
-        );
-        $subClassTemplate = ModuleResourceLoader::singleton()->resolveResource(
-            'silverstripe/framework:tests/php/Control/Email/EmailTest/templates/'
-            . str_replace('\\', '/', EmailSubClass::class)
-            . '.ss'
-        );
-        $this->assertTrue($emailTemplate->exists());
-        $this->assertTrue($subClassTemplate->exists());
-
-        // Check template is auto-found
         $email = new Email();
-        $this->assertEquals($emailTemplate->getPath(), $email->getHTMLTemplate());
+        $this->assertSame(SSViewer::get_templates_by_class(Email::class, '', Email::class), $email->getHTMLTemplate());
         $email->setHTMLTemplate('MyTemplate');
         $this->assertEquals('MyTemplate', $email->getHTMLTemplate());
 
-        // Check subclass template is found
+        // Check subclass template
         $email2 = new EmailSubClass();
-        $this->assertEquals($subClassTemplate->getPath(), $email2->getHTMLTemplate());
+        $this->assertSame(SSViewer::get_templates_by_class(EmailSubClass::class, '', Email::class), $email2->getHTMLTemplate());
         $email->setHTMLTemplate('MyTemplate');
         $this->assertEquals('MyTemplate', $email->getHTMLTemplate());
     }

tests/php/Core/KernelTest.php

@@ -11,6 +11,10 @@ use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Core\Injector\InjectorLoader;
 use SilverStripe\Core\Kernel;
 use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Core\Environment;
+use ReflectionClass;
+use SilverStripe\ORM\DB;
+use ReflectionObject;
 
 class KernelTest extends SapphireTest
 {
@@ -81,4 +85,32 @@ class KernelTest extends SapphireTest
 
         $kernel->getConfigLoader()->getManifest();
     }
+    
+    public function testReplicaDatabaseVarsLoaded()
+    {
+        // Set environment variables for a fake replica database
+        Environment::setEnv('SS_DATABASE_SERVER_REPLICA_01', 'the-moon');
+        Environment::setEnv('SS_DATABASE_USERNAME_REPLICA_01', 'alien');
+        Environment::setEnv('SS_DATABASE_PASSWORD_REPLICA_01', 'hi_people');
+        // Get the CoreKernel
+        /** @var Kernel $kernel */
+        $kernel = Injector::inst()->get(Kernel::class);
+        /** @var CoreKernel $coreKernel */
+        $coreKernel = $kernel->nest();
+        $this->assertTrue(is_a($coreKernel, CoreKernel::class));
+        // Boot the database environment variables
+        $reflector = new ReflectionObject($coreKernel);
+        $method = $reflector->getMethod('bootDatabaseEnvVars');
+        $method->setAccessible(true);
+        $method->invoke($coreKernel);
+        // Assert DB config was updated
+        $default = DB::getConfig(DB::CONN_PRIMARY);
+        $configs = (new ReflectionClass(DB::class))->getStaticPropertyValue('configs');
+        $this->assertSame([
+            'type' => $default['type'],
+            'server' => 'the-moon',
+            'username' => 'alien',
+            'password' => 'hi_people',
+        ], $configs['replica_01']);
+    }
 }

tests/php/Core/Manifest/ThemeResourceLoaderTest.php

@@ -2,7 +2,6 @@
 
 namespace SilverStripe\Core\Tests\Manifest;
 
-use Psr\SimpleCache\CacheInterface;
 use SilverStripe\Control\Director;
 use SilverStripe\Core\Manifest\ModuleLoader;
 use SilverStripe\View\ThemeResourceLoader;
@@ -67,188 +66,6 @@ class ThemeResourceLoaderTest extends SapphireTest
         parent::tearDown();
     }
 
-    /**
-     * Test that 'main' and 'Layout' templates are loaded from module
-     */
-    public function testFindTemplatesInModule()
-    {
-        $this->assertEquals(
-            "$this->base/module/templates/Page.ss",
-            $this->loader->findTemplate('Page', ['$default'])
-        );
-
-        $this->assertEquals(
-            "$this->base/module/templates/Layout/Page.ss",
-            $this->loader->findTemplate(['type' => 'Layout', 'Page'], ['$default'])
-        );
-    }
-
-    public function testFindNestedThemeTemplates()
-    {
-        // Without including the theme this template cannot be found
-        $this->assertEquals(null, $this->loader->findTemplate('NestedThemePage', ['$default']));
-
-        // With a nested theme available then it is available
-        $this->assertEquals(
-            "{$this->base}/module/themes/subtheme/templates/NestedThemePage.ss",
-            $this->loader->findTemplate(
-                'NestedThemePage',
-                [
-                    'silverstripe/module:subtheme',
-                    '$default'
-                ]
-            )
-        );
-
-        // Can also be found if excluding $default theme
-        $this->assertEquals(
-            "{$this->base}/module/themes/subtheme/templates/NestedThemePage.ss",
-            $this->loader->findTemplate(
-                'NestedThemePage',
-                [
-                    'silverstripe/module:subtheme',
-                ]
-            )
-        );
-    }
-
-    public function testFindTemplateByType()
-    {
-        // Test that "type" is respected properly
-        $this->assertEquals(
-            "{$this->base}/module/templates/MyNamespace/Layout/MyClass.ss",
-            $this->loader->findTemplate(
-                [
-                    [
-                        'type' => 'Layout',
-                        'MyNamespace/NonExistantTemplate'
-                    ],
-                    [
-                        'type' => 'Layout',
-                        'MyNamespace/MyClass'
-                    ],
-                    'MyNamespace/MyClass'
-                ],
-                [
-                    'silverstripe/module:subtheme',
-                    'theme',
-                    '$default',
-                ]
-            )
-        );
-
-        // Non-typed template can be found even if looking for typed theme at a lower priority
-        $this->assertEquals(
-            "{$this->base}/module/templates/MyNamespace/MyClass.ss",
-            $this->loader->findTemplate(
-                [
-                    [
-                        'type' => 'Layout',
-                        'MyNamespace/NonExistantTemplate'
-                    ],
-                    'MyNamespace/MyClass',
-                    [
-                        'type' => 'Layout',
-                        'MyNamespace/MyClass'
-                    ]
-                ],
-                [
-                    'silverstripe/module',
-                    'theme',
-                    '$default',
-                ]
-            )
-        );
-    }
-
-    public function testFindTemplatesByPath()
-    {
-        // Items given as full paths are returned directly
-        $this->assertEquals(
-            "$this->base/themes/theme/templates/Page.ss",
-            $this->loader->findTemplate("$this->base/themes/theme/templates/Page.ss", ['theme'])
-        );
-
-        $this->assertEquals(
-            "$this->base/themes/theme/templates/Page.ss",
-            $this->loader->findTemplate(
-                [
-                    "$this->base/themes/theme/templates/Page.ss",
-                    "Page"
-                ],
-                ['theme']
-            )
-        );
-
-        // Ensure checks for file_exists
-        $this->assertEquals(
-            "$this->base/themes/theme/templates/Page.ss",
-            $this->loader->findTemplate(
-                [
-                    "$this->base/themes/theme/templates/NotAPage.ss",
-                    "$this->base/themes/theme/templates/Page.ss",
-                ],
-                ['theme']
-            )
-        );
-    }
-
-    /**
-     * Test that 'main' and 'Layout' templates are loaded from set theme
-     */
-    public function testFindTemplatesInTheme()
-    {
-        $this->assertEquals(
-            "$this->base/themes/theme/templates/Page.ss",
-            $this->loader->findTemplate('Page', ['theme'])
-        );
-
-        $this->assertEquals(
-            "$this->base/themes/theme/templates/Layout/Page.ss",
-            $this->loader->findTemplate(['type' => 'Layout', 'Page'], ['theme'])
-        );
-    }
-
-    /**
-     * Test that 'main' and 'Layout' templates are loaded from project without a set theme
-     */
-    public function testFindTemplatesInApplication()
-    {
-        $templates = [
-            $this->base . '/myproject/templates/Page.ss',
-            $this->base . '/myproject/templates/Layout/Page.ss'
-        ];
-        $this->createTestTemplates($templates);
-
-        $this->assertEquals(
-            "$this->base/myproject/templates/Page.ss",
-            $this->loader->findTemplate('Page', ['$default'])
-        );
-
-        $this->assertEquals(
-            "$this->base/myproject/templates/Layout/Page.ss",
-            $this->loader->findTemplate(['type' => 'Layout', 'Page'], ['$default'])
-        );
-
-        $this->removeTestTemplates($templates);
-    }
-
-    /**
-     * Test that 'main' template is found in theme and 'Layout' is found in module
-     */
-    public function testFindTemplatesMainThemeLayoutModule()
-    {
-        $this->assertEquals(
-            "$this->base/themes/theme/templates/CustomThemePage.ss",
-            $this->loader->findTemplate('CustomThemePage', ['theme', '$default'])
-        );
-
-        $this->assertEquals(
-            "$this->base/module/templates/Layout/CustomThemePage.ss",
-            $this->loader->findTemplate(['type' => 'Layout', 'CustomThemePage'], ['theme', '$default'])
-        );
-    }
-
     public function testFindThemedCSS()
     {
         $this->assertEquals(
@@ -303,20 +120,6 @@ class ThemeResourceLoaderTest extends SapphireTest
         );
     }
 
-    protected function createTestTemplates($templates)
-    {
-        foreach ($templates as $template) {
-            file_put_contents($template ?? '', '');
-        }
-    }
-
-    protected function removeTestTemplates($templates)
-    {
-        foreach ($templates as $template) {
-            unlink($template ?? '');
-        }
-    }
-
     public static function providerTestGetPath()
     {
         return [
@@ -381,28 +184,4 @@ class ThemeResourceLoaderTest extends SapphireTest
     {
         $this->assertEquals($path, $this->loader->getPath($name));
     }
-
-    public function testFindTemplateWithCacheMiss()
-    {
-        $mockCache = $this->createMock(CacheInterface::class);
-        $mockCache->expects($this->once())->method('has')->willReturn(false);
-        $mockCache->expects($this->never())->method('get');
-        $mockCache->expects($this->once())->method('set');
-
-        $loader = new ThemeResourceLoader();
-        $loader->setCache($mockCache);
-        $loader->findTemplate('Page', ['$default']);
-    }
-
-    public function testFindTemplateWithCacheHit()
-    {
-        $mockCache = $this->createMock(CacheInterface::class);
-        $mockCache->expects($this->once())->method('has')->willReturn(true);
-        $mockCache->expects($this->never())->method('set');
-        $mockCache->expects($this->once())->method('get')->willReturn('mock_template.ss');
-
-        $loader = new ThemeResourceLoader();
-        $loader->setCache($mockCache);
-        $this->assertSame('mock_template.ss', $loader->findTemplate('Page', ['$default']));
-    }
 }

tests/php/Forms/GridField/GridFieldFilterHeaderTest.php

@@ -3,6 +3,7 @@
 namespace SilverStripe\Forms\Tests\GridField;
 
 use LogicException;
+use ReflectionMethod;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Core\Config\Config;
 use SilverStripe\Dev\SapphireTest;
@@ -117,6 +118,29 @@ class GridFieldFilterHeaderTest extends SapphireTest
         $this->assertEquals('testfield', $searchSchema->gridfield);
     }
 
+    /**
+     * Tests the private method that returns the placeholder for the search field
+     */
+    public function testGetPlaceHolder()
+    {
+        $gridField = new GridField('test');
+        $filterHeader = new GridFieldFilterHeader();
+        $reflectionGetPlaceHolder = new ReflectionMethod($filterHeader, 'getPlaceHolder');
+        $reflectionGetPlaceHolder->setAccessible(true);
+
+        // No explicit placeholder or model i18n_plural_name method
+        $this->assertSame('Search "ArrayData"', $reflectionGetPlaceHolder->invoke($filterHeader, new ArrayData()));
+
+        // No explicit placeholder, but model has i18n_plural_name method
+        $model = new DataObject();
+        $this->assertSame('Search "' . $model->i18n_plural_name() . '"', $reflectionGetPlaceHolder->invoke($filterHeader, $model));
+
+        // Explicit placeholder is set, which overrides both of the above cases
+        $filterHeader->setPlaceHolderText('This is the text');
+        $this->assertSame('This is the text', $reflectionGetPlaceHolder->invoke($filterHeader, $model));
+        $this->assertSame('This is the text', $reflectionGetPlaceHolder->invoke($filterHeader, new ArrayData()));
+    }
+
     public function testHandleActionReset()
     {
         // Init Grid state with some pre-existing filters

tests/php/Forms/GridField/GridField_URLHandlerTest/TestComponent.php

@@ -56,7 +56,7 @@ class TestComponent extends RequestHandler implements GridField_URLHandler
     public function showform(GridField $gridField, HTTPRequest $request)
     {
         $this->setRequest($request);
-        return "<head>" . SSViewer::get_base_tag("") . "</head>" . $this->Form($gridField, $request)->forTemplate();
+        return "<head>" . SSViewer::getBaseTag() . "</head>" . $this->Form($gridField, $request)->forTemplate();
     }
 
     /**

tests/php/Forms/GridField/GridField_URLHandlerTest/TestComponent_ItemRequest.php

@@ -36,7 +36,7 @@ class TestComponent_ItemRequest extends RequestHandler
 
     public function showform()
     {
-        return "<head>" . SSViewer::get_base_tag("") . "</head>" . $this->Form()->forTemplate();
+        return "<head>" . SSViewer::getBaseTag() . "</head>" . $this->Form()->forTemplate();
     }
 
     public function Form()

tests/php/Forms/TreeDropdownFieldTest.php

@@ -314,7 +314,7 @@ class TreeDropdownFieldTest extends SapphireTest
         $noResult = $parser->getBySelector($cssPath);
         $this->assertEmpty(
             $noResult,
-            $subObject2 . ' is not found'
+            get_class($subObject2) . ' is not found'
         );
     }
 

tests/php/Forms/TreeMultiselectFieldTest.php

@@ -7,6 +7,8 @@ use SilverStripe\Dev\SapphireTest;
 use SilverStripe\Forms\Form;
 use SilverStripe\Forms\FormTemplateHelper;
 use SilverStripe\Forms\TreeMultiselectField;
+use SilverStripe\ORM\Tests\HierarchyTest\HierarchyOnSubclassTestObject;
+use SilverStripe\ORM\Tests\HierarchyTest\HierarchyOnSubclassTestSubObject;
 use SilverStripe\ORM\Tests\HierarchyTest\TestObject;
 use SilverStripe\View\SSViewer;
 
@@ -16,6 +18,8 @@ class TreeMultiselectFieldTest extends SapphireTest
 
     protected static $extra_dataobjects = [
         TestObject::class,
+        HierarchyOnSubclassTestObject::class,
+        HierarchyOnSubclassTestSubObject::class,
     ];
 
     protected $formId = 'TheFormID';

tests/php/Model/ModelDataTest.php

@@ -12,6 +12,7 @@ use SilverStripe\Model\Tests\ModelDataTest\ModelDataTestExtension;
 use SilverStripe\Model\Tests\ModelDataTest\ModelDataTestObject;
 use SilverStripe\Model\ModelData;
 use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Model\Tests\ModelDataTest\TestModelData;
 
 /**
  * See {@link SSViewerTest->testCastingHelpers()} for more tests related to casting and ModelData behaviour,
@@ -54,6 +55,18 @@ class ModelDataTest extends SapphireTest
         $this->assertEquals($htmlString, $textField->obj('XML')->forTemplate());
     }
 
+    public function testCastingValues()
+    {
+        $caster = new ModelDataTest\Castable();
+
+        $this->assertEquals('casted', $caster->obj('alwaysCasted')->forTemplate());
+        $this->assertEquals('casted', $caster->obj('noCastingInformation')->forTemplate());
+
+        // Test automatic escaping is applied even to fields with no 'casting'
+        $this->assertEquals('casted', $caster->obj('unsafeXML')->forTemplate());
+        $this->assertEquals('<foo>', $caster->obj('castedUnsafeXML')->forTemplate());
+    }
+
     public function testRequiresCasting()
     {
         $caster = new ModelDataTest\Castable();
@@ -78,18 +91,6 @@ class ModelDataTest extends SapphireTest
         $this->assertInstanceOf(ModelDataTest\Caster::class, $caster->obj('noCastingInformation'));
     }
 
-    public function testCastingXMLVal()
-    {
-        $caster = new ModelDataTest\Castable();
-
-        $this->assertEquals('casted', $caster->XML_val('alwaysCasted'));
-        $this->assertEquals('casted', $caster->XML_val('noCastingInformation'));
-
-        // Test automatic escaping is applied even to fields with no 'casting'
-        $this->assertEquals('casted', $caster->XML_val('unsafeXML'));
-        $this->assertEquals('<foo>', $caster->XML_val('castedUnsafeXML'));
-    }
-
     public function testArrayCustomise()
     {
         $modelData    = new ModelDataTest\Castable();
@@ -100,11 +101,11 @@ class ModelDataTest extends SapphireTest
              ]
         );
 
-        $this->assertEquals('test', $modelData->XML_val('test'));
+        $this->assertEquals('test', $modelData->obj('test')->forTemplate());
-        $this->assertEquals('casted', $modelData->XML_val('alwaysCasted'));
+        $this->assertEquals('casted', $modelData->obj('alwaysCasted')->forTemplate());
 
-        $this->assertEquals('overwritten', $newModelData->XML_val('test'));
+        $this->assertEquals('overwritten', $newModelData->obj('test')->forTemplate());
-        $this->assertEquals('overwritten', $newModelData->XML_val('alwaysCasted'));
+        $this->assertEquals('overwritten', $newModelData->obj('alwaysCasted')->forTemplate());
 
         $this->assertEquals('castable', $modelData->forTemplate());
         $this->assertEquals('castable', $newModelData->forTemplate());
@@ -115,14 +116,14 @@ class ModelDataTest extends SapphireTest
         $modelData    = new ModelDataTest\Castable();
         $newModelData = $modelData->customise(new ModelDataTest\RequiresCasting());
 
-        $this->assertEquals('test', $modelData->XML_val('test'));
+        $this->assertEquals('test', $modelData->obj('test')->forTemplate());
-        $this->assertEquals('casted', $modelData->XML_val('alwaysCasted'));
+        $this->assertEquals('casted', $modelData->obj('alwaysCasted')->forTemplate());
 
-        $this->assertEquals('overwritten', $newModelData->XML_val('test'));
+        $this->assertEquals('overwritten', $newModelData->obj('test')->forTemplate());
-        $this->assertEquals('casted', $newModelData->XML_val('alwaysCasted'));
+        $this->assertEquals('casted', $newModelData->obj('alwaysCasted')->forTemplate());
 
         $this->assertEquals('castable', $modelData->forTemplate());
-        $this->assertEquals('casted', $newModelData->forTemplate());
+        $this->assertEquals('castable', $newModelData->forTemplate());
     }
 
     public function testDefaultValueWrapping()
@@ -139,25 +140,6 @@ class ModelDataTest extends SapphireTest
         $this->assertEquals('SomeTitleValue', $obj->forTemplate());
     }
 
-    public function testCastingClass()
-    {
-        $expected = [
-            //'NonExistant'   => null,
-            'Field'         => 'CastingType',
-            'Argument'      => 'ArgumentType',
-            'ArrayArgument' => 'ArrayArgumentType'
-        ];
-        $obj = new ModelDataTest\CastingClass();
-
-        foreach ($expected as $field => $class) {
-            $this->assertEquals(
-                $class,
-                $obj->castingClass($field),
-                "castingClass() returns correct results for ::\$$field"
-            );
-        }
-    }
-
     public function testObjWithCachedStringValueReturnsValidObject()
     {
         $obj = new ModelDataTest\NoCastingInformation();
@@ -273,6 +255,114 @@ class ModelDataTest extends SapphireTest
         $this->assertTrue($output, 'Property should be accessible');
     }
 
+    public static function provideObj(): array
+    {
+        return [
+            'returned value is caught' => [
+                'name' => 'justCallMethod',
+                'args' => [],
+                'expectRequested' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'justCallMethod',
+                        'args' => [],
+                    ],
+                ],
+                'expected' => 'This is a method value',
+            ],
+            'getter is used' => [
+                'name' => 'ActualValue',
+                'args' => [],
+                'expectRequested' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'getActualValue',
+                        'args' => [],
+                    ],
+                ],
+                'expected' => 'this is the value',
+            ],
+            'if no method exists, only property is fetched' => [
+                'name' => 'NoMethod',
+                'args' => [],
+                'expectRequested' => [
+                    [
+                        'type' => 'property',
+                        'name' => 'NoMethod',
+                    ],
+                ],
+                'expected' => null,
+            ],
+            'property value is caught' => [
+                'name' => 'ActualValueField',
+                'args' => [],
+                'expectRequested' => [
+                    [
+                        'type' => 'property',
+                        'name' => 'ActualValueField',
+                    ],
+                ],
+                'expected' => 'the value is here',
+            ],
+            'not set and no method' => [
+                'name' => 'NotSet',
+                'args' => [],
+                'expectRequested' => [],
+                'expected' => null,
+            ],
+            'args but no method' => [
+                'name' => 'SomeField',
+                'args' => ['abc', 123],
+                'expectRequested' => [
+                    [
+                        'type' => 'property',
+                        'name' => 'SomeField',
+                    ],
+                ],
+                'expected' => null,
+            ],
+            'method with args' => [
+                'name' => 'justCallMethod',
+                'args' => ['abc', 123],
+                'expectRequested' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'justCallMethod',
+                        'args' => ['abc', 123],
+                    ],
+                ],
+                'expected' => 'This is a method value',
+            ],
+            'getter with args' => [
+                'name' => 'ActualValue',
+                'args' => ['abc', 123],
+                'expectRequested' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'getActualValue',
+                        'args' => ['abc', 123],
+                    ],
+                ],
+                'expected' => 'this is the value',
+            ],
+        ];
+    }
+
+    #[DataProvider('provideObj')]
+    public function testObj(string $name, array $args, array $expectRequested, ?string $expected): void
+    {
+        $fixture = new TestModelData();
+        $value = $fixture->obj($name, $args);
+        $this->assertSame($expectRequested, $fixture->getRequested());
+        $this->assertEquals($expected, ($value instanceof DBField) ? $value->getValue() : $value);
+        // Ensure value is being wrapped when not null
+        // Don't bother testing actual casting, there's some coverage for that in this class already
+        // but mostly it's tested in CastingServiceTest
+        if ($value !== null) {
+            $this->assertTrue(is_object($value));
+        }
+    }
+
     public function testDynamicData()
     {
         $obj = (object) ['SomeField' => [1, 2, 3]];

tests/php/Model/ModelDataTest/NotCached.php

@@ -9,7 +9,7 @@ class NotCached extends ModelData implements TestOnly
 {
     public $Test;
 
-    protected function objCacheGet($key)
+    public function objCacheGet(string $fieldName, array $arguments = []): mixed
     {
         // Disable caching
         return null;

tests/php/Model/ModelDataTest/TestModelData.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace SilverStripe\Model\Tests\ModelDataTest;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\Model\ModelData;
+
+/**
+ * A model that captures information about what's being fetched on it for some methods
+ */
+class TestModelData extends ModelData implements TestOnly
+{
+    private array $requested = [];
+
+    public function justCallMethod(): string
+    {
+        $this->requested[] = [
+            'type' => 'method',
+            'name' => __FUNCTION__,
+            'args' => func_get_args(),
+        ];
+        return 'This is a method value';
+    }
+
+    public function getActualValue(): string
+    {
+        $this->requested[] = [
+            'type' => 'method',
+            'name' => __FUNCTION__,
+            'args' => func_get_args(),
+        ];
+        return 'this is the value';
+    }
+
+    public function getField(string $name): ?string
+    {
+        $this->requested[] = [
+            'type' => 'property',
+            'name' => $name,
+        ];
+        if ($name === 'ActualValueField') {
+            return 'the value is here';
+        }
+        return null;
+    }
+
+    /**
+     * We need this so we always try to fetch a property.
+     */
+    public function hasField(string $name): bool
+    {
+        return $name !== 'NotSet';
+    }
+
+    public function getRequested(): array
+    {
+        return $this->requested;
+    }
+}

tests/php/ORM/DBReplicaTest.php

@@ -0,0 +1,260 @@
+<?php
+
+namespace SilverStripe\ORM\Tests;
+
+use ReflectionClass;
+use SilverStripe\Dev\FunctionalTest;
+use SilverStripe\ORM\DB;
+use SilverStripe\Control\Director;
+use SilverStripe\Security\Security;
+use SilverStripe\Core\Config\Config;
+use SilverStripe\ORM\Tests\DBReplicaTest\TestController;
+use SilverStripe\ORM\Tests\DBReplicaTest\TestObject;
+use SilverStripe\Security\Group;
+use SilverStripe\Security\Member;
+use SilverStripe\ORM\DataQuery;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class DBReplicaTest extends FunctionalTest
+{
+    protected static $extra_dataobjects = [
+        TestObject::class,
+    ];
+
+    protected static $fixture_file = 'DBReplicaTest.yml';
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->setupConfigsAndConnections(true);
+        // Set DB:$mustUsePrimary to true to allow using replicas
+        // This is disabled by default in SapphireTest::setUpBeforeClass()
+        // Also reset mustUsePrimary after using mutable sql to create yml fixtures
+        // and also because by default an ADMIN user is logged in when using fixtures in SapphireTest::setUp()
+        // and also prevent tests from affecting subsequent tests
+        (new ReflectionClass(DB::class))->setStaticPropertyValue('mustUsePrimary', false);
+    }
+
+    protected function tearDown(): void
+    {
+        $this->setupConfigsAndConnections(false);
+        // Reset DB:$mustUsePrimary to true which is the default set by SapphireTest::setUpBeforeClass()
+        (new ReflectionClass(DB::class))->setStaticPropertyValue('mustUsePrimary', true);
+        parent::tearDown();
+    }
+    
+    public function testUsesReplica(): void
+    {
+        // Assert uses replica by default
+        TestObject::get()->count();
+        $this->assertSame('replica_01', $this->getLastConnectionName());
+        // Assert uses primary when using withPrimary()
+        DB::withPrimary(fn() => TestObject::get()->count());
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that withPrimary() was only temporary
+        TestObject::get()->count();
+        $this->assertSame('replica_01', $this->getLastConnectionName());
+        // Assert DB::setMustUsePrimary() forces primary from now on
+        DB::setMustUsePrimary();
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    public function testMutableSql(): void
+    {
+        // Assert that using mutable sql in an ORM method with a dataclass uses primary
+        TestObject::create(['Title' => 'testing'])->write();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that now all subsequent queries use primary
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    public function testMutableSqlDbQuery(): void
+    {
+        // Assert that using mutable sql in DB::query() uses primary
+        DB::query('INSERT INTO "DBReplicaTest_TestObject" ("Title") VALUES (\'testing\')');
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that now all subsequent queries use primary
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    public function testMutableSqlDbPreparedQuery(): void
+    {
+        // Assert that using mutable sql in DB::prepared_query() uses primary
+        DB::prepared_query('INSERT INTO "DBReplicaTest_TestObject" ("Title") VALUES (?)', ['testing']);
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that now all subsequent queries use primary
+        TestObject::get()->count();
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+    }
+
+    #[DataProvider('provideSetCurrentUser')]
+    public function testSetCurrentUser(string $firstName, string $expected): void
+    {
+        $member = Member::get()->find('FirstName', $firstName);
+        Security::setCurrentUser($member);
+        TestObject::get()->count();
+        $this->assertSame($expected, $this->getLastConnectionName());
+    }
+
+    public function testDataObjectMustUsePrimaryDb(): void
+    {
+        // Assert that DataList::getIterator() respect DataObject.must_use_primary_db
+        foreach (TestObject::get() as $object) {
+            $object->Title = 'test2';
+        }
+        $this->assertSame('replica_01', $this->getLastConnectionName());
+        foreach (Group::get() as $group) {
+            $group->Title = 'test2';
+        }
+        $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName());
+        // Assert that DataQuery methods without params respect DataObject.must_use_primary_db
+        $methods = [
+            'count',
+            'exists',
+            'firstRow',
+            'lastRow'
+        ];
+        foreach ($methods as $method) {
+            (new DataQuery(TestObject::class))->$method();
+            $this->assertSame('replica_01', $this->getLastConnectionName(), "method is $method");
+            (new DataQuery(Group::class))->$method();
+            $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName(), "method is $method");
+        }
+        // Assert that DataQuery methods with a param respect DataObject.must_use_primary_db
+        $methods = [
+            'max',
+            'min',
+            'avg',
+            'sum',
+            'column',
+        ];
+        foreach ($methods as $method) {
+            (new DataQuery(TestObject::class))->$method('ID');
+            $this->assertSame('replica_01', $this->getLastConnectionName(), "method is $method");
+            (new DataQuery(Group::class))->$method('ID');
+            $this->assertSame(DB::CONN_PRIMARY, $this->getLastConnectionName(), "method is $method");
+        }
+    }
+
+    public static function provideSetCurrentUser(): array
+    {
+        return [
+            'non_cms_user' => [
+                'firstName' => 'random',
+                'expected' => 'replica_01'
+            ],
+            'cms_user' => [
+                'firstName' => 'cmsuser',
+                'expected' => DB::CONN_PRIMARY
+            ],
+        ];
+    }
+
+    public static function provideRoutes(): array
+    {
+        return [
+            'normal_route' => [
+                'path' => 'test',
+                'expected' => 'replica_01'
+            ],
+            'security_route' => [
+                'path' => 'Security/login',
+                'expected' => DB::CONN_PRIMARY
+            ],
+            'dev_route' => [
+                'path' => 'dev/tasks',
+                'expected' => DB::CONN_PRIMARY
+            ],
+            'dev_in_path_but_not_dev_route' => [
+                'path' => 'test/dev',
+                'expected' => 'replica_01'
+            ],
+        ];
+    }
+
+    #[DataProvider('provideRoutes')]
+    public function testRoutes(string $path, string $expected): void
+    {
+        // Create a custom rule to test our controller that should default to using a replica
+        $rules = Config::inst()->get(Director::class, 'rules');
+        $rules['test'] = TestController::class;
+        // Ensure that routes staring with '$' are at the bottom of the assoc array index and don't override
+        // our new 'test' route
+        uksort($rules, fn($a, $b) => str_starts_with($a, '$') ? 1 : (str_starts_with($b, '$') ? -1 : 0));
+        $this->get($path);
+        $this->assertSame($expected, $this->getLastConnectionName());
+    }
+
+    public static function provideHasReplicaConfig(): array
+    {
+        return [
+            'no_replica' => [
+                'includeReplica' => false,
+                'expected' => false
+            ],
+            'with_replica' => [
+                'includeReplica' => true,
+                'expected' => true
+            ],
+        ];
+    }
+
+    #[DataProvider('provideHasReplicaConfig')]
+    public function testHasReplicaConfig(bool $includeReplica, bool $expected): void
+    {
+        $this->assertTrue(DB::hasReplicaConfig());
+        $primaryConfig = DB::getConfig(DB::CONN_PRIMARY);
+        $config = [DB::CONN_PRIMARY => $primaryConfig];
+        if ($includeReplica) {
+            $config['replica_01'] = $primaryConfig;
+        }
+        (new ReflectionClass(DB::class))->setStaticPropertyValue('configs', $config);
+        $this->assertSame($expected, DB::hasReplicaConfig());
+    }
+
+    public function testHasConfig(): void
+    {
+        $this->assertFalse(DB::hasConfig('lorem'));
+        DB::setConfig(['type' => 'lorem'], 'lorem');
+        $this->assertTrue(DB::hasConfig('lorem'));
+    }
+
+    public function testGetReplicaConfigKey(): void
+    {
+        $this->assertSame('replica_03', DB::getReplicaConfigKey(3));
+        $this->assertSame('replica_58', DB::getReplicaConfigKey(58));
+    }
+
+    /**
+     * Using reflection, set DB::configs and DB::connections with a fake a replica connection
+     * that points to the same connection as the primary connection.
+     */
+    private function setupConfigsAndConnections($includeReplica = true): void
+    {
+        $reflector = new ReflectionClass(DB::class);
+        $primaryConfig = DB::getConfig(DB::CONN_PRIMARY);
+        $configs = [DB::CONN_PRIMARY => $primaryConfig];
+        if ($includeReplica) {
+            $configs['replica_01'] = $primaryConfig;
+        }
+        $reflector->setStaticPropertyValue('configs', $configs);
+        // Create connections
+        $primaryConnection = DB::get_conn(DB::CONN_PRIMARY);
+        $connections = [DB::CONN_PRIMARY => $primaryConnection];
+        if ($includeReplica) {
+            $connections['replica_01'] = $primaryConnection;
+        }
+        $reflector->setStaticPropertyValue('connections', $connections);
+    }
+
+    /**
+     * Get the last connection name used by the DB class. This shows if a replica was used.
+     */
+    private function getLastConnectionName(): string
+    {
+        return (new ReflectionClass(DB::class))->getStaticPropertyValue('lastConnectionName');
+    }
+}

tests/php/ORM/DBReplicaTest.yml

@@ -0,0 +1,18 @@
+SilverStripe\ORM\Tests\DBReplicaTest\TestObject:
+  test:
+    Title: 'test'
+SilverStripe\Security\Permission:
+  test:
+    Code: 'CMS_ACCESS_Something'
+SilverStripe\Security\Group:
+  test:
+    Title: 'test'
+    Permissions:
+      - =>SilverStripe\Security\Permission.test
+SilverStripe\Security\Member:
+  cmsuser:
+    FirstName: 'CmsUser'
+    Groups:
+      - =>SilverStripe\Security\Group.test
+  random:
+    FirstName: 'Random'

tests/php/ORM/DBReplicaTest/TestController.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace SilverStripe\ORM\Tests\DBReplicaTest;
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Dev\TestOnly;
+
+class TestController extends Controller implements TestOnly
+{
+    public function index()
+    {
+        // Make a call to the database
+        TestObject::get()->count();
+        $response = $this->getResponse();
+        $response->setBody('DB_REPLICA_TEST_CONTROLLER');
+        return $response;
+    }
+}

tests/php/ORM/DBReplicaTest/TestObject.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace SilverStripe\ORM\Tests\DBReplicaTest;
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class TestObject extends DataObject implements TestOnly
+{
+    private static $db = [
+        'Title' => 'Varchar',
+    ];
+
+    private static $table_name = 'DBReplicaTest_TestObject';
+}

tests/php/ORM/Filters/EndsWithFilterTest.php

@@ -197,20 +197,6 @@ class EndsWithFilterTest extends SapphireTest
                 'modifiers' => [],
                 'matches' => false,
             ],
-            // These will both evaluate to true because the __toString() method just returns the class name.
-            // We're testing this scenario because ArrayList might contain arbitrary values
-            [
-                'filterValue' => new ArrayData(['SomeField' => 'some value']),
-                'matchValue' => new ArrayData(['SomeField' => 'some value']),
-                'modifiers' => [],
-                'matches' => true,
-            ],
-            [
-                'filterValue' => new ArrayData(['SomeField' => 'SoMe VaLuE']),
-                'matchValue' => new ArrayData(['SomeField' => 'some value']),
-                'modifiers' => [],
-                'matches' => true,
-            ],
             // case insensitive
             [
                 'filterValue' => 'somevalue',

tests/php/ORM/Filters/PartialMatchFilterTest.php

@@ -197,20 +197,6 @@ class PartialMatchFilterTest extends SapphireTest
                 'modifiers' => [],
                 'matches' => false,
             ],
-            // These will both evaluate to true because the __toString() method just returns the class name.
-            // We're testing this scenario because ArrayList might contain arbitrary values
-            [
-                'filterValue' => new ArrayData(['SomeField' => 'some value']),
-                'matchValue' => new ArrayData(['SomeField' => 'some value']),
-                'modifiers' => [],
-                'matches' => true,
-            ],
-            [
-                'filterValue' => new ArrayData(['SomeField' => 'SoMe VaLuE']),
-                'matchValue' => new ArrayData(['SomeField' => 'some value']),
-                'modifiers' => [],
-                'matches' => true,
-            ],
             // case insensitive
             [
                 'filterValue' => 'somevalue',

tests/php/ORM/Filters/StartsWithFilterTest.php

@@ -197,20 +197,6 @@ class StartsWithFilterTest extends SapphireTest
                 'modifiers' => [],
                 'matches' => false,
             ],
-            // These will both evaluate to true because the __toString() method just returns the class name.
-            // We're testing this scenario because ArrayList might contain arbitrary values
-            [
-                'filterValue' => new ArrayData(['SomeField' => 'some value']),
-                'matchValue' => new ArrayData(['SomeField' => 'some value']),
-                'modifiers' => [],
-                'matches' => true,
-            ],
-            [
-                'filterValue' => new ArrayData(['SomeField' => 'SoMe VaLuE']),
-                'matchValue' => new ArrayData(['SomeField' => 'some value']),
-                'modifiers' => [],
-                'matches' => true,
-            ],
             // case insensitive
             [
                 'filterValue' => 'somevalue',

tests/php/ORM/LabelFieldTest.php

@@ -11,6 +11,6 @@ class LabelFieldTest extends SapphireTest
     public function testFieldHasNoNameAttribute()
     {
         $field = new LabelField('MyName', 'MyTitle');
-        $this->assertEquals(trim($field->Field() ?? ''), '<label id="MyName" class="readonly">MyTitle</label>');
+        $this->assertEquals('<label id="MyName" class="readonly">MyTitle</label>', trim($field->Field()));
     }
 }

tests/php/ORM/MySQLiConnectorTest.php

@@ -41,7 +41,7 @@ class MySQLiConnectorTest extends SapphireTest implements TestOnly
     {
         parent::setUp();
 
-        $config = DB::getConfig();
+        $config = DB::getConfig(DB::CONN_PRIMARY);
 
         if (strtolower(substr($config['type'] ?? '', 0, 5)) !== 'mysql') {
             $this->markTestSkipped("The test only relevant for MySQL - but $config[type] is in use");

tests/php/View/CastingServiceTest.php

@@ -0,0 +1,206 @@
+<?php
+
+namespace SilverStripe\View\Tests;
+
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Model\ArrayData;
+use SilverStripe\Model\List\ArrayList;
+use SilverStripe\ORM\FieldType\DBBoolean;
+use SilverStripe\ORM\FieldType\DBCurrency;
+use SilverStripe\ORM\FieldType\DBDate;
+use SilverStripe\ORM\FieldType\DBField;
+use SilverStripe\ORM\FieldType\DBFloat;
+use SilverStripe\ORM\FieldType\DBHTMLText;
+use SilverStripe\ORM\FieldType\DBInt;
+use SilverStripe\ORM\FieldType\DBText;
+use SilverStripe\ORM\FieldType\DBTime;
+use SilverStripe\View\CastingService;
+use SilverStripe\View\Tests\CastingServiceTest\TestDataObject;
+use stdClass;
+
+class CastingServiceTest extends SapphireTest
+{
+    // protected static $extra_dataobjects = [
+    //     TestDataObject::class,
+    // ];
+
+    protected $usesDatabase = false;
+
+    public static function provideCast(): array
+    {
+        return [
+            [
+                'data' => null,
+                'source' => null,
+                'fieldName' => '',
+                'expected' => null,
+            ],
+            [
+                'data' => new stdClass(),
+                'source' => null,
+                'fieldName' => '',
+                'expected' => stdClass::class,
+            ],
+            [
+                'data' => new stdClass(),
+                'source' => TestDataObject::class,
+                'fieldName' => 'DateField',
+                'expected' => stdClass::class,
+            ],
+            [
+                'data' => new DBText(),
+                'source' => TestDataObject::class,
+                'fieldName' => 'DateField',
+                'expected' => stdClass::class,
+            ],
+            [
+                'data' => '2024-10-10',
+                'source' => TestDataObject::class,
+                'fieldName' => 'DateField',
+                'expected' => DBDate::class,
+            ],
+            [
+                'data' => 'some value',
+                'source' => TestDataObject::class,
+                'fieldName' => 'HtmlField',
+                'expected' => DBHTMLText::class,
+            ],
+            [
+                'data' => '12.35',
+                'source' => TestDataObject::class,
+                'fieldName' => 'OverrideCastingHelper',
+                'expected' => DBCurrency::class,
+            ],
+            [
+                'data' => '10:17:36',
+                'source' => TestDataObject::class,
+                'fieldName' => 'TimeField',
+                'expected' => DBTime::class,
+            ],
+            [
+                'data' => 123456,
+                'source' => TestDataObject::class,
+                'fieldName' => 'RandomField',
+                'expected' => DBInt::class,
+            ],
+            [
+                'data' => '<body>some text</body>',
+                'source' => TestDataObject::class,
+                'fieldName' => 'RandomField',
+                'expected' => DBText::class,
+            ],
+            [
+                'data' => '12.35',
+                'source' => null,
+                'fieldName' => 'OverrideCastingHelper',
+                'expected' => DBText::class,
+            ],
+            [
+                'data' => 123456,
+                'source' => null,
+                'fieldName' => 'RandomField',
+                'expected' => DBInt::class,
+            ],
+            [
+                'data' => '10:17:36',
+                'source' => null,
+                'fieldName' => 'TimeField',
+                'expected' => DBText::class,
+            ],
+            [
+                'data' => '<body>some text</body>',
+                'source' => null,
+                'fieldName' => '',
+                'expected' => DBText::class,
+            ],
+            [
+                'data' => true,
+                'source' => null,
+                'fieldName' => '',
+                'expected' => DBBoolean::class,
+            ],
+            [
+                'data' => false,
+                'source' => null,
+                'fieldName' => '',
+                'expected' => DBBoolean::class,
+            ],
+            [
+                'data' => 1.234,
+                'source' => null,
+                'fieldName' => '',
+                'expected' => DBFloat::class,
+            ],
+            [
+                'data' => [],
+                'source' => null,
+                'fieldName' => '',
+                'expected' => ArrayList::class,
+            ],
+            [
+                'data' => [1,2,3,4],
+                'source' => null,
+                'fieldName' => '',
+                'expected' => ArrayList::class,
+            ],
+            [
+                'data' => ['one' => 1, 'two' => 2],
+                'source' => null,
+                'fieldName' => '',
+                'expected' => ArrayData::class,
+            ],
+            [
+                'data' => ['one' => 1, 'two' => 2],
+                'source' => TestDataObject::class,
+                'fieldName' => 'AnyField',
+                'expected' => ArrayData::class,
+            ],
+            [
+                'data' => ['one' => 1, 'two' => 2],
+                'source' => TestDataObject::class,
+                'fieldName' => 'ArrayAsText',
+                'expected' => DBText::class,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideCast')]
+    public function testCast(mixed $data, ?string $source, string $fieldName, ?string $expected): void
+    {
+        // Can't instantiate DataObject in a data provider
+        if (is_string($source)) {
+            $source = new $source();
+        }
+        $service = new CastingService();
+        $value = $service->cast($data, $source, $fieldName);
+
+        // Check the cast object is the correct type
+        if ($expected === null) {
+            $this->assertNull($value);
+        } elseif (is_object($data)) {
+            $this->assertSame($data, $value);
+        } else {
+            $this->assertInstanceOf($expected, $value);
+        }
+
+        // Check the value is retained
+        if ($value instanceof DBField && !is_object($data)) {
+            $this->assertSame($data, $value->getValue());
+        }
+        if ($value instanceof ArrayData && !is_object($data)) {
+            $this->assertSame($data, $value->toMap());
+        }
+        if ($value instanceof ArrayList && !is_object($data)) {
+            $this->assertSame($data, $value->toArray());
+        }
+    }
+
+    public function testCastStrict(): void
+    {
+        $service = new CastingService();
+        $value = $service->cast(null, strict: true);
+        $this->assertInstanceOf(DBText::class, $value);
+        $this->assertNull($value->getValue());
+    }
+}

tests/php/View/CastingServiceTest/TestDataObject.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace SilverStripe\View\Tests\CastingServiceTest;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class TestDataObject extends DataObject implements TestOnly
+{
+    private static string $table_name = 'CastingServiceTest_TestDataObject';
+
+    private static array $db = [
+        'HtmlField' => 'HTMLText',
+        'DateField' => 'Date',
+    ];
+
+    private static array $casting = [
+        'DateField' => 'Text', // won't override
+        'TimeField' => 'Time',
+        'ArrayAsText' => 'Text',
+    ];
+
+    public function castingHelper(string $field): ?string
+    {
+        if ($field === 'OverrideCastingHelper') {
+            return 'Currency';
+        }
+        return parent::castingHelper($field);
+    }
+}

tests/php/View/ContentNegotiatorTest.php

@@ -6,31 +6,17 @@ use SilverStripe\Dev\SapphireTest;
 use SilverStripe\Control\ContentNegotiator;
 use SilverStripe\Control\HTTPResponse;
 use SilverStripe\View\SSViewer;
-use SilverStripe\View\Tests\SSViewerTest\TestFixture;
 
 class ContentNegotiatorTest extends SapphireTest
 {
-
-    /**
-     * Small helper to render templates from strings
-     * Cloned from SSViewerTest
-     */
-    private function render($templateString, $data = null)
-    {
-        $t = SSViewer::fromString($templateString);
-        if (!$data) {
-            $data = new TestFixture();
-        }
-        return $t->process($data);
-    }
-
     public function testXhtmltagReplacement()
     {
-        $tmpl1 = '<?xml version="1.0" encoding="UTF-8"?>
+        $baseTag = SSViewer::getBaseTag(true);
+        $renderedOutput = '<?xml version="1.0" encoding="UTF-8"?>
 			<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"'
                 . ' "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 			<html>
-				<head><% base_tag %></head>
+				<head>' . $baseTag . '</head>
 				<body>
 				<form action="#">
 					<select>
@@ -53,8 +39,7 @@ class ContentNegotiatorTest extends SapphireTest
 
         // Check that the content negotiator converts to the equally legal formats
         $negotiator = new ContentNegotiator();
-
+        $response = new HTTPResponse($renderedOutput);
-        $response = new HTTPResponse($this->render($tmpl1));
         $negotiator->xhtml($response);
 
         ////////////////////////

tests/php/View/Embed/MockUri.php

@@ -3,8 +3,9 @@
 namespace SilverStripe\View\Tests\Embed;
 
 use Psr\Http\Message\UriInterface;
+use Stringable;
 
-class MockUri implements UriInterface
+class MockUri implements UriInterface, Stringable
 {
     private string $scheme;
     private string $host;
@@ -91,7 +92,7 @@ class MockUri implements UriInterface
         return $this;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         $query = $this->getQuery();
         return sprintf(

tests/php/View/RequirementsTest.php

@@ -2,7 +2,6 @@
 
 namespace SilverStripe\View\Tests;
 
-use InvalidArgumentException;
 use SilverStripe\Control\Director;
 use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Dev\SapphireTest;
@@ -14,13 +13,12 @@ use SilverStripe\View\Requirements_Backend;
 use SilverStripe\Core\Manifest\ResourceURLGenerator;
 use SilverStripe\Control\SimpleResourceURLGenerator;
 use SilverStripe\Core\Config\Config;
-use SilverStripe\Dev\Deprecation;
 use SilverStripe\View\SSViewer;
 use SilverStripe\View\ThemeResourceLoader;
+use Symfony\Component\Filesystem\Path;
 
 class RequirementsTest extends SapphireTest
 {
-
     /**
      * @var ThemeResourceLoader
      */
@@ -31,9 +29,8 @@ class RequirementsTest extends SapphireTest
     protected function setUp(): void
     {
         parent::setUp();
-        Director::config()->set('alternate_base_folder', __DIR__ . '/SSViewerTest');
+        Director::config()->set('alternate_base_folder', __DIR__ . '/RequirementsTest');
         Director::config()->set('alternate_base_url', 'http://www.mysite.com/basedir/');
-        Director::config()->set('alternate_public_dir', 'public'); // Enforce public dir
         // Add public as a theme in itself
         SSViewer::set_themes([SSViewer::PUBLIC_THEME, SSViewer::DEFAULT_THEME]);
         TestAssetStore::activate('RequirementsTest'); // Set backend root to /RequirementsTest
@@ -959,12 +956,12 @@ class RequirementsTest extends SapphireTest
 
     public function testConditionalTemplateRequire()
     {
-        // Set /SSViewerTest and /SSViewerTest/public as themes
+        // Set /RequirementsTest and /RequirementsTest/public as themes
         SSViewer::set_themes([
             '/',
             SSViewer::PUBLIC_THEME
         ]);
-        ThemeResourceLoader::set_instance(new ThemeResourceLoader(__DIR__ . '/SSViewerTest'));
+        ThemeResourceLoader::set_instance(new ThemeResourceLoader(__DIR__ . '/RequirementsTest'));
 
         /** @var Requirements_Backend $backend */
         $backend = Injector::inst()->create(Requirements_Backend::class);
@@ -1501,4 +1498,35 @@ EOS
             'Head Tag is correctly not displaying original write'
         );
     }
+
+    public function testRequirementsCombine()
+    {
+        // Need to reset base folder for this test, which requires also resetting the asset store.
+        Director::config()->remove('alternate_base_folder');
+        TestAssetStore::reset();
+        TestAssetStore::activate('RequirementsTest');
+        /** @var Requirements_Backend $testBackend */
+        $testBackend = Injector::inst()->create(Requirements_Backend::class);
+        $testBackend->setSuffixRequirements(false);
+        $testBackend->setCombinedFilesEnabled(true);
+
+        //$combinedTestFilePath = BASE_PATH . '/' . $testBackend->getCombinedFilesFolder() . '/testRequirementsCombine.js';
+
+        $jsFile = Path::makeAbsolute($this->getCurrentRelativePath() . '/RequirementsTest/javascript/bad.js', BASE_PATH);
+        $jsFileContents = file_get_contents($jsFile);
+        $testBackend->combineFiles('testRequirementsCombine.js', [$jsFile]);
+
+        // secondly, make sure that requirements is generated, even though minification failed
+        $testBackend->processCombinedFiles();
+        $js = array_keys($testBackend->getJavascript() ?? []);
+        $combinedTestFilePath = Path::join(Director::publicFolder(), reset($js));
+        $this->assertStringContainsString('_combinedfiles/testRequirementsCombine-4c0e97a.js', $combinedTestFilePath);
+
+        // and make sure the combined content matches the input content, i.e. no loss of functionality
+        if (!file_exists($combinedTestFilePath ?? '')) {
+            $this->fail('No combined file was created at expected path: ' . $combinedTestFilePath);
+        }
+        $combinedTestFileContents = file_get_contents($combinedTestFilePath ?? '');
+        $this->assertStringContainsString($jsFileContents, $combinedTestFileContents);
+    }
 }

tests/php/View/SSTemplateEngineCacheBlockTest.php

@@ -9,18 +9,19 @@ use SilverStripe\Versioned\Versioned;
 use Psr\SimpleCache\CacheInterface;
 use SilverStripe\Dev\SapphireTest;
 use SilverStripe\Control\Director;
+use SilverStripe\View\SSTemplateEngine;
 use SilverStripe\View\SSTemplateParseException;
-use SilverStripe\View\SSViewer;
+use SilverStripe\View\ViewLayerData;
 use Symfony\Component\Cache\Adapter\FilesystemAdapter;
 use Symfony\Component\Cache\Adapter\NullAdapter;
 use Symfony\Component\Cache\Psr16Cache;
 
 // Not actually a data object, we just want a ModelData object that's just for us
 
-class SSViewerCacheBlockTest extends SapphireTest
+class SSTemplateEngineCacheBlockTest extends SapphireTest
 {
     protected static $extra_dataobjects = [
-        SSViewerCacheBlockTest\TestModel::class
+        SSTemplateEngineCacheBlockTest\TestModel::class
     ];
 
     public static function getExtraDataObjects()
@@ -29,19 +30,19 @@ class SSViewerCacheBlockTest extends SapphireTest
 
         // Add extra classes if versioning is enabled
         if (class_exists(Versioned::class)) {
-            $classes[] = SSViewerCacheBlockTest\VersionedModel::class;
+            $classes[] = SSTemplateEngineCacheBlockTest\VersionedModel::class;
         }
         return $classes;
     }
 
     /**
-     * @var SSViewerCacheBlockTest\TestModel
+     * @var SSTemplateEngineCacheBlockTest\TestModel
      */
     protected $data = null;
 
     protected function _reset($cacheOn = true)
     {
-        $this->data = new SSViewerCacheBlockTest\TestModel();
+        $this->data = new SSTemplateEngineCacheBlockTest\TestModel();
 
         $cache = null;
         if ($cacheOn) {
@@ -64,7 +65,8 @@ class SSViewerCacheBlockTest extends SapphireTest
             $data = $this->data->customise($data);
         }
 
-        return SSViewer::execute_string($template, $data);
+        $engine = new SSTemplateEngine();
+        return $engine->renderString($template, new ViewLayerData($data));
     }
 
     public function testParsing()
@@ -74,52 +76,52 @@ class SSViewerCacheBlockTest extends SapphireTest
 
         // Make sure an empty cached block parses
         $this->_reset();
-        $this->assertEquals($this->_runtemplate('<% cached %><% end_cached %>'), '');
+        $this->assertEquals('', $this->_runtemplate('<% cached %><% end_cached %>'));
 
         // Make sure an empty cacheblock block parses
         $this->_reset();
-        $this->assertEquals($this->_runtemplate('<% cacheblock %><% end_cacheblock %>'), '');
+        $this->assertEquals('', $this->_runtemplate('<% cacheblock %><% end_cacheblock %>'));
 
         // Make sure an empty uncached block parses
         $this->_reset();
-        $this->assertEquals($this->_runtemplate('<% uncached %><% end_uncached %>'), '');
+        $this->assertEquals('', $this->_runtemplate('<% uncached %><% end_uncached %>'));
 
         // ** Argument checks **
 
         // Make sure a simple cacheblock parses
         $this->_reset();
-        $this->assertEquals($this->_runtemplate('<% cached %>Yay<% end_cached %>'), 'Yay');
+        $this->assertEquals('Yay', $this->_runtemplate('<% cached %>Yay<% end_cached %>'));
 
         // Make sure a moderately complicated cacheblock parses
         $this->_reset();
-        $this->assertEquals($this->_runtemplate('<% cached \'block\', Foo, "jumping" %>Yay<% end_cached %>'), 'Yay');
+        $this->assertEquals('Yay', $this->_runtemplate('<% cached \'block\', Foo, "jumping" %>Yay<% end_cached %>'));
 
         // Make sure a complicated cacheblock parses
         $this->_reset();
         $this->assertEquals(
+            'Yay',
             $this->_runtemplate(
                 '<% cached \'block\', Foo, Test.Test(4).Test(jumping).Foo %>Yay<% end_cached %>'
-            ),
+            )
-            'Yay'
         );
 
         // ** Conditional Checks **
 
         // Make sure a cacheblock with a simple conditional parses
         $this->_reset();
-        $this->assertEquals($this->_runtemplate('<% cached if true %>Yay<% end_cached %>'), 'Yay');
+        $this->assertEquals('Yay', $this->_runtemplate('<% cached if true %>Yay<% end_cached %>'));
 
         // Make sure a cacheblock with a complex conditional parses
         $this->_reset();
-        $this->assertEquals($this->_runtemplate('<% cached if Test.Test(yank).Foo %>Yay<% end_cached %>'), 'Yay');
+        $this->assertEquals('Yay', $this->_runtemplate('<% cached if Test.Test(yank).Foo %>Yay<% end_cached %>'));
 
         // Make sure a cacheblock with a complex conditional and arguments parses
         $this->_reset();
         $this->assertEquals(
+            'Yay',
             $this->_runtemplate(
                 '<% cached Foo, Test.Test(4).Test(jumping).Foo if Test.Test(yank).Foo %>Yay<% end_cached %>'
-            ),
+            )
-            'Yay'
         );
     }
 
@@ -131,14 +133,14 @@ class SSViewerCacheBlockTest extends SapphireTest
         // First, run twice without caching, to prove we get two different values
         $this->_reset(false);
 
-        $this->assertEquals($this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 1]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 1]));
-        $this->assertEquals($this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 2]), '2');
+        $this->assertEquals('2', $this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 2]));
 
         // Then twice with caching, should get same result each time
         $this->_reset(true);
 
-        $this->assertEquals($this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 1]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 1]));
-        $this->assertEquals($this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 2]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 2]));
     }
 
     /**
@@ -150,17 +152,17 @@ class SSViewerCacheBlockTest extends SapphireTest
         $this->_reset(true);
 
         // Generate cached value for foo = 1
-        $this->assertEquals($this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 1]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 1]));
 
         // Test without flush
         Injector::inst()->get(Kernel::class)->boot();
         Director::test('/');
-        $this->assertEquals($this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 3]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 3]));
 
         // Test with flush
         Injector::inst()->get(Kernel::class)->boot(true);
         Director::test('/?flush=1');
-        $this->assertEquals($this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 2]), '2');
+        $this->assertEquals('2', $this->_runtemplate('<% cached %>$Foo<% end_cached %>', ['Foo' => 2]));
     }
 
     public function testVersionedCache()
@@ -173,29 +175,29 @@ class SSViewerCacheBlockTest extends SapphireTest
         // Run without caching in stage to prove data is uncached
         $this->_reset(false);
         Versioned::set_stage(Versioned::DRAFT);
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('default');
         $this->assertEquals(
             'default Stage.Stage',
-            SSViewer::execute_string('<% cached %>$Inspect<% end_cached %>', $data)
+            $this->_runtemplate('<% cached %>$Inspect<% end_cached %>', $data)
         );
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('first');
         $this->assertEquals(
             'first Stage.Stage',
-            SSViewer::execute_string('<% cached %>$Inspect<% end_cached %>', $data)
+            $this->_runtemplate('<% cached %>$Inspect<% end_cached %>', $data)
         );
 
         // Run without caching in live to prove data is uncached
         $this->_reset(false);
         Versioned::set_stage(Versioned::LIVE);
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('default');
         $this->assertEquals(
             'default Stage.Live',
             $this->_runtemplate('<% cached %>$Inspect<% end_cached %>', $data)
         );
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('first');
         $this->assertEquals(
             'first Stage.Live',
@@ -207,13 +209,13 @@ class SSViewerCacheBlockTest extends SapphireTest
         // within them
         $this->_reset(true);
         Versioned::set_stage(Versioned::DRAFT);
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('default');
         $this->assertEquals(
             'default Stage.Stage',
             $this->_runtemplate('<% cached %>$Inspect<% end_cached %>', $data)
         );
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('first');
         $this->assertEquals(
             'default Stage.Stage', // entropy should be ignored due to caching
@@ -221,13 +223,13 @@ class SSViewerCacheBlockTest extends SapphireTest
         );
 
         Versioned::set_stage(Versioned::LIVE);
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('first');
         $this->assertEquals(
             'first Stage.Live', // First hit in live, so display current entropy
             $this->_runtemplate('<% cached %>$Inspect<% end_cached %>', $data)
         );
-        $data = new SSViewerCacheBlockTest\VersionedModel();
+        $data = new SSTemplateEngineCacheBlockTest\VersionedModel();
         $data->setEntropy('second');
         $this->assertEquals(
             'first Stage.Live', // entropy should be ignored due to caching
@@ -245,48 +247,48 @@ class SSViewerCacheBlockTest extends SapphireTest
         // First, run twice with caching
         $this->_reset(true);
 
-        $this->assertEquals($this->_runtemplate('<% cached if True %>$Foo<% end_cached %>', ['Foo' => 1]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached if True %>$Foo<% end_cached %>', ['Foo' => 1]));
-        $this->assertEquals($this->_runtemplate('<% cached if True %>$Foo<% end_cached %>', ['Foo' => 2]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached if True %>$Foo<% end_cached %>', ['Foo' => 2]));
 
         // Then twice without caching
         $this->_reset(true);
 
-        $this->assertEquals($this->_runtemplate('<% cached if False %>$Foo<% end_cached %>', ['Foo' => 1]), '1');
+        $this->assertEquals('1', $this->_runtemplate('<% cached if False %>$Foo<% end_cached %>', ['Foo' => 1]));
-        $this->assertEquals($this->_runtemplate('<% cached if False %>$Foo<% end_cached %>', ['Foo' => 2]), '2');
+        $this->assertEquals('2', $this->_runtemplate('<% cached if False %>$Foo<% end_cached %>', ['Foo' => 2]));
 
         // Then once cached, once not (and the opposite)
         $this->_reset(true);
 
         $this->assertEquals(
+            '1',
             $this->_runtemplate(
                 '<% cached if Cache %>$Foo<% end_cached %>',
                 ['Foo' => 1, 'Cache' => true ]
-            ),
+            )
-            '1'
         );
         $this->assertEquals(
+            '2',
             $this->_runtemplate(
                 '<% cached if Cache %>$Foo<% end_cached %>',
                 ['Foo' => 2, 'Cache' => false]
-            ),
+            )
-            '2'
         );
 
         $this->_reset(true);
 
         $this->assertEquals(
+            '1',
             $this->_runtemplate(
                 '<% cached if Cache %>$Foo<% end_cached %>',
                 ['Foo' => 1, 'Cache' => false]
-            ),
+            )
-            '1'
         );
         $this->assertEquals(
+            '2',
             $this->_runtemplate(
                 '<% cached if Cache %>$Foo<% end_cached %>',
                 ['Foo' => 2, 'Cache' => true ]
-            ),
+            )
-            '2'
         );
     }
 

tests/php/View/SSTemplateEngineCacheBlockTest/TestModel.php

@@ -1,13 +1,13 @@
 <?php
 
-namespace SilverStripe\View\Tests\SSViewerCacheBlockTest;
+namespace SilverStripe\View\Tests\SSTemplateEngineCacheBlockTest;
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\ORM\DataObject;
 
 class TestModel extends DataObject implements TestOnly
 {
-    private static $table_name = 'SSViewerCacheBlockTest_Model';
+    private static $table_name = 'SSTemplateEngineCacheBlockTest_Model';
 
     public function Test($arg = null)
     {

tests/php/View/SSTemplateEngineCacheBlockTest/VersionedModel.php

@@ -1,6 +1,6 @@
 <?php
 
-namespace SilverStripe\View\Tests\SSViewerCacheBlockTest;
+namespace SilverStripe\View\Tests\SSTemplateEngineCacheBlockTest;
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\ORM\DataObject;
@@ -8,7 +8,7 @@ use SilverStripe\Versioned\Versioned;
 
 class VersionedModel extends DataObject implements TestOnly
 {
-    private static $table_name = 'SSViewerCacheBlockTest_VersionedModel';
+    private static $table_name = 'SSTemplateEngineCacheBlockTest_VersionedModel';
 
     protected $entropy = 'default';
 

tests/php/View/SSTemplateEngineFindTemplateTest.php

@@ -0,0 +1,321 @@
+<?php
+
+namespace SilverStripe\View\Tests;
+
+use SilverStripe\Control\Director;
+use SilverStripe\Dev\SapphireTest;
+use Psr\SimpleCache\CacheInterface;
+use ReflectionMethod;
+use SilverStripe\Core\Manifest\ModuleLoader;
+use SilverStripe\Core\Manifest\ModuleManifest;
+use SilverStripe\View\SSTemplateEngine;
+use SilverStripe\View\ThemeManifest;
+use SilverStripe\View\ThemeResourceLoader;
+
+/**
+ * Tests for SSTemplateEngine::findTemplate().
+ * These have been separated out from SSTemplateEngineTest because of the extreme setup requirements.
+ */
+class SSTemplateEngineFindTemplateTest extends SapphireTest
+{
+    private string $base;
+
+    private ThemeResourceLoader $origLoader;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        // Fake project root
+        $this->base = dirname(__FILE__) . '/SSTemplateEngineTest_findTemplate';
+        Director::config()->set('alternate_base_folder', $this->base);
+        ModuleManifest::config()->set('module_priority', ['$project', '$other_modules']);
+        ModuleManifest::config()->set('project', 'myproject');
+
+        $moduleManifest = new ModuleManifest($this->base);
+        $moduleManifest->init();
+        $moduleManifest->sort();
+        ModuleLoader::inst()->pushManifest($moduleManifest);
+
+        // New ThemeManifest for that root
+        $themeManifest = new ThemeManifest($this->base);
+        $themeManifest->setProject('myproject');
+        $themeManifest->init();
+        // New Loader for that root
+        $this->origLoader = ThemeResourceLoader::inst();
+        $themeResourceLoader = new ThemeResourceLoader($this->base);
+        $themeResourceLoader->addSet('$default', $themeManifest);
+        ThemeResourceLoader::set_instance($themeResourceLoader);
+
+        // Ensure the cache is flushed between tests
+        ThemeResourceLoader::flush();
+    }
+
+    protected function tearDown(): void
+    {
+        ThemeResourceLoader::set_instance($this->origLoader);
+        ModuleLoader::inst()->popManifest();
+        parent::tearDown();
+    }
+
+    /**
+     * Test that 'main' and 'Layout' templates are loaded from module
+     */
+    public function testFindTemplatesInModule()
+    {
+        $base = ThemeResourceLoader::inst()->getBase();
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        $this->assertEquals(
+            "$base/module/templates/Page.ss",
+            $reflectionFindTemplate->invoke($engine, 'Page', ['$default'])
+        );
+
+        $this->assertEquals(
+            "$base/module/templates/Layout/Page.ss",
+            $reflectionFindTemplate->invoke($engine, ['type' => 'Layout', 'Page'], ['$default'])
+        );
+    }
+
+    public function testFindNestedThemeTemplates()
+    {
+        $base = ThemeResourceLoader::inst()->getBase();
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        // Without including the theme this template cannot be found
+        $this->assertEquals(null, $reflectionFindTemplate->invoke($engine, 'NestedThemePage', ['$default']));
+
+        // With a nested theme available then it is available
+        $this->assertEquals(
+            "{$base}/module/themes/subtheme/templates/NestedThemePage.ss",
+            $reflectionFindTemplate->invoke(
+                $engine,
+                'NestedThemePage',
+                [
+                    'silverstripe/module:subtheme',
+                    '$default'
+                ]
+            )
+        );
+
+        // Can also be found if excluding $default theme
+        $this->assertEquals(
+            "{$base}/module/themes/subtheme/templates/NestedThemePage.ss",
+            $reflectionFindTemplate->invoke(
+                $engine,
+                'NestedThemePage',
+                [
+                    'silverstripe/module:subtheme',
+                ]
+            )
+        );
+    }
+
+    public function testFindTemplateByType()
+    {
+        $base = ThemeResourceLoader::inst()->getBase();
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        // Test that "type" is respected properly
+        $this->assertEquals(
+            "{$base}/module/templates/MyNamespace/Layout/MyClass.ss",
+            $reflectionFindTemplate->invoke(
+                $engine,
+                [
+                    [
+                        'type' => 'Layout',
+                        'MyNamespace/NonExistantTemplate'
+                    ],
+                    [
+                        'type' => 'Layout',
+                        'MyNamespace/MyClass'
+                    ],
+                    'MyNamespace/MyClass'
+                ],
+                [
+                    'silverstripe/module:subtheme',
+                    'theme',
+                    '$default',
+                ]
+            )
+        );
+
+        // Non-typed template can be found even if looking for typed theme at a lower priority
+        $this->assertEquals(
+            "{$base}/module/templates/MyNamespace/MyClass.ss",
+            $reflectionFindTemplate->invoke(
+                $engine,
+                [
+                    [
+                        'type' => 'Layout',
+                        'MyNamespace/NonExistantTemplate'
+                    ],
+                    'MyNamespace/MyClass',
+                    [
+                        'type' => 'Layout',
+                        'MyNamespace/MyClass'
+                    ]
+                ],
+                [
+                    'silverstripe/module',
+                    'theme',
+                    '$default',
+                ]
+            )
+        );
+    }
+
+    public function testFindTemplatesByPath()
+    {
+        $base = ThemeResourceLoader::inst()->getBase();
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        // Items given as full paths are returned directly
+        $this->assertEquals(
+            "$base/themes/theme/templates/Page.ss",
+            $reflectionFindTemplate->invoke($engine, "$base/themes/theme/templates/Page.ss", ['theme'])
+        );
+
+        $this->assertEquals(
+            "$base/themes/theme/templates/Page.ss",
+            $reflectionFindTemplate->invoke(
+                $engine,
+                [
+                    "$base/themes/theme/templates/Page.ss",
+                    "Page"
+                ],
+                ['theme']
+            )
+        );
+
+        // Ensure checks for file_exists
+        $this->assertEquals(
+            "$base/themes/theme/templates/Page.ss",
+            $reflectionFindTemplate->invoke(
+                $engine,
+                [
+                    "$base/themes/theme/templates/NotAPage.ss",
+                    "$base/themes/theme/templates/Page.ss",
+                ],
+                ['theme']
+            )
+        );
+    }
+
+    /**
+     * Test that 'main' and 'Layout' templates are loaded from set theme
+     */
+    public function testFindTemplatesInTheme()
+    {
+        $base = ThemeResourceLoader::inst()->getBase();
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        $this->assertEquals(
+            "$base/themes/theme/templates/Page.ss",
+            $reflectionFindTemplate->invoke($engine, 'Page', ['theme'])
+        );
+
+        $this->assertEquals(
+            "$base/themes/theme/templates/Layout/Page.ss",
+            $reflectionFindTemplate->invoke($engine, ['type' => 'Layout', 'Page'], ['theme'])
+        );
+    }
+
+    /**
+     * Test that 'main' and 'Layout' templates are loaded from project without a set theme
+     */
+    public function testFindTemplatesInApplication()
+    {
+        $base = ThemeResourceLoader::inst()->getBase();
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        $templates = [
+            $base . '/myproject/templates/Page.ss',
+            $base . '/myproject/templates/Layout/Page.ss'
+        ];
+        foreach ($templates as $template) {
+            file_put_contents($template, '');
+        }
+
+        try {
+            $this->assertEquals(
+                "$base/myproject/templates/Page.ss",
+                $reflectionFindTemplate->invoke($engine, 'Page', ['$default'])
+            );
+
+            $this->assertEquals(
+                "$base/myproject/templates/Layout/Page.ss",
+                $reflectionFindTemplate->invoke($engine, ['type' => 'Layout', 'Page'], ['$default'])
+            );
+
+        } finally {
+            foreach ($templates as $template) {
+                unlink($template);
+            }
+        }
+    }
+
+    /**
+     * Test that 'main' template is found in theme and 'Layout' is found in module
+     */
+    public function testFindTemplatesMainThemeLayoutModule()
+    {
+        $base = ThemeResourceLoader::inst()->getBase();
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        $this->assertEquals(
+            "$base/themes/theme/templates/CustomThemePage.ss",
+            $reflectionFindTemplate->invoke($engine, 'CustomThemePage', ['theme', '$default'])
+        );
+
+        $this->assertEquals(
+            "$base/module/templates/Layout/CustomThemePage.ss",
+            $reflectionFindTemplate->invoke($engine, ['type' => 'Layout', 'CustomThemePage'], ['theme', '$default'])
+        );
+    }
+
+    public function testFindTemplateWithCacheMiss()
+    {
+        $mockCache = $this->createMock(CacheInterface::class);
+        $mockCache->expects($this->once())->method('has')->willReturn(false);
+        $mockCache->expects($this->never())->method('get');
+        $mockCache->expects($this->once())->method('set');
+        ThemeResourceLoader::inst()->setCache($mockCache);
+
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        $reflectionFindTemplate->invoke($engine, 'Page', ['$default']);
+    }
+
+    public function testFindTemplateWithCacheHit()
+    {
+        $mockCache = $this->createMock(CacheInterface::class);
+        $mockCache->expects($this->once())->method('has')->willReturn(true);
+        $mockCache->expects($this->never())->method('set');
+        $mockCache->expects($this->once())->method('get')->willReturn('mock_template.ss');
+        ThemeResourceLoader::inst()->setCache($mockCache);
+
+        $engine = new SSTemplateEngine();
+        $reflectionFindTemplate = new ReflectionMethod($engine, 'findTemplate');
+        $reflectionFindTemplate->setAccessible(true);
+
+        $result = $reflectionFindTemplate->invoke($engine, 'Page', ['$default']);
+        $this->assertSame('mock_template.ss', $result);
+    }
+}

