diff --git a/core/modules/field/tests/modules/field_test/field_test.entity.inc b/core/modules/field/tests/modules/field_test/field_test.entity.inc
index b6aa86e..3873d2f 100644
--- a/core/modules/field/tests/modules/field_test/field_test.entity.inc
+++ b/core/modules/field/tests/modules/field_test/field_test.entity.inc
@@ -44,7 +44,7 @@ function field_test_entity_info_translatable($entity_type = NULL, $translatable
 /**
  * Form combining two separate entities.
  *
- * @deprecated Use \Drupal\field_test\Form\FieldTestForm::testEntityNestedForm()
+ * @deprecated Use \Drupal\field_test\Form\EntityNestedForm::buildForm()
  */
 function field_test_entity_nested_form($form, &$form_state, $entity_1, $entity_2) {
   // First entity.
@@ -85,6 +85,8 @@ function field_test_entity_nested_form($form, &$form_state, $entity_1, $entity_2
 
 /**
  * Validate handler for field_test_entity_nested_form().
+ *
+ * @deprecated Use \Drupal\field_test\Form\EntityNestedForm::validateForm()
  */
 function field_test_entity_nested_form_validate($form, &$form_state) {
   $entity_1 = entity_create('entity_test', array(
@@ -104,6 +106,8 @@ function field_test_entity_nested_form_validate($form, &$form_state) {
 
 /**
  * Submit handler for field_test_entity_nested_form().
+ *
+ * @deprecated Use \Drupal\field_test\Form\EntityNestedForm::submitForm()
  */
 function field_test_entity_nested_form_submit($form, &$form_state) {
   $entity_1 = entity_create('entity_test', array(
diff --git a/core/modules/field/tests/modules/field_test/field_test.routing.yml b/core/modules/field/tests/modules/field_test/field_test.routing.yml
index b7ba00c..5d2d7ee 100644
--- a/core/modules/field/tests/modules/field_test/field_test.routing.yml
+++ b/core/modules/field/tests/modules/field_test/field_test.routing.yml
@@ -2,12 +2,12 @@ field_test.entity_nested_form:
   path: '/test-entity/nested/{entity_1}/{entity_2}'
   defaults:
     _title: 'Nested entity form'
-    _content: '\Drupal\field_test\Form\FieldTestForm::testEntityNestedForm'
+    _form: '\Drupal\field_test\Form\EntityNestedForm'
+  requirements:
+    _permission: 'administer entity_test content'
   options:
     parameters:
       entity_1:
         type: 'entity:entity_test'
       entity_2:
         type: 'entity:entity_test'
-  requirements:
-    _permission: 'administer entity_test content'
diff --git a/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Form/EntityNestedForm.php b/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Form/EntityNestedForm.php
new file mode 100644
index 0000000..0c31ea7
--- /dev/null
+++ b/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Form/EntityNestedForm.php
@@ -0,0 +1,61 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\field_test\Form\EntityNestedForm.
+ */
+
+namespace Drupal\field_test\Form;
+
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Form\FormBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Form combining two separate entities.
+ */
+class EntityNestedForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormID() {
+    return 'field_test_entity_nested_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity_1
+   *   The first entity.
+   * @param \Drupal\Core\Entity\EntityInterface $entity_2
+   *   The second entity.
+   */
+  public function buildForm(array $form, array &$form_state, EntityInterface $entity_1 = NULL, EntityInterface $entity_2 = NULL) {
+    module_load_include('entity.inc', 'field_test');
+    return field_test_entity_nested_form($form, $form_state, $entity_1, $entity_2);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, array &$form_state) {
+    module_load_include('entity.inc', 'field_test');
+    field_test_entity_nested_form_validate($form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    field_test_entity_nested_form_submit($form, $form_state);
+  }
+
+}
diff --git a/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Form/FieldTestForm.php b/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Form/FieldTestForm.php
deleted file mode 100644
index 8c9e913..0000000
--- a/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Form/FieldTestForm.php
+++ /dev/null
@@ -1,25 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\field_test\Form\FieldTestForm.
- */
-
-namespace Drupal\field_test\Form;
-
-use Drupal\Core\Entity\EntityInterface;
-
-/**
- * Provides a form for field_test routes.
- */
-class FieldTestForm {
-
-  /**
-   * @todo Remove field_test_entity_nested_form().
-   */
-  public function testEntityNestedForm(EntityInterface $entity_1, EntityInterface $entity_2) {
-    module_load_include('entity.inc', 'field_test');
-    return drupal_get_form('field_test_entity_nested_form', $entity_1, $entity_2);
-  }
-
-}