Add tests for DatalessField

tests/php/Forms/DatalessFieldTest.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace SilverStripe\Forms;
+
+use PHPUnit_Framework_MockObject_MockObject;
+use SilverStripe\Dev\SapphireTest;
+
+class DatalessFieldTest extends SapphireTest
+{
+    public function testGetAttributes()
+    {
+        $field = new DatalessField('Name');
+        $result = $field->getAttributes();
+        $this->assertSame('hidden', $result['type']);
+    }
+
+    public function testFieldHolderAndSmallFieldHolderReturnField()
+    {
+        /** @var DatalessField|PHPUnit_Framework_MockObject_MockObject $mock */
+        $mock = $this->getMockBuilder(DatalessField::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['Field'])
+            ->getMock();
+
+        $properties = [
+            'foo' => 'bar',
+        ];
+
+        $mock->expects($this->exactly(2))->method('Field')->with($properties)->willReturn('boo!');
+
+        $fieldHolder = $mock->FieldHolder($properties);
+        $smallFieldHolder = $mock->SmallFieldHolder($properties);
+
+        $this->assertSame('boo!', $fieldHolder);
+        $this->assertSame('boo!', $smallFieldHolder);
+    }
+
+    public function testPerformReadonlyTransformation()
+    {
+        $field = new DatalessField('Test');
+        $result = $field->performReadonlyTransformation();
+        $this->assertInstanceOf(DatalessField::class, $result);
+        $this->assertTrue($result->isReadonly());
+    }
+}