diff --git a/core/lib/Drupal/Core/Ajax/AjaxResponseRenderer.php b/core/lib/Drupal/Core/Ajax/AjaxResponseRenderer.php
index 5fa31f4..642e2b9 100644
--- a/core/lib/Drupal/Core/Ajax/AjaxResponseRenderer.php
+++ b/core/lib/Drupal/Core/Ajax/AjaxResponseRenderer.php
@@ -26,8 +26,8 @@ class AjaxResponseRenderer {
    *   An Ajax response containing the controller result.
    */
   public function render($content) {
-    // If there is already an AjaxResponse, then return it without manipulation.
-    if ($content instanceof AjaxResponse && $content->isOk()) {
+    // If there is already an response object return it without manipulation.
+    if ($content instanceof Response && $content->isOk()) {
       return $content;
     }
 
@@ -35,9 +35,6 @@ public function render($content) {
     if ($content instanceof HtmlFragment) {
       $content = $content->getContent();
     }
-    elseif ($content instanceof Response) {
-      $content = $content->getContent();
-    }
     // Most controllers return a render array, but some return a string.
     if (!is_array($content)) {
       $content = array(
@@ -50,7 +47,7 @@ public function render($content) {
     if (isset($content['#type']) && ($content['#type'] == 'ajax')) {
       // Complex Ajax callbacks can return a result that contains an error
       // message or a specific set of commands to send to the browser.
-      $content += element_info('ajax');
+      $content += $this->elementInfo('ajax');
       $error = $content['#error'];
       if (!empty($error)) {
         // Fall back to some default message otherwise use the specific one.
@@ -61,18 +58,34 @@ public function render($content) {
       }
     }
 
-    $html = drupal_render($content);
+    $html = $this->drupalRender($content);
 
     // The selector for the insert command is NULL as the new content will
     // replace the element making the Ajax call. The default 'replaceWith'
     // behavior can be changed with #ajax['method'].
     $response->addCommand(new InsertCommand(NULL, $html));
     $status_messages = array('#theme' => 'status_messages');
-    $output = drupal_render($status_messages);
+    $output = $this->drupalRender($status_messages);
     if (!empty($output)) {
       $response->addCommand(new PrependCommand(NULL, $output));
     }
     return $response;
   }
 
