Issue #2929798 by neclimdul, Sut3kh, alexpott, George Bills, mr.baileys,...

   *   The response event.

   */

  public function onResponse(FilterResponseEvent $event) {

    $response = $event->getResponse();

    // Only care about HTML responses.

    if (stripos($event->getResponse()->headers->get('Content-Type'), 'text/html') === FALSE) {

    if (stripos($response->headers->get('Content-Type'), 'text/html') === FALSE) {

      return;

    }

      return;

    }

    $response = $event->getResponse();

    // If content is FALSE, assume the response does not support the

    // setContent() method and skip it, for example,

    // \Symfony\Component\HttpFoundation\BinaryFileResponse.

    $content = $response->getContent();

    if ($content !== FALSE) {

      $response->setContent(static::setLinkActiveClass(

      $response->getContent(),

        $content,

        ltrim($this->currentPath->getPath(), '/'),

        $this->pathMatcher->isFrontPage(),

      $this->languageManager->getCurrentLanguage(LanguageInterface::TYPE_URL)->getId(),

        $this->languageManager->getCurrentLanguage(LanguageInterface::TYPE_URL)

          ->getId(),

        $event->getRequest()->query->all()

      ));

    }

  }

  /**

   * Sets the "is-active" class on relevant links.

use Drupal\Component\Serialization\Json;

use Drupal\Core\EventSubscriber\ActiveLinkResponseFilter;

use Drupal\Core\Language\LanguageDefault;

use Drupal\Core\Language\LanguageManager;

use Drupal\Core\Path\CurrentPathStack;

use Drupal\Core\Path\PathMatcherInterface;

use Drupal\Core\Session\AnonymousUserSession;

use Drupal\Core\Template\Attribute;

use Drupal\Tests\UnitTestCase;

use Symfony\Component\HttpFoundation\BinaryFileResponse;

use Symfony\Component\HttpFoundation\Request;

use Symfony\Component\HttpFoundation\RequestStack;

use Symfony\Component\HttpFoundation\Response;

use Symfony\Component\HttpFoundation\StreamedResponse;

use Symfony\Component\HttpKernel\Event\FilterResponseEvent;

use Symfony\Component\HttpKernel\HttpKernelInterface;

use Symfony\Component\HttpKernel\KