diff --git a/core/modules/system/tests/modules/batch_test/batch_test.module b/core/modules/system/tests/modules/batch_test/batch_test.module
index c7dddd6..d08d293 100644
--- a/core/modules/system/tests/modules/batch_test/batch_test.module
+++ b/core/modules/system/tests/modules/batch_test/batch_test.module
@@ -76,34 +76,7 @@ function batch_test_menu() {
  */
 function _batch_test_nested_drupal_form_submit_callback($value) {
   $state['values']['test_value'] = $value;
-  drupal_form_submit('batch_test_mock_form', $state);
-}
-
-/**
- * Form constructor for a simple form with a textfield and submit button.
- *
- * @see batch_test_mock_form_submit()
- */
-function batch_test_mock_form($form, $form_state) {
-  $form['test_value'] = array(
-    '#title' => t('Test value'),
-    '#type' => 'textfield',
-  );
-  $form['submit'] = array(
-    '#type' => 'submit',
-    '#value' => t('Submit'),
-  );
-
-  return $form;
-}
-
-/**
- * Form submission handler for batch_test_mock_form().
- *
- * @see batch_test_mock_form()
- */
-function batch_test_mock_form_submit($form, &$form_state) {
-  batch_test_stack('mock form submitted with value = ' . $form_state['values']['test_value']);
+  \Drupal::formBuilder()->submitForm('Drupal\batch_test\Form\BatchTestMockForm', $state);
 }
 
 /**
diff --git a/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestChainedForm.php b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestChainedForm.php
index e84eece..bc36db0 100644
--- a/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestChainedForm.php
+++ b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestChainedForm.php
@@ -7,12 +7,12 @@
 
 namespace Drupal\batch_test\Form;
 
-use \Drupal\Core\Form\FormBase;
+use \Drupal\Core\Form\FormInterface;
 
 /**
  * Generate form of id batch_test_chained_form.
  */
-class BatchTestChainedForm extends FormBase{
+class BatchTestChainedForm implements FormInterface {
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestMockForm.php b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestMockForm.php
new file mode 100644
index 0000000..9924924
--- /dev/null
+++ b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestMockForm.php
@@ -0,0 +1,47 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\batch_test\Form\BatchTestMockForm.
+ */
+
+namespace Drupal\batch_test\Form;
+
+use \Drupal\Core\Form\FormInterface;
+
+/**
+ * Generate form of id batch_test_mock_form.
+ */
+class BatchTestMockForm implements FormInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'batch_test_mock_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['test_value'] = array(
+      '#title' => t('Test value'),
+      '#type' => 'textfield',
+    );
+    $form['submit'] = array(
+      '#type' => 'submit',
+      '#value' => t('Submit'),
+    );
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    batch_test_stack('mock form submitted with value = ' . $form_state['values']['test_value']);
+  }
+
+}
diff --git a/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestMultiStepForm.php b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestMultiStepForm.php
index d299cb0..74bbe48 100644
--- a/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestMultiStepForm.php
+++ b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestMultiStepForm.php
@@ -7,12 +7,12 @@
 
 namespace Drupal\batch_test\Form;
 
-use \Drupal\Core\Form\FormBase;
+use \Drupal\Core\Form\FormInterface;
 
 /**
  * Generate form of id batch_test_multistep_form.
  */
-class BatchTestMultiStepForm extends FormBase{
+class BatchTestMultiStepForm implements FormInterface {
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestSimpleForm.php b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestSimpleForm.php
index bc61ead..4e79a76 100644
--- a/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestSimpleForm.php
+++ b/core/modules/system/tests/modules/batch_test/lib/Drupal/batch_test/Form/BatchTestSimpleForm.php
@@ -7,12 +7,12 @@
 
 namespace Drupal\batch_test\Form;
 
-use \Drupal\Core\Form\FormBase;
+use \Drupal\Core\Form\FormInterface;
 
 /**
  * Generate form of id batch_test_simple_form.
  */
-class BatchTestSimpleForm extends FormBase{
+class BatchTestSimpleForm implements FormInterface {
 
   /**
    * {@inheritdoc}