tests/php/View/SSTemplateEngineTest.php

@@ -0,0 +1,2279 @@
+<?php
+
+namespace SilverStripe\View\Tests;
+
+use LogicException;
+use PHPUnit\Framework\MockObject\MockObject;
+use Silverstripe\Assets\Dev\TestAssetStore;
+use SilverStripe\Control\ContentNegotiator;
+use SilverStripe\Control\Director;
+use SilverStripe\Control\HTTPResponse;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\i18n\i18n;
+use SilverStripe\Model\List\ArrayList;
+use SilverStripe\Model\List\PaginatedList;
+use SilverStripe\Security\Permission;
+use SilverStripe\Security\Security;
+use SilverStripe\Security\SecurityToken;
+use SilverStripe\Model\ArrayData;
+use SilverStripe\View\Requirements;
+use SilverStripe\View\Requirements_Backend;
+use SilverStripe\View\SSTemplateParseException;
+use SilverStripe\View\SSTemplateParser;
+use SilverStripe\View\SSViewer;
+use SilverStripe\View\Tests\SSTemplateEngineTest\TestModelData;
+use SilverStripe\Model\ModelData;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\DoesNotPerformAssertions;
+use SilverStripe\View\Exception\MissingTemplateException;
+use SilverStripe\View\SSTemplateEngine;
+use SilverStripe\View\ViewLayerData;
+use stdClass;
+
+class SSTemplateEngineTest extends SapphireTest
+{
+    protected static $extra_dataobjects = [
+        SSTemplateEngineTest\TestObject::class,
+    ];
+
+    protected $usesDatabase = true;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        SSViewer::config()->set('source_file_comments', false);
+        TestAssetStore::activate('SSTemplateEngineTest');
+    }
+
+    protected function tearDown(): void
+    {
+        TestAssetStore::reset();
+        parent::tearDown();
+    }
+
+    /**
+     * Test that a template without a <head> tag still renders.
+     */
+    public function testTemplateWithoutHeadRenders()
+    {
+        $data = new ArrayData([ 'Var' => 'var value' ]);
+        $engine = new SSTemplateEngine('SSTemplateEngineTestPartialTemplate');
+        $result = $engine->render(new ViewLayerData($data));
+        $this->assertEquals('Test partial template: var value', trim(preg_replace("/<!--.*-->/U", '', $result ?? '') ?? ''));
+    }
+
+    /**
+     * Ensure global methods aren't executed
+     */
+    public function testTemplateExecution()
+    {
+        $data = new ArrayData([ 'Var' => 'phpinfo' ]);
+        $engine = new SSTemplateEngine('SSTemplateEngineTestPartialTemplate');
+        $result = $engine->render(new ViewLayerData($data));
+        $this->assertEquals('Test partial template: phpinfo', trim(preg_replace("/<!--.*-->/U", '', $result ?? '') ?? ''));
+    }
+
+    public function testIncludeScopeInheritance()
+    {
+        $data = $this->getScopeInheritanceTestData();
+        $expected = [
+            'Item 1 - First-ODD top:Item 1',
+            'Item 2 - EVEN top:Item 2',
+            'Item 3 - ODD top:Item 3',
+            'Item 4 - EVEN top:Item 4',
+            'Item 5 - ODD top:Item 5',
+            'Item 6 - Last-EVEN top:Item 6',
+        ];
+
+        $engine = new SSTemplateEngine('SSTemplateEngineTestIncludeScopeInheritance');
+        $result = $engine->render(new ViewLayerData($data));
+        $this->assertExpectedStrings($result, $expected);
+
+        // reset results for the tests that include arguments (the title is passed as an arg)
+        $expected = [
+            'Item 1 _ Item 1 - First-ODD top:Item 1',
+            'Item 2 _ Item 2 - EVEN top:Item 2',
+            'Item 3 _ Item 3 - ODD top:Item 3',
+            'Item 4 _ Item 4 - EVEN top:Item 4',
+            'Item 5 _ Item 5 - ODD top:Item 5',
+            'Item 6 _ Item 6 - Last-EVEN top:Item 6',
+        ];
+
+        $engine = new SSTemplateEngine('SSTemplateEngineTestIncludeScopeInheritanceWithArgs');
+        $result = $engine->render(new ViewLayerData($data));
+        $this->assertExpectedStrings($result, $expected);
+    }
+
+    public function testIncludeTruthyness()
+    {
+        $data = new ArrayData([
+            'Title' => 'TruthyTest',
+            'Items' => new ArrayList([
+                new ArrayData(['Title' => 'Item 1']),
+                new ArrayData(['Title' => '']),
+                new ArrayData(['Title' => true]),
+                new ArrayData(['Title' => false]),
+                new ArrayData(['Title' => null]),
+                new ArrayData(['Title' => 0]),
+                new ArrayData(['Title' => 7])
+            ])
+        ]);
+        $engine = new SSTemplateEngine('SSTemplateEngineTestIncludeScopeInheritanceWithArgs');
+        $result = $engine->render(new ViewLayerData($data));
+
+        // We should not end up with empty values appearing as empty
+        $expected = [
+            'Item 1 _ Item 1 - First-ODD top:Item 1',
+            'Untitled - EVEN top:',
+            '1 _ 1 - ODD top:1',
+            'Untitled - EVEN top:',
+            'Untitled - ODD top:',
+            'Untitled - EVEN top:0',
+            '7 _ 7 - Last-ODD top:7',
+        ];
+        $this->assertExpectedStrings($result, $expected);
+    }
+
+    public function testRequirements()
+    {
+        /** @var Requirements_Backend|MockObject $requirements */
+        $requirements = $this
+            ->getMockBuilder(Requirements_Backend::class)
+            ->onlyMethods(['javascript', 'css'])
+            ->getMock();
+        $jsFile = FRAMEWORK_DIR . '/tests/forms/a.js';
+        $cssFile = FRAMEWORK_DIR . '/tests/forms/a.js';
+
+        $requirements->expects($this->once())->method('javascript')->with($jsFile);
+        $requirements->expects($this->once())->method('css')->with($cssFile);
+
+        $origReq = Requirements::backend();
+        Requirements::set_backend($requirements);
+        $result = $this->render(
+            "<% require javascript($jsFile) %>
+		    <% require css($cssFile) %>"
+        );
+        Requirements::set_backend($origReq);
+
+        // Injecting the actual requirements is the responsibility of SSViewer, so we shouldn't see it in the result
+        $this->assertFalse((bool)trim($result), 'Should be no content in this return.');
+    }
+
+    public function testRequireCallInTemplateInclude()
+    {
+        /** @var Requirements_Backend|MockObject $requirements */
+        $requirements = $this
+            ->getMockBuilder(Requirements_Backend::class)
+            ->onlyMethods(['themedJavascript', 'css'])
+            ->getMock();
+
+        $requirements->expects($this->once())->method('themedJavascript')->with('RequirementsTest_a');
+        $requirements->expects($this->never())->method('css');
+
+        $engine = new SSTemplateEngine('SSTemplateEngineTestProcess');
+        $origReq = Requirements::backend();
+        Requirements::set_backend($requirements);
+        Requirements::set_suffix_requirements(false);
+        $result = $engine->render(new ViewLayerData([]));
+        Requirements::set_backend($origReq);
+
+        // Injecting the actual requirements is the responsibility of SSViewer, so we shouldn't see it in the result
+        $this->assertEqualIgnoringWhitespace('<html><head></head><body></body></html>', $result);
+    }
+
+    public function testComments()
+    {
+        $input = <<<SS
+        This is my template<%-- this is a comment --%>This is some content<%-- this is another comment --%>Final content
+        <%-- Alone multi
+            line comment --%>
+        Some more content
+        Mixing content and <%-- multi
+            line comment --%> Final final
+        content
+        <%--commentwithoutwhitespace--%>last content
+        SS;
+        $actual = $this->render($input);
+        $expected = <<<SS
+        This is my templateThis is some contentFinal content
+
+        Some more content
+        Mixing content and  Final final
+        content
+        last content
+        SS;
+        $this->assertEquals($expected, $actual);
+
+        $input = <<<SS
+        <%--
+
+        --%>empty comment1
+        <%-- --%>empty comment2
+        <%----%>empty comment3
+        SS;
+        $actual = $this->render($input);
+        $expected = <<<SS
+        empty comment1
+        empty comment2
+        empty comment3
+        SS;
+        $this->assertEquals($expected, $actual);
+    }
+
+    public function testBasicText()
+    {
+        $this->assertEquals('"', $this->render('"'), 'Double-quotes are left alone');
+        $this->assertEquals("'", $this->render("'"), 'Single-quotes are left alone');
+        $this->assertEquals('A', $this->render('\\A'), 'Escaped characters are unescaped');
+        $this->assertEquals('\\A', $this->render('\\\\A'), 'Escaped back-slashed are correctly unescaped');
+    }
+
+    public function testBasicInjection()
+    {
+        $this->assertEquals('[out:Test]', $this->render('$Test'), 'Basic stand-alone injection');
+        $this->assertEquals('[out:Test]', $this->render('{$Test}'), 'Basic stand-alone wrapped injection');
+        $this->assertEquals('A[out:Test]!', $this->render('A$Test!'), 'Basic surrounded injection');
+        $this->assertEquals('A[out:Test]B', $this->render('A{$Test}B'), 'Basic surrounded wrapped injection');
+
+        $this->assertEquals('A$B', $this->render('A\\$B'), 'No injection as $ escaped');
+        $this->assertEquals('A$ B', $this->render('A$ B'), 'No injection as $ not followed by word character');
+        $this->assertEquals('A{$ B', $this->render('A{$ B'), 'No injection as {$ not followed by word character');
+
+        $this->assertEquals('{$Test}', $this->render('{\\$Test}'), 'Escapes can be used to avoid injection');
+        $this->assertEquals(
+            '{\\[out:Test]}',
+            $this->render('{\\\\$Test}'),
+            'Escapes before injections are correctly unescaped'
+        );
+    }
+
+    public function testBasicInjectionMismatchedBrackets()
+    {
+        $this->expectException(SSTemplateParseException::class);
+        $this->expectExceptionMessageMatches('/Malformed bracket injection {\$Value(.*)/');
+        $this->render('A {$Value here');
+        $this->fail("Parser didn't error when encountering mismatched brackets in an injection");
+    }
+
+    public function testGlobalVariableCalls()
+    {
+        $this->assertEquals('automatic', $this->render('$SSTemplateEngineTest_GlobalAutomatic'));
+        $this->assertEquals('reference', $this->render('$SSTemplateEngineTest_GlobalReferencedByString'));
+        $this->assertEquals('reference', $this->render('$SSTemplateEngineTest_GlobalReferencedInArray'));
+    }
+
+    public function testGlobalVariableCallsWithArguments()
+    {
+        $this->assertEquals('zz', $this->render('$SSTemplateEngineTest_GlobalThatTakesArguments'));
+        $this->assertEquals('zFooz', $this->render('$SSTemplateEngineTest_GlobalThatTakesArguments("Foo")'));
+        $this->assertEquals(
+            'zFoo:Bar:Bazz',
+            $this->render('$SSTemplateEngineTest_GlobalThatTakesArguments("Foo", "Bar", "Baz")')
+        );
+        $this->assertEquals(
+            'zreferencez',
+            $this->render('$SSTemplateEngineTest_GlobalThatTakesArguments($SSTemplateEngineTest_GlobalReferencedByString)')
+        );
+    }
+
+    public function testGlobalVariablesAreEscaped()
+    {
+        $this->assertEquals('<div></div>', $this->render('$SSTemplateEngineTest_GlobalHTMLFragment'));
+        $this->assertEquals('&lt;div&gt;&lt;/div&gt;', $this->render('$SSTemplateEngineTest_GlobalHTMLEscaped'));
+
+        $this->assertEquals(
+            'z<div></div>z',
+            $this->render('$SSTemplateEngineTest_GlobalThatTakesArguments($SSTemplateEngineTest_GlobalHTMLFragment)')
+        );
+        // Don't escape value when passing into a method call
+        $this->assertEquals(
+            'z<div></div>z',
+            $this->render('$SSTemplateEngineTest_GlobalThatTakesArguments($SSTemplateEngineTest_GlobalHTMLEscaped)')
+        );
+    }
+
+    public function testGlobalVariablesReturnNull()
+    {
+        $this->assertEquals('<p></p>', $this->render('<p>$SSTemplateEngineTest_GlobalReturnsNull</p>'));
+        $this->assertEquals('<p></p>', $this->render('<p>$SSTemplateEngineTest_GlobalReturnsNull.Chained.Properties</p>'));
+    }
+
+    public function testCoreGlobalVariableCalls()
+    {
+        $this->assertEquals(
+            Director::absoluteBaseURL(),
+            $this->render('{$absoluteBaseURL}'),
+            'Director::absoluteBaseURL can be called from within template'
+        );
+        $this->assertEquals(
+            Director::absoluteBaseURL(),
+            $this->render('{$AbsoluteBaseURL}'),
+            'Upper-case %AbsoluteBaseURL can be called from within template'
+        );
+
+        $this->assertEquals(
+            Director::is_ajax(),
+            $this->render('{$isAjax}'),
+            'All variations of is_ajax result in the correct call'
+        );
+        $this->assertEquals(
+            Director::is_ajax(),
+            $this->render('{$IsAjax}'),
+            'All variations of is_ajax result in the correct call'
+        );
+        $this->assertEquals(
+            Director::is_ajax(),
+            $this->render('{$is_ajax}'),
+            'All variations of is_ajax result in the correct call'
+        );
+        $this->assertEquals(
+            Director::is_ajax(),
+            $this->render('{$Is_ajax}'),
+            'All variations of is_ajax result in the correct call'
+        );
+
+        $this->assertEquals(
+            i18n::get_locale(),
+            $this->render('{$i18nLocale}'),
+            'i18n template functions result correct result'
+        );
+        $this->assertEquals(
+            i18n::get_locale(),
+            $this->render('{$get_locale}'),
+            'i18n template functions result correct result'
+        );
+
+        $this->assertEquals(
+            Security::getCurrentUser()->ID,
+            $this->render('{$CurrentMember.ID}'),
+            'Member template functions result correct result'
+        );
+        $this->assertEquals(
+            Security::getCurrentUser()->ID,
+            $this->render('{$CurrentUser.ID}'),
+            'Member template functions result correct result'
+        );
+        $this->assertEquals(
+            Security::getCurrentUser()->ID,
+            $this->render('{$currentMember.ID}'),
+            'Member template functions result correct result'
+        );
+        $this->assertEquals(
+            Security::getCurrentUser()->ID,
+            $this->render('{$currentUser.ID}'),
+            'Member template functions result correct result'
+        );
+
+        $this->assertEquals(
+            SecurityToken::getSecurityID(),
+            $this->render('{$getSecurityID}'),
+            'SecurityToken template functions result correct result'
+        );
+        $this->assertEquals(
+            SecurityToken::getSecurityID(),
+            $this->render('{$SecurityID}'),
+            'SecurityToken template functions result correct result'
+        );
+
+        $this->assertEquals(
+            Permission::check("ADMIN"),
+            (bool)$this->render('{$HasPerm(\'ADMIN\')}'),
+            'Permissions template functions result correct result'
+        );
+        $this->assertEquals(
+            Permission::check("ADMIN"),
+            (bool)$this->render('{$hasPerm(\'ADMIN\')}'),
+            'Permissions template functions result correct result'
+        );
+    }
+
+    public function testNonFieldCastingHelpersNotUsedInHasValue()
+    {
+        // check if Link without $ in front of variable
+        $result = $this->render(
+            'A<% if Link %>$Link<% end_if %>B',
+            new SSTemplateEngineTest\TestObject()
+        );
+        $this->assertEquals('Asome/url.htmlB', $result, 'casting helper not used for <% if Link %>');
+
+        // check if Link with $ in front of variable
+        $result = $this->render(
+            'A<% if $Link %>$Link<% end_if %>B',
+            new SSTemplateEngineTest\TestObject()
+        );
+        $this->assertEquals('Asome/url.htmlB', $result, 'casting helper not used for <% if $Link %>');
+    }
+
+    public function testLocalFunctionsTakePriorityOverGlobals()
+    {
+        $data = new ArrayData([
+            'Page' => new SSTemplateEngineTest\TestObject()
+        ]);
+
+        //call method with lots of arguments
+        $result = $this->render(
+            '<% with Page %>$lotsOfArguments11("a","b","c","d","e","f","g","h","i","j","k")<% end_with %>',
+            $data
+        );
+        $this->assertEquals("abcdefghijk", $result, "public function can accept up to 11 arguments");
+
+        //call method that does not exist
+        $result = $this->render('<% with Page %><% if IDoNotExist %>hello<% end_if %><% end_with %>', $data);
+        $this->assertEquals("", $result, "Method does not exist - empty result");
+
+        //call if that does not exist
+        $result = $this->render('<% with Page %>$IDoNotExist("hello")<% end_with %>', $data);
+        $this->assertEquals("", $result, "Method does not exist - empty result");
+
+        //call method with same name as a global method (local call should take priority)
+        $result = $this->render('<% with Page %>$absoluteBaseURL<% end_with %>', $data);
+        $this->assertEquals(
+            "testLocalFunctionPriorityCalled",
+            $result,
+            "Local Object's public function called. Did not return the actual baseURL of the current site"
+        );
+    }
+
+    public function testCurrentScopeLoop(): void
+    {
+        $data = new ArrayList([['Val' => 'one'], ['Val' => 'two'], ['Val' => 'three']]);
+        $this->assertEqualIgnoringWhitespace(
+            'one two three',
+            $this->render('<% loop %>$Val<% end_loop %>', $data)
+        );
+    }
+
+    public function testCurrentScopeLoopWith()
+    {
+        // Data to run the loop tests on - one sequence of three items, each with a subitem
+        $data = new ArrayData([
+            'Foo' => new ArrayList([
+                'Subocean' => new ArrayData([
+                    'Name' => 'Higher'
+                ]),
+                new ArrayData([
+                    'Sub' => new ArrayData([
+                        'Name' => 'SubKid1'
+                    ])
+                ]),
+                new ArrayData([
+                    'Sub' => new ArrayData([
+                        'Name' => 'SubKid2'
+                    ])
+                ]),
+                new SSTemplateEngineTest\TestObject('Number6')
+            ])
+        ]);
+
+        $result = $this->render(
+            '<% loop Foo %>$Number<% if Sub %><% with Sub %>$Name<% end_with %><% end_if %><% end_loop %>',
+            $data
+        );
+        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop works");
+
+        $result = $this->render(
+            '<% loop Foo %>$Number<% if Sub %><% with Sub %>$Name<% end_with %><% end_if %><% end_loop %>',
+            $data
+        );
+        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop works");
+
+        $result = $this->render('<% with Foo %>$Count<% end_with %>', $data);
+        $this->assertEquals("4", $result, "4 items in the DataObjectSet");
+
+        $result = $this->render(
+            '<% with Foo %><% loop Up.Foo %>$Number<% if Sub %><% with Sub %>$Name<% end_with %>'
+            . '<% end_if %><% end_loop %><% end_with %>',
+            $data
+        );
+        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop in with Up.Foo scope works");
+
+        $result = $this->render(
+            '<% with Foo %><% loop %>$Number<% if Sub %><% with Sub %>$Name<% end_with %>'
+            . '<% end_if %><% end_loop %><% end_with %>',
+            $data
+        );
+        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop in current scope works");
+    }
+
+    public static function provideArgumentTypes()
+    {
+        return [
+            [
+                'arg0:0,arg1:"string",arg2:true',
+                '$methodWithTypedArguments(0, "string", true).RAW',
+            ],
+            [
+                'arg0:false,arg1:"string",arg2:true',
+                '$methodWithTypedArguments(false, "string", true).RAW',
+            ],
+            [
+                'arg0:null,arg1:"string",arg2:true',
+                '$methodWithTypedArguments(null, "string", true).RAW',
+            ],
+            [
+                'arg0:"",arg1:"string",arg2:true',
+                '$methodWithTypedArguments("", "string", true).RAW',
+            ],
+            [
+                'arg0:0,arg1:1,arg2:2',
+                '$methodWithTypedArguments(0, 1, 2).RAW',
+            ],
+        ];
+    }
+
+    #[DataProvider('provideArgumentTypes')]
+    public function testArgumentTypes(string $expected, string $template)
+    {
+        $this->assertEquals($expected, $this->render($template, new TestModelData()));
+    }
+
+    public static function provideEvaluatedArgumentTypes(): array
+    {
+        $stdobj = new stdClass();
+        $stdobj->key = 'value';
+        $scenarios = [
+            'null value' => [
+                'data' => ['Value' => null],
+                'useOverlay' => true,
+                'expected' => 'arg0:null',
+            ],
+            'int value' => [
+                'data' => ['Value' => 1],
+                'useOverlay' => true,
+                'expected' => 'arg0:1',
+            ],
+            'string value' => [
+                'data' => ['Value' => '1'],
+                'useOverlay' => true,
+                'expected' => 'arg0:"1"',
+            ],
+            'boolean true' => [
+                'data' => ['Value' => true],
+                'useOverlay' => true,
+                'expected' => 'arg0:true',
+            ],
+            'boolean false' => [
+                'data' => ['Value' => false],
+                'useOverlay' => true,
+                'expected' => 'arg0:false',
+            ],
+            'object value' => [
+                'data' => ['Value' => $stdobj],
+                'useOverlay' => true,
+                'expected' => 'arg0:{"key":"value"}',
+            ],
+        ];
+        foreach ($scenarios as $key => $scenario) {
+            $scenario['useOverlay'] = false;
+            $scenarios[$key . ' no overlay'] = $scenario;
+        }
+        return $scenarios;
+    }
+
+    #[DataProvider('provideEvaluatedArgumentTypes')]
+    public function testEvaluatedArgumentTypes(array $data, bool $useOverlay, string $expected): void
+    {
+        $template = '$methodWithTypedArguments($Value).RAW';
+        $model = new TestModelData();
+        $overlay = $data;
+        if (!$useOverlay) {
+            $model = $model->customise($data);
+            $overlay = [];
+        }
+        $this->assertEquals($expected, $this->render($template, $model, $overlay));
+    }
+
+    public function testObjectDotArguments()
+    {
+        $this->assertEquals(
+            '[out:TestObject.methodWithOneArgument(one)]
+				[out:TestObject.methodWithTwoArguments(one,two)]
+				[out:TestMethod(Arg1,Arg2).Bar.Val]
+				[out:TestMethod(Arg1,Arg2).Bar]
+				[out:TestMethod(Arg1,Arg2)]
+				[out:TestMethod(Arg1).Bar.Val]
+				[out:TestMethod(Arg1).Bar]
+				[out:TestMethod(Arg1)]',
+            $this->render(
+                '$TestObject.methodWithOneArgument(one)
+				$TestObject.methodWithTwoArguments(one,two)
+				$TestMethod(Arg1, Arg2).Bar.Val
+				$TestMethod(Arg1, Arg2).Bar
+				$TestMethod(Arg1, Arg2)
+				$TestMethod(Arg1).Bar.Val
+				$TestMethod(Arg1).Bar
+				$TestMethod(Arg1)'
+            )
+        );
+    }
+
+    public function testEscapedArguments()
+    {
+        $this->assertEquals(
+            '[out:Foo(Arg1,Arg2).Bar.Val].Suffix
+				[out:Foo(Arg1,Arg2).Val]_Suffix
+				[out:Foo(Arg1,Arg2)]/Suffix
+				[out:Foo(Arg1).Bar.Val]textSuffix
+				[out:Foo(Arg1).Bar].Suffix
+				[out:Foo(Arg1)].Suffix
+				[out:Foo.Bar.Val].Suffix
+				[out:Foo.Bar].Suffix
+				[out:Foo].Suffix',
+            $this->render(
+                '{$Foo(Arg1, Arg2).Bar.Val}.Suffix
+				{$Foo(Arg1, Arg2).Val}_Suffix
+				{$Foo(Arg1, Arg2)}/Suffix
+				{$Foo(Arg1).Bar.Val}textSuffix
+				{$Foo(Arg1).Bar}.Suffix
+				{$Foo(Arg1)}.Suffix
+				{$Foo.Bar.Val}.Suffix
+				{$Foo.Bar}.Suffix
+				{$Foo}.Suffix'
+            )
+        );
+    }
+
+    public function testLoopWhitespace()
+    {
+        $data = new ArrayList([new SSTemplateEngineTest\TestFixture()]);
+        $this->assertEquals(
+            'before[out:Test]after
+				beforeTestafter',
+            $this->render(
+                'before<% loop %>$Test<% end_loop %>after
+				before<% loop %>Test<% end_loop %>after',
+                $data
+            )
+        );
+
+        // The control tags are removed from the output, but no whitespace
+        // This is a quirk that could be changed, but included in the test to make the current
+        // behaviour explicit
+        $this->assertEquals(
+            'before
+
+[out:ItemOnItsOwnLine]
+
+after',
+            $this->render(
+                'before
+<% loop %>
+$ItemOnItsOwnLine
+<% end_loop %>
+after',
+                $data
+            )
+        );
+
+        // The whitespace within the control tags is preserve in a loop
+        // This is a quirk that could be changed, but included in the test to make the current
+        // behaviour explicit
+        $this->assertEquals(
+            'before
+
+[out:Loop3.ItemOnItsOwnLine]
+
+[out:Loop3.ItemOnItsOwnLine]
+
+[out:Loop3.ItemOnItsOwnLine]
+
+after',
+            $this->render(
+                'before
+<% loop Loop3 %>
+$ItemOnItsOwnLine
+<% end_loop %>
+after'
+            )
+        );
+    }
+
+    public static function typePreservationDataProvider()
+    {
+        return [
+            // Null
+            ['NULL:', 'null'],
+            ['NULL:', 'NULL'],
+            // Booleans
+            ['boolean:1', 'true'],
+            ['boolean:1', 'TRUE'],
+            ['boolean:', 'false'],
+            ['boolean:', 'FALSE'],
+            // Strings which may look like booleans/null to the parser
+            ['string:nullish', 'nullish'],
+            ['string:notnull', 'notnull'],
+            ['string:truethy', 'truethy'],
+            ['string:untrue', 'untrue'],
+            ['string:falsey', 'falsey'],
+            // Integers
+            ['integer:0', '0'],
+            ['integer:1', '1'],
+            ['integer:15', '15'],
+            ['integer:-15', '-15'],
+            // Octal integers
+            ['integer:83', '0123'],
+            ['integer:-83', '-0123'],
+            // Hexadecimal integers
+            ['integer:26', '0x1A'],
+            ['integer:-26', '-0x1A'],
+            // Binary integers
+            ['integer:255', '0b11111111'],
+            ['integer:-255', '-0b11111111'],
+            // Floats (aka doubles)
+            ['double:0', '0.0'],
+            ['double:1', '1.0'],
+            ['double:15.25', '15.25'],
+            ['double:-15.25', '-15.25'],
+            ['double:1200', '1.2e3'],
+            ['double:-1200', '-1.2e3'],
+            ['double:0.07', '7E-2'],
+            ['double:-0.07', '-7E-2'],
+            // Explicitly quoted strings
+            ['string:0', '"0"'],
+            ['string:1', '\'1\''],
+            ['string:foobar', '"foobar"'],
+            ['string:foo bar baz', '"foo bar baz"'],
+            ['string:false', '\'false\''],
+            ['string:true', '\'true\''],
+            ['string:null', '\'null\''],
+            ['string:false', '"false"'],
+            ['string:true', '"true"'],
+            ['string:null', '"null"'],
+            // Implicit strings
+            ['string:foobar', 'foobar'],
+            ['string:foo bar baz', 'foo bar baz']
+        ];
+    }
+
+    #[DataProvider('typePreservationDataProvider')]
+    public function testTypesArePreserved($expected, $templateArg)
+    {
+        $data = new ArrayData([
+            'Test' => new TestModelData()
+        ]);
+
+        $this->assertEquals($expected, $this->render("\$Test.Type({$templateArg})", $data));
+    }
+
+    #[DataProvider('typePreservationDataProvider')]
+    public function testTypesArePreservedAsIncludeArguments($expected, $templateArg)
+    {
+        $data = new ArrayData([
+            'Test' => new TestModelData()
+        ]);
+
+        $this->assertEquals(
+            $expected,
+            $this->render("<% include SSTemplateEngineTestTypePreservation Argument={$templateArg} %>", $data)
+        );
+    }
+
+    public function testTypePreservationInConditionals()
+    {
+        $data = new ArrayData([
+            'Test' => new TestModelData()
+        ]);
+
+        // Types in conditionals
+        $this->assertEquals('pass', $this->render('<% if true %>pass<% else %>fail<% end_if %>', $data));
+        $this->assertEquals('pass', $this->render('<% if false %>fail<% else %>pass<% end_if %>', $data));
+        $this->assertEquals('pass', $this->render('<% if 1 %>pass<% else %>fail<% end_if %>', $data));
+        $this->assertEquals('pass', $this->render('<% if 0 %>fail<% else %>pass<% end_if %>', $data));
+    }
+
+    public function testControls()
+    {
+        // Single item controls
+        $this->assertEquals(
+            'a[out:Foo.Bar.Item]b
+				[out:Foo.Bar(Arg1).Item]
+				[out:Foo(Arg1).Item]
+				[out:Foo(Arg1,Arg2).Item]
+				[out:Foo(Arg1,Arg2,Arg3).Item]',
+            $this->render(
+                '<% with Foo.Bar %>a{$Item}b<% end_with %>
+				<% with Foo.Bar(Arg1) %>$Item<% end_with %>
+				<% with Foo(Arg1) %>$Item<% end_with %>
+				<% with Foo(Arg1, Arg2) %>$Item<% end_with %>
+				<% with Foo(Arg1, Arg2, Arg3) %>$Item<% end_with %>'
+            )
+        );
+
+        // Loop controls
+        $this->assertEquals(
+            'a[out:Foo.Loop2.Item]ba[out:Foo.Loop2.Item]b',
+            $this->render('<% loop Foo.Loop2 %>a{$Item}b<% end_loop %>')
+        );
+
+        $this->assertEquals(
+            '[out:Foo.Loop2(Arg1).Item][out:Foo.Loop2(Arg1).Item]',
+            $this->render('<% loop Foo.Loop2(Arg1) %>$Item<% end_loop %>')
+        );
+
+        $this->assertEquals(
+            '[out:Loop2(Arg1).Item][out:Loop2(Arg1).Item]',
+            $this->render('<% loop Loop2(Arg1) %>$Item<% end_loop %>')
+        );
+
+        $this->assertEquals(
+            '[out:Loop2(Arg1,Arg2).Item][out:Loop2(Arg1,Arg2).Item]',
+            $this->render('<% loop Loop2(Arg1, Arg2) %>$Item<% end_loop %>')
+        );
+
+        $this->assertEquals(
+            '[out:Loop2(Arg1,Arg2,Arg3).Item][out:Loop2(Arg1,Arg2,Arg3).Item]',
+            $this->render('<% loop Loop2(Arg1, Arg2, Arg3) %>$Item<% end_loop %>')
+        );
+    }
+
+    public function testIfBlocks()
+    {
+        // Basic test
+        $this->assertEquals(
+            'AC',
+            $this->render('A<% if NotSet %>B$NotSet<% end_if %>C')
+        );
+
+        // Nested test
+        $this->assertEquals(
+            'AB1C',
+            $this->render('A<% if IsSet %>B$NotSet<% if IsSet %>1<% else %>2<% end_if %><% end_if %>C')
+        );
+
+        // else_if
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if NotSet %>B<% else_if IsSet %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if NotSet %>B<% else_if AlsoNotset %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ADE',
+            $this->render('A<% if NotSet %>B<% else_if AlsoNotset %>C<% else_if IsSet %>D<% end_if %>E')
+        );
+
+        $this->assertEquals(
+            'ADE',
+            $this->render('A<% if NotSet %>B<% else_if AlsoNotset %>C<% else_if IsSet %>D<% end_if %>E')
+        );
+
+        // Dot syntax
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if Foo.NotSet %>B<% else_if Foo.IsSet %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if Foo.Bar.NotSet %>B<% else_if Foo.Bar.IsSet %>C<% end_if %>D')
+        );
+
+        // Params
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if NotSet(Param) %>B<% else %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ABD',
+            $this->render('A<% if IsSet(Param) %>B<% else %>C<% end_if %>D')
+        );
+
+        // Negation
+        $this->assertEquals(
+            'AC',
+            $this->render('A<% if not IsSet %>B<% end_if %>C')
+        );
+        $this->assertEquals(
+            'ABC',
+            $this->render('A<% if not NotSet %>B<% end_if %>C')
+        );
+
+        // Or
+        $this->assertEquals(
+            'ABD',
+            $this->render('A<% if IsSet || NotSet %>B<% else_if A %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if IsSet %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if NotSet3 %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if IsSet || NotSet %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if NotSet2 || NotSet3 %>C<% end_if %>D')
+        );
+
+        // Negated Or
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if not IsSet || AlsoNotSet %>B<% else_if A %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ABD',
+            $this->render('A<% if not NotSet || AlsoNotSet %>B<% else_if A %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ABD',
+            $this->render('A<% if NotSet || not AlsoNotSet %>B<% else_if A %>C<% end_if %>D')
+        );
+
+        // And
+        $this->assertEquals(
+            'ABD',
+            $this->render('A<% if IsSet && AlsoSet %>B<% else_if A %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if IsSet && NotSet %>B<% else_if IsSet %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if NotSet && NotSet2 %>B<% else_if NotSet3 %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if IsSet && NotSet %>B<% else_if IsSet && AlsoSet %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if NotSet && NotSet2 %>B<% else_if IsSet && NotSet3 %>C<% end_if %>D')
+        );
+
+        // Equality
+        $this->assertEquals(
+            'ABC',
+            $this->render('A<% if RawVal == RawVal %>B<% end_if %>C')
+        );
+        $this->assertEquals(
+            'ACD',
+            $this->render('A<% if Right == Wrong %>B<% else_if RawVal == RawVal %>C<% end_if %>D')
+        );
+        $this->assertEquals(
+            'ABC',
+            $this->render('A<% if Right != Wrong %>B<% end_if %>C')
+        );
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if Right == Wrong %>B<% else_if RawVal != RawVal %>C<% end_if %>D')
+        );
+
+        // test inequalities with simple numbers
+        $this->assertEquals('ABD', $this->render('A<% if 5 > 3 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ABD', $this->render('A<% if 5 >= 3 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ACD', $this->render('A<% if 3 > 5 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ACD', $this->render('A<% if 3 >= 5 %>B<% else %>C<% end_if %>D'));
+
+        $this->assertEquals('ABD', $this->render('A<% if 3 < 5 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ABD', $this->render('A<% if 3 <= 5 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ACD', $this->render('A<% if 5 < 3 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ACD', $this->render('A<% if 5 <= 3 %>B<% else %>C<% end_if %>D'));
+
+        $this->assertEquals('ABD', $this->render('A<% if 4 <= 4 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ABD', $this->render('A<% if 4 >= 4 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ACD', $this->render('A<% if 4 > 4 %>B<% else %>C<% end_if %>D'));
+        $this->assertEquals('ACD', $this->render('A<% if 4 < 4 %>B<% else %>C<% end_if %>D'));
+
+        // empty else_if and else tags, if this would not be supported,
+        // the output would stop after A, thereby failing the assert
+        $this->assertEquals('AD', $this->render('A<% if IsSet %><% else %><% end_if %>D'));
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if NotSet %><% else_if IsSet %><% else %><% end_if %>D')
+        );
+        $this->assertEquals(
+            'AD',
+            $this->render('A<% if NotSet %><% else_if AlsoNotSet %><% else %><% end_if %>D')
+        );
+
+        // Bare words with ending space
+        $this->assertEquals(
+            'ABC',
+            $this->render('A<% if "RawVal" == RawVal %>B<% end_if %>C')
+        );
+
+        // Else
+        $this->assertEquals(
+            'ADE',
+            $this->render('A<% if Right == Wrong %>B<% else_if RawVal != RawVal %>C<% else %>D<% end_if %>E')
+        );
+
+        // Empty if with else
+        $this->assertEquals(
+            'ABC',
+            $this->render('A<% if NotSet %><% else %>B<% end_if %>C')
+        );
+    }
+
+    public static function provideIfBlockWithIterable(): array
+    {
+        $scenarios = [
+            'empty array' => [
+                'iterable' => [],
+                'inScope' => false,
+            ],
+            'array' => [
+                'iterable' => [1, 2, 3],
+                'inScope' => false,
+            ],
+            'ArrayList' => [
+                'iterable' => new ArrayList([['Val' => 1], ['Val' => 2], ['Val' => 3]]),
+                'inScope' => false,
+            ],
+        ];
+        foreach ($scenarios as $name => $scenario) {
+            $scenario['inScope'] = true;
+            $scenarios[$name . ' in scope'] = $scenario;
+        }
+        return $scenarios;
+    }
+
+    #[DataProvider('provideIfBlockWithIterable')]
+    public function testIfBlockWithIterable(iterable $iterable, bool $inScope): void
+    {
+        $expected = count($iterable) ? 'has value' : 'no value';
+        $data = new ArrayData(['Iterable' => $iterable]);
+        if ($inScope) {
+            $template = '<% with $Iterable %><% if $Me %>has value<% else %>no value<% end_if %><% end_with %>';
+        } else {
+            $template = '<% if $Iterable %>has value<% else %>no value<% end_if %>';
+        }
+        $this->assertEqualIgnoringWhitespace($expected, $this->render($template, $data));
+    }
+
+    public function testBaseTagGeneration()
+    {
+        // XHTML will have a closed base tag
+        $tmpl1 = '<?xml version="1.0" encoding="UTF-8"?>
+			<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"'
+            . ' "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+			<html>
+				<head><% base_tag %></head>
+				<body><p>test</p><body>
+			</html>';
+        $this->assertMatchesRegularExpression('/<head><base href=".*" \/><\/head>/', $this->render($tmpl1));
+
+        // HTML4 and 5 will only have it for IE
+        $tmpl2 = '<!DOCTYPE html>
+			<html>
+				<head><% base_tag %></head>
+				<body><p>test</p><body>
+			</html>';
+        $this->assertMatchesRegularExpression(
+            '/<head><base href=".*"><\/head>/',
+            $this->render($tmpl2)
+        );
+
+
+        $tmpl3 = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
+			<html>
+				<head><% base_tag %></head>
+				<body><p>test</p><body>
+			</html>';
+        $this->assertMatchesRegularExpression(
+            '/<head><base href=".*"><\/head>/',
+            $this->render($tmpl3)
+        );
+
+        // Check that the content negotiator converts to the equally legal formats
+        $negotiator = new ContentNegotiator();
+
+        $response = new HTTPResponse($this->render($tmpl1));
+        $negotiator->html($response);
+        $this->assertMatchesRegularExpression(
+            '/<head><base href=".*"><\/head>/',
+            $response->getBody()
+        );
+
+        $response = new HTTPResponse($this->render($tmpl1));
+        $negotiator->xhtml($response);
+        $this->assertMatchesRegularExpression('/<head><base href=".*" \/><\/head>/', $response->getBody());
+    }
+
+    public function testIncludeWithArguments()
+    {
+        $this->assertEquals(
+            '<p>[out:Arg1]</p><p>[out:Arg2]</p><p>[out:Arg2.Count]</p>',
+            $this->render('<% include SSTemplateEngineTestIncludeWithArguments %>')
+        );
+
+        $this->assertEquals(
+            '<p>A</p><p>[out:Arg2]</p><p>[out:Arg2.Count]</p>',
+            $this->render('<% include SSTemplateEngineTestIncludeWithArguments Arg1=A %>')
+        );
+
+        $this->assertEquals(
+            '<p>A</p><p>B</p><p></p>',
+            $this->render('<% include SSTemplateEngineTestIncludeWithArguments Arg1=A, Arg2=B %>')
+        );
+
+        $this->assertEquals(
+            '<p>A Bare String</p><p>B Bare String</p><p></p>',
+            $this->render('<% include SSTemplateEngineTestIncludeWithArguments Arg1=A Bare String, Arg2=B Bare String %>')
+        );
+
+        $this->assertEquals(
+            '<p>A</p><p>Bar</p><p></p>',
+            $this->render(
+                '<% include SSTemplateEngineTestIncludeWithArguments Arg1="A", Arg2=$B %>',
+                new ArrayData(['B' => 'Bar'])
+            )
+        );
+
+        $this->assertEquals(
+            '<p>A</p><p>Bar</p><p></p>',
+            $this->render(
+                '<% include SSTemplateEngineTestIncludeWithArguments Arg1="A" %>',
+                new ArrayData(['Arg1' => 'Foo', 'Arg2' => 'Bar'])
+            )
+        );
+
+        $this->assertEquals(
+            '<p>A</p><p>0</p><p></p>',
+            $this->render('<% include SSTemplateEngineTestIncludeWithArguments Arg1="A", Arg2=0 %>')
+        );
+
+        $this->assertEquals(
+            '<p>A</p><p></p><p></p>',
+            $this->render('<% include SSTemplateEngineTestIncludeWithArguments Arg1="A", Arg2=false %>')
+        );
+
+        $this->assertEquals(
+            '<p>A</p><p></p><p></p>',
+            // Note Arg2 is explicitly overridden with null
+            $this->render('<% include SSTemplateEngineTestIncludeWithArguments Arg1="A", Arg2=null %>')
