diff --git a/tests/controller/CMSMainTest.php b/tests/controller/CMSMainTest.php
index b440ef4c..0a1f37de 100644
--- a/tests/controller/CMSMainTest.php
+++ b/tests/controller/CMSMainTest.php
@@ -169,7 +169,7 @@ class CMSMainTest extends FunctionalTest
      */
     public function testThatGetCMSFieldsWorksOnEveryPageType()
     {
-        $classes = ClassInfo::subclassesFor("SilverStripe\\CMS\\Model\\SiteTree");
+        $classes = ClassInfo::subclassesFor(SiteTree::class);
         array_shift($classes);
 
         foreach ($classes as $class) {
@@ -184,7 +184,7 @@ class CMSMainTest extends FunctionalTest
             $page->Title = "Test $class page";
             $page->write();
             $page->flushCache();
-            $page = DataObject::get_by_id("SilverStripe\\CMS\\Model\\SiteTree", $page->ID);
+            $page = DataObject::get_by_id(SiteTree::class, $page->ID);
 
             $this->assertTrue($page->getCMSFields() instanceof FieldList);
         }
@@ -194,7 +194,7 @@ class CMSMainTest extends FunctionalTest
     {
         $this->logInWithPermission('ADMIN');
 
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'enforce_strict_hierarchy', true);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', true);
         $parentPage = $this->objFromFixture(Page::class, 'page3');
         $childPage = $this->objFromFixture(Page::class, 'page1');
 
@@ -207,7 +207,7 @@ class CMSMainTest extends FunctionalTest
             $actions,
             'Can publish a page with an unpublished parent with strict hierarchy off'
         );
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'enforce_strict_hierarchy', false);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', false);
     }
 
     /**
@@ -228,7 +228,7 @@ class CMSMainTest extends FunctionalTest
         $livePage = Versioned::get_one_by_stage(SiteTree::class, Versioned::LIVE, array(
                 '"SiteTree"."ID"' => $pageID
         ));
-        $this->assertInstanceOf('SilverStripe\\CMS\\Model\\SiteTree', $livePage);
+        $this->assertInstanceOf(SiteTree::class, $livePage);
         $this->assertTrue($livePage->canDelete());
 
         // Check that the 'restore' button exists as a simple way of checking that the correct page is returned.
diff --git a/tests/controller/ContentControllerTest.php b/tests/controller/ContentControllerTest.php
index 604a3edc..75caf2db 100755
--- a/tests/controller/ContentControllerTest.php
+++ b/tests/controller/ContentControllerTest.php
@@ -35,7 +35,7 @@ class ContentControllerTest extends FunctionalTest
     public function testNestedPages()
     {
         RootURLController::reset();
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $this->assertEquals('Home Page', $this->get('/')->getBody());
         $this->assertEquals('Home Page', $this->get('/home/index/')->getBody());
@@ -50,7 +50,7 @@ class ContentControllerTest extends FunctionalTest
         $this->assertEquals('Third Level Page', $this->get('/home/second-level/third-level/second-index/')->getBody());
 
         RootURLController::reset();
-        SiteTree::config()->nested_urls = false;
+        Config::modify()->set(SiteTree::class, 'nested_urls', false);
 
         $this->assertEquals('Home Page', $this->get('/')->getBody());
         $this->assertEquals('Home Page', $this->get('/home/')->getBody());
@@ -72,7 +72,7 @@ class ContentControllerTest extends FunctionalTest
     {
         $controller = new ContentController();
 
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $this->assertEquals(1, $controller->ChildrenOf('/')->Count());
         $this->assertEquals(1, $controller->ChildrenOf('/home/')->Count());
@@ -89,7 +89,7 @@ class ContentControllerTest extends FunctionalTest
 
     public function testDeepNestedURLs()
     {
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $page = new Page();
         $page->URLSegment = 'base-page';
diff --git a/tests/controller/ModelAsControllerTest.php b/tests/controller/ModelAsControllerTest.php
index a0a3ac2c..79b44d4b 100644
--- a/tests/controller/ModelAsControllerTest.php
+++ b/tests/controller/ModelAsControllerTest.php
@@ -29,7 +29,7 @@ class ModelAsControllerTest extends FunctionalTest
     public function setUp()
     {
         parent::setUp();
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
     }
 
