diff --git a/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php b/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php
index 7bd51bc..3e58c15 100644
--- a/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php
+++ b/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php
@@ -570,6 +570,35 @@ public function testExceededFileSize() {
 
   /**
    * @covers ::buildForm
+   */
+  public function testGetPostAjaxRequest() {
+    $request = new Request([FormBuilderInterface::AJAX_FORM_REQUEST => TRUE], ['form_id' => 'different_form_id']);
+    $request->setMethod('POST');
+    $request_stack = new RequestStack();
+    $request_stack->push($request);
+    $this->formBuilder = $this->getMockBuilder('\Drupal\Core\Form\FormBuilder')
+      ->setConstructorArgs([$this->formValidator, $this->formSubmitter, $this->formCache, $this->moduleHandler, $this->eventDispatcher, $request_stack, $this->classResolver, $this->elementInfo, $this->themeManager, $this->csrfToken])
+      ->getMock();
+
+    $form_id = '\Drupal\Tests\Core\Form\TestForm';
+    $object = new TestForm();
+    $form = array();
+    $form_state = new FormState();
+    //$form_state->setUserInput([FormBuilderInterface::AJAX_FORM_REQUEST => TRUE]);
+    $form_state->setMethod('get')
+      ->setAlwaysProcess()
+      ->disableRedirect()
+      ->set('ajax', TRUE);
+    $expected_form = $object->buildForm($form, $form_state);
+
+    $form = $this->formBuilder->buildForm($form_id, $form_state);
+    print_r($form);
+    //$this->assertFormElement($expected_form, $form, 'test');
+    //$this->assertSame('test-form', $form['#id']);
+  }
+
+  /**
+   * @covers ::buildForm
    *
    * @dataProvider providerTestChildAccessInheritance
    */