+        );
+
+        $this->assertEquals(
+            'SomeArg - Foo - Bar - SomeArg',
+            $this->render(
+                '<% include SSTemplateEngineTestIncludeScopeInheritanceWithArgsInLoop Title="SomeArg" %>',
+                new ArrayData(
+                    ['Items' => new ArrayList(
+                        [
+                        new ArrayData(['Title' => 'Foo']),
+                        new ArrayData(['Title' => 'Bar'])
+                        ]
+                    )]
+                )
+            )
+        );
+
+        $this->assertEquals(
+            'A - B - A',
+            $this->render(
+                '<% include SSTemplateEngineTestIncludeScopeInheritanceWithArgsInWith Title="A" %>',
+                new ArrayData(['Item' => new ArrayData(['Title' =>'B'])])
+            )
+        );
+
+        $this->assertEquals(
+            'A - B - C - B - A',
+            $this->render(
+                '<% include SSTemplateEngineTestIncludeScopeInheritanceWithArgsInNestedWith Title="A" %>',
+                new ArrayData(
+                    [
+                    'Item' => new ArrayData(
+                        [
+                        'Title' =>'B', 'NestedItem' => new ArrayData(['Title' => 'C'])
+                        ]
+                    )]
+                )
+            )
+        );
+
+        $this->assertEquals(
+            'A - A - A',
+            $this->render(
+                '<% include SSTemplateEngineTestIncludeScopeInheritanceWithUpAndTop Title="A" %>',
+                new ArrayData(
+                    [
+                    'Item' => new ArrayData(
+                        [
+                        'Title' =>'B', 'NestedItem' => new ArrayData(['Title' => 'C'])
+                        ]
+                    )]
+                )
+            )
+        );
+
+        $data = new ArrayData(
+            [
+            'Nested' => new ArrayData(
+                [
+                'Object' => new ArrayData(['Key' => 'A'])
+                ]
+            ),
+            'Object' => new ArrayData(['Key' => 'B'])
+            ]
+        );
+
+        $res = $this->render('<% include SSTemplateEngineTestIncludeObjectArguments A=$Nested.Object, B=$Object %>', $data);
+        $this->assertEqualIgnoringWhitespace('A B', $res, 'Objects can be passed as named arguments');
+    }
+
+    public function testNamespaceInclude()
+    {
+        $data = new ArrayData([]);
+
+        $this->assertEquals(
+            "tests:( NamespaceInclude\n )",
+            $this->render('tests:( <% include Namespace\NamespaceInclude %> )', $data),
+            'Backslashes work for namespace references in includes'
+        );
+
+        $this->assertEquals(
+            "tests:( NamespaceInclude\n )",
+            $this->render('tests:( <% include Namespace\\NamespaceInclude %> )', $data),
+            'Escaped backslashes work for namespace references in includes'
+        );
+
+        $this->assertEquals(
+            "tests:( NamespaceInclude\n )",
+            $this->render('tests:( <% include Namespace/NamespaceInclude %> )', $data),
+            'Forward slashes work for namespace references in includes'
+        );
+    }
+
+    /**
+     * Test search for includes fallback to non-includes folder
+     */
+    public function testIncludeFallbacks()
+    {
+        $data = new ArrayData([]);
+
+        $this->assertEquals(
+            "tests:( Namespace/Includes/IncludedTwice.ss\n )",
+            $this->render('tests:( <% include Namespace\\IncludedTwice %> )', $data),
+            'Prefer Includes in the Includes folder'
+        );
+
+        $this->assertEquals(
+            "tests:( Namespace/Includes/IncludedOnceSub.ss\n )",
+            $this->render('tests:( <% include Namespace\\IncludedOnceSub %> )', $data),
+            'Includes in only Includes folder can be found'
+        );
+
+        $this->assertEquals(
+            "tests:( Namespace/IncludedOnceBase.ss\n )",
+            $this->render('tests:( <% include Namespace\\IncludedOnceBase %> )', $data),
+            'Includes outside of Includes folder can be found'
+        );
+    }
+
+    public function testRecursiveInclude()
+    {
+        $data = new ArrayData(
+            [
+            'Title' => 'A',
+            'Children' => new ArrayList(
+                [
+                new ArrayData(
+                    [
+                    'Title' => 'A1',
+                    'Children' => new ArrayList(
+                        [
+                        new ArrayData([ 'Title' => 'A1 i', ]),
+                        new ArrayData([ 'Title' => 'A1 ii', ]),
+                        ]
+                    ),
+                    ]
+                ),
+                new ArrayData([ 'Title' => 'A2', ]),
+                new ArrayData([ 'Title' => 'A3', ]),
+                ]
+            ),
+            ]
+        );
+
+        $engine = new SSTemplateEngine('Includes/SSTemplateEngineTestRecursiveInclude');
+        $result = $engine->render(new ViewLayerData($data));
+        // We don't care about whitespace
+        $rationalisedResult = trim(preg_replace('/\s+/', ' ', $result ?? '') ?? '');
+
+        $this->assertEquals('A A1 A1 i A1 ii A2 A3', $rationalisedResult);
+    }
+
+    /**
+     * See {@link ModelDataTest} for more extensive casting tests,
+     * this test just ensures that basic casting is correctly applied during template parsing.
+     */
+    public function testCastingHelpers()
+    {
+        $vd = new SSTemplateEngineTest\TestModelData();
+        $vd->TextValue = '<b>html</b>';
+        $vd->HTMLValue = '<b>html</b>';
+        $vd->UncastedValue = '<b>html</b>';
+
+        // Value casted as "Text"
+        $this->assertEquals(
+            '&lt;b&gt;html&lt;/b&gt;',
+            $this->render('$TextValue', $vd)
+        );
+        $this->assertEquals(
+            '<b>html</b>',
+            $this->render('$TextValue.RAW', $vd)
+        );
+        $this->assertEquals(
+            '&lt;b&gt;html&lt;/b&gt;',
+            $this->render('$TextValue.XML', $vd)
+        );
+
+        // Value casted as "HTMLText"
+        $this->assertEquals(
+            '<b>html</b>',
+            $this->render('$HTMLValue', $vd)
+        );
+        $this->assertEquals(
+            '<b>html</b>',
+            $this->render('$HTMLValue.RAW', $vd)
+        );
+        $this->assertEquals(
+            '&lt;b&gt;html&lt;/b&gt;',
+            $this->render('$HTMLValue.XML', $vd)
+        );
+
+        // Uncasted value (falls back to the relevant DBField class for the data type)
+        $vd = new SSTemplateEngineTest\TestModelData();
+        $vd->UncastedValue = '<b>html</b>';
+        $this->assertEquals(
+            '&lt;b&gt;html&lt;/b&gt;',
+            $this->render('$UncastedValue', $vd)
+        );
+        $this->assertEquals(
+            '<b>html</b>',
+            $this->render('$UncastedValue.RAW', $vd)
+        );
+        $this->assertEquals(
+            '&lt;b&gt;html&lt;/b&gt;',
+            $this->render('$UncastedValue.XML', $vd)
+        );
+    }
+
+    public static function provideLoop(): array
+    {
+        return [
+            'nested array and iterator' => [
+                'iterable' => [
+                    [
+                        'value 1',
+                        'value 2',
+                    ],
+                    new ArrayList([
+                        'value 3',
+                        'value 4',
+                    ]),
+                ],
+                'template' => '<% loop $Iterable %><% loop $Me %>$Me<% end_loop %><% end_loop %>',
+                'expected' => 'value 1 value 2 value 3 value 4',
+            ],
+            'nested associative arrays' => [
+                'iterable' => [
+                    [
+                        'Foo' => 'one',
+                    ],
+                    [
+                        'Foo' => 'two',
+                    ],
+                    [
+                        'Foo' => 'three',
+                    ],
+                ],
+                'template' => '<% loop $Iterable %>$Foo<% end_loop %>',
+                'expected' => 'one two three',
+            ],
+        ];
+    }
+
+    #[DataProvider('provideLoop')]
+    public function testLoop(iterable $iterable, string $template, string $expected): void
+    {
+        $data = new ArrayData(['Iterable' => $iterable]);
+        $this->assertEqualIgnoringWhitespace($expected, $this->render($template, $data));
+    }
+
+    public static function provideCountIterable(): array
+    {
+        $scenarios = [
+            'empty array' => [
+                'iterable' => [],
+                'inScope' => false,
+            ],
+            'array' => [
+                'iterable' => [1, 2, 3],
+                'inScope' => false,
+            ],
+            'ArrayList' => [
+                'iterable' => new ArrayList([['Val' => 1], ['Val' => 2], ['Val' => 3]]),
+                'inScope' => false,
+            ],
+        ];
+        foreach ($scenarios as $name => $scenario) {
+            $scenario['inScope'] = true;
+            $scenarios[$name . ' in scope'] = $scenario;
+        }
+        return $scenarios;
+    }
+
+    #[DataProvider('provideCountIterable')]
+    public function testCountIterable(iterable $iterable, bool $inScope): void
+    {
+        $expected = count($iterable);
+        $data = new ArrayData(['Iterable' => $iterable]);
+        if ($inScope) {
+            $template = '<% with $Iterable %>$Count<% end_with %>';
+        } else {
+            $template = '$Iterable.Count';
+        }
+        $this->assertEqualIgnoringWhitespace($expected, $this->render($template, $data));
+    }
+
+    public function testSSViewerBasicIteratorSupport()
+    {
+        $data = new ArrayData(
+            [
+            'Set' => new ArrayList(
+                [
+                new SSTemplateEngineTest\TestObject("1"),
+                new SSTemplateEngineTest\TestObject("2"),
+                new SSTemplateEngineTest\TestObject("3"),
+                new SSTemplateEngineTest\TestObject("4"),
+                new SSTemplateEngineTest\TestObject("5"),
+                new SSTemplateEngineTest\TestObject("6"),
+                new SSTemplateEngineTest\TestObject("7"),
+                new SSTemplateEngineTest\TestObject("8"),
+                new SSTemplateEngineTest\TestObject("9"),
+                new SSTemplateEngineTest\TestObject("10"),
+                ]
+            )
+            ]
+        );
+
+        //base test
+        $result = $this->render('<% loop Set %>$Number<% end_loop %>', $data);
+        $this->assertEquals("12345678910", $result, "Numbers rendered in order");
+
+        //test First
+        $result = $this->render('<% loop Set %><% if $IsFirst %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("1", $result, "Only the first number is rendered");
+
+        //test Last
+        $result = $this->render('<% loop Set %><% if $IsLast %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("10", $result, "Only the last number is rendered");
+
+        //test Even
+        $result = $this->render('<% loop Set %><% if $Even() %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("246810", $result, "Even numbers rendered in order");
+
+        //test Even with quotes
+        $result = $this->render('<% loop Set %><% if $Even("1") %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("246810", $result, "Even numbers rendered in order");
+
+        //test Even without quotes
+        $result = $this->render('<% loop Set %><% if $Even(1) %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("246810", $result, "Even numbers rendered in order");
+
+        //test Even with zero-based start index
+        $result = $this->render('<% loop Set %><% if $Even("0") %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("13579", $result, "Even (with zero-based index) numbers rendered in order");
+
+        //test Odd
+        $result = $this->render('<% loop Set %><% if $Odd %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("13579", $result, "Odd numbers rendered in order");
+
+        //test FirstLast
+        $result = $this->render('<% loop Set %><% if $FirstLast %>$Number$FirstLast<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("1first10last", $result, "First and last numbers rendered in order");
+
+        //test Middle
+        $result = $this->render('<% loop Set %><% if $Middle %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("23456789", $result, "Middle numbers rendered in order");
+
+        //test MiddleString
+        $result = $this->render(
+            '<% loop Set %><% if MiddleString == "middle" %>$Number$MiddleString<% end_if %>'
+            . '<% end_loop %>',
+            $data
+        );
+        $this->assertEquals(
+            "2middle3middle4middle5middle6middle7middle8middle9middle",
+            $result,
+            "Middle numbers rendered in order"
+        );
+
+        //test EvenOdd
+        $result = $this->render('<% loop Set %>$EvenOdd<% end_loop %>', $data);
+        $this->assertEquals(
+            "oddevenoddevenoddevenoddevenoddeven",
+            $result,
+            "Even and Odd is returned in sequence numbers rendered in order"
+        );
+
+        //test Pos
+        $result = $this->render('<% loop Set %>$Pos<% end_loop %>', $data);
+        $this->assertEquals("12345678910", $result, '$Pos is rendered in order');
+
+        //test Pos
+        $result = $this->render('<% loop Set %>$Pos(0)<% end_loop %>', $data);
+        $this->assertEquals("0123456789", $result, '$Pos(0) is rendered in order');
+
+        //test FromEnd
+        $result = $this->render('<% loop Set %>$FromEnd<% end_loop %>', $data);
+        $this->assertEquals("10987654321", $result, '$FromEnd is rendered in order');
+
+        //test FromEnd
+        $result = $this->render('<% loop Set %>$FromEnd(0)<% end_loop %>', $data);
+        $this->assertEquals("9876543210", $result, '$FromEnd(0) rendered in order');
+
+        //test Total
+        $result = $this->render('<% loop Set %>$TotalItems<% end_loop %>', $data);
+        $this->assertEquals("10101010101010101010", $result, "10 total items X 10 are returned");
+
+        //test Modulus
+        $result = $this->render('<% loop Set %>$Modulus(2,1)<% end_loop %>', $data);
+        $this->assertEquals("1010101010", $result, "1-indexed pos modular divided by 2 rendered in order");
+
+        //test MultipleOf 3
+        $result = $this->render('<% loop Set %><% if MultipleOf(3) %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("369", $result, "Only numbers that are multiples of 3 are returned");
+
+        //test MultipleOf 4
+        $result = $this->render('<% loop Set %><% if MultipleOf(4) %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("48", $result, "Only numbers that are multiples of 4 are returned");
+
+        //test MultipleOf 5
+        $result = $this->render('<% loop Set %><% if MultipleOf(5) %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("510", $result, "Only numbers that are multiples of 5 are returned");
+
+        //test MultipleOf 10
+        $result = $this->render('<% loop Set %><% if MultipleOf(10,1) %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("10", $result, "Only numbers that are multiples of 10 (with 1-based indexing) are returned");
+
+        //test MultipleOf 9 zero-based
+        $result = $this->render('<% loop Set %><% if MultipleOf(9,0) %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals(
+            "110",
+            $result,
+            "Only numbers that are multiples of 9 with zero-based indexing are returned. (The first and last item)"
+        );
+
+        //test MultipleOf 11
+        $result = $this->render('<% loop Set %><% if MultipleOf(11) %>$Number<% end_if %><% end_loop %>', $data);
+        $this->assertEquals("", $result, "Only numbers that are multiples of 11 are returned. I.e. nothing returned");
+    }
+
+    /**
+     * Test $Up works when the scope $Up refers to was entered with a "with" block
+     */
+    public function testUpInWith()
+    {
+
+        // Data to run the loop tests on - three levels deep
+        $data = new ArrayData(
+            [
+            'Name' => 'Top',
+            'Foo' => new ArrayData(
+                [
+                'Name' => 'Foo',
+                'Bar' => new ArrayData(
+                    [
+                    'Name' => 'Bar',
+                    'Baz' => new ArrayData(
+                        [
+                        'Name' => 'Baz'
+                        ]
+                    ),
+                    'Qux' => new ArrayData(
+                        [
+                        'Name' => 'Qux'
+                        ]
+                    )
+                    ]
+                )
+                ]
+            )
+            ]
+        );
+
+        // Basic functionality
+        $this->assertEquals(
+            'BarFoo',
+            $this->render('<% with Foo %><% with Bar %>{$Name}{$Up.Name}<% end_with %><% end_with %>', $data)
+        );
+
+        // Two level with block, up refers to internally referenced Bar
+        $this->assertEquals(
+            'BarTop',
+            $this->render('<% with Foo.Bar %>{$Name}{$Up.Name}<% end_with %>', $data)
+        );
+
+        // Stepping up & back down the scope tree
+        $this->assertEquals(
+            'BazFooBar',
+            $this->render('<% with Foo.Bar.Baz %>{$Name}{$Up.Foo.Name}{$Up.Foo.Bar.Name}<% end_with %>', $data)
+        );
+
+        // Using $Up in a with block
+        $this->assertEquals(
+            'BazTopBar',
+            $this->render(
+                '<% with Foo.Bar.Baz %>{$Name}<% with $Up %>{$Name}{$Foo.Bar.Name}<% end_with %>'
+                . '<% end_with %>',
+                $data
+            )
+        );
+
+        // Stepping up & back down the scope tree with with blocks
+        $this->assertEquals(
+            'BazTopBarTopBaz',
+            $this->render(
+                '<% with Foo.Bar.Baz %>{$Name}<% with $Up %>{$Name}<% with Foo.Bar %>{$Name}<% end_with %>'
+                . '{$Name}<% end_with %>{$Name}<% end_with %>',
+                $data
+            )
+        );
+
+        // Using $Up.Up, where first $Up points to a previous scope entered using $Up, thereby skipping up to Foo
+        $this->assertEquals(
+            'Foo',
+            $this->render(
+                '<% with Foo %><% with Bar %><% with Baz %>{$Up.Up.Name}<% end_with %><% end_with %>'
+                . '<% end_with %>',
+                $data
+            )
+        );
+
+        // Using $Up as part of a lookup chain in <% with %>
+        $this->assertEquals(
+            'Top',
+            $this->render('<% with Foo.Bar.Baz.Up.Qux %>{$Up.Name}<% end_with %>', $data)
+        );
+    }
+
+    public function testTooManyUps()
+    {
+        $this->expectException(LogicException::class);
+        $this->expectExceptionMessage("Up called when we're already at the top of the scope");
+        $data = new ArrayData([
+            'Foo' => new ArrayData([
+                'Name' => 'Foo',
+                'Bar' => new ArrayData([
+                    'Name' => 'Bar'
+                ])
+            ])
+        ]);
+
+        $this->assertEquals(
+            'Foo',
+            $this->render('<% with Foo.Bar %>{$Up.Up.Name}<% end_with %>', $data)
+        );
+    }
+
+    /**
+     * Test $Up works when the scope $Up refers to was entered with a "loop" block
+     */
+    public function testUpInLoop()
+    {
+
+        // Data to run the loop tests on - one sequence of three items, each with a subitem
+        $data = new ArrayData(
+            [
+            'Name' => 'Top',
+            'Foo' => new ArrayList(
+                [
+                new ArrayData(
+                    [
+                    'Name' => '1',
+                    'Sub' => new ArrayData(
+                        [
+                        'Name' => 'Bar'
+                        ]
+                    )
+                    ]
+                ),
+                new ArrayData(
+                    [
+                    'Name' => '2',
+                    'Sub' => new ArrayData(
+                        [
+                        'Name' => 'Baz'
+                        ]
+                    )
+                    ]
+                ),
+                new ArrayData(
+                    [
+                    'Name' => '3',
+                    'Sub' => new ArrayData(
+                        [
+                        'Name' => 'Qux'
+                        ]
+                    )
+                    ]
+                )
+                ]
+            )
+            ]
+        );
+
+        // Make sure inside a loop, $Up refers to the current item of the loop
+        $this->assertEqualIgnoringWhitespace(
+            '111 222 333',
+            $this->render(
+                '<% loop $Foo %>$Name<% with $Sub %>$Up.Name<% end_with %>$Name<% end_loop %>',
+                $data
+            )
+        );
+
+        // Make sure inside a loop, looping over $Up uses a separate iterator,
+        // and doesn't interfere with the original iterator
+        $this->assertEqualIgnoringWhitespace(
+            '1Bar123Bar1 2Baz123Baz2 3Qux123Qux3',
+            $this->render(
+                '<% loop $Foo %>
+					$Name
+					<% with $Sub %>
+						$Name
+						<% loop $Up %>$Name<% end_loop %>
+						$Name
+					<% end_with %>
+					$Name
+				<% end_loop %>',
+                $data
+            )
+        );
+
+        // Make sure inside a loop, looping over $Up uses a separate iterator,
+        // and doesn't interfere with the original iterator or local lookups
+        $this->assertEqualIgnoringWhitespace(
+            '1 Bar1 123 1Bar 1   2 Baz2 123 2Baz 2   3 Qux3 123 3Qux 3',
+            $this->render(
+                '<% loop $Foo %>
+					$Name
+					<% with $Sub %>
+						{$Name}{$Up.Name}
+						<% loop $Up %>$Name<% end_loop %>
+						{$Up.Name}{$Name}
+					<% end_with %>
+					$Name
+				<% end_loop %>',
+                $data
+            )
+        );
+    }
+
+    /**
+     * Test that nested loops restore the loop variables correctly when pushing and popping states
+     */
+    public function testNestedLoops()
+    {
+
+        // Data to run the loop tests on - one sequence of three items, one with child elements
+        // (of a different size to the main sequence)
+        $data = new ArrayData(
+            [
+            'Foo' => new ArrayList(
+                [
+                new ArrayData(
+                    [
+                    'Name' => '1',
+                    'Children' => new ArrayList(
+                        [
+                        new ArrayData(
+                            [
+                            'Name' => 'a'
+                            ]
+                        ),
+                        new ArrayData(
+                            [
+                            'Name' => 'b'
+                            ]
+                        ),
+                        ]
+                    ),
+                    ]
+                ),
+                new ArrayData(
+                    [
+                    'Name' => '2',
+                    'Children' => new ArrayList(),
+                    ]
+                ),
+                new ArrayData(
+                    [
+                    'Name' => '3',
+                    'Children' => new ArrayList(),
+                    ]
+                ),
+                ]
+            ),
+            ]
+        );
+
+        // Make sure that including a loop inside a loop will not destroy the internal count of
+        // items, checked by using "Last"
+        $this->assertEqualIgnoringWhitespace(
+            '1ab23last',
+            $this->render(
+                '<% loop $Foo %>$Name<% loop Children %>$Name<% end_loop %><% if $IsLast %>last<% end_if %>'
+                . '<% end_loop %>',
+                $data
+            )
+        );
+    }
+
+    public function testLayout()
+    {
+        $this->useTestTheme(
+            __DIR__ . '/SSTemplateEngineTest',
+            'layouttest',
+            function () {
+                $engine = new SSTemplateEngine('Page');
+                $this->assertEquals("Foo\n\n", $engine->render(new ViewLayerData([])));
+
+                $engine = new SSTemplateEngine(['Shortcodes', 'Page']);
+                $this->assertEquals("[file_link]\n\n", $engine->render(new ViewLayerData([])));
+            }
+        );
+    }
+
+    public static function provideRenderWithSourceFileComments(): array
+    {
+        $i = __DIR__ . '/SSTemplateEngineTest/templates/Includes';
+        $f = __DIR__ . '/SSTemplateEngineTest/templates/SSTemplateEngineTestComments';
+        return [
+            [
+                'name' => 'SSTemplateEngineTestCommentsFullSource',
+                'expected' => ""
+                    . "<!doctype html>"
+                    . "<!-- template $f/SSTemplateEngineTestCommentsFullSource.ss -->"
+                    . "<html>"
+                    . "\t<head></head>"
+                    . "\t<body></body>"
+                    . "</html>"
+                    . "<!-- end template $f/SSTemplateEngineTestCommentsFullSource.ss -->",
+            ],
+            [
+                'name' => 'SSTemplateEngineTestCommentsFullSourceHTML4Doctype',
+                'expected' => ""
+                    . "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML "
+                    . "4.01//EN\"\t\t\"http://www.w3.org/TR/html4/strict.dtd\">"
+                    . "<!-- template $f/SSTemplateEngineTestCommentsFullSourceHTML4Doctype.ss -->"
+                    . "<html>"
+                    . "\t<head></head>"
+                    . "\t<body></body>"
+                    . "</html>"
+                    . "<!-- end template $f/SSTemplateEngineTestCommentsFullSourceHTML4Doctype.ss -->",
+            ],
+            [
+                'name' => 'SSTemplateEngineTestCommentsFullSourceNoDoctype',
+                'expected' => ""
+                    . "<html><!-- template $f/SSTemplateEngineTestCommentsFullSourceNoDoctype.ss -->"
+                    . "\t<head></head>"
+                    . "\t<body></body>"
+                    . "<!-- end template $f/SSTemplateEngineTestCommentsFullSourceNoDoctype.ss --></html>",
+            ],
+            [
+                'name' => 'SSTemplateEngineTestCommentsFullSourceIfIE',
+                'expected' => ""
+                    . "<!doctype html>"
+                    . "<!-- template $f/SSTemplateEngineTestCommentsFullSourceIfIE.ss -->"
+                    . "<!--[if lte IE 8]> <html class='old-ie'> <![endif]-->"
+                    . "<!--[if gt IE 8]> <html class='new-ie'> <![endif]-->"
+                    . "<!--[if !IE]><!--> <html class='no-ie'> <!--<![endif]-->"
+                    . "\t<head></head>"
+                    . "\t<body></body>"
+                    . "</html>"
+                    . "<!-- end template $f/SSTemplateEngineTestCommentsFullSourceIfIE.ss -->",
+            ],
+            [
+                'name' => 'SSTemplateEngineTestCommentsFullSourceIfIENoDoctype',
+                'expected' => ""
+                    . "<!--[if lte IE 8]> <html class='old-ie'> <![endif]-->"
+                    . "<!--[if gt IE 8]> <html class='new-ie'> <![endif]-->"
+                    . "<!--[if !IE]><!--> <html class='no-ie'>"
+                    . "<!-- template $f/SSTemplateEngineTestCommentsFullSourceIfIENoDoctype.ss -->"
+                    . " <!--<![endif]-->"
+                    . "\t<head></head>"
+                    . "\t<body></body>"
+                    . "<!-- end template $f/SSTemplateEngineTestCommentsFullSourceIfIENoDoctype.ss --></html>",
+            ],
+            [
+                'name' => 'SSTemplateEngineTestCommentsPartialSource',
+                'expected' =>
+                "<!-- template $f/SSTemplateEngineTestCommentsPartialSource.ss -->"
+                    . "<div class='typography'></div>"
+                    . "<!-- end template $f/SSTemplateEngineTestCommentsPartialSource.ss -->",
+            ],
+            [
+                'name' => 'SSTemplateEngineTestCommentsWithInclude',
+                'expected' =>
+                "<!-- template $f/SSTemplateEngineTestCommentsWithInclude.ss -->"
+                    . "<div class='typography'>"
+                    . "<!-- include 'SSTemplateEngineTestCommentsInclude' -->"
+                    . "<!-- template $i/SSTemplateEngineTestCommentsInclude.ss -->"
+                    . "Included"
+                    . "<!-- end template $i/SSTemplateEngineTestCommentsInclude.ss -->"
+                    . "<!-- end include 'SSTemplateEngineTestCommentsInclude' -->"
+                    . "</div>"
+                    . "<!-- end template $f/SSTemplateEngineTestCommentsWithInclude.ss -->",
+            ],
+        ];
+    }
+
+    #[DataProvider('provideRenderWithSourceFileComments')]
+    public function testRenderWithSourceFileComments(string $name, string $expected)
+    {
+        SSViewer::config()->set('source_file_comments', true);
+        $this->_renderWithSourceFileComments('SSTemplateEngineTestComments/' . $name, $expected);
+    }
+
+    public static function provideRenderWithMissingTemplate(): array
+    {
+        return [
+            [
+                'templateCandidates' => [],
+            ],
+            [
+                'templateCandidates' => '',
+            ],
+            [
+                'templateCandidates' => ['noTemplate'],
+            ],
+            [
+                'templateCandidates' => 'noTemplate',
+            ],
+        ];
+    }
+
+    #[DataProvider('provideRenderWithMissingTemplate')]
+    public function testRenderWithMissingTemplate(string|array $templateCandidates): void
+    {
+        if (empty($templateCandidates)) {
+            $message = 'No template to render. Try calling setTemplate() or passing template candidates into the constructor.';
+        } else {
+            $message = 'None of the following templates could be found: '
+                . print_r($templateCandidates, true)
+                . ' in themes "' . print_r(SSViewer::get_themes(), true) . '"';
+        }
+        $engine = new SSTemplateEngine($templateCandidates);
+        $this->expectException(MissingTemplateException::class);
+        $this->expectExceptionMessage($message);
+        $engine->render(new ViewLayerData([]));
+    }
+
+    public function testLoopIteratorIterator()
+    {
+        $list = new PaginatedList(new ArrayList());
+        $result = $this->render(
+            '<% loop List %>$ID - $FirstName<br /><% end_loop %>',
+            new ArrayData(['List' => $list])
+        );
+        $this->assertEquals('', $result);
+    }
+
+    public static function provideCallsWithArguments(): array
+    {
+        return [
+            [
+                'template' => '$Level.output(1)',
+                'expected' => '1-1',
+            ],
+            [
+                'template' => '$Nest.Level.output($Set.First.Number)',
+                'expected' => '2-1',
+            ],
+            [
+                'template' => '<% with $Set %>$Up.Level.output($First.Number)<% end_with %>',
+                'expected' => '1-1',
+            ],
+            [
+                'template' => '<% with $Set %>$Top.Nest.Level.output($First.Number)<% end_with %>',
+                'expected' => '2-1',
+            ],
+            [
+                'template' => '<% loop $Set %>$Up.Nest.Level.output($Number)<% end_loop %>',
+                'expected' => '2-12-22-32-42-5',
+            ],
+            [
+                'template' => '<% loop $Set %>$Top.Level.output($Number)<% end_loop %>',
+                'expected' => '1-11-21-31-41-5',
+            ],
+            [
+                'template' => '<% with $Nest %>$Level.output($Top.Set.First.Number)<% end_with %>',
+                'expected' => '2-1',
+            ],
+            [
+                'template' => '<% with $Level %>$output($Up.Set.Last.Number)<% end_with %>',
+                'expected' => '1-5',
+            ],
+            [
+                'template' => '<% with $Level.forWith($Set.Last.Number) %>$output("hi")<% end_with %>',
+                'expected' => '5-hi',
+            ],
+            [
+                'template' => '<% loop $Level.forLoop($Set.First.Number) %>$Number<% end_loop %>',
+                'expected' => '!0',
+            ],
+            [
+                'template' => '<% with $Nest %>
+                        <% with $Level.forWith($Up.Set.First.Number) %>$output("hi")<% end_with %>
+                    <% end_with %>',
+                'expected' => '1-hi',
+            ],
+            [
+                'template' => '<% with $Nest %>
+                        <% loop $Level.forLoop($Top.Set.Last.Number) %>$Number<% end_loop %>
+                    <% end_with %>',
+                'expected' => '!0!1!2!3!4',
+            ],
+        ];
+    }
+
+    #[DataProvider('provideCallsWithArguments')]
+    public function testCallsWithArguments(string $template, string $expected): void
+    {
+        $data = new ArrayData(
+            [
+                'Set' => new ArrayList(
+                    [
+                        new SSTemplateEngineTest\TestObject("1"),
+                        new SSTemplateEngineTest\TestObject("2"),
+                        new SSTemplateEngineTest\TestObject("3"),
+                        new SSTemplateEngineTest\TestObject("4"),
+                        new SSTemplateEngineTest\TestObject("5"),
+                    ]
+                ),
+                'Level' => new SSTemplateEngineTest\LevelTestData(1),
+                'Nest' => [
+                    'Level' => new SSTemplateEngineTest\LevelTestData(2),
+                ],
+            ]
+        );
+
+        $this->assertEquals($expected, trim($this->render($template, $data) ?? ''));
+    }
+
+    public function testRepeatedCallsAreCached()
+    {
+        $data = new SSTemplateEngineTest\CacheTestData();
+        $template = '
+			<% if $TestWithCall %>
+				<% with $TestWithCall %>
+					{$Message}
+				<% end_with %>
+
+				{$TestWithCall.Message}
+			<% end_if %>';
+
+        $this->assertEquals('HiHi', preg_replace('/\s+/', '', $this->render($template, $data) ?? ''));
+        $this->assertEquals(
+            1,
+            $data->testWithCalls,
+            'SSTemplateEngineTest_CacheTestData::TestWithCall() should only be called once. Subsequent calls should be cached'
+        );
+
+        $data = new SSTemplateEngineTest\CacheTestData();
+        $template = '
+			<% if $TestLoopCall %>
+				<% loop $TestLoopCall %>
+					{$Message}
+				<% end_loop %>
+			<% end_if %>';
+
+        $this->assertEquals('OneTwo', preg_replace('/\s+/', '', $this->render($template, $data) ?? ''));
+        $this->assertEquals(
+            1,
+            $data->testLoopCalls,
+            'SSTemplateEngineTest_CacheTestData::TestLoopCall() should only be called once. Subsequent calls should be cached'
+        );
+    }
+
+    public function testClosedBlockExtension()
+    {
+        $count = 0;
+        $parser = new SSTemplateParser();
+        $parser->addClosedBlock(
+            'test',
+            function () use (&$count) {
+                $count++;
+            }
+        );
+
+        $engine = new SSTemplateEngine('SSTemplateEngineTestRecursiveInclude');
+        $engine->setParser($parser);
+        $engine->renderString('<% test %><% end_test %>', new ViewLayerData([]));
+
+        $this->assertEquals(1, $count);
+    }
+
+    public function testOpenBlockExtension()
+    {
+        $count = 0;
+        $parser = new SSTemplateParser();
+        $parser->addOpenBlock(
+            'test',
+            function () use (&$count) {
+                $count++;
+            }
+        );
+
+        $engine = new SSTemplateEngine('SSTemplateEngineTestRecursiveInclude');
+        $engine->setParser($parser);
+        $engine->renderString('<% test %>', new ViewLayerData([]));
+
+        $this->assertEquals(1, $count);
+    }
+
+    public function testFromStringCaching()
+    {
+        $content = 'Test content';
+        $cacheFile = TEMP_PATH . DIRECTORY_SEPARATOR . '.cache.' . sha1($content ?? '');
+        if (file_exists($cacheFile ?? '')) {
+            unlink($cacheFile ?? '');
+        }
+
+        // Test instance behaviors
+        $this->render($content, cache: false);
+        $this->assertFileDoesNotExist($cacheFile, 'Cache file was created when caching was off');
+
+        $this->render($content, cache: true);
+        $this->assertFileExists($cacheFile, 'Cache file wasn\'t created when it was meant to');
+        unlink($cacheFile ?? '');
+    }
+
+    public function testPrimitivesConvertedToDBFields()
+    {
+        $data = new ArrayData([
+            // null value should not be rendered, though should also not throw exception
+            'Foo' => new ArrayList(['hello', true, 456, 7.89, null])
+        ]);
+        $this->assertEqualIgnoringWhitespace(
+            'hello 1 456 7.89',
+            $this->render('<% loop $Foo %>$Me<% end_loop %>', $data)
+        );
+    }
+
+    #[DoesNotPerformAssertions]
+    public function testMe(): void
+    {
+        $myArrayData = new class extends ArrayData {
+            public function forTemplate(): string
+            {
+                return '';
+            }
+        };
+        $this->render('$Me', $myArrayData);
+    }
+
+    public function testLoopingThroughArrayInOverlay(): void
+    {
+        $modelData = new ModelData();
+        $theArray = [
+            ['Val' => 'one'],
+            ['Val' => 'two'],
+            ['Val' => 'red'],
+            ['Val' => 'blue'],
+        ];
+        $engine = new SSTemplateEngine('SSTemplateEngineTestLoopArray');
+        $output = $engine->render(new ViewLayerData($modelData), ['MyArray' => $theArray]);
+        $this->assertEqualIgnoringWhitespace('one two red blue', $output);
+    }
+
+    public static function provideGetterMethod(): array
+    {
+        return [
+            'as property (not getter)' => [
+                'template' => '$MyProperty',
+                'expected' => 'Nothing passed in',
+            ],
+            'as method (not getter)' => [
+                'template' => '$MyProperty()',
+                'expected' => 'Nothing passed in',
+            ],
+            'as method (not getter), with arg' => [
+                'template' => '$MyProperty("Some Value")',
+                'expected' => 'Was passed in: Some Value',
+            ],
+            'as property (getter)' => [
+                'template' => '$getMyProperty',
+                'expected' => 'Nothing passed in',
+            ],
+            'as method (getter)' => [
+                'template' => '$getMyProperty()',
+                'expected' => 'Nothing passed in',
+            ],
+            'as method (getter), with arg' => [
+                'template' => '$getMyProperty("Some Value")',
+                'expected' => 'Was passed in: Some Value',
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGetterMethod')]
+    public function testGetterMethod(string $template, string $expected): void
+    {
+        $model = new SSTemplateEngineTest\TestObject();
+        $this->assertSame($expected, $this->render($template, $model));
+    }
+
+    /**
+     * Small helper to render templates from strings
+     */
+    private function render(string $templateString, mixed $data = null, array $overlay = [], bool $cache = false): string
+    {
+        $engine = new SSTemplateEngine();
+        if ($data === null) {
+            $data = new SSTemplateEngineTest\TestFixture();
+        }
+        $data = new ViewLayerData($data);
+        return trim('' . $engine->renderString($templateString, $data, $overlay, $cache));
+    }
+
+    private function _renderWithSourceFileComments($name, $expected)
+    {
+        $viewer = new SSViewer([$name]);
+        $data = new ArrayData([]);
+        $result = $viewer->process($data);
+        $expected = str_replace(["\r", "\n"], '', $expected ?? '');
+        $result = str_replace(["\r", "\n"], '', $result ?? '');
+        $this->assertEquals($result, $expected);
+    }
+
+    private function getScopeInheritanceTestData()
+    {
+        return new ArrayData([
+            'Title' => 'TopTitleValue',
+            'Items' => new ArrayList([
+                new ArrayData(['Title' => 'Item 1']),
+                new ArrayData(['Title' => 'Item 2']),
+                new ArrayData(['Title' => 'Item 3']),
+                new ArrayData(['Title' => 'Item 4']),
+                new ArrayData(['Title' => 'Item 5']),
+                new ArrayData(['Title' => 'Item 6'])
+            ])
+        ]);
+    }
+
+    private function assertExpectedStrings($result, $expected)
+    {
+        foreach ($expected as $expectedStr) {
+            $this->assertTrue(
+                (boolean) preg_match("/{$expectedStr}/", $result ?? ''),
+                "Didn't find '{$expectedStr}' in:\n{$result}"
+            );
+        }
+    }
+
+    private function assertEqualIgnoringWhitespace($a, $b, $message = '')
+    {
+        $this->assertEquals(preg_replace('/\s+/', '', $a ?? ''), preg_replace('/\s+/', '', $b ?? ''), $message);
+    }
+}

