simplify code example as suggested by @webmozart and @stof

Author: Henry Snoek

cookbook/form/unit_testing.rst

@@ -39,37 +39,24 @@ The simplest ``TypeTestCase`` implementation looks like the following::
     // src/AppBundle/Tests/Form/Type/TestedTypeTest.php
     namespace AppBundle\Tests\Form\Type;
 
-    use AppBundle\Form\Type\TestedType;
-    use AppBundle\Model\TestObject;
+    use Symfony\Component\Form\Extension\Validator\ValidatorExtension;
     use Symfony\Component\Form\Test\TypeTestCase;
+    use Symfony\Component\Validator\ConstraintViolationList;
+    use Symfony\Component\Validator\Validator\ValidatorInterface;
 
     class TestedTypeTest extends TypeTestCase
     {
-        public function testSubmitValidData()
+        protected function getExtensions()
         {
-            $formData = array(
-                'test' => 'test',
-                'test2' => 'test2',
-            );
-
-            $type = new TestedType();
-            $form = $this->factory->create($type);
-
-            $object = TestObject::fromArray($formData);
-
-            // submit the data to the form directly
-            $form->submit($formData);
-
-            $this->assertTrue($form->isSynchronized());
-            $this->assertEquals($object, $form->getData());
-
-            $view = $form->createView();
-            $children = $view->children;
+            $validator = $this->getMock('ValidatorInterface::class');
+            $validator->method('validate')->will($this->returnValue(new ConstraintViolationList()));
 
-            foreach (array_keys($formData) as $key) {
-                $this->assertArrayHasKey($key, $children);
-            }
+            return array(
+                new ValidatorExtension($validator),
+            );
         }
+
+        // ... your tests
     }
 
 So, what does it test? Here comes a detailed explanation.