 
@@ -303,7 +303,7 @@ class ModelAsControllerTest extends FunctionalTest
     public function testChildOfDraft()
     {
         RootURLController::reset();
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $draft = new Page();
         $draft->Title = 'Root Leve Draft Page';
diff --git a/tests/controller/RootURLControllerTest.php b/tests/controller/RootURLControllerTest.php
index 21421599..61a3d64d 100644
--- a/tests/controller/RootURLControllerTest.php
+++ b/tests/controller/RootURLControllerTest.php
@@ -17,9 +17,9 @@ class RootURLControllerTest extends SapphireTest
     {
         $default = $this->objFromFixture('Page', 'home');
 
-        SiteTree::config()->nested_urls = false;
+        Config::modify()->set(SiteTree::class, 'nested_urls', false);
         $this->assertEquals('home', RootURLController::get_homepage_link());
-        Config::inst()->update('SilverStripe\\CMS\\Model\\SiteTree', 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
         $this->assertEquals('home', RootURLController::get_homepage_link());
     }
 }
diff --git a/tests/model/SiteTreeTest.php b/tests/model/SiteTreeTest.php
index d68487dc..2e31fe8e 100644
--- a/tests/model/SiteTreeTest.php
+++ b/tests/model/SiteTreeTest.php
@@ -353,7 +353,7 @@ class SiteTreeTest extends SapphireTest
         $this->assertEquals($staff->ID, SiteTree::get_by_link($staff->Link(), false)->ID);
         $this->assertEquals($product->ID, SiteTree::get_by_link($product->Link(), false)->ID);
 
-        Config::inst()->update(SiteTree::class, 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $this->assertEquals($home->ID, SiteTree::get_by_link('/', false)->ID);
         $this->assertEquals($home->ID, SiteTree::get_by_link('/home/', false)->ID);
@@ -373,7 +373,7 @@ class SiteTreeTest extends SapphireTest
         $about    = $this->objFromFixture('Page', 'about');
         $staff    = $this->objFromFixture('Page', 'staff');
 
-        Config::inst()->update(SiteTree::class, 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $this->assertEquals('about-us/', $about->RelativeLink(), 'Matches URLSegment on top level without parameters');
         $this->assertEquals('about-us/my-staff/', $staff->RelativeLink(), 'Matches URLSegment plus parent on second level without parameters');
@@ -394,7 +394,7 @@ class SiteTreeTest extends SapphireTest
         $parent = $this->objFromFixture('Page', 'about');
         $child = $this->objFromFixture('Page', 'staff');
 
-        Config::inst()->update(SiteTree::class, 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $child->copyVersionToStage(Versioned::DRAFT, Versioned::LIVE);
         $parent->URLSegment = 'changed-on-live';
@@ -442,7 +442,7 @@ class SiteTreeTest extends SapphireTest
 
     public function testDeleteFromStageOperatesRecursively()
     {
-        Config::inst()->update(SiteTree::class, 'enforce_strict_hierarchy', false);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', false);
         $pageAbout = $this->objFromFixture('Page', 'about');
         $pageStaff = $this->objFromFixture('Page', 'staff');
         $pageStaffDuplicate = $this->objFromFixture('Page', 'staffduplicate');
@@ -452,7 +452,7 @@ class SiteTreeTest extends SapphireTest
         $this->assertNull(DataObject::get_by_id('Page', $pageAbout->ID));
         $this->assertTrue(DataObject::get_by_id('Page', $pageStaff->ID) instanceof Page);
         $this->assertTrue(DataObject::get_by_id('Page', $pageStaffDuplicate->ID) instanceof Page);
-        Config::inst()->update(SiteTree::class, 'enforce_strict_hierarchy', true);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', true);
     }
 
     public function testDeleteFromStageOperatesRecursivelyStrict()
@@ -479,7 +479,7 @@ class SiteTreeTest extends SapphireTest
 
     public function testDeleteFromLiveOperatesRecursively()
     {
-        Config::inst()->update(SiteTree::class, 'enforce_strict_hierarchy', false);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', false);
         $this->logInWithPermission('ADMIN');
 