tests/php/View/SSTemplateEngineTest/CacheTestData.php

@@ -1,6 +1,6 @@
 <?php
 
-namespace SilverStripe\View\Tests\SSViewerTest;
+namespace SilverStripe\View\Tests\SSTemplateEngineTest;
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\Model\List\ArrayList;

tests/php/View/SSTemplateEngineTest/LevelTestData.php

@@ -1,6 +1,6 @@
 <?php
 
-namespace SilverStripe\View\Tests\SSViewerTest;
+namespace SilverStripe\View\Tests\SSTemplateEngineTest;
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\Model\List\ArrayList;

tests/php/View/SSTemplateEngineTest/TestFixture.php

@@ -0,0 +1,85 @@
+<?php
+
+namespace SilverStripe\View\Tests\SSTemplateEngineTest;
+
+use ReflectionClass;
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\View\SSViewer_Scope;
+use Stringable;
+
+/**
+ * A test fixture that will echo back the template item
+ */
+class TestFixture implements TestOnly, Stringable
+{
+    private ?string $name;
+
+    public function __construct($name = null)
+    {
+        $this->name = $name;
+    }
+
+    public function __call(string $name, array $arguments = []): static|array|null
+    {
+        return $this->getValue($name, $arguments);
+    }
+
+    public function __get(string $name): static|array|null
+    {
+        return $this->getValue($name);
+    }
+
+    public function __isset(string $name): bool
+    {
+        if (preg_match('/NotSet/i', $name)) {
+            return false;
+        }
+        $reflectionScope = new ReflectionClass(SSViewer_Scope::class);
+        $globalProperties = $reflectionScope->getStaticPropertyValue('globalProperties');
+        if (array_key_exists($name, $globalProperties)) {
+            return false;
+        }
+        return true;
+    }
+
+    public function __toString(): string
+    {
+        if (preg_match('/NotSet/i', $this->name ?? '')) {
+            return '';
+        }
+        if (preg_match('/Raw/i', $this->name ?? '')) {
+            return $this->name ?? '';
+        }
+        return '[out:' . $this->name . ']';
+    }
+
+    private function getValue(string $name, array $arguments = []): static|array|null
+    {
+        $childName = $this->argedName($name, $arguments);
+
+        // Special field name Loop### to create a list
+        if (preg_match('/^Loop([0-9]+)$/', $name ?? '', $matches)) {
+            $output = [];
+            for ($i = 0; $i < $matches[1]; $i++) {
+                $output[] = new TestFixture($childName);
+            }
+            return $output;
+        }
+
+        if (preg_match('/NotSet/i', $name)) {
+            return null;
+        }
+
+        return new TestFixture($childName);
+    }
+
+    private function argedName(string $fieldName, array $arguments): string
+    {
+        $childName = $this->name ? "$this->name.$fieldName" : $fieldName;
+        if ($arguments) {
+            return $childName . '(' . implode(',', $arguments) . ')';
+        } else {
+            return $childName;
+        }
+    }
+}

tests/php/View/SSTemplateEngineTest/TestGlobalProvider.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace SilverStripe\View\Tests\SSTemplateEngineTest;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\View\TemplateGlobalProvider;
+
+class TestGlobalProvider implements TemplateGlobalProvider, TestOnly
+{
+
+    public static function get_template_global_variables()
+    {
+        return [
+            'SSTemplateEngineTest_GlobalHTMLFragment' => ['method' => 'get_html', 'casting' => 'HTMLFragment'],
+            'SSTemplateEngineTest_GlobalHTMLEscaped' => ['method' => 'get_html'],
+
+            'SSTemplateEngineTest_GlobalAutomatic',
+            'SSTemplateEngineTest_GlobalReferencedByString' => 'get_reference',
+            'SSTemplateEngineTest_GlobalReferencedInArray' => ['method' => 'get_reference'],
+
+            'SSTemplateEngineTest_GlobalThatTakesArguments' => ['method' => 'get_argmix', 'casting' => 'HTMLFragment'],
+            'SSTemplateEngineTest_GlobalReturnsNull' => 'getNull',
+        ];
+    }
+
+    public static function get_html()
+    {
+        return '<div></div>';
+    }
+
+    public static function SSTemplateEngineTest_GlobalAutomatic()
+    {
+        return 'automatic';
+    }
+
+    public static function get_reference()
+    {
+        return 'reference';
+    }
+
+    public static function get_argmix()
+    {
+        $args = func_get_args();
+        return 'z' . implode(':', $args) . 'z';
+    }
+
+    public static function getNull()
+    {
+        return null;
+    }
+}

tests/php/View/SSTemplateEngineTest/TestModelData.php

@@ -1,6 +1,6 @@
 <?php
 
-namespace SilverStripe\View\Tests\SSViewerTest;
+namespace SilverStripe\View\Tests\SSTemplateEngineTest;
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\Model\ModelData;
@@ -29,9 +29,13 @@ class TestModelData extends ModelData implements TestOnly
         return "arg1:{$arg1},arg2:{$arg2}";
     }
 
-    public function methodWithTypedArguments($arg1, $arg2, $arg3)
+    public function methodWithTypedArguments(...$args)
     {
-        return 'arg1:' . json_encode($arg1) . ',arg2:' . json_encode($arg2) . ',arg3:' . json_encode($arg3);
+        $ret = [];
+        foreach ($args as $i => $arg) {
+            $ret[] = "arg$i:" . json_encode($arg);
+        }
+        return implode(',', $ret);
     }
 
     public function Type($arg)

tests/php/View/SSTemplateEngineTest/TestObject.php

@@ -1,13 +1,13 @@
 <?php
 
-namespace SilverStripe\View\Tests\SSViewerTest;
+namespace SilverStripe\View\Tests\SSTemplateEngineTest;
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\ORM\DataObject;
 
 class TestObject extends DataObject implements TestOnly
 {
-    private static $table_name = 'SSViewerTest_Object';
+    private static $table_name = 'SSTemplateEngineTest_Object';
 
     public $number = null;
 
@@ -41,4 +41,12 @@ class TestObject extends DataObject implements TestOnly
     {
         return 'some/url.html';
     }
+
+    public function getMyProperty(mixed $someArg = null): string
+    {
+        if ($someArg) {
+            return "Was passed in: $someArg";
+        }
+        return 'Nothing passed in';
+    }
 }

tests/php/View/SSTemplateEngineTest/javascript/RequirementsTest_a.js

@@ -0,0 +1 @@
+alert('a');

tests/php/View/SSTemplateEngineTest/templates/Includes/SSTemplateEngineTestRecursiveInclude.ss

@@ -1,6 +1,6 @@
 $Title
 <% if Children %>
 <% loop Children %>
-<% include SSViewerTestRecursiveInclude %>
+<% include SSTemplateEngineTestRecursiveInclude %>
 <% end_loop %>
 <% end_if %>

tests/php/View/SSTemplateEngineTest/templates/SSTemplateEngineTestComments/SSTemplateEngineTestCommentsWithInclude.ss

@@ -0,0 +1 @@
+<div class='typography'><% include SSTemplateEngineTestCommentsInclude %></div>

tests/php/View/SSTemplateEngineTest/templates/SSTemplateEngineTestIncludeScopeInheritance.ss

@@ -0,0 +1,3 @@
+<% loop Items %>
+	<% include SSTemplateEngineTestIncludeScopeInheritanceInclude %>
+<% end_loop %>

tests/php/View/SSTemplateEngineTest/templates/SSTemplateEngineTestIncludeScopeInheritanceWithArgs.ss

@@ -0,0 +1,3 @@
+<% loop Items %>
+	<% include SSTemplateEngineTestIncludeScopeInheritanceInclude ArgA=$Title %>
+<% end_loop %>

tests/php/View/SSTemplateEngineTest/templates/SSTemplateEngineTestProcess.ss

@@ -0,0 +1,6 @@
+<html>
+	<% include SSTemplateEngineTestProcessHead %>
+
+	<body>
+	</body>
+</html>

tests/php/View/SSTemplateEngineTest/themes/layouttest/templates/TestNamespace/SSTemplateEngineTestModel_Controller.ss

@@ -0,0 +1 @@
+SSTemplateEngineTest

tests/php/View/SSTemplateEngineTest_findTemplate/module/composer.json

@@ -0,0 +1,4 @@
+{
+    "name": "silverstripe/module",
+    "type": "silverstripe-vendormodule"
+}

tests/php/View/SSTemplateEngineTest_findTemplate/myproject/_config.php

@@ -0,0 +1 @@
+<?php

tests/php/View/SSViewerTest.php

@@ -2,69 +2,19 @@
 
 namespace SilverStripe\View\Tests;
 
-use Exception;
-use InvalidArgumentException;
-use LogicException;
-use PHPUnit\Framework\MockObject\MockObject;
-use Silverstripe\Assets\Dev\TestAssetStore;
-use SilverStripe\Control\ContentNegotiator;
 use SilverStripe\Control\Controller;
-use SilverStripe\Control\Director;
-use SilverStripe\Control\HTTPResponse;
 use SilverStripe\Core\Convert;
-use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Dev\SapphireTest;
-use SilverStripe\i18n\i18n;
-use SilverStripe\Model\List\ArrayList;
 use SilverStripe\ORM\DataObject;
-use SilverStripe\ORM\FieldType\DBField;
-use SilverStripe\Model\List\PaginatedList;
-use SilverStripe\Security\Permission;
-use SilverStripe\Security\Security;
-use SilverStripe\Security\SecurityToken;
-use SilverStripe\Model\ArrayData;
 use SilverStripe\View\Requirements;
-use SilverStripe\View\Requirements_Backend;
-use SilverStripe\View\SSTemplateParseException;
-use SilverStripe\View\SSTemplateParser;
 use SilverStripe\View\SSViewer;
-use SilverStripe\View\SSViewer_FromString;
 use SilverStripe\View\Tests\SSViewerTest\SSViewerTestModel;
 use SilverStripe\View\Tests\SSViewerTest\SSViewerTestModelController;
-use SilverStripe\View\Tests\SSViewerTest\TestModelData;
+use SilverStripe\View\Tests\SSViewerTest\DummyTemplateEngine;
-use SilverStripe\Model\ModelData;
-use PHPUnit\Framework\Attributes\DataProvider;
-use PHPUnit\Framework\Attributes\DoesNotPerformAssertions;
 
 class SSViewerTest extends SapphireTest
 {
-
+    protected $usesDatabase = false;
-    /**
-     * Backup of $_SERVER global
-     *
-     * @var array
-     */
-    protected $oldServer = [];
-
-    protected static $extra_dataobjects = [
-        SSViewerTest\TestObject::class,
-    ];
-
-    protected function setUp(): void
-    {
-        parent::setUp();
-        SSViewer::config()->set('source_file_comments', false);
-        SSViewer_FromString::config()->set('cache_template', false);
-        TestAssetStore::activate('SSViewerTest');
-        $this->oldServer = $_SERVER;
-    }
-
-    protected function tearDown(): void
-    {
-        $_SERVER = $this->oldServer;
-        TestAssetStore::reset();
-        parent::tearDown();
-    }
 
     /**
      * Tests for themes helper functions, ensuring they behave as defined in the RFC at
@@ -85,1786 +35,28 @@ class SSViewerTest extends SapphireTest
         $this->assertEquals(['mytheme', 'my_more_important_theme', '$default'], SSViewer::get_themes());
     }
 
-    /**
+    public function testRequirementsInjected()
-     * Test that a template without a <head> tag still renders.
-     */
-    public function testTemplateWithoutHeadRenders()
     {
-        $data = new ArrayData([ 'Var' => 'var value' ]);
+        Requirements::clear();
-        $result = $data->renderWith("SSViewerTestPartialTemplate");
+
-        $this->assertEquals('Test partial template: var value', trim(preg_replace("/<!--.*-->/U", '', $result ?? '') ?? ''));
+        try {
+            Requirements::customCSS('pretend this is real css');
+            $viewer = new SSViewer([], new DummyTemplateEngine());
+            $result1 = $viewer->process('pretend this is a model')->getValue();
+            // if we disable the requirements then we should get nothing
+            $viewer->includeRequirements(false);
+            $result2 = $viewer->process('pretend this is a model')->getValue();
+        } finally {
+            Requirements::restore();
         }
 