+  /**
+   * Wraps drupal_render().
+   *
+   * @todo: Remove as part of https://drupal.org/node/2182149
+   */
+  protected function drupalRender(&$elements, $is_recursive_call = FALSE) {
+    return drupal_render($elements, $is_recursive_call);
+  }
+
+  /**
+   * Wraps element_info().
+   */
+  protected function elementInfo($type) {
+    return element_info($type);
+  }
+
 }
diff --git a/core/modules/toolbar/toolbar.routing.yml b/core/modules/toolbar/toolbar.routing.yml
index 2e1e4cd..6e2f255 100644
--- a/core/modules/toolbar/toolbar.routing.yml
+++ b/core/modules/toolbar/toolbar.routing.yml
@@ -3,4 +3,4 @@ toolbar.subtrees:
   defaults:
     _controller: '\Drupal\toolbar\Controller\ToolbarController::subtreesJsonp'
   requirements:
-    _custom_access: '\Drupal\toolbar\Routing\ToolbarController::checkSubTreeAccess'
+    _custom_access: '\Drupal\toolbar\Controller\ToolbarController::checkSubTreeAccess'
diff --git a/core/tests/Drupal/Tests/Core/Ajax/AjaxResponseRendererTest.php b/core/tests/Drupal/Tests/Core/Ajax/AjaxResponseRendererTest.php
new file mode 100644
index 0000000..2278e75
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Ajax/AjaxResponseRendererTest.php
@@ -0,0 +1,144 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Ajax\AjaxResponseRendererTest.
+ */
+
+namespace Drupal\Tests\Core\Ajax;
+
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\AjaxResponseRenderer;
+use Drupal\Core\Page\HtmlFragment;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\HttpFoundation\JsonResponse;
+
+/**
+ * Tests \Drupal\Core\Ajax\AjaxResponseRenderer.
+ *
+ * @coversClass \Drupal\Core\Ajax\AjaxResponseRenderer
+ */
+class AjaxResponseRendererTest extends UnitTestCase {
+
+  /**
+   * The tested ajax response renderer.
+   *
+   * @var \Drupal\Tests\Core\Ajax\TestAjaxResponseRenderer
+   */
+  protected $ajaxResponseRenderer;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getInfo() {
+    return array(
+      'name' => 'Tests \Drupal\Core\Ajax\AjaxResponseRenderer.',
+      'description' => '',
+      'group' => 'Ajax',
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    $this->ajaxResponseRenderer = new TestAjaxResponseRenderer();
+  }
+
+  /**
+   * Tests the render method with an HtmlFragment object.
+   *
+   * @covers \Drupal\Core\Ajax\AjaxResponseRenderer::render
+   */
+  public function testRenderWithFragmentObject() {
+    $html_fragment = new HtmlFragment('example content');
+    /** @var \Drupal\Core\Ajax\AjaxResponse $result */
+    $result = $this->ajaxResponseRenderer->render($html_fragment);
+
+    $this->assertInstanceOf('Drupal\Core\Ajax\AjaxResponse', $result);
+
+    $commands = $result->getCommands();
+    $this->assertEquals('insert', $commands[0]['command']);
+    $this->assertEquals('example content', $commands[0]['data']);
+
+    $this->assertEquals('insert', $commands[1]['command']);
+    $this->assertEquals('status_messages', $commands[1]['data']);
+  }
+
+  /**
+   * Tests the render method with an HtmlFragment object.
+   *
+   * @covers \Drupal\Core\Ajax\AjaxResponseRenderer::render
+   */
+  public function testRenderWithString() {
+    $html_fragment = 'example content';
+    /** @var \Drupal\Core\Ajax\AjaxResponse $result */
+    $result = $this->ajaxResponseRenderer->render($html_fragment);
+
+    $this->assertInstanceOf('Drupal\Core\Ajax\AjaxResponse', $result);
+
+    $commands = $result->getCommands();
+    $this->assertEquals('insert', $commands[0]['command']);
+    $this->assertEquals('example content', $commands[0]['data']);
+
+    $this->assertEquals('insert', $commands[1]['command']);
+    $this->assertEquals('status_messages', $commands[1]['data']);
+  }
+
+
+  /**
+   * Tests the render method with an response object.
+   *
+   * @covers \Drupal\Core\Ajax\AjaxResponseRenderer::render
+   */
+  public function testRenderWithResponseObject() {
+    $json_response = new JsonResponse(array('foo' => 'bar'));
+    $this->assertSame($json_response, $this->ajaxResponseRenderer->render($json_response));
+  }
+
+  /**
+   * Tests the render method with an Ajax response object.
+   *
+   * @covers \Drupal\Core\Ajax\AjaxResponseRenderer::render
+   */
+  public function testRenderWithAjaxResponseObject() {
+    $ajax_response = new AjaxResponse(array('foo' => 'bar'));
+    $this->assertSame($ajax_response, $this->ajaxResponseRenderer->render($ajax_response));
+  }
+
+}
+
+class TestAjaxResponseRenderer extends AjaxResponseRenderer {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function drupalRender(&$elements, $is_recursive_call = FALSE) {
+    if (isset($elements['#markup'])) {
+      return $elements['#markup'];
+    }
+    elseif (isset($elements['#theme'])) {
+      return $elements['#theme'];
+    }
+    else {
+      return 'Markup';
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function elementInfo($type) {
+    if ($type == 'ajax') {
+      return array(
+        '#header' => TRUE,
+        '#commands' => array(),
+        '#error' => NULL,
+      );
+    }
+    else {
+      return array();
+    }
+  }
+
+}