         $pageAbout = $this->objFromFixture('Page', 'about');
@@ -499,12 +499,12 @@ class SiteTreeTest extends SapphireTest
         $this->assertTrue(DataObject::get_by_id('Page', $pageStaff->ID) instanceof Page);
         $this->assertTrue(DataObject::get_by_id('Page', $pageStaffDuplicate->ID) instanceof Page);
         Versioned::set_stage(Versioned::DRAFT);
-        Config::inst()->update(SiteTree::class, 'enforce_strict_hierarchy', true);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', true);
     }
 
     public function testUnpublishDoesNotDeleteChildrenWithLooseHierachyOn()
     {
-        Config::inst()->update(SiteTree::class, 'enforce_strict_hierarchy', false);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', false);
         $this->logInWithPermission('ADMIN');
 
         $pageAbout = $this->objFromFixture('Page', 'about');
@@ -522,7 +522,7 @@ class SiteTreeTest extends SapphireTest
         $this->assertTrue(DataObject::get_by_id('Page', $pageStaff->ID) instanceof Page);
         $this->assertTrue(DataObject::get_by_id('Page', $pageStaffDuplicate->ID) instanceof Page);
         Versioned::set_stage(Versioned::DRAFT);
-        Config::inst()->update(SiteTree::class, 'enforce_strict_hierarchy', true);
+        Config::modify()->set(SiteTree::class, 'enforce_strict_hierarchy', true);
     }
 
     public function testDeleteFromLiveOperatesRecursivelyStrict()
@@ -909,7 +909,7 @@ class SiteTreeTest extends SapphireTest
         $sitetree->URLSegment = 'home';
         $this->assertFalse($sitetree->validURLSegment(), 'Conflicts are still recognised with a ParentID value');
 
-        Config::inst()->update(SiteTree::class, 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $sitetree->ParentID   = 0;
         $sitetree->URLSegment = 'home';
@@ -940,7 +940,7 @@ class SiteTreeTest extends SapphireTest
      */
     public function testValidURLSegmentControllerConflicts()
     {
-        Config::inst()->update(SiteTree::class, 'nested_urls', true);
+        Config::modify()->set(SiteTree::class, 'nested_urls', true);
 
         $sitetree = new SiteTree();
         $sitetree->ParentID = $this->idFromFixture('SiteTreeTest_Conflicted', 'parent');
@@ -1023,7 +1023,7 @@ class SiteTreeTest extends SapphireTest
         $this->assertContains('Page', $classes, 'Page types do contain subclasses');
 
         // Testing what happens in an incorrect config value is set - hide_ancestor should be a string
-        Config::inst()->update(SiteTreeTest_ClassA::class, 'hide_ancestor', true);
+        Config::modify()->set(SiteTreeTest_ClassA::class, 'hide_ancestor', true);
         $newClasses = SiteTree::page_type_classes();
         $this->assertEquals(
             $classes,
@@ -1220,7 +1220,7 @@ class SiteTreeTest extends SapphireTest
         );
 
         // test proper escaping of quotes in attribute value
-        Config::inst()->update(SiteTree::class, 'meta_generator', 'Generator with "quotes" in it');
+        Config::modify()->set(SiteTree::class, 'meta_generator', 'Generator with "quotes" in it');
         $meta = $page->MetaTags();
         $this->assertEquals(
             1,
@@ -1229,7 +1229,7 @@ class SiteTreeTest extends SapphireTest
         );
 
         // test empty generator - no tag should appear at all
-        Config::inst()->update(SiteTree::class, 'meta_generator', '');
+        Config::modify()->set(SiteTree::class, 'meta_generator', '');
         $meta = $page->MetaTags();
         $this->assertEquals(
             0,
@@ -1238,7 +1238,7 @@ class SiteTreeTest extends SapphireTest
         );
 
         // reset original value
-        Config::inst()->update(SiteTree::class, 'meta_generator', $generator);
+        Config::modify()->set(SiteTree::class, 'meta_generator', $generator);
     }
 
 
diff --git a/tests/model/VirtualPageTest.php b/tests/model/VirtualPageTest.php
index a0ed18c7..86fd8b6c 100644
--- a/tests/model/VirtualPageTest.php
+++ b/tests/model/VirtualPageTest.php
@@ -47,8 +47,8 @@ class VirtualPageTest extends FunctionalTest
         $this->logInWithPermission("ADMIN");
 
         // Add extra fields
-        Config::inst()->update('SilverStripe\\CMS\\Model\\VirtualPage', 'initially_copied_fields', array('MyInitiallyCopiedField'));
-        Config::inst()->update('SilverStripe\\CMS\\Model\\VirtualPage', 'non_virtual_fields', array('MyNonVirtualField', 'MySharedNonVirtualField'));
+        Config::modify()->merge(VirtualPage::class, 'initially_copied_fields', array('MyInitiallyCopiedField'));
+        Config::modify()->merge(VirtualPage::class, 'non_virtual_fields', array('MyNonVirtualField', 'MySharedNonVirtualField'));
     }
 