-    /**
-     * Ensure global methods aren't executed
-     */
-    public function testTemplateExecution()
-    {
-        $data = new ArrayData([ 'Var' => 'phpinfo' ]);
-        $result = $data->renderWith("SSViewerTestPartialTemplate");
-        $this->assertEquals('Test partial template: phpinfo', trim(preg_replace("/<!--.*-->/U", '', $result ?? '') ?? ''));
-    }
-
-    public function testIncludeScopeInheritance()
-    {
-        $data = $this->getScopeInheritanceTestData();
-        $expected = [
-        'Item 1 - First-ODD top:Item 1',
-        'Item 2 - EVEN top:Item 2',
-        'Item 3 - ODD top:Item 3',
-        'Item 4 - EVEN top:Item 4',
-        'Item 5 - ODD top:Item 5',
-        'Item 6 - Last-EVEN top:Item 6',
-        ];
-
-        $result = $data->renderWith('SSViewerTestIncludeScopeInheritance');
-        $this->assertExpectedStrings($result, $expected);
-
-        // reset results for the tests that include arguments (the title is passed as an arg)
-        $expected = [
-        'Item 1 _ Item 1 - First-ODD top:Item 1',
-        'Item 2 _ Item 2 - EVEN top:Item 2',
-        'Item 3 _ Item 3 - ODD top:Item 3',
-        'Item 4 _ Item 4 - EVEN top:Item 4',
-        'Item 5 _ Item 5 - ODD top:Item 5',
-        'Item 6 _ Item 6 - Last-EVEN top:Item 6',
-        ];
-
-        $result = $data->renderWith('SSViewerTestIncludeScopeInheritanceWithArgs');
-        $this->assertExpectedStrings($result, $expected);
-    }
-
-    public function testIncludeTruthyness()
-    {
-        $data = new ArrayData([
-            'Title' => 'TruthyTest',
-            'Items' => new ArrayList([
-                new ArrayData(['Title' => 'Item 1']),
-                new ArrayData(['Title' => '']),
-                new ArrayData(['Title' => true]),
-                new ArrayData(['Title' => false]),
-                new ArrayData(['Title' => null]),
-                new ArrayData(['Title' => 0]),
-                new ArrayData(['Title' => 7])
-            ])
-        ]);
-        $result = $data->renderWith('SSViewerTestIncludeScopeInheritanceWithArgs');
-
-        // We should not end up with empty values appearing as empty
-        $expected = [
-            'Item 1 _ Item 1 - First-ODD top:Item 1',
-            'Untitled - EVEN top:',
-            '1 _ 1 - ODD top:1',
-            'Untitled - EVEN top:',
-            'Untitled - ODD top:',
-            'Untitled - EVEN top:0',
-            '7 _ 7 - Last-ODD top:7',
-        ];
-        $this->assertExpectedStrings($result, $expected);
-    }
-
-    private function getScopeInheritanceTestData()
-    {
-        return new ArrayData([
-            'Title' => 'TopTitleValue',
-            'Items' => new ArrayList([
-                new ArrayData(['Title' => 'Item 1']),
-                new ArrayData(['Title' => 'Item 2']),
-                new ArrayData(['Title' => 'Item 3']),
-                new ArrayData(['Title' => 'Item 4']),
-                new ArrayData(['Title' => 'Item 5']),
-                new ArrayData(['Title' => 'Item 6'])
-            ])
-        ]);
-    }
-
-    private function assertExpectedStrings($result, $expected)
-    {
-        foreach ($expected as $expectedStr) {
-            $this->assertTrue(
-                (boolean) preg_match("/{$expectedStr}/", $result ?? ''),
-                "Didn't find '{$expectedStr}' in:\n{$result}"
-            );
-        }
-    }
-
-    /**
-     * Small helper to render templates from strings
-     *
-     * @param  string $templateString
-     * @param  null   $data
-     * @param  bool   $cacheTemplate
-     * @return string
-     */
-    public function render($templateString, $data = null, $cacheTemplate = false)
-    {
-        $t = SSViewer::fromString($templateString, $cacheTemplate);
-        if (!$data) {
-            $data = new SSViewerTest\TestFixture();
-        }
-        return trim('' . $t->process($data));
-    }
-
-    public function testRequirements()
-    {
-        /** @var Requirements_Backend|MockObject $requirements */
-        $requirements = $this
-            ->getMockBuilder(Requirements_Backend::class)
-            ->onlyMethods(["javascript", "css"])
-            ->getMock();
-        $jsFile = FRAMEWORK_DIR . '/tests/forms/a.js';
-        $cssFile = FRAMEWORK_DIR . '/tests/forms/a.js';
-
-        $requirements->expects($this->once())->method('javascript')->with($jsFile);
-        $requirements->expects($this->once())->method('css')->with($cssFile);
-
-        $origReq = Requirements::backend();
-        Requirements::set_backend($requirements);
-        $template = $this->render(
-            "<% require javascript($jsFile) %>
-		<% require css($cssFile) %>"
-        );
-        Requirements::set_backend($origReq);
-
-        $this->assertFalse((bool)trim($template ?? ''), "Should be no content in this return.");
-    }
-
-    public function testRequirementsCombine()
-    {
-        /** @var Requirements_Backend $testBackend */
-        $testBackend = Injector::inst()->create(Requirements_Backend::class);
-        $testBackend->setSuffixRequirements(false);
-        $testBackend->setCombinedFilesEnabled(true);
-
-        //$combinedTestFilePath = BASE_PATH . '/' . $testBackend->getCombinedFilesFolder() . '/testRequirementsCombine.js';
-
-        $jsFile = $this->getCurrentRelativePath() . '/SSViewerTest/javascript/bad.js';
-        $jsFileContents = file_get_contents(BASE_PATH . '/' . $jsFile);
-        $testBackend->combineFiles('testRequirementsCombine.js', [$jsFile]);
-
-        // secondly, make sure that requirements is generated, even though minification failed
-        $testBackend->processCombinedFiles();
-        $js = array_keys($testBackend->getJavascript() ?? []);
-        $combinedTestFilePath = Director::publicFolder() . reset($js);
-        $this->assertStringContainsString('_combinedfiles/testRequirementsCombine-4c0e97a.js', $combinedTestFilePath);
-
-        // and make sure the combined content matches the input content, i.e. no loss of functionality
-        if (!file_exists($combinedTestFilePath ?? '')) {
-            $this->fail('No combined file was created at expected path: ' . $combinedTestFilePath);
-        }
-        $combinedTestFileContents = file_get_contents($combinedTestFilePath ?? '');
-        $this->assertStringContainsString($jsFileContents, $combinedTestFileContents);
-    }
-
-    public function testComments()
-    {
-        $input = <<<SS
-This is my template<%-- this is a comment --%>This is some content<%-- this is another comment --%>Final content
-<%-- Alone multi
-	line comment --%>
-Some more content
-Mixing content and <%-- multi
-	line comment --%> Final final
-content
-<%--commentwithoutwhitespace--%>last content
-SS;
-        $actual = $this->render($input);
-        $expected = <<<SS
-This is my templateThis is some contentFinal content
-
-Some more content
-Mixing content and  Final final
-content
-last content
-SS;
-        $this->assertEquals($expected, $actual);
-
-        $input = <<<SS
-<%--
-
---%>empty comment1
-<%-- --%>empty comment2
-<%----%>empty comment3
-SS;
-        $actual = $this->render($input);
-        $expected = <<<SS
-empty comment1
-empty comment2
-empty comment3
-SS;
-        $this->assertEquals($expected, $actual);
-    }
-
-    public function testBasicText()
-    {
-        $this->assertEquals('"', $this->render('"'), 'Double-quotes are left alone');
-        $this->assertEquals("'", $this->render("'"), 'Single-quotes are left alone');
-        $this->assertEquals('A', $this->render('\\A'), 'Escaped characters are unescaped');
-        $this->assertEquals('\\A', $this->render('\\\\A'), 'Escaped back-slashed are correctly unescaped');
-    }
-
-    public function testBasicInjection()
-    {
-        $this->assertEquals('[out:Test]', $this->render('$Test'), 'Basic stand-alone injection');
-        $this->assertEquals('[out:Test]', $this->render('{$Test}'), 'Basic stand-alone wrapped injection');
-        $this->assertEquals('A[out:Test]!', $this->render('A$Test!'), 'Basic surrounded injection');
-        $this->assertEquals('A[out:Test]B', $this->render('A{$Test}B'), 'Basic surrounded wrapped injection');
-
-        $this->assertEquals('A$B', $this->render('A\\$B'), 'No injection as $ escaped');
-        $this->assertEquals('A$ B', $this->render('A$ B'), 'No injection as $ not followed by word character');
-        $this->assertEquals('A{$ B', $this->render('A{$ B'), 'No injection as {$ not followed by word character');
-
-        $this->assertEquals('{$Test}', $this->render('{\\$Test}'), 'Escapes can be used to avoid injection');
-        $this->assertEquals(
-            '{\\[out:Test]}',
-            $this->render('{\\\\$Test}'),
-            'Escapes before injections are correctly unescaped'
-        );
-    }
-
-    public function testBasicInjectionMismatchedBrackets()
-    {
-        $this->expectException(SSTemplateParseException::class);
-        $this->expectExceptionMessageMatches('/Malformed bracket injection {\$Value(.*)/');
-        $this->render('A {$Value here');
-        $this->fail("Parser didn't error when encountering mismatched brackets in an injection");
-    }
-
-    public function testGlobalVariableCalls()
-    {
-        $this->assertEquals('automatic', $this->render('$SSViewerTest_GlobalAutomatic'));
-        $this->assertEquals('reference', $this->render('$SSViewerTest_GlobalReferencedByString'));
-        $this->assertEquals('reference', $this->render('$SSViewerTest_GlobalReferencedInArray'));
-    }
-
-    public function testGlobalVariableCallsWithArguments()
-    {
-        $this->assertEquals('zz', $this->render('$SSViewerTest_GlobalThatTakesArguments'));
-        $this->assertEquals('zFooz', $this->render('$SSViewerTest_GlobalThatTakesArguments("Foo")'));
-        $this->assertEquals(
-            'zFoo:Bar:Bazz',
-            $this->render('$SSViewerTest_GlobalThatTakesArguments("Foo", "Bar", "Baz")')
-        );
-        $this->assertEquals(
-            'zreferencez',
-            $this->render('$SSViewerTest_GlobalThatTakesArguments($SSViewerTest_GlobalReferencedByString)')
-        );
-    }
-
-    public function testGlobalVariablesAreEscaped()
-    {
-        $this->assertEquals('<div></div>', $this->render('$SSViewerTest_GlobalHTMLFragment'));
-        $this->assertEquals('&lt;div&gt;&lt;/div&gt;', $this->render('$SSViewerTest_GlobalHTMLEscaped'));
-
-        $this->assertEquals(
-            'z<div></div>z',
-            $this->render('$SSViewerTest_GlobalThatTakesArguments($SSViewerTest_GlobalHTMLFragment)')
-        );
-        $this->assertEquals(
-            'z&lt;div&gt;&lt;/div&gt;z',
-            $this->render('$SSViewerTest_GlobalThatTakesArguments($SSViewerTest_GlobalHTMLEscaped)')
-        );
-    }
-
-    public function testGlobalVariablesReturnNull()
-    {
-        $this->assertEquals('<p></p>', $this->render('<p>$SSViewerTest_GlobalReturnsNull</p>'));
-        $this->assertEquals('<p></p>', $this->render('<p>$SSViewerTest_GlobalReturnsNull.Chained.Properties</p>'));
-    }
-
-    public function testCoreGlobalVariableCalls()
-    {
-        $this->assertEquals(
-            Director::absoluteBaseURL(),
-            $this->render('{$absoluteBaseURL}'),
-            'Director::absoluteBaseURL can be called from within template'
-        );
-        $this->assertEquals(
-            Director::absoluteBaseURL(),
-            $this->render('{$AbsoluteBaseURL}'),
-            'Upper-case %AbsoluteBaseURL can be called from within template'
-        );
-
-        $this->assertEquals(
-            Director::is_ajax(),
-            $this->render('{$isAjax}'),
-            'All variations of is_ajax result in the correct call'
-        );
-        $this->assertEquals(
-            Director::is_ajax(),
-            $this->render('{$IsAjax}'),
-            'All variations of is_ajax result in the correct call'
-        );
-        $this->assertEquals(
-            Director::is_ajax(),
-            $this->render('{$is_ajax}'),
-            'All variations of is_ajax result in the correct call'
-        );
-        $this->assertEquals(
-            Director::is_ajax(),
-            $this->render('{$Is_ajax}'),
-            'All variations of is_ajax result in the correct call'
-        );
-
-        $this->assertEquals(
-            i18n::get_locale(),
-            $this->render('{$i18nLocale}'),
-            'i18n template functions result correct result'
-        );
-        $this->assertEquals(
-            i18n::get_locale(),
-            $this->render('{$get_locale}'),
-            'i18n template functions result correct result'
-        );
-
-        $this->assertEquals(
-            (string)Security::getCurrentUser(),
-            $this->render('{$CurrentMember}'),
-            'Member template functions result correct result'
-        );
-        $this->assertEquals(
-            (string)Security::getCurrentUser(),
-            $this->render('{$CurrentUser}'),
-            'Member template functions result correct result'
-        );
-        $this->assertEquals(
-            (string)Security::getCurrentUser(),
-            $this->render('{$currentMember}'),
-            'Member template functions result correct result'
-        );
-        $this->assertEquals(
-            (string)Security::getCurrentUser(),
-            $this->render('{$currentUser}'),
-            'Member template functions result correct result'
-        );
-
-        $this->assertEquals(
-            SecurityToken::getSecurityID(),
-            $this->render('{$getSecurityID}'),
-            'SecurityToken template functions result correct result'
-        );
-        $this->assertEquals(
-            SecurityToken::getSecurityID(),
-            $this->render('{$SecurityID}'),
-            'SecurityToken template functions result correct result'
-        );
-
-        $this->assertEquals(
-            Permission::check("ADMIN"),
-            (bool)$this->render('{$HasPerm(\'ADMIN\')}'),
-            'Permissions template functions result correct result'
-        );
-        $this->assertEquals(
-            Permission::check("ADMIN"),
-            (bool)$this->render('{$hasPerm(\'ADMIN\')}'),
-            'Permissions template functions result correct result'
-        );
-    }
-
-    public function testNonFieldCastingHelpersNotUsedInHasValue()
-    {
-        // check if Link without $ in front of variable
-        $result = $this->render(
-            'A<% if Link %>$Link<% end_if %>B',
-            new SSViewerTest\TestObject()
-        );
-        $this->assertEquals('Asome/url.htmlB', $result, 'casting helper not used for <% if Link %>');
-
-        // check if Link with $ in front of variable
-        $result = $this->render(
-            'A<% if $Link %>$Link<% end_if %>B',
-            new SSViewerTest\TestObject()
-        );
-        $this->assertEquals('Asome/url.htmlB', $result, 'casting helper not used for <% if $Link %>');
-    }
-
-    public function testLocalFunctionsTakePriorityOverGlobals()
-    {
-        $data = new ArrayData([
-            'Page' => new SSViewerTest\TestObject()
-        ]);
-
-        //call method with lots of arguments
-        $result = $this->render(
-            '<% with Page %>$lotsOfArguments11("a","b","c","d","e","f","g","h","i","j","k")<% end_with %>',
-            $data
-        );
-        $this->assertEquals("abcdefghijk", $result, "public function can accept up to 11 arguments");
-
-        //call method that does not exist
-        $result = $this->render('<% with Page %><% if IDoNotExist %>hello<% end_if %><% end_with %>', $data);
-        $this->assertEquals("", $result, "Method does not exist - empty result");
-
-        //call if that does not exist
-        $result = $this->render('<% with Page %>$IDoNotExist("hello")<% end_with %>', $data);
-        $this->assertEquals("", $result, "Method does not exist - empty result");
-
-        //call method with same name as a global method (local call should take priority)
-        $result = $this->render('<% with Page %>$absoluteBaseURL<% end_with %>', $data);
-        $this->assertEquals(
-            "testLocalFunctionPriorityCalled",
-            $result,
-            "Local Object's public function called. Did not return the actual baseURL of the current site"
-        );
-    }
-
-    public function testCurrentScopeLoop(): void
-    {
-        $data = new ArrayList([['Val' => 'one'], ['Val' => 'two'], ['Val' => 'three']]);
         $this->assertEqualIgnoringWhitespace(
-            'one two three',
+            '<html><head><style type="text/css">pretend this is real css</style></head><body></body></html>',
-            $this->render('<% loop %>$Val<% end_loop %>', $data)
+            $result1
         );
-    }
-
-    public function testCurrentScopeLoopWith()
-    {
-        // Data to run the loop tests on - one sequence of three items, each with a subitem
-        $data = new ArrayData([
-            'Foo' => new ArrayList([
-                'Subocean' => new ArrayData([
-                    'Name' => 'Higher'
-                ]),
-                new ArrayData([
-                    'Sub' => new ArrayData([
-                        'Name' => 'SubKid1'
-                    ])
-                ]),
-                new ArrayData([
-                    'Sub' => new ArrayData([
-                        'Name' => 'SubKid2'
-                    ])
-                ]),
-                new SSViewerTest\TestObject('Number6')
-            ])
-        ]);
-
-        $result = $this->render(
-            '<% loop Foo %>$Number<% if Sub %><% with Sub %>$Name<% end_with %><% end_if %><% end_loop %>',
-            $data
-        );
-        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop works");
-
-        $result = $this->render(
-            '<% loop Foo %>$Number<% if Sub %><% with Sub %>$Name<% end_with %><% end_if %><% end_loop %>',
-            $data
-        );
-        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop works");
-
-        $result = $this->render('<% with Foo %>$Count<% end_with %>', $data);
-        $this->assertEquals("4", $result, "4 items in the DataObjectSet");
-
-        $result = $this->render(
-            '<% with Foo %><% loop Up.Foo %>$Number<% if Sub %><% with Sub %>$Name<% end_with %>'
-            . '<% end_if %><% end_loop %><% end_with %>',
-            $data
-        );
-        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop in with Up.Foo scope works");
-
-        $result = $this->render(
-            '<% with Foo %><% loop %>$Number<% if Sub %><% with Sub %>$Name<% end_with %>'
-            . '<% end_if %><% end_loop %><% end_with %>',
-            $data
-        );
-        $this->assertEquals("SubKid1SubKid2Number6", $result, "Loop in current scope works");
-    }
-
-    public static function provideArgumentTypes()
-    {
-        return [
-            [
-                'arg1:0,arg2:"string",arg3:true',
-                '$methodWithTypedArguments(0, "string", true).RAW',
-            ],
-            [
-                'arg1:false,arg2:"string",arg3:true',
-                '$methodWithTypedArguments(false, "string", true).RAW',
-            ],
-            [
-                'arg1:null,arg2:"string",arg3:true',
-                '$methodWithTypedArguments(null, "string", true).RAW',
-            ],
-            [
-                'arg1:"",arg2:"string",arg3:true',
-                '$methodWithTypedArguments("", "string", true).RAW',
-            ],
-            [
-                'arg1:0,arg2:1,arg3:2',
-                '$methodWithTypedArguments(0, 1, 2).RAW',
-            ],
-        ];
-    }
-
-    #[DataProvider('provideArgumentTypes')]
-    public function testArgumentTypes(string $expected, string $template)
-    {
-        $this->assertEquals($expected, $this->render($template, new TestModelData()));
-    }
-
-    public function testObjectDotArguments()
-    {
-        $this->assertEquals(
-            '[out:TestObject.methodWithOneArgument(one)]
-				[out:TestObject.methodWithTwoArguments(one,two)]
-				[out:TestMethod(Arg1,Arg2).Bar.Val]
-				[out:TestMethod(Arg1,Arg2).Bar]
-				[out:TestMethod(Arg1,Arg2)]
-				[out:TestMethod(Arg1).Bar.Val]
-				[out:TestMethod(Arg1).Bar]
-				[out:TestMethod(Arg1)]',
-            $this->render(
-                '$TestObject.methodWithOneArgument(one)
-				$TestObject.methodWithTwoArguments(one,two)
-				$TestMethod(Arg1, Arg2).Bar.Val
-				$TestMethod(Arg1, Arg2).Bar
-				$TestMethod(Arg1, Arg2)
-				$TestMethod(Arg1).Bar.Val
-				$TestMethod(Arg1).Bar
-				$TestMethod(Arg1)'
-            )
-        );
-    }
-
-    public function testEscapedArguments()
-    {
-        $this->assertEquals(
-            '[out:Foo(Arg1,Arg2).Bar.Val].Suffix
-				[out:Foo(Arg1,Arg2).Val]_Suffix
-				[out:Foo(Arg1,Arg2)]/Suffix
-				[out:Foo(Arg1).Bar.Val]textSuffix
-				[out:Foo(Arg1).Bar].Suffix
-				[out:Foo(Arg1)].Suffix
-				[out:Foo.Bar.Val].Suffix
-				[out:Foo.Bar].Suffix
-				[out:Foo].Suffix',
-            $this->render(
-                '{$Foo(Arg1, Arg2).Bar.Val}.Suffix
-				{$Foo(Arg1, Arg2).Val}_Suffix
-				{$Foo(Arg1, Arg2)}/Suffix
-				{$Foo(Arg1).Bar.Val}textSuffix
-				{$Foo(Arg1).Bar}.Suffix
-				{$Foo(Arg1)}.Suffix
-				{$Foo.Bar.Val}.Suffix
-				{$Foo.Bar}.Suffix
-				{$Foo}.Suffix'
-            )
-        );
-    }
-
-    public function testLoopWhitespace()
-    {
-        $data = new ArrayList([new SSViewerTest\TestFixture()]);
-        $this->assertEquals(
-            'before[out:Test]after
-				beforeTestafter',
-            $this->render(
-                'before<% loop %>$Test<% end_loop %>after
-				before<% loop %>Test<% end_loop %>after',
-                $data
-            )
-        );
-
-        // The control tags are removed from the output, but no whitespace
-        // This is a quirk that could be changed, but included in the test to make the current
-        // behaviour explicit
-        $this->assertEquals(
-            'before
-
-[out:ItemOnItsOwnLine]
-
-after',
-            $this->render(
-                'before
-<% loop %>
-$ItemOnItsOwnLine
-<% end_loop %>
-after',
-                $data
-            )
-        );
-
-        // The whitespace within the control tags is preserve in a loop
-        // This is a quirk that could be changed, but included in the test to make the current
-        // behaviour explicit
-        $this->assertEquals(
-            'before
-
-[out:Loop3.ItemOnItsOwnLine]
-
-[out:Loop3.ItemOnItsOwnLine]
-
-[out:Loop3.ItemOnItsOwnLine]
-
-after',
-            $this->render(
-                'before
-<% loop Loop3 %>
-$ItemOnItsOwnLine
-<% end_loop %>
-after'
-            )
-        );
-    }
-
-    public static function typePreservationDataProvider()
-    {
-        return [
-            // Null
-            ['NULL:', 'null'],
-            ['NULL:', 'NULL'],
-            // Booleans
-            ['boolean:1', 'true'],
-            ['boolean:1', 'TRUE'],
-            ['boolean:', 'false'],
-            ['boolean:', 'FALSE'],
-            // Strings which may look like booleans/null to the parser
-            ['string:nullish', 'nullish'],
-            ['string:notnull', 'notnull'],
-            ['string:truethy', 'truethy'],
-            ['string:untrue', 'untrue'],
-            ['string:falsey', 'falsey'],
-            // Integers
-            ['integer:0', '0'],
-            ['integer:1', '1'],
-            ['integer:15', '15'],
-            ['integer:-15', '-15'],
-            // Octal integers
-            ['integer:83', '0123'],
-            ['integer:-83', '-0123'],
-            // Hexadecimal integers
-            ['integer:26', '0x1A'],
-            ['integer:-26', '-0x1A'],
-            // Binary integers
-            ['integer:255', '0b11111111'],
-            ['integer:-255', '-0b11111111'],
-            // Floats (aka doubles)
-            ['double:0', '0.0'],
-            ['double:1', '1.0'],
-            ['double:15.25', '15.25'],
-            ['double:-15.25', '-15.25'],
-            ['double:1200', '1.2e3'],
-            ['double:-1200', '-1.2e3'],
-            ['double:0.07', '7E-2'],
-            ['double:-0.07', '-7E-2'],
-            // Explicitly quoted strings
-            ['string:0', '"0"'],
-            ['string:1', '\'1\''],
-            ['string:foobar', '"foobar"'],
-            ['string:foo bar baz', '"foo bar baz"'],
-            ['string:false', '\'false\''],
-            ['string:true', '\'true\''],
-            ['string:null', '\'null\''],
-            ['string:false', '"false"'],
-            ['string:true', '"true"'],
-            ['string:null', '"null"'],
-            // Implicit strings
-            ['string:foobar', 'foobar'],
-            ['string:foo bar baz', 'foo bar baz']
-        ];
-    }
-
-    #[DataProvider('typePreservationDataProvider')]
-    public function testTypesArePreserved($expected, $templateArg)
-    {
-        $data = new ArrayData([
-            'Test' => new TestModelData()
-        ]);
-
-        $this->assertEquals($expected, $this->render("\$Test.Type({$templateArg})", $data));
-    }
-
-    #[DataProvider('typePreservationDataProvider')]
-    public function testTypesArePreservedAsIncludeArguments($expected, $templateArg)
-    {
-        $data = new ArrayData([
-            'Test' => new TestModelData()
-        ]);
-
-        $this->assertEquals(
-            $expected,
-            $this->render("<% include SSViewerTestTypePreservation Argument={$templateArg} %>", $data)
-        );
-    }
-
-    public function testTypePreservationInConditionals()
-    {
-        $data = new ArrayData([
-            'Test' => new TestModelData()
-        ]);
-
-        // Types in conditionals
-        $this->assertEquals('pass', $this->render('<% if true %>pass<% else %>fail<% end_if %>', $data));
-        $this->assertEquals('pass', $this->render('<% if false %>fail<% else %>pass<% end_if %>', $data));
-        $this->assertEquals('pass', $this->render('<% if 1 %>pass<% else %>fail<% end_if %>', $data));
-        $this->assertEquals('pass', $this->render('<% if 0 %>fail<% else %>pass<% end_if %>', $data));
-    }
-
-    public function testControls()
-    {
-        // Single item controls
-        $this->assertEquals(
-            'a[out:Foo.Bar.Item]b
-				[out:Foo.Bar(Arg1).Item]
-				[out:Foo(Arg1).Item]
-				[out:Foo(Arg1,Arg2).Item]
-				[out:Foo(Arg1,Arg2,Arg3).Item]',
-            $this->render(
-                '<% with Foo.Bar %>a{$Item}b<% end_with %>
-				<% with Foo.Bar(Arg1) %>$Item<% end_with %>
-				<% with Foo(Arg1) %>$Item<% end_with %>
-				<% with Foo(Arg1, Arg2) %>$Item<% end_with %>
-				<% with Foo(Arg1, Arg2, Arg3) %>$Item<% end_with %>'
-            )
-        );
-
-        // Loop controls
-        $this->assertEquals(
-            'a[out:Foo.Loop2.Item]ba[out:Foo.Loop2.Item]b',
-            $this->render('<% loop Foo.Loop2 %>a{$Item}b<% end_loop %>')
-        );
-
-        $this->assertEquals(
-            '[out:Foo.Loop2(Arg1).Item][out:Foo.Loop2(Arg1).Item]',
-            $this->render('<% loop Foo.Loop2(Arg1) %>$Item<% end_loop %>')
-        );
-
-        $this->assertEquals(
-            '[out:Loop2(Arg1).Item][out:Loop2(Arg1).Item]',
-            $this->render('<% loop Loop2(Arg1) %>$Item<% end_loop %>')
-        );
-
-        $this->assertEquals(
-            '[out:Loop2(Arg1,Arg2).Item][out:Loop2(Arg1,Arg2).Item]',
-            $this->render('<% loop Loop2(Arg1, Arg2) %>$Item<% end_loop %>')
-        );
-
-        $this->assertEquals(
-            '[out:Loop2(Arg1,Arg2,Arg3).Item][out:Loop2(Arg1,Arg2,Arg3).Item]',
-            $this->render('<% loop Loop2(Arg1, Arg2, Arg3) %>$Item<% end_loop %>')
-        );
-    }
-
-    public function testIfBlocks()
-    {
-        // Basic test
-        $this->assertEquals(
-            'AC',
-            $this->render('A<% if NotSet %>B$NotSet<% end_if %>C')
-        );
-
-        // Nested test
-        $this->assertEquals(
-            'AB1C',
-            $this->render('A<% if IsSet %>B$NotSet<% if IsSet %>1<% else %>2<% end_if %><% end_if %>C')
-        );
-
-        // else_if
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if NotSet %>B<% else_if IsSet %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if NotSet %>B<% else_if AlsoNotset %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ADE',
-            $this->render('A<% if NotSet %>B<% else_if AlsoNotset %>C<% else_if IsSet %>D<% end_if %>E')
-        );
-
-        $this->assertEquals(
-            'ADE',
-            $this->render('A<% if NotSet %>B<% else_if AlsoNotset %>C<% else_if IsSet %>D<% end_if %>E')
-        );
-
-        // Dot syntax
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if Foo.NotSet %>B<% else_if Foo.IsSet %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if Foo.Bar.NotSet %>B<% else_if Foo.Bar.IsSet %>C<% end_if %>D')
-        );
-
-        // Params
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if NotSet(Param) %>B<% else %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ABD',
-            $this->render('A<% if IsSet(Param) %>B<% else %>C<% end_if %>D')
-        );
-
-        // Negation
-        $this->assertEquals(
-            'AC',
-            $this->render('A<% if not IsSet %>B<% end_if %>C')
-        );
-        $this->assertEquals(
-            'ABC',
-            $this->render('A<% if not NotSet %>B<% end_if %>C')
-        );
-
-        // Or
-        $this->assertEquals(
-            'ABD',
-            $this->render('A<% if IsSet || NotSet %>B<% else_if A %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if IsSet %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if NotSet3 %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if IsSet || NotSet %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if NotSet || AlsoNotSet %>B<% else_if NotSet2 || NotSet3 %>C<% end_if %>D')
-        );
-
-        // Negated Or
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if not IsSet || AlsoNotSet %>B<% else_if A %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ABD',
-            $this->render('A<% if not NotSet || AlsoNotSet %>B<% else_if A %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ABD',
-            $this->render('A<% if NotSet || not AlsoNotSet %>B<% else_if A %>C<% end_if %>D')
-        );
-
-        // And
-        $this->assertEquals(
-            'ABD',
-            $this->render('A<% if IsSet && AlsoSet %>B<% else_if A %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if IsSet && NotSet %>B<% else_if IsSet %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if NotSet && NotSet2 %>B<% else_if NotSet3 %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if IsSet && NotSet %>B<% else_if IsSet && AlsoSet %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if NotSet && NotSet2 %>B<% else_if IsSet && NotSet3 %>C<% end_if %>D')
-        );
-
-        // Equality
-        $this->assertEquals(
-            'ABC',
-            $this->render('A<% if RawVal == RawVal %>B<% end_if %>C')
-        );
-        $this->assertEquals(
-            'ACD',
-            $this->render('A<% if Right == Wrong %>B<% else_if RawVal == RawVal %>C<% end_if %>D')
-        );
-        $this->assertEquals(
-            'ABC',
-            $this->render('A<% if Right != Wrong %>B<% end_if %>C')
-        );
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if Right == Wrong %>B<% else_if RawVal != RawVal %>C<% end_if %>D')
-        );
-
-        // test inequalities with simple numbers
-        $this->assertEquals('ABD', $this->render('A<% if 5 > 3 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ABD', $this->render('A<% if 5 >= 3 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ACD', $this->render('A<% if 3 > 5 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ACD', $this->render('A<% if 3 >= 5 %>B<% else %>C<% end_if %>D'));
-
-        $this->assertEquals('ABD', $this->render('A<% if 3 < 5 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ABD', $this->render('A<% if 3 <= 5 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ACD', $this->render('A<% if 5 < 3 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ACD', $this->render('A<% if 5 <= 3 %>B<% else %>C<% end_if %>D'));
-
-        $this->assertEquals('ABD', $this->render('A<% if 4 <= 4 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ABD', $this->render('A<% if 4 >= 4 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ACD', $this->render('A<% if 4 > 4 %>B<% else %>C<% end_if %>D'));
-        $this->assertEquals('ACD', $this->render('A<% if 4 < 4 %>B<% else %>C<% end_if %>D'));
-
-        // empty else_if and else tags, if this would not be supported,
-        // the output would stop after A, thereby failing the assert
-        $this->assertEquals('AD', $this->render('A<% if IsSet %><% else %><% end_if %>D'));
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if NotSet %><% else_if IsSet %><% else %><% end_if %>D')
-        );
-        $this->assertEquals(
-            'AD',
-            $this->render('A<% if NotSet %><% else_if AlsoNotSet %><% else %><% end_if %>D')
-        );
-
-        // Bare words with ending space
-        $this->assertEquals(
-            'ABC',
-            $this->render('A<% if "RawVal" == RawVal %>B<% end_if %>C')
-        );
-
-        // Else
-        $this->assertEquals(
-            'ADE',
-            $this->render('A<% if Right == Wrong %>B<% else_if RawVal != RawVal %>C<% else %>D<% end_if %>E')
-        );
-
-        // Empty if with else
-        $this->assertEquals(
-            'ABC',
-            $this->render('A<% if NotSet %><% else %>B<% end_if %>C')
-        );
-    }
-
-    public static function provideIfBlockWithIterable(): array
-    {
-        $scenarios = [
-            'empty array' => [
-                'iterable' => [],
-                'inScope' => false,
-            ],
-            'array' => [
-                'iterable' => [1, 2, 3],
-                'inScope' => false,
-            ],
-            'ArrayList' => [
-                'iterable' => new ArrayList([['Val' => 1], ['Val' => 2], ['Val' => 3]]),
-                'inScope' => false,
-            ],
-        ];
-        foreach ($scenarios as $name => $scenario) {
-            $scenario['inScope'] = true;
-            $scenarios[$name . ' in scope'] = $scenario;
-        }
-        return $scenarios;
-    }
-
-    #[DataProvider('provideIfBlockWithIterable')]
-    public function testIfBlockWithIterable(iterable $iterable, bool $inScope): void
-    {
-        $expected = count($iterable) ? 'has value' : 'no value';
-        $data = new ArrayData(['Iterable' => $iterable]);
-        if ($inScope) {
-            $template = '<% with $Iterable %><% if $Me %>has value<% else %>no value<% end_if %><% end_with %>';
-        } else {
-            $template = '<% if $Iterable %>has value<% else %>no value<% end_if %>';
-        }
-        $this->assertEqualIgnoringWhitespace($expected, $this->render($template, $data));
-    }
-
-    public function testBaseTagGeneration()
-    {
-        // XHTML will have a closed base tag
-        $tmpl1 = '<?xml version="1.0" encoding="UTF-8"?>
-			<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"'
-            . ' "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-			<html>
-				<head><% base_tag %></head>
-				<body><p>test</p><body>
-			</html>';
-        $this->assertMatchesRegularExpression('/<head><base href=".*" \/><\/head>/', $this->render($tmpl1));
-
-        // HTML4 and 5 will only have it for IE
-        $tmpl2 = '<!DOCTYPE html>
-			<html>
-				<head><% base_tag %></head>
-				<body><p>test</p><body>
-			</html>';
-        $this->assertMatchesRegularExpression(
-            '/<head><base href=".*"><!--\[if lte IE 6\]><\/base><!\[endif\]--><\/head>/',
-            $this->render($tmpl2)
-        );
-
-
-        $tmpl3 = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
-			<html>
-				<head><% base_tag %></head>
-				<body><p>test</p><body>
-			</html>';
-        $this->assertMatchesRegularExpression(
-            '/<head><base href=".*"><!--\[if lte IE 6\]><\/base><!\[endif\]--><\/head>/',
-            $this->render($tmpl3)
-        );
-
-        // Check that the content negotiator converts to the equally legal formats
-        $negotiator = new ContentNegotiator();
-
-        $response = new HTTPResponse($this->render($tmpl1));
-        $negotiator->html($response);
-        $this->assertMatchesRegularExpression(
-            '/<head><base href=".*"><!--\[if lte IE 6\]><\/base><!\[endif\]--><\/head>/',
-            $response->getBody()
-        );
-
-        $response = new HTTPResponse($this->render($tmpl1));
-        $negotiator->xhtml($response);
-        $this->assertMatchesRegularExpression('/<head><base href=".*" \/><\/head>/', $response->getBody());
-    }
-
-    public function testIncludeWithArguments()
-    {
-        $this->assertEquals(
-            $this->render('<% include SSViewerTestIncludeWithArguments %>'),
-            '<p>[out:Arg1]</p><p>[out:Arg2]</p><p>[out:Arg2.Count]</p>'
-        );
-
-        $this->assertEquals(
-            $this->render('<% include SSViewerTestIncludeWithArguments Arg1=A %>'),
-            '<p>A</p><p>[out:Arg2]</p><p>[out:Arg2.Count]</p>'
-        );
-
-        $this->assertEquals(
-            $this->render('<% include SSViewerTestIncludeWithArguments Arg1=A, Arg2=B %>'),
-            '<p>A</p><p>B</p><p></p>'
-        );
-
-        $this->assertEquals(
-            $this->render('<% include SSViewerTestIncludeWithArguments Arg1=A Bare String, Arg2=B Bare String %>'),
-            '<p>A Bare String</p><p>B Bare String</p><p></p>'
-        );
-
-        $this->assertEquals(
-            $this->render(
-                '<% include SSViewerTestIncludeWithArguments Arg1="A", Arg2=$B %>',
-                new ArrayData(['B' => 'Bar'])
-            ),
-            '<p>A</p><p>Bar</p><p></p>'
-        );
-
-        $this->assertEquals(
-            $this->render(
-                '<% include SSViewerTestIncludeWithArguments Arg1="A" %>',
-                new ArrayData(['Arg1' => 'Foo', 'Arg2' => 'Bar'])
-            ),
-            '<p>A</p><p>Bar</p><p></p>'
-        );
-
-        $this->assertEquals(
-            $this->render('<% include SSViewerTestIncludeWithArguments Arg1="A", Arg2=0 %>'),
-            '<p>A</p><p>0</p><p></p>'
-        );
-
-        $this->assertEquals(
-            $this->render('<% include SSViewerTestIncludeWithArguments Arg1="A", Arg2=false %>'),
-            '<p>A</p><p></p><p></p>'
-        );
-
-        $this->assertEquals(
-            $this->render('<% include SSViewerTestIncludeWithArguments Arg1="A", Arg2=null %>'),
-            '<p>A</p><p></p><p></p>'
-        );
-
-        $this->assertEquals(
-            $this->render(
-                '<% include SSViewerTestIncludeScopeInheritanceWithArgsInLoop Title="SomeArg" %>',
-                new ArrayData(
-                    ['Items' => new ArrayList(
-                        [
-                        new ArrayData(['Title' => 'Foo']),
-                        new ArrayData(['Title' => 'Bar'])
-                        ]
-                    )]
-                )
-            ),
-            'SomeArg - Foo - Bar - SomeArg'
-        );
-
-        $this->assertEquals(
-            $this->render(
-                '<% include SSViewerTestIncludeScopeInheritanceWithArgsInWith Title="A" %>',
-                new ArrayData(['Item' => new ArrayData(['Title' =>'B'])])
-            ),
-            'A - B - A'
-        );
-
-        $this->assertEquals(
-            $this->render(
-                '<% include SSViewerTestIncludeScopeInheritanceWithArgsInNestedWith Title="A" %>',
-                new ArrayData(
-                    [
-                    'Item' => new ArrayData(
-                        [
-                        'Title' =>'B', 'NestedItem' => new ArrayData(['Title' => 'C'])
-                        ]
-                    )]
-                )
-            ),
-            'A - B - C - B - A'
-        );
-
-        $this->assertEquals(
-            $this->render(
-                '<% include SSViewerTestIncludeScopeInheritanceWithUpAndTop Title="A" %>',
-                new ArrayData(
-                    [
-                    'Item' => new ArrayData(
-                        [
-                        'Title' =>'B', 'NestedItem' => new ArrayData(['Title' => 'C'])
-                        ]
-                    )]
-                )
-            ),
-            'A - A - A'
-        );
-
-        $data = new ArrayData(
-            [
-            'Nested' => new ArrayData(
-                [
-                'Object' => new ArrayData(['Key' => 'A'])
-                ]
-            ),
-            'Object' => new ArrayData(['Key' => 'B'])
-            ]
-        );
-
-        $tmpl = SSViewer::fromString('<% include SSViewerTestIncludeObjectArguments A=$Nested.Object, B=$Object %>');
-        $res  = $tmpl->process($data);
-        $this->assertEqualIgnoringWhitespace('A B', $res, 'Objects can be passed as named arguments');
-    }
-
-    public function testNamespaceInclude()
-    {
-        $data = new ArrayData([]);
-
-        $this->assertEquals(
-            "tests:( NamespaceInclude\n )",
-            $this->render('tests:( <% include Namespace\NamespaceInclude %> )', $data),
-            'Backslashes work for namespace references in includes'
-        );
-
-        $this->assertEquals(
-            "tests:( NamespaceInclude\n )",
-            $this->render('tests:( <% include Namespace\\NamespaceInclude %> )', $data),
-            'Escaped backslashes work for namespace references in includes'
-        );
-
-        $this->assertEquals(
-            "tests:( NamespaceInclude\n )",
-            $this->render('tests:( <% include Namespace/NamespaceInclude %> )', $data),
-            'Forward slashes work for namespace references in includes'
-        );
-    }
-
-    /**
-     * Test search for includes fallback to non-includes folder
-     */
-    public function testIncludeFallbacks()
-    {
-        $data = new ArrayData([]);
-
-        $this->assertEquals(
-            "tests:( Namespace/Includes/IncludedTwice.ss\n )",
-            $this->render('tests:( <% include Namespace\\IncludedTwice %> )', $data),
-            'Prefer Includes in the Includes folder'
-        );
-
-        $this->assertEquals(
-            "tests:( Namespace/Includes/IncludedOnceSub.ss\n )",
-            $this->render('tests:( <% include Namespace\\IncludedOnceSub %> )', $data),
-            'Includes in only Includes folder can be found'
-        );
-
-        $this->assertEquals(
-            "tests:( Namespace/IncludedOnceBase.ss\n )",
-            $this->render('tests:( <% include Namespace\\IncludedOnceBase %> )', $data),
-            'Includes outside of Includes folder can be found'
-        );
-    }
-
-    public function testRecursiveInclude()
-    {
-        $view = new SSViewer(['Includes/SSViewerTestRecursiveInclude']);
-
-        $data = new ArrayData(
-            [
-            'Title' => 'A',
-            'Children' => new ArrayList(
-                [
-                new ArrayData(
-                    [
-                    'Title' => 'A1',
-                    'Children' => new ArrayList(
-                        [
-                        new ArrayData([ 'Title' => 'A1 i', ]),
-                        new ArrayData([ 'Title' => 'A1 ii', ]),
-                        ]
-                    ),
-                    ]
-                ),
-                new ArrayData([ 'Title' => 'A2', ]),
-                new ArrayData([ 'Title' => 'A3', ]),
-                ]
-            ),
-            ]
-        );
-
-        $result = $view->process($data);
-        // We don't care about whitespace
-        $rationalisedResult = trim(preg_replace('/\s+/', ' ', $result ?? '') ?? '');
-
-        $this->assertEquals('A A1 A1 i A1 ii A2 A3', $rationalisedResult);
-    }
-
-    public function assertEqualIgnoringWhitespace($a, $b, $message = '')
-    {
-        $this->assertEquals(preg_replace('/\s+/', '', $a ?? ''), preg_replace('/\s+/', '', $b ?? ''), $message);
-    }
-
-    /**
-     * See {@link ModelDataTest} for more extensive casting tests,
-     * this test just ensures that basic casting is correctly applied during template parsing.
-     */
-    public function testCastingHelpers()
-    {
-        $vd = new SSViewerTest\TestModelData();
-        $vd->TextValue = '<b>html</b>';
-        $vd->HTMLValue = '<b>html</b>';
-        $vd->UncastedValue = '<b>html</b>';
-
-        // Value casted as "Text"
-        $this->assertEquals(
-            '&lt;b&gt;html&lt;/b&gt;',
-            $t = SSViewer::fromString('$TextValue')->process($vd)
-        );
-        $this->assertEquals(
-            '<b>html</b>',
-            $t = SSViewer::fromString('$TextValue.RAW')->process($vd)
-        );
-        $this->assertEquals(
-            '&lt;b&gt;html&lt;/b&gt;',
-            $t = SSViewer::fromString('$TextValue.XML')->process($vd)
-        );
-
-        // Value casted as "HTMLText"
-        $this->assertEquals(
-            '<b>html</b>',
-            $t = SSViewer::fromString('$HTMLValue')->process($vd)
-        );
-        $this->assertEquals(
-            '<b>html</b>',
-            $t = SSViewer::fromString('$HTMLValue.RAW')->process($vd)
-        );
-        $this->assertEquals(
-            '&lt;b&gt;html&lt;/b&gt;',
-            $t = SSViewer::fromString('$HTMLValue.XML')->process($vd)
-        );
-
-        // Uncasted value (falls back to ModelData::$default_cast="Text")
-        $vd = new SSViewerTest\TestModelData();
-        $vd->UncastedValue = '<b>html</b>';
-        $this->assertEquals(
-            '&lt;b&gt;html&lt;/b&gt;',
-            $t = SSViewer::fromString('$UncastedValue')->process($vd)
-        );
-        $this->assertEquals(
-            '<b>html</b>',
-            $t = SSViewer::fromString('$UncastedValue.RAW')->process($vd)
-        );
-        $this->assertEquals(
-            '&lt;b&gt;html&lt;/b&gt;',
-            $t = SSViewer::fromString('$UncastedValue.XML')->process($vd)
-        );
-    }
-
-    public static function provideLoop(): array
-    {
-        return [
-            'nested array and iterator' => [
-                'iterable' => [
-                    [
-                        'value 1',
-                        'value 2',
-                    ],
-                    new ArrayList([
-                        'value 3',
-                        'value 4',
-                    ]),
-                ],
-                'template' => '<% loop $Iterable %><% loop $Me %>$Me<% end_loop %><% end_loop %>',
-                'expected' => 'value 1 value 2 value 3 value 4',
-            ],
-            'nested associative arrays' => [
-                'iterable' => [
-                    [
-                        'Foo' => 'one',
-                    ],
-                    [
-                        'Foo' => 'two',
-                    ],
-                    [
-                        'Foo' => 'three',
-                    ],
-                ],
-                'template' => '<% loop $Iterable %>$Foo<% end_loop %>',
-                'expected' => 'one two three',
-            ],
-        ];
-    }
-
-    #[DataProvider('provideLoop')]
-    public function testLoop(iterable $iterable, string $template, string $expected): void
-    {
-        $data = new ArrayData(['Iterable' => $iterable]);
-        $this->assertEqualIgnoringWhitespace($expected, $this->render($template, $data));
-    }
-
-    public static function provideCountIterable(): array
-    {
-        $scenarios = [
-            'empty array' => [
-                'iterable' => [],
-                'inScope' => false,
-            ],
-            'array' => [
-                'iterable' => [1, 2, 3],
-                'inScope' => false,
-            ],
-            'ArrayList' => [
-                'iterable' => new ArrayList([['Val' => 1], ['Val' => 2], ['Val' => 3]]),
-                'inScope' => false,
-            ],
-        ];
-        foreach ($scenarios as $name => $scenario) {
-            $scenario['inScope'] = true;
-            $scenarios[$name . ' in scope'] = $scenario;
-        }
-        return $scenarios;
-    }
-
-    #[DataProvider('provideCountIterable')]
-    public function testCountIterable(iterable $iterable, bool $inScope): void
-    {
-        $expected = count($iterable);
-        $data = new ArrayData(['Iterable' => $iterable]);
-        if ($inScope) {
-            $template = '<% with $Iterable %>$Count<% end_with %>';
-        } else {
-            $template = '$Iterable.Count';
-        }
-        $this->assertEqualIgnoringWhitespace($expected, $this->render($template, $data));
-    }
-
-    public function testSSViewerBasicIteratorSupport()
-    {
-        $data = new ArrayData(
-            [
-            'Set' => new ArrayList(
-                [
-                new SSViewerTest\TestObject("1"),
-                new SSViewerTest\TestObject("2"),
-                new SSViewerTest\TestObject("3"),
-                new SSViewerTest\TestObject("4"),
-                new SSViewerTest\TestObject("5"),
-                new SSViewerTest\TestObject("6"),
-                new SSViewerTest\TestObject("7"),
-                new SSViewerTest\TestObject("8"),
-                new SSViewerTest\TestObject("9"),
-                new SSViewerTest\TestObject("10"),
-                ]
-            )
-            ]
-        );
-
-        //base test
-        $result = $this->render('<% loop Set %>$Number<% end_loop %>', $data);
-        $this->assertEquals("12345678910", $result, "Numbers rendered in order");
-
-        //test First
-        $result = $this->render('<% loop Set %><% if $IsFirst %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("1", $result, "Only the first number is rendered");
-
-        //test Last
-        $result = $this->render('<% loop Set %><% if $IsLast %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("10", $result, "Only the last number is rendered");
-
-        //test Even
-        $result = $this->render('<% loop Set %><% if $Even() %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("246810", $result, "Even numbers rendered in order");
-
-        //test Even with quotes
-        $result = $this->render('<% loop Set %><% if $Even("1") %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("246810", $result, "Even numbers rendered in order");
-
-        //test Even without quotes
-        $result = $this->render('<% loop Set %><% if $Even(1) %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("246810", $result, "Even numbers rendered in order");
-
-        //test Even with zero-based start index
-        $result = $this->render('<% loop Set %><% if $Even("0") %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("13579", $result, "Even (with zero-based index) numbers rendered in order");
-
-        //test Odd
-        $result = $this->render('<% loop Set %><% if $Odd %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("13579", $result, "Odd numbers rendered in order");
-
-        //test FirstLast
-        $result = $this->render('<% loop Set %><% if $FirstLast %>$Number$FirstLast<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("1first10last", $result, "First and last numbers rendered in order");
-
-        //test Middle
-        $result = $this->render('<% loop Set %><% if $Middle %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("23456789", $result, "Middle numbers rendered in order");
-
-        //test MiddleString
-        $result = $this->render(
-            '<% loop Set %><% if MiddleString == "middle" %>$Number$MiddleString<% end_if %>'
-            . '<% end_loop %>',
-            $data
-        );
-        $this->assertEquals(
-            "2middle3middle4middle5middle6middle7middle8middle9middle",
-            $result,
-            "Middle numbers rendered in order"
-        );
-
-        //test EvenOdd
-        $result = $this->render('<% loop Set %>$EvenOdd<% end_loop %>', $data);
-        $this->assertEquals(
-            "oddevenoddevenoddevenoddevenoddeven",
-            $result,
-            "Even and Odd is returned in sequence numbers rendered in order"
-        );
-
-        //test Pos
-        $result = $this->render('<% loop Set %>$Pos<% end_loop %>', $data);
-        $this->assertEquals("12345678910", $result, '$Pos is rendered in order');
-
-        //test Pos
-        $result = $this->render('<% loop Set %>$Pos(0)<% end_loop %>', $data);
-        $this->assertEquals("0123456789", $result, '$Pos(0) is rendered in order');
-
-        //test FromEnd
-        $result = $this->render('<% loop Set %>$FromEnd<% end_loop %>', $data);
-        $this->assertEquals("10987654321", $result, '$FromEnd is rendered in order');
-
-        //test FromEnd
-        $result = $this->render('<% loop Set %>$FromEnd(0)<% end_loop %>', $data);
-        $this->assertEquals("9876543210", $result, '$FromEnd(0) rendered in order');
-
-        //test Total
-        $result = $this->render('<% loop Set %>$TotalItems<% end_loop %>', $data);
-        $this->assertEquals("10101010101010101010", $result, "10 total items X 10 are returned");
-
-        //test Modulus
-        $result = $this->render('<% loop Set %>$Modulus(2,1)<% end_loop %>', $data);
-        $this->assertEquals("1010101010", $result, "1-indexed pos modular divided by 2 rendered in order");
-
-        //test MultipleOf 3
-        $result = $this->render('<% loop Set %><% if MultipleOf(3) %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("369", $result, "Only numbers that are multiples of 3 are returned");
-
-        //test MultipleOf 4
-        $result = $this->render('<% loop Set %><% if MultipleOf(4) %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("48", $result, "Only numbers that are multiples of 4 are returned");
-
-        //test MultipleOf 5
-        $result = $this->render('<% loop Set %><% if MultipleOf(5) %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("510", $result, "Only numbers that are multiples of 5 are returned");
-
-        //test MultipleOf 10
-        $result = $this->render('<% loop Set %><% if MultipleOf(10,1) %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("10", $result, "Only numbers that are multiples of 10 (with 1-based indexing) are returned");
-
-        //test MultipleOf 9 zero-based
-        $result = $this->render('<% loop Set %><% if MultipleOf(9,0) %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals(
-            "110",
-            $result,
-            "Only numbers that are multiples of 9 with zero-based indexing are returned. (The first and last item)"
-        );
-
-        //test MultipleOf 11
-        $result = $this->render('<% loop Set %><% if MultipleOf(11) %>$Number<% end_if %><% end_loop %>', $data);
-        $this->assertEquals("", $result, "Only numbers that are multiples of 11 are returned. I.e. nothing returned");
-    }
-
-    /**
-     * Test $Up works when the scope $Up refers to was entered with a "with" block
-     */
-    public function testUpInWith()
-    {
-
-        // Data to run the loop tests on - three levels deep
-        $data = new ArrayData(
-            [
-            'Name' => 'Top',
-            'Foo' => new ArrayData(
-                [
-                'Name' => 'Foo',
-                'Bar' => new ArrayData(
-                    [
-                    'Name' => 'Bar',
-                    'Baz' => new ArrayData(
-                        [
-                        'Name' => 'Baz'
-                        ]
-                    ),
-                    'Qux' => new ArrayData(
-                        [
-                        'Name' => 'Qux'
-                        ]
-                    )
-                    ]
-                )
-                ]
-            )
-            ]
-        );
-
-        // Basic functionality
-        $this->assertEquals(
-            'BarFoo',
-            $this->render('<% with Foo %><% with Bar %>{$Name}{$Up.Name}<% end_with %><% end_with %>', $data)
-        );
-
-        // Two level with block, up refers to internally referenced Bar
-        $this->assertEquals(
-            'BarTop',
-            $this->render('<% with Foo.Bar %>{$Name}{$Up.Name}<% end_with %>', $data)
-        );
-
-        // Stepping up & back down the scope tree
-        $this->assertEquals(
-            'BazFooBar',
-            $this->render('<% with Foo.Bar.Baz %>{$Name}{$Up.Foo.Name}{$Up.Foo.Bar.Name}<% end_with %>', $data)
-        );
-
-        // Using $Up in a with block
-        $this->assertEquals(
-            'BazTopBar',
-            $this->render(
-                '<% with Foo.Bar.Baz %>{$Name}<% with $Up %>{$Name}{$Foo.Bar.Name}<% end_with %>'
-                . '<% end_with %>',
-                $data
-            )
-        );
-
-        // Stepping up & back down the scope tree with with blocks
-        $this->assertEquals(
-            'BazTopBarTopBaz',
-            $this->render(
-                '<% with Foo.Bar.Baz %>{$Name}<% with $Up %>{$Name}<% with Foo.Bar %>{$Name}<% end_with %>'
-                . '{$Name}<% end_with %>{$Name}<% end_with %>',
-                $data
-            )
-        );
-
-        // Using $Up.Up, where first $Up points to a previous scope entered using $Up, thereby skipping up to Foo
-        $this->assertEquals(
-            'Foo',
-            $this->render(
-                '<% with Foo %><% with Bar %><% with Baz %>{$Up.Up.Name}<% end_with %><% end_with %>'
-                . '<% end_with %>',
-                $data
-            )
-        );
-
-        // Using $Up as part of a lookup chain in <% with %>
-        $this->assertEquals(
-            'Top',
-            $this->render('<% with Foo.Bar.Baz.Up.Qux %>{$Up.Name}<% end_with %>', $data)
-        );
-    }
-
-    public function testTooManyUps()
-    {
-        $this->expectException(LogicException::class);
-        $this->expectExceptionMessage("Up called when we're already at the top of the scope");
-        $data = new ArrayData([
-            'Foo' => new ArrayData([
-                'Name' => 'Foo',
-                'Bar' => new ArrayData([
-                    'Name' => 'Bar'
-                ])
-            ])
-        ]);
-
-        $this->assertEquals(
-            'Foo',
-            $this->render('<% with Foo.Bar %>{$Up.Up.Name}<% end_with %>', $data)
-        );
-    }
-
-    /**
-     * Test $Up works when the scope $Up refers to was entered with a "loop" block
-     */
-    public function testUpInLoop()
-    {
-
-        // Data to run the loop tests on - one sequence of three items, each with a subitem
-        $data = new ArrayData(
-            [
-            'Name' => 'Top',
-            'Foo' => new ArrayList(
-                [
-                new ArrayData(
-                    [
-                    'Name' => '1',
-                    'Sub' => new ArrayData(
-                        [
-                        'Name' => 'Bar'
-                        ]
-                    )
-                    ]
-                ),
-                new ArrayData(
-                    [
-                    'Name' => '2',
-                    'Sub' => new ArrayData(
-                        [
-                        'Name' => 'Baz'
-                        ]
-                    )
-                    ]
-                ),
-                new ArrayData(
-                    [
-                    'Name' => '3',
-                    'Sub' => new ArrayData(
-                        [
-                        'Name' => 'Qux'
-                        ]
-                    )
-                    ]
-                )
-                ]
-            )
-            ]
-        );
-
-        // Make sure inside a loop, $Up refers to the current item of the loop
         $this->assertEqualIgnoringWhitespace(
-            '111 222 333',
+            '<html><head></head><body></body></html>',
-            $this->render(
+            $result2
-                '<% loop $Foo %>$Name<% with $Sub %>$Up.Name<% end_with %>$Name<% end_loop %>',
-                $data
-            )
-        );
-
-        // Make sure inside a loop, looping over $Up uses a separate iterator,
-        // and doesn't interfere with the original iterator
-        $this->assertEqualIgnoringWhitespace(
-            '1Bar123Bar1 2Baz123Baz2 3Qux123Qux3',
-            $this->render(
-                '<% loop $Foo %>
-					$Name
-					<% with $Sub %>
-						$Name
-						<% loop $Up %>$Name<% end_loop %>
-						$Name
-					<% end_with %>
-					$Name
-				<% end_loop %>',
-                $data
-            )
-        );
-
-        // Make sure inside a loop, looping over $Up uses a separate iterator,
-        // and doesn't interfere with the original iterator or local lookups
-        $this->assertEqualIgnoringWhitespace(
-            '1 Bar1 123 1Bar 1   2 Baz2 123 2Baz 2   3 Qux3 123 3Qux 3',
-            $this->render(
-                '<% loop $Foo %>
-					$Name
-					<% with $Sub %>
-						{$Name}{$Up.Name}
-						<% loop $Up %>$Name<% end_loop %>
-						{$Up.Name}{$Name}
-					<% end_with %>
-					$Name
-				<% end_loop %>',
-                $data
-            )
-        );
-    }
-
-    /**
-     * Test that nested loops restore the loop variables correctly when pushing and popping states
-     */
-    public function testNestedLoops()
-    {
-
-        // Data to run the loop tests on - one sequence of three items, one with child elements
-        // (of a different size to the main sequence)
-        $data = new ArrayData(
-            [
-            'Foo' => new ArrayList(
-                [
-                new ArrayData(
-                    [
-                    'Name' => '1',
-                    'Children' => new ArrayList(
-                        [
-                        new ArrayData(
-                            [
-                            'Name' => 'a'
-                            ]
-                        ),
-                        new ArrayData(
-                            [
-                            'Name' => 'b'
-                            ]
-                        ),
-                        ]
-                    ),
-                    ]
-                ),
-                new ArrayData(
-                    [
-                    'Name' => '2',
-                    'Children' => new ArrayList(),
-                    ]
-                ),
-                new ArrayData(
-                    [
-                    'Name' => '3',
-                    'Children' => new ArrayList(),
-                    ]
-                ),
-                ]
-            ),
-            ]
-        );
-
-        // Make sure that including a loop inside a loop will not destroy the internal count of
-        // items, checked by using "Last"
-        $this->assertEqualIgnoringWhitespace(
-            '1ab23last',
-            $this->render(
-                '<% loop $Foo %>$Name<% loop Children %>$Name<% end_loop %><% if $IsLast %>last<% end_if %>'
-                . '<% end_loop %>',
-                $data
-            )
-        );
-    }
-
-    public function testLayout()
-    {
-        $this->useTestTheme(
-            __DIR__ . '/SSViewerTest',
-            'layouttest',
-            function () {
-                $template = new SSViewer(['Page']);
-                $this->assertEquals("Foo\n\n", $template->process(new ArrayData([])));
-
-                $template = new SSViewer(['Shortcodes', 'Page']);
-                $this->assertEquals("[file_link]\n\n", $template->process(new ArrayData([])));
-            }
         );
     }
 