     /**
@@ -63,8 +63,8 @@ class VirtualPageTest extends FunctionalTest
         $master->Content = "<p>New content</p>";
         $master->write();
 
-        $vp1 = $this->objFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp1');
-        $vp2 = $this->objFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp2');
+        $vp1 = $this->objFromFixture(VirtualPage::class, 'vp1');
+        $vp2 = $this->objFromFixture(VirtualPage::class, 'vp2');
 
         $this->assertEquals("New title", $vp1->Title);
         $this->assertEquals("New title", $vp2->Title);
@@ -90,16 +90,16 @@ class VirtualPageTest extends FunctionalTest
         $master->Content = "<p>New content</p>";
         $master->write();
 
-        $vp1 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp1'));
-        $vp2 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp2'));
+        $vp1 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture(VirtualPage::class, 'vp1'));
+        $vp2 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture(VirtualPage::class, 'vp2'));
         $this->assertTrue($vp1->publishRecursive());
         $this->assertTrue($vp2->publishRecursive());
 
         $master->publishRecursive();
 
         Versioned::set_stage(Versioned::LIVE);
-        $vp1 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp1'));
-        $vp2 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp2'));
+        $vp1 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture(VirtualPage::class, 'vp1'));
+        $vp2 = DataObject::get_by_id(VirtualPage::class, $this->idFromFixture(VirtualPage::class, 'vp2'));
 
         $this->assertNotNull($vp1);
         $this->assertNotNull($vp2);
@@ -242,7 +242,7 @@ class VirtualPageTest extends FunctionalTest
     public function testCanEdit()
     {
         $parentPage = $this->objFromFixture('Page', 'master3');
-        $virtualPage = $this->objFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp3');
+        $virtualPage = $this->objFromFixture(VirtualPage::class, 'vp3');
         $bob = $this->objFromFixture('SilverStripe\\Security\\Member', 'bob');
         $andrew = $this->objFromFixture('SilverStripe\\Security\\Member', 'andrew');
 
@@ -261,7 +261,7 @@ class VirtualPageTest extends FunctionalTest
     {
         $parentPage = $this->objFromFixture('Page', 'master3');
         $parentPage->copyVersionToStage(Versioned::DRAFT, Versioned::LIVE);
-        $virtualPage = $this->objFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp3');
+        $virtualPage = $this->objFromFixture(VirtualPage::class, 'vp3');
         $virtualPage->copyVersionToStage(Versioned::DRAFT, Versioned::LIVE);
         $cindy = $this->objFromFixture('SilverStripe\\Security\\Member', 'cindy');
         $alice = $this->objFromFixture('SilverStripe\\Security\\Member', 'alice');
@@ -487,7 +487,7 @@ class VirtualPageTest extends FunctionalTest
         $virtual->CopyContentFromID = $page->ID;
         $virtual->write();
 
-        $virtual = DataObject::get_by_id('SilverStripe\\CMS\\Model\\VirtualPage', $virtual->ID, false);
+        $virtual = DataObject::get_by_id(VirtualPage::class, $virtual->ID, false);
         $virtual->CopyContentFromID = $notRootPage->ID;
         $virtual->flushCache();
 
@@ -632,7 +632,7 @@ class VirtualPageTest extends FunctionalTest
 
     public function testMethod()
     {
-        $virtualPage = $this->objFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp4');
+        $virtualPage = $this->objFromFixture(VirtualPage::class, 'vp4');
         $controller = ModelAsController::controller_for($virtualPage);
 
         $this->assertInstanceOf('VirtualPageTest_ClassAController', $controller);
@@ -644,7 +644,7 @@ class VirtualPageTest extends FunctionalTest
 
     public function testAllowedActions()
     {
-        $virtualPage = $this->objFromFixture('SilverStripe\\CMS\\Model\\VirtualPage', 'vp4');
+        $virtualPage = $this->objFromFixture(VirtualPage::class, 'vp4');
         $controller = ModelAsController::controller_for($virtualPage);
         $this->assertContains('testaction', $controller->allowedActions());
     }