@@ -1939,7 +131,7 @@ after'
 
                 // Let's throw something random in there.
                 $this->expectException(\InvalidArgumentException::class);
-                SSViewer::get_templates_by_class(null);
+                SSViewer::get_templates_by_class('no-class');
             }
         );
     }
@@ -1947,43 +139,31 @@ after'
     public function testRewriteHashlinks()
     {
         SSViewer::setRewriteHashLinksDefault(true);
+        $oldServerVars = $_SERVER;
 
-        $_SERVER['HTTP_HOST'] = 'www.mysite.com';
+        try {
             $_SERVER['REQUEST_URI'] = '//file.com?foo"onclick="alert(\'xss\')""';
 
-        // Emulate SSViewer::process()
             // Note that leading double slashes have been rewritten to prevent these being mis-interepreted
             // as protocol-less absolute urls
             $base = Convert::raw2att('/file.com?foo"onclick="alert(\'xss\')""');
 
-        $tmplFile = TEMP_PATH . DIRECTORY_SEPARATOR . 'SSViewerTest_testRewriteHashlinks_' . sha1(rand()) . '.ss';
+            $engine = new DummyTemplateEngine();
-
+            $engine->setOutput(
-        // Note: SSViewer_FromString doesn't rewrite hash links.
-        file_put_contents(
-            $tmplFile ?? '',
                 '<!DOCTYPE html>
                 <html>
-				<head><% base_tag %></head>
+                    <head><base href="http://www.example.com/"></head>
                     <body>
                     <a class="external-inline" href="http://google.com#anchor">ExternalInlineLink</a>
-				$ExternalInsertedLink
+                    <a class="external-inserted" href="http://google.com#anchor">ExternalInsertedLink</a>
                     <a class="inline" href="#anchor">InlineLink</a>
-				$InsertedLink
+                    <a class="inserted" href="#anchor">InsertedLink</a>
                     <svg><use xlink:href="#sprite"></use></svg>
                     <body>
                 </html>'
             );
-        $tmpl = new SSViewer($tmplFile);
+            $tmpl = new SSViewer([], $engine);
-        $obj = new ModelData();
+            $result = $tmpl->process('pretend this is a model');
-        $obj->InsertedLink = DBField::create_field(
-            'HTMLFragment',
-            '<a class="inserted" href="#anchor">InsertedLink</a>'
-        );
-        $obj->ExternalInsertedLink = DBField::create_field(
-            'HTMLFragment',
-            '<a class="external-inserted" href="http://google.com#anchor">ExternalInsertedLink</a>'
-        );
-        $result = $tmpl->process($obj);
             $this->assertStringContainsString(
                 '<a class="inserted" href="' . $base . '#anchor">InsertedLink</a>',
                 $result
@@ -2005,36 +185,28 @@ after'
                 $result,
                 'SSTemplateParser should only rewrite anchor hrefs'
             );
-
+        } finally {
-        unlink($tmplFile ?? '');
+            $_SERVER = $oldServerVars;
+        }
     }
 
     public function testRewriteHashlinksInPhpMode()
     {
         SSViewer::setRewriteHashLinksDefault('php');
-
+        $engine = new DummyTemplateEngine();
-        $tmplFile = TEMP_PATH . DIRECTORY_SEPARATOR . 'SSViewerTest_testRewriteHashlinksInPhpMode_' . sha1(rand()) . '.ss';
+        $engine->setOutput(
-
-        // Note: SSViewer_FromString doesn't rewrite hash links.
-        file_put_contents(
-            $tmplFile ?? '',
             '<!DOCTYPE html>
             <html>
-				<head><% base_tag %></head>
+                <head><base href="http://www.example.com/"></head>
                 <body>
                 <a class="inline" href="#anchor">InlineLink</a>
-				$InsertedLink
+                <a class="inserted" href="#anchor">InsertedLink</a>
                 <svg><use xlink:href="#sprite"></use></svg>
                 <body>
             </html>'
         );
-        $tmpl = new SSViewer($tmplFile);
+        $tmpl = new SSViewer([], $engine);
-        $obj = new ModelData();
+        $result = $tmpl->process('pretend this is a model');
-        $obj->InsertedLink = DBField::create_field(
-            'HTMLFragment',
-            '<a class="inserted" href="#anchor">InsertedLink</a>'
-        );
-        $result = $tmpl->process($obj);
 
         $code = <<<'EOC'
 <a class="inserted" href="<?php echo \SilverStripe\Core\Convert::raw2att(preg_replace("/^(\/)+/", "/", $_SERVER['REQUEST_URI'])); ?>#anchor">InsertedLink</a>
@@ -2045,339 +217,10 @@ EOC;
             $result,
             'SSTemplateParser should only rewrite anchor hrefs'
         );
-
-        unlink($tmplFile ?? '');
     }
 
-    public function testRenderWithSourceFileComments()
+    private function assertEqualIgnoringWhitespace(string $a, string $b, string $message = ''): void
     {
-        SSViewer::config()->set('source_file_comments', true);
+        $this->assertEquals(preg_replace('/\s+/', '', $a ), preg_replace('/\s+/', '', $b), $message);
-        $i = __DIR__ . '/SSViewerTest/templates/Includes';
-        $f = __DIR__ . '/SSViewerTest/templates/SSViewerTestComments';
-        $templates = [
-        [
-            'name' => 'SSViewerTestCommentsFullSource',
-            'expected' => ""
-                . "<!doctype html>"
-                . "<!-- template $f/SSViewerTestCommentsFullSource.ss -->"
-                . "<html>"
-                . "\t<head></head>"
-                . "\t<body></body>"
-                . "</html>"
-                . "<!-- end template $f/SSViewerTestCommentsFullSource.ss -->",
-        ],
-        [
-            'name' => 'SSViewerTestCommentsFullSourceHTML4Doctype',
-            'expected' => ""
-                . "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML "
-                . "4.01//EN\"\t\t\"http://www.w3.org/TR/html4/strict.dtd\">"
-                . "<!-- template $f/SSViewerTestCommentsFullSourceHTML4Doctype.ss -->"
-                . "<html>"
-                . "\t<head></head>"
-                . "\t<body></body>"
-                . "</html>"
-                . "<!-- end template $f/SSViewerTestCommentsFullSourceHTML4Doctype.ss -->",
-        ],
-        [
-            'name' => 'SSViewerTestCommentsFullSourceNoDoctype',
-            'expected' => ""
-                . "<html><!-- template $f/SSViewerTestCommentsFullSourceNoDoctype.ss -->"
-                . "\t<head></head>"
-                . "\t<body></body>"
-                . "<!-- end template $f/SSViewerTestCommentsFullSourceNoDoctype.ss --></html>",
-        ],
-        [
-            'name' => 'SSViewerTestCommentsFullSourceIfIE',
-            'expected' => ""
-                . "<!doctype html>"
-                . "<!-- template $f/SSViewerTestCommentsFullSourceIfIE.ss -->"
-                . "<!--[if lte IE 8]> <html class='old-ie'> <![endif]-->"
-                . "<!--[if gt IE 8]> <html class='new-ie'> <![endif]-->"
-                . "<!--[if !IE]><!--> <html class='no-ie'> <!--<![endif]-->"
-                . "\t<head></head>"
-                . "\t<body></body>"
-                . "</html>"
-                . "<!-- end template $f/SSViewerTestCommentsFullSourceIfIE.ss -->",
-        ],
-        [
-            'name' => 'SSViewerTestCommentsFullSourceIfIENoDoctype',
-            'expected' => ""
-                . "<!--[if lte IE 8]> <html class='old-ie'> <![endif]-->"
-                . "<!--[if gt IE 8]> <html class='new-ie'> <![endif]-->"
-                . "<!--[if !IE]><!--> <html class='no-ie'>"
-                . "<!-- template $f/SSViewerTestCommentsFullSourceIfIENoDoctype.ss -->"
-                . " <!--<![endif]-->"
-                . "\t<head></head>"
-                . "\t<body></body>"
-                . "<!-- end template $f/SSViewerTestCommentsFullSourceIfIENoDoctype.ss --></html>",
-        ],
-        [
-            'name' => 'SSViewerTestCommentsPartialSource',
-            'expected' =>
-            "<!-- template $f/SSViewerTestCommentsPartialSource.ss -->"
-                . "<div class='typography'></div>"
-                . "<!-- end template $f/SSViewerTestCommentsPartialSource.ss -->",
-        ],
-        [
-            'name' => 'SSViewerTestCommentsWithInclude',
-            'expected' =>
-            "<!-- template $f/SSViewerTestCommentsWithInclude.ss -->"
-                . "<div class='typography'>"
-                . "<!-- include 'SSViewerTestCommentsInclude' -->"
-                . "<!-- template $i/SSViewerTestCommentsInclude.ss -->"
-                . "Included"
-                . "<!-- end template $i/SSViewerTestCommentsInclude.ss -->"
-                . "<!-- end include 'SSViewerTestCommentsInclude' -->"
-                . "</div>"
-                . "<!-- end template $f/SSViewerTestCommentsWithInclude.ss -->",
-        ],
-        ];
-        foreach ($templates as $template) {
-            $this->_renderWithSourceFileComments('SSViewerTestComments/' . $template['name'], $template['expected']);
-        }
-    }
-    private function _renderWithSourceFileComments($name, $expected)
-    {
-        $viewer = new SSViewer([$name]);
-        $data = new ArrayData([]);
-        $result = $viewer->process($data);
-        $expected = str_replace(["\r", "\n"], '', $expected ?? '');
-        $result = str_replace(["\r", "\n"], '', $result ?? '');
-        $this->assertEquals($result, $expected);
-    }
-
-    public function testLoopIteratorIterator()
-    {
-        $list = new PaginatedList(new ArrayList());
-        $viewer = new SSViewer_FromString('<% loop List %>$ID - $FirstName<br /><% end_loop %>');
-        $result = $viewer->process(new ArrayData(['List' => $list]));
-        $this->assertEquals($result, '');
-    }
-
-    public function testProcessOnlyIncludesRequirementsOnce()
-    {
-        $template = new SSViewer(['SSViewerTestProcess']);
-        $basePath = $this->getCurrentRelativePath() . '/SSViewerTest';
-
-        $backend = Injector::inst()->create(Requirements_Backend::class);
-        $backend->setCombinedFilesEnabled(false);
-        $backend->combineFiles(
-            'RequirementsTest_ab.css',
-            [
-            $basePath . '/css/RequirementsTest_a.css',
-            $basePath . '/css/RequirementsTest_b.css'
-            ]
-        );
-
-        Requirements::set_backend($backend);
-
-        $this->assertEquals(1, substr_count($template->process(new ModelData()) ?? '', "a.css"));
-        $this->assertEquals(1, substr_count($template->process(new ModelData()) ?? '', "b.css"));
-
-        // if we disable the requirements then we should get nothing
-        $template->includeRequirements(false);
-        $this->assertEquals(0, substr_count($template->process(new ModelData()) ?? '', "a.css"));
-        $this->assertEquals(0, substr_count($template->process(new ModelData()) ?? '', "b.css"));
-    }
-
-    public function testRequireCallInTemplateInclude()
-    {
-        if (FRAMEWORK_DIR === 'framework') {
-            $template = new SSViewer(['SSViewerTestProcess']);
-
-            Requirements::set_suffix_requirements(false);
-
-            $this->assertEquals(
-                1,
-                substr_count(
-                    $template->process(new ModelData()) ?? '',
-                    "tests/php/View/SSViewerTest/javascript/RequirementsTest_a.js"
-                )
-            );
-        } else {
-            $this->markTestSkipped(
-                'Requirement will always fail if the framework dir is not ' .
-                'named \'framework\', since templates require hard coded paths'
-            );
-        }
-    }
-
-    public function testCallsWithArguments()
-    {
-        $data = new ArrayData(
-            [
-            'Set' => new ArrayList(
-                [
-                new SSViewerTest\TestObject("1"),
-                new SSViewerTest\TestObject("2"),
-                new SSViewerTest\TestObject("3"),
-                new SSViewerTest\TestObject("4"),
-                new SSViewerTest\TestObject("5"),
-                ]
-            ),
-            'Level' => new SSViewerTest\LevelTestData(1),
-            'Nest' => [
-            'Level' => new SSViewerTest\LevelTestData(2),
-            ],
-            ]
-        );
-
-        $tests = [
-        '$Level.output(1)' => '1-1',
-        '$Nest.Level.output($Set.First.Number)' => '2-1',
-        '<% with $Set %>$Up.Level.output($First.Number)<% end_with %>' => '1-1',
-        '<% with $Set %>$Top.Nest.Level.output($First.Number)<% end_with %>' => '2-1',
-        '<% loop $Set %>$Up.Nest.Level.output($Number)<% end_loop %>' => '2-12-22-32-42-5',
-        '<% loop $Set %>$Top.Level.output($Number)<% end_loop %>' => '1-11-21-31-41-5',
-        '<% with $Nest %>$Level.output($Top.Set.First.Number)<% end_with %>' => '2-1',
-        '<% with $Level %>$output($Up.Set.Last.Number)<% end_with %>' => '1-5',
-        '<% with $Level.forWith($Set.Last.Number) %>$output("hi")<% end_with %>' => '5-hi',
-        '<% loop $Level.forLoop($Set.First.Number) %>$Number<% end_loop %>' => '!0',
-        '<% with $Nest %>
-				<% with $Level.forWith($Up.Set.First.Number) %>$output("hi")<% end_with %>
-			<% end_with %>' => '1-hi',
-        '<% with $Nest %>
-				<% loop $Level.forLoop($Top.Set.Last.Number) %>$Number<% end_loop %>
-			<% end_with %>' => '!0!1!2!3!4',
-        ];
-
-        foreach ($tests as $template => $expected) {
-            $this->assertEquals($expected, trim($this->render($template, $data) ?? ''));
-        }
-    }
-
-    public function testRepeatedCallsAreCached()
-    {
-        $data = new SSViewerTest\CacheTestData();
-        $template = '
-			<% if $TestWithCall %>
-				<% with $TestWithCall %>
-					{$Message}
-				<% end_with %>
-
-				{$TestWithCall.Message}
-			<% end_if %>';
-
-        $this->assertEquals('HiHi', preg_replace('/\s+/', '', $this->render($template, $data) ?? ''));
-        $this->assertEquals(
-            1,
-            $data->testWithCalls,
-            'SSViewerTest_CacheTestData::TestWithCall() should only be called once. Subsequent calls should be cached'
-        );
-
-        $data = new SSViewerTest\CacheTestData();
-        $template = '
-			<% if $TestLoopCall %>
-				<% loop $TestLoopCall %>
-					{$Message}
-				<% end_loop %>
-			<% end_if %>';
-
-        $this->assertEquals('OneTwo', preg_replace('/\s+/', '', $this->render($template, $data) ?? ''));
-        $this->assertEquals(
-            1,
-            $data->testLoopCalls,
-            'SSViewerTest_CacheTestData::TestLoopCall() should only be called once. Subsequent calls should be cached'
-        );
-    }
-
-    public function testClosedBlockExtension()
-    {
-        $count = 0;
-        $parser = new SSTemplateParser();
-        $parser->addClosedBlock(
-            'test',
-            function ($res) use (&$count) {
-                $count++;
-            }
-        );
-
-        $template = new SSViewer_FromString("<% test %><% end_test %>", $parser);
-        $template->process(new SSViewerTest\TestFixture());
-
-        $this->assertEquals(1, $count);
-    }
-
-    public function testOpenBlockExtension()
-    {
-        $count = 0;
-        $parser = new SSTemplateParser();
-        $parser->addOpenBlock(
-            'test',
-            function ($res) use (&$count) {
-                $count++;
-            }
-        );
-
-        $template = new SSViewer_FromString("<% test %>", $parser);
-        $template->process(new SSViewerTest\TestFixture());
-
-        $this->assertEquals(1, $count);
-    }
-
-    /**
-     * Tests if caching for SSViewer_FromString is working
-     */
-    public function testFromStringCaching()
-    {
-        $content = 'Test content';
-        $cacheFile = TEMP_PATH . DIRECTORY_SEPARATOR . '.cache.' . sha1($content ?? '');
-        if (file_exists($cacheFile ?? '')) {
-            unlink($cacheFile ?? '');
-        }
-
-        // Test global behaviors
-        $this->render($content, null, null);
-        $this->assertFalse(file_exists($cacheFile ?? ''), 'Cache file was created when caching was off');
-
-        SSViewer_FromString::config()->set('cache_template', true);
-        $this->render($content, null, null);
-        $this->assertTrue(file_exists($cacheFile ?? ''), 'Cache file wasn\'t created when it was meant to');
-        unlink($cacheFile ?? '');
-
-        // Test instance behaviors
-        $this->render($content, null, false);
-        $this->assertFalse(file_exists($cacheFile ?? ''), 'Cache file was created when caching was off');
-
-        $this->render($content, null, true);
-        $this->assertTrue(file_exists($cacheFile ?? ''), 'Cache file wasn\'t created when it was meant to');
-        unlink($cacheFile ?? '');
-    }
-
-    public function testPrimitivesConvertedToDBFields()
-    {
-        $data = new ArrayData([
-            // null value should not be rendered, though should also not throw exception
-            'Foo' => new ArrayList(['hello', true, 456, 7.89, null])
-        ]);
-        $this->assertEqualIgnoringWhitespace(
-            'hello 1 456 7.89',
-            $this->render('<% loop $Foo %>$Me<% end_loop %>', $data)
-        );
-    }
-
-    #[DoesNotPerformAssertions]
-    public function testMe(): void
-    {
-        $myArrayData = new class extends ArrayData {
-            public function forTemplate()
-            {
-                return '';
-            }
-        };
-        $this->render('$Me', $myArrayData);
-    }
-
-    public function testLoopingThroughArrayInOverlay(): void
-    {
-        $modelData = new ModelData();
-        $theArray = [
-            ['Val' => 'one'],
-            ['Val' => 'two'],
-            ['Val' => 'red'],
-            ['Val' => 'blue'],
-        ];
-        $output = $modelData->renderWith('SSViewerTestLoopArray', ['MyArray' => $theArray]);
-        $this->assertEqualIgnoringWhitespace('one two red blue', $output);
     }
 }

tests/php/View/SSViewerTest/DummyTemplateEngine.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace SilverStripe\View\Tests\SSViewerTest;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\View\TemplateEngine;
+use SilverStripe\View\ViewLayerData;
+
+/**
+ * A dummy template renderer that doesn't actually render any templates.
+ */
+class DummyTemplateEngine implements TemplateEngine, TestOnly
+{
+    private string $output = '<html><head></head><body></body></html>';
+
+    public function __construct(string|array $templateCandidates = [])
+    {
+        // no-op
+    }
+
+    public function setTemplate(string|array $templateCandidates): static
+    {
+        return $this;
+    }
+
+    public function hasTemplate(string|array $templateCandidates): bool
+    {
+        return true;
+    }
+
+    public function renderString(string $template, ViewLayerData $model, array $overlay = [], bool $cache = true): string
+    {
+        return $this->output;
+    }
+
+    public function render(ViewLayerData $model, array $overlay = []): string
+    {
+        return $this->output;
+    }
+
+    public function setOutput(string $output): void
+    {
+        $this->output = $output;
+    }
+}

tests/php/View/SSViewerTest/TestFixture.php

@@ -1,72 +0,0 @@
-<?php
-
-namespace SilverStripe\View\Tests\SSViewerTest;
-
-use SilverStripe\Model\List\ArrayList;
-use SilverStripe\Model\ModelData;
-
-/**
- * A test fixture that will echo back the template item
- */
-class TestFixture extends ModelData
-{
-    protected $name;
-
-    public function __construct($name = null)
-    {
-        $this->name = $name;
-        parent::__construct();
-    }
-
-    private function argedName($fieldName, $arguments)
-    {
-        $childName = $this->name ? "$this->name.$fieldName" : $fieldName;
-        if ($arguments) {
-            return $childName . '(' . implode(',', $arguments) . ')';
-        } else {
-            return $childName;
-        }
-    }
-
-    public function obj(
-        string $fieldName,
-        array $arguments = [],
-        bool $cache = false,
-        ?string $cacheName = null
-    ): ?object {
-        $childName = $this->argedName($fieldName, $arguments);
-
-        // Special field name Loop### to create a list
-        if (preg_match('/^Loop([0-9]+)$/', $fieldName ?? '', $matches)) {
-            $output = new ArrayList();
-            for ($i = 0; $i < $matches[1]; $i++) {
-                $output->push(new TestFixture($childName));
-            }
-            return $output;
-        } else {
-            if (preg_match('/NotSet/i', $fieldName ?? '')) {
-                return new ModelData();
-            } else {
-                return new TestFixture($childName);
-            }
-        }
-    }
-
-    public function XML_val(string $fieldName, array $arguments = [], bool $cache = false): string
-    {
-        if (preg_match('/NotSet/i', $fieldName ?? '')) {
-            return '';
-        } else {
-            if (preg_match('/Raw/i', $fieldName ?? '')) {
-                return $fieldName;
-            } else {
-                return '[out:' . $this->argedName($fieldName, $arguments) . ']';
-            }
-        }
-    }
-
-    public function hasValue(string $fieldName, array $arguments = [], bool $cache = true): bool
-    {
-        return (bool)$this->XML_val($fieldName, $arguments);
-    }
-}

tests/php/View/SSViewerTest/TestGlobalProvider.php

@@ -1,51 +0,0 @@
-<?php
-
-namespace SilverStripe\View\Tests\SSViewerTest;
-
-use SilverStripe\Dev\TestOnly;
-use SilverStripe\View\TemplateGlobalProvider;
-
-class TestGlobalProvider implements TemplateGlobalProvider, TestOnly
-{
-
-    public static function get_template_global_variables()
-    {
-        return [
-            'SSViewerTest_GlobalHTMLFragment' => ['method' => 'get_html', 'casting' => 'HTMLFragment'],
-            'SSViewerTest_GlobalHTMLEscaped' => ['method' => 'get_html'],
-
-            'SSViewerTest_GlobalAutomatic',
-            'SSViewerTest_GlobalReferencedByString' => 'get_reference',
-            'SSViewerTest_GlobalReferencedInArray' => ['method' => 'get_reference'],
-
-            'SSViewerTest_GlobalThatTakesArguments' => ['method' => 'get_argmix', 'casting' => 'HTMLFragment'],
-            'SSViewerTest_GlobalReturnsNull' => 'getNull',
-        ];
-    }
-
-    public static function get_html()
-    {
-        return '<div></div>';
-    }
-
-    public static function SSViewerTest_GlobalAutomatic()
-    {
-        return 'automatic';
-    }
-
-    public static function get_reference()
-    {
-        return 'reference';
-    }
-
-    public static function get_argmix()
-    {
-        $args = func_get_args();
-        return 'z' . implode(':', $args) . 'z';
-    }
-
-    public static function getNull()
-    {
-        return null;
-    }
-}

tests/php/View/SSViewerTest/templates/SSViewerTestComments/SSViewerTestCommentsWithInclude.ss

@@ -1 +0,0 @@
-<div class='typography'><% include SSViewerTestCommentsInclude %></div>

tests/php/View/SSViewerTest/templates/SSViewerTestIncludeScopeInheritance.ss

@@ -1,3 +0,0 @@
-<% loop Items %>
-	<% include SSViewerTestIncludeScopeInheritanceInclude %>
-<% end_loop %>

tests/php/View/SSViewerTest/templates/SSViewerTestIncludeScopeInheritanceWithArgs.ss

@@ -1,3 +0,0 @@
-<% loop Items %>
-	<% include SSViewerTestIncludeScopeInheritanceInclude ArgA=$Title %>
-<% end_loop %>

tests/php/View/SSViewerTest/templates/SSViewerTestProcess.ss

@@ -1,6 +0,0 @@
-<html>
-	<% include SSViewerTestProcessHead %>
-
-	<body>
-	</body>
-</html>

tests/php/View/SSViewerTest/themes/layouttest/templates/TestNamespace/SSViewerTestModel_Controller.ss

@@ -1 +0,0 @@
-SSViewerTest

tests/php/View/ViewLayerDataTest.php

@@ -0,0 +1,751 @@
+<?php
+
+namespace SilverStripe\View\Tests;
+
+use ArrayIterator;
+use BadMethodCallException;
+use Error;
+use InvalidArgumentException;
+use PHPUnit\Framework\Attributes\DataProvider;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Model\ArrayData;
+use SilverStripe\Model\List\ArrayList;
+use SilverStripe\Model\ModelData;
+use SilverStripe\ORM\FieldType\DBDate;
+use SilverStripe\ORM\FieldType\DBHTMLText;
+use SilverStripe\View\Exception\MissingTemplateException;
+use SilverStripe\View\Tests\ViewLayerDataTest\CountableObject;
+use SilverStripe\View\Tests\ViewLayerDataTest\ExtensibleObject;
+use SilverStripe\View\Tests\ViewLayerDataTest\ExtensibleObjectExtension;
+use SilverStripe\View\Tests\ViewLayerDataTest\GetCountObject;
+use SilverStripe\View\Tests\ViewLayerDataTest\NonIterableObject;
+use SilverStripe\View\Tests\ViewLayerDataTest\StringableObject;
+use SilverStripe\View\Tests\ViewLayerDataTest\TestFixture;
+use SilverStripe\View\Tests\ViewLayerDataTest\TestFixtureComplex;
+use SilverStripe\View\ViewLayerData;
+use stdClass;
+use Throwable;
+
+class ViewLayerDataTest extends SapphireTest
+{
+    protected static $required_extensions = [
+        ExtensibleObject::class => [
+            ExtensibleObjectExtension::class
+        ],
+    ];
+
+    public static function provideGetIterator(): array
+    {
+        return [
+            'non-iterable object' => [
+                'data' => new ArrayData(['Field1' => 'value1', 'Field2' => 'value2']),
+                'expected' => BadMethodCallException::class,
+            ],
+            'non-iterable scalar' => [
+                'data' => 'This is some text, aint iterable',
+                'expected' => BadMethodCallException::class,
+            ],
+            'empty array' => [
+                'data' => [],
+                'expected' => [],
+            ],
+            'single item array' => [
+                'data' => ['one value'],
+                'expected' => ['one value'],
+            ],
+            'multi-item array' => [
+                'data' => ['one', 'two', 'three'],
+                'expected' => ['one', 'two', 'three'],
+            ],
+            'object implements an Iterable interface' => [
+                'data' => new ArrayList(['one', 'two', 'three']),
+                'expected' => ['one', 'two', 'three'],
+            ],
+            'built-in PHP iterator' => [
+                'data' => new ArrayIterator(['one', 'two', 'three']),
+                'expected' => ['one', 'two', 'three'],
+            ],
+            'non-iterable object with getIterator method' => [
+                'data' => new NonIterableObject(),
+                'expected' => ['some value', 'another value', 'isnt this nice'],
+            ],
+            'extensible object with getIterator extension' => [
+                'data' => new ExtensibleObject(),
+                'expected' => ['1','2','3','4','5','6','7','8','9','a','b','c','d','e'],
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGetIterator')]
+    public function testGetIterator(mixed $data, string|array $expected): void
+    {
+        $viewLayerData = new ViewLayerData($data);
+        if ($expected === BadMethodCallException::class) {
+            $this->expectException(BadMethodCallException::class);
+            $this->expectExceptionMessageMatches('/is not iterable.$/');
+        }
+        $this->assertEquals($expected, iterator_to_array($viewLayerData->getIterator()));
+        // Ensure the iterator is always wrapping values
+        foreach ($viewLayerData as $value) {
+            $this->assertInstanceOf(ViewLayerData::class, $value);
+        }
+    }
+
+    public static function provideGetIteratorCount(): array
+    {
+        return [
+            'uncountable object' => [
+                'data' => new ArrayData(['Field1' => 'value1', 'Field2' => 'value2']),
+                'expected' => 0,
+            ],
+            'uncountable object - has count field' => [
+                'data' => new ArrayData(['count' => 12, 'Field2' => 'value2']),
+                'expected' => 12,
+            ],
+            'uncountable object - has count field (non-int)' => [
+                'data' => new ArrayData(['count' => 'aahhh', 'Field2' => 'value2']),
+                'expected' => 0,
+            ],
+            'empty array' => [
+                'data' => [],
+                'expected' => 0,
+            ],
+            'array with values' => [
+                'data' => [1, 2],
+                'expected' => 2,
+            ],
+            'explicitly countable object' => [
+                'data' => new CountableObject(),
+                'expected' => 53,
+            ],
+            'non-countable object with getCount method' => [
+                'data' => new GetCountObject(),
+                'expected' => 12,
+            ],
+            'non-countable object with getIterator method' => [
+                'data' => new NonIterableObject(),
+                'expected' => 3,
+            ],
+            'extensible object with getIterator extension' => [
+                'data' => new ExtensibleObject(),
+                'expected' => 14,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGetIteratorCount')]
+    public function testGetIteratorCount(mixed $data, int $expected): void
+    {
+        $viewLayerData = new ViewLayerData($data);
+        $this->assertSame($expected, $viewLayerData->getIteratorCount());
+    }
+
+    public static function provideIsSet(): array
+    {
+        return [
+            'list array' => [
+                'data' => ['anything'],
+                'name' => 'anything',
+                'expected' => false,
+            ],
+            'associative array has key' => [
+                'data' => ['anything' => 'some value'],
+                'name' => 'anything',
+                'expected' => true,
+            ],
+            'ModelData without field' => [
+                'data' => new ArrayData(['nothing' => 'some value']),
+                'name' => 'anything',
+                'expected' => false,
+            ],
+            'ModelData with field' => [
+                'data' => new ArrayData(['anything' => 'some value']),
+                'name' => 'anything',
+                'expected' => true,
+            ],
+            'extensible class with getter extension' => [
+                'data' => new ExtensibleObject(),
+                'name' => 'anything',
+                'expected' => true,
+            ],
+            'extensible class not set' => [
+                'data' => new ExtensibleObject(),
+                'name' => 'anythingelse',
+                'expected' => false,
+            ],
+            'class with method' => [
+                'data' => new CountableObject(),
+                'name' => 'count',
+                'expected' => true,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideIsSet')]
+    public function testIsSet(mixed $data, string $name, bool $expected): void
+    {
+        $viewLayerData = new ViewLayerData($data);
+        $this->assertSame($expected, isset($viewLayerData->$name));
+    }
+
+    public static function provideGet(): array
+    {
+        return [
+            'basic field' => [
+                'name' => 'SomeField',
+                'throwException' => true,
+                'expected' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'SomeField',
+                        'args' => [],
+                    ],
+                    [
+                        'type' => 'method',
+                        'name' => 'getSomeField',
+                        'args' => [],
+                    ],
+                    [
+                        'type' => 'property',
+                        'name' => 'SomeField',
+                    ],
+                ],
+            ],
+            'getter as property' => [
+                'name' => 'getSomeField',
+                'throwException' => true,
+                'expected' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'getSomeField',
+                        'args' => [],
+                    ],
+                    [
+                        'type' => 'method',
+                        'name' => 'getgetSomeField',
+                        'args' => [],
+                    ],
+                    [
+                        'type' => 'property',
+                        'name' => 'getSomeField',
+                    ],
+                ],
+            ],
+            'basic field (lowercase)' => [
+                'name' => 'somefield',
+                'throwException' => true,
+                'expected' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'somefield',
+                        'args' => [],
+                    ],
+                    [
+                        'type' => 'method',
+                        'name' => 'getsomefield',
+                        'args' => [],
+                    ],
+                    [
+                        'type' => 'property',
+                        'name' => 'somefield',
+                    ],
+                ],
+            ],
+            'property not set, dont even try it' => [
+                'name' => 'NotSet',
+                'throwException' => true,
+                'expected' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'NotSet',
+                        'args' => [],
+                    ],
+                    [
+                        'type' => 'method',
+                        'name' => 'getNotSet',
+                        'args' => [],
+                    ],
+                ],
+            ],
+            'stops after method when not throwing' => [
+                'name' => 'SomeField',
+                'throwException' => false,
+                'expected' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'SomeField',
+                        'args' => [],
+                    ],
+                ],
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGet')]
+    public function testGet(string $name, bool $throwException, array $expected): void
+    {
+        $fixture = new TestFixture();
+        $fixture->throwException = $throwException;
+        $viewLayerData = new ViewLayerData($fixture);
+        $value = $viewLayerData->$name;
+        $this->assertSame($expected, $fixture->getRequested());
+        $this->assertNull($value);
+    }
+
+    public static function provideGetComplex(): array
+    {
+        // Note the actual value checks aren't very comprehensive here because that's done
+        // in more detail in testGetRawDataValue
+        return [
+            'exception gets thrown if not __call() method' => [
+                'name' => 'badMethodCall',
+                'expectRequested' => BadMethodCallException::class,
+                'expected' => null,
+            ],
+            'returning nothing is like returning null' => [
+                'name' => 'voidMethod',
+                'expectRequested' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'voidMethod',
+                        'args' => [],
+                    ],
+                ],
+                'expected' => null,
+            ],
+            'returned value is caught' => [
+                'name' => 'justCallMethod',
+                'expectRequested' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'justCallMethod',
+                        'args' => [],
+                    ],
+                ],
+                'expected' => 'This is a method value',
+            ],
+            'getter is used' => [
+                'name' => 'ActualValue',
+                'expectRequested' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'getActualValue',
+                        'args' => [],
+                    ],
+                ],
+                'expected' => 'this is the value',
+            ],
+            'if no method exists, only property is fetched' => [
+                'name' => 'NoMethod',
+                'expectRequested' => [
+                    [
+                        'type' => 'property',
+                        'name' => 'NoMethod',
+                    ],
+                ],
+                'expected' => null,
+            ],
+            'property value is caught' => [
+                'name' => 'ActualValueField',
+                'expectRequested' => [
+                    [
+                        'type' => 'property',
+                        'name' => 'ActualValueField',
+                    ],
+                ],
+                'expected' => 'the value is here',
+            ],
+            'not set and no method' => [
+                'name' => 'NotSet',
+                'expectRequested' => [],
+                'expected' => null,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGetComplex')]
+    public function testGetComplex(string $name, string|array $expectRequested, ?string $expected): void
+    {
+        $fixture = new TestFixtureComplex();
+        $viewLayerData = new ViewLayerData($fixture);
+        if ($expectRequested === BadMethodCallException::class) {
+            $this->expectException(BadMethodCallException::class);
+        }
+        $value = $viewLayerData->$name;
+        $this->assertSame($expectRequested, $fixture->getRequested());
+        $this->assertEquals($expected, $value);
+        // Ensure value is being wrapped when not null
+        if ($value !== null) {
+            $this->assertInstanceOf(ViewLayerData::class, $value);
+        }
+    }
+
+    public static function provideCall(): array
+    {
+        // Currently there is no distinction between trying to get a property or call a method from ViewLayerData
+        // so the "get" examples should produce the same results when calling a method.
+        $scenarios = static::provideGet();
+        foreach ($scenarios as &$scenario) {
+            $scenario['args'] = [];
+        }
+        return [
+            ...$scenarios,
+            'basic field with args' => [
+                'name' => 'SomeField',
+                'args' => ['abc', 123],
+                'throwException' => true,
+                'expected' => [
+                    [
+                        'type' => 'method',
+                        'name' => 'SomeField',
+                        'args' => ['abc', 123],
+                    ],
+                    [
+                        'type' => 'method',
+                        'name' => 'getSomeField',
+                        'args' => ['abc', 123],
+                    ],
+                    [
+                        'type' => 'property',
+                        'name' => 'SomeField',
+                    ],
+                ],
+            ],
+        ];
+    }
+
+    #[DataProvider('provideCall')]
+    public function testCall(string $name, array $args, bool $throwException, array $expected): void
+    {
+        $fixture = new TestFixture();
+        $fixture->throwException = $throwException;
+        $viewLayerData = new ViewLayerData($fixture);
+        $value = $viewLayerData->$name(...$args);
+        $this->assertSame($expected, $fixture->getRequested());
+        $this->assertNull($value);
+    }
+
+    public static function provideCallComplex(): array
+    {
+        // Currently there is no distinction between trying to get a property or call a method from ViewLayerData
+        // so the "get" examples should produce the same results when calling a method.
+        return static::provideGetComplex();
+    }
+
+    #[DataProvider('provideCallComplex')]
+    public function testCallComplex(string $name, string|array $expectRequested, ?string $expected): void
+    {
+        $fixture = new TestFixtureComplex();
+        $viewLayerData = new ViewLayerData($fixture);
+        if ($expectRequested === BadMethodCallException::class) {
+            $this->expectException(BadMethodCallException::class);
+        }
+        $value = $viewLayerData->$name();
+        $this->assertSame($expectRequested, $fixture->getRequested());
+        $this->assertEquals($expected, $value);
+        // Ensure value is being wrapped when not null
+        if ($value !== null) {
+            $this->assertInstanceOf(ViewLayerData::class, $value);
+        }
+    }
+
+    public static function provideToString(): array
+    {
+        return [
+            // These three all evaluate to ArrayList or ArrayData, which don't have templates to render
+            'empty array' => [
+                'data' => [],
+                'expected' => MissingTemplateException::class,
+            ],
+            'array with values' => [
+                'data' => ['value1', 'value2'],
+                'expected' => MissingTemplateException::class,
+            ],
+            'Class with no template' => [
+                // Note we won't check classes WITH templates because we're not testing the template engine here
+                'data' => new ArrayData(['Field1' => 'value1', 'Field2' => 'value2']),
+                'expected' => MissingTemplateException::class,
+            ],
+            'string value' => [
+                'data' => 'just a string',
+                'expected' => 'just a string',
+            ],
+            'html gets escaped by default' => [
+                'data' => '<span>HTML string</span>',
+                'expected' => '&lt;span&gt;HTML string&lt;/span&gt;',
+            ],
+            'explicit HTML text not escaped' => [
+                'data' => (new DBHTMLText())->setValue('<span>HTML string</span>'),
+                'expected' => '<span>HTML string</span>',
+            ],
+            'DBField' => [
+                'data' => (new DBDate())->setValue('2024-03-24'),
+                'expected' => (new DBDate())->setValue('2024-03-24')->forTemplate(),
+            ],
+            '__toString() method' => [
+                'data' => new StringableObject(),
+                'expected' => 'This is the string representation',
+            ],
+            'forTemplate called from extension' => [
+                'data' => new ExtensibleObject(),
+                'expected' => 'This text comes from the extension class',
+            ],
+            'cannot convert this class to string' => [
+                'data' => new CountableObject(),
+                'expected' => Error::class,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideToString')]
+    public function testToString(mixed $data, string $expected): void
+    {
+        $viewLayerData = new ViewLayerData($data);
+        if (is_a($expected, Throwable::class, true)) {
+            $this->expectException($expected);
+        }
+        $this->assertSame($expected, (string) $viewLayerData);
+    }
+
+    public static function provideHasDataValue(): array
+    {
+        return [
+            'empty array' => [
+                'data' => [],
+                'name' => null,
+                'expected' => false,
+            ],
+            'empty ArrayList' => [
+                'data' => new ArrayList(),
+                'name' => null,
+                'expected' => false,
+            ],
+            'empty ArrayData' => [
+                'data' => new ArrayData(),
+                'name' => null,
+                'expected' => false,
+            ],
+            'empty ArrayIterator' => [
+                'data' => new ArrayIterator(),
+                'name' => null,
+                'expected' => false,
+            ],
+            'empty ModelData' => [
+                'data' => new ModelData(),
+                'name' => null,
+                'expected' => true,
+            ],
+            'non-countable object' => [
+                'data' => new ExtensibleObject(),
+                'name' => null,
+                'expected' => true,
+            ],
+            'array with data' => [
+                'data' => [1,2,3],
+                'name' => null,
+                'expected' => true,
+            ],
+            'associative array' => [
+                'data' => ['one' => 1, 'two' => 2],
+                'name' => null,
+                'expected' => true,
+            ],
+            'ArrayList with data' => [
+                'data' => new ArrayList([1,2,3]),
+                'name' => null,
+                'expected' => true,
+            ],
+            'ArrayData with data' => [
+                'data' => new ArrayData(['one' => 1, 'two' => 2]),
+                'name' => null,
+                'expected' => true,
+            ],
+            'ArrayIterator with data' => [
+                'data' => new ArrayIterator([1,2,3]),
+                'name' => null,
+                'expected' => true,
+            ],
+            'ArrayData missing value' => [
+                'data' => new ArrayData(['one' => 1, 'two' => 2]),
+                'name' => 'three',
+                'expected' => false,
+            ],
+            'ArrayData with truthy value' => [
+                'data' => new ArrayData(['one' => 1, 'two' => 2]),
+                'name' => 'one',
+                'expected' => true,
+            ],
+            'ArrayData with null value' => [
+                'data' => new ArrayData(['nullVal' => null, 'two' => 2]),
+                'name' => 'nullVal',
+                'expected' => false,
+            ],
+            'ArrayData with falsy value' => [
+                'data' => new ArrayData(['zero' => 0, 'two' => 2]),
+                'name' => 'zero',
+                'expected' => false,
+            ],
+            'Empty string' => [
+                'data' => '',
+                'name' => null,
+                'expected' => false,
+            ],
+            'Truthy string' => [
+                'data' => 'has a value',
+                'name' => null,
+                'expected' => true,
+            ],
+            'Field on a string' => [
+                'data' => 'has a value',
+                'name' => 'SomeField',
+                'expected' => false,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideHasDataValue')]
+    public function testHasDataValue(mixed $data, ?string $name, bool $expected): void
+    {
+        $viewLayerData = new ViewLayerData($data);
+        $this->assertSame($expected, $viewLayerData->hasDataValue($name));
+    }
+
+    public static function provideGetRawDataValue(): array
+    {
+        $dbHtml = (new DBHTMLText())->setValue('Some html text');
+        // Note we're not checking the fetch order or passing args here - see testGet and testCall for that.
+        return [
+            [
+                'data' => ['MyField' => 'some value'],
+                'name' => 'MissingField',
+                'expected' => null,
+            ],
+            [
+                'data' => ['MyField' => null],
+                'name' => 'MyField',
+                'expected' => null,
+            ],
+            [
+                'data' => ['MyField' => 'some value'],
+                'name' => 'MyField',
+                'expected' => 'some value',
+            ],
+            [
+                'data' => ['MyField' => 123],
+                'name' => 'MyField',
+                'expected' => 123,
+            ],
+            [
+                'data' => ['MyField' => true],
+                'name' => 'MyField',
+                'expected' => true,
+            ],
+            [
+                'data' => ['MyField' => false],
+                'name' => 'MyField',
+                'expected' => false,
+            ],
+            [
+                'data' => ['MyField' => $dbHtml],
+                'name' => 'MyField',
+                'expected' => $dbHtml,
+            ],
+            [
+                'data' => (new ArrayData(['MyField' => 1234]))->customise(new ArrayData(['MyField' => 'overridden value'])),
+                'name' => 'MyField',
+                'expected' => 'overridden value',
+            ],
+            [
+                'data' => (new ArrayData(['MyField' => 1234]))->customise(new ArrayData(['FieldTwo' => 'checks here'])),
+                'name' => 'FieldTwo',
+                'expected' => 'checks here',
+            ],
+            [
+                'data' => (new ArrayData(['MyField' => 1234]))->customise(new ArrayData(['FieldTwo' => 'not here'])),
+                'name' => 'MyField',
+                'expected' => 1234,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGetRawDataValue')]
+    public function testGetRawDataValue(mixed $data, string $name, mixed $expected): void
+    {
+        $viewLayerData = new ViewLayerData($data);
+        $this->assertSame($expected, $viewLayerData->getRawDataValue($name));
+    }
+
+    public static function provideGetRawDataValueType(): array
+    {
+        // The types aren't currently used, but are passed in so we can use them later
+        // if we find the distinction useful. We should test they do what we expect
+        // in the meantime.
+        return [
+            [
+                'type' => 'property',
+                'shouldThrow' => false,
+            ],
+            [
+                'type' => 'method',
+                'shouldThrow' => false,
+            ],
+            [
+                'type' => 'any',
+                'shouldThrow' => false,
+            ],
+            [
+                'type' => 'constant',
+                'shouldThrow' => true,
+            ],
+            [
+                'type' => 'randomtext',
+                'shouldThrow' => true,
+            ],
+        ];
+    }
+
+    #[DataProvider('provideGetRawDataValueType')]
+    public function testGetRawDataValueType(string $type, bool $shouldThrow): void
+    {
+        $viewLayerData = new ViewLayerData([]);
+        if ($shouldThrow) {
+            $this->expectException(InvalidArgumentException::class);
+        } else {
+            $this->expectNotToPerformAssertions();
+        }
+        $viewLayerData->getRawDataValue('something', type: $type);
+    }
+
+    public function testCache(): void
+    {
+        $data = new ArrayData(['MyField' => 'some value']);
+        $viewLayerData = new ViewLayerData($data);
+
+        // No cache because we haven't fetched anything
+        $this->assertNull($data->objCacheGet('MyField'));
+
+        // Fetching the value caches it
+        $viewLayerData->MyField;
+        $this->assertSame('some value', $data->objCacheGet('MyField'));
+    }
+
+    public function testSpecialNames(): void
+    {
+        $data = new stdClass;
+        $viewLayerData = new ViewLayerData($data);
+
+        // Metadata values are available when there's nothing in the actual data
+        $this->assertTrue(isset($viewLayerData->ClassName));
+        $this->assertTrue(isset($viewLayerData->Me));
+        $this->assertSame(stdClass::class, $viewLayerData->getRawDataValue('ClassName')->getValue());
+        $this->assertSame($data, $viewLayerData->getRawDataValue('Me'));
+
+        // Metadata values are lower priority than real values in the actual data
+        $data->ClassName = 'some other class';
+        $data->Me = 'something else';
+        $this->assertTrue(isset($viewLayerData->ClassName));
+        $this->assertTrue(isset($viewLayerData->Me));
+        $this->assertSame('some other class', $viewLayerData->getRawDataValue('ClassName'));
+        $this->assertSame('something else', $viewLayerData->getRawDataValue('Me'));
+    }
+}

tests/php/View/ViewLayerDataTest/CountableObject.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use Countable;
+use SilverStripe\Dev\TestOnly;
+
+class CountableObject implements Countable, TestOnly
+{
+    public function count(): int
+    {
+        return 53;
+    }
+}

tests/php/View/ViewLayerDataTest/ExtensibleObject.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use SilverStripe\Core\Extensible;
+use SilverStripe\Dev\TestOnly;
+
+class ExtensibleObject implements TestOnly
+{
+    use Extensible;
+}

tests/php/View/ViewLayerDataTest/ExtensibleObjectExtension.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use SilverStripe\Core\Extension;
+use SilverStripe\Dev\TestOnly;
+
+class ExtensibleObjectExtension extends Extension implements TestOnly
+{
+    public function getIterator(): iterable
+    {
+        return ['1','2','3','4','5','6','7','8','9','a','b','c','d','e'];
+    }
+
+    public function getAnything(): string
+    {
+        return 'something';
+    }
+
+    public function forTemplate(): string
+    {
+        return 'This text comes from the extension class';
+    }
+}

tests/php/View/ViewLayerDataTest/GetCountObject.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use SilverStripe\Dev\TestOnly;
+
+class GetCountObject implements TestOnly
+{
+    public function getCount(): int
+    {
+        return 12;
+    }
+}

tests/php/View/ViewLayerDataTest/NonIterableObject.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use SilverStripe\Dev\TestOnly;
+
+class NonIterableObject implements TestOnly
+{
+    public function getIterator(): iterable
+    {
+        return [
+            'some value',
+            'another value',
+            'isnt this nice',
+        ];
+    }
+}

tests/php/View/ViewLayerDataTest/StringableObject.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use SilverStripe\Dev\TestOnly;
+use Stringable;
+
+class StringableObject implements Stringable, TestOnly
+{
+    public function __toString(): string
+    {
+        return 'This is the string representation';
+    }
+}

tests/php/View/ViewLayerDataTest/TestFixture.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use BadMethodCallException;
+use SilverStripe\Dev\TestOnly;
+
+/**
+ * A test fixture that captures information about what's being fetched on it
+ */
+class TestFixture implements TestOnly
+{
+    private array $requested = [];
+
+    public bool $throwException = true;
+
+    public function __call(string $name, array $arguments = []): null
+    {
+        $this->requested[] = [
+            'type' => 'method',
+            'name' => $name,
+            'args' => $arguments,
+        ];
+        if ($this->throwException) {
+            throw new BadMethodCallException('We need this so ViewLayerData will try the next step');
+        } else {
+            return null;
+        }
+    }
+
+    public function __get(string $name): null
+    {
+        $this->requested[] = [
+            'type' => 'property',
+            'name' => $name,
+        ];
+        return null;
+    }
+
+    public function __isset(string $name): bool
+    {
+        return $name !== 'NotSet';
+    }
+
+    public function getRequested(): array
+    {
+        return $this->requested;
+    }
+}

tests/php/View/ViewLayerDataTest/TestFixtureComplex.php

@@ -0,0 +1,79 @@
+<?php
+
+namespace SilverStripe\View\Tests\ViewLayerDataTest;
+
+use BadMethodCallException;
+use SilverStripe\Dev\TestOnly;
+
+/**
+ * A test fixture that captures information about what's being fetched on it
+ * Has explicit methods instead of relying on __call()
+ */
+class TestFixtureComplex implements TestOnly
+{
+    private array $requested = [];
+
+    public function badMethodCall(): void
+    {
+        $this->requested[] = [
+            'type' => 'method',
+            'name' => __FUNCTION__,
+            'args' => func_get_args(),
+        ];
+        throw new BadMethodCallException('Without a __call() method this will actually be thrown');
+    }
+
+    public function voidMethod(): void
+    {
+        $this->requested[] = [
+            'type' => 'method',
+            'name' => __FUNCTION__,
+            'args' => func_get_args(),
+        ];
+    }
+
+    public function justCallMethod(): string
+    {
+        $this->requested[] = [
+            'type' => 'method',
+            'name' => __FUNCTION__,
+            'args' => func_get_args(),
+        ];
+        return 'This is a method value';
+    }
+
+    public function getActualValue(): string
+    {
+        $this->requested[] = [
+            'type' => 'method',
+            'name' => __FUNCTION__,
+            'args' => func_get_args(),
+        ];
+        return 'this is the value';
+    }
+
+    public function __get(string $name): ?string
+    {
+        $this->requested[] = [
+            'type' => 'property',
+            'name' => $name,
+        ];
+        if ($name === 'ActualValueField') {
+            return 'the value is here';
+        }
+        return null;
+    }
+
+    /**
+     * We need this so we always try to fetch a property.
+     */
+    public function __isset(string $name): bool
+    {
+        return $name !== 'NotSet';
+    }
+
+    public function getRequested(): array
+    {
+        return $this->requested;
+    }
+}

tests/php/i18n/i18nTestManifest.php

@@ -17,10 +17,11 @@ use SilverStripe\i18n\Tests\i18nTest\MyObject;
 use SilverStripe\i18n\Tests\i18nTest\MySubObject;
 use SilverStripe\i18n\Tests\i18nTest\TestDataObject;
 use SilverStripe\View\SSViewer;
-use SilverStripe\View\SSViewer_DataPresenter;
 use SilverStripe\View\ThemeResourceLoader;
 use SilverStripe\View\ThemeManifest;
 use SilverStripe\Model\ModelData;
+use SilverStripe\View\SSViewer_Scope;
+use SilverStripe\View\ViewLayerData;
 use Symfony\Component\Translation\Loader\ArrayLoader;
 use Symfony\Component\Translation\Translator;
 
@@ -71,9 +72,9 @@ trait i18nTestManifest
 
     public function setupManifest()
     {
-        // force SSViewer_DataPresenter to cache global template vars before we switch to the
+        // force SSViewer_Scope to cache global template vars before we switch to the
         // test-project class manifest (since it will lose visibility of core classes)
-        $presenter = new SSViewer_DataPresenter(new ModelData());
+        $presenter = new SSViewer_Scope(new ViewLayerData([]));
         unset($presenter);
 
         // Switch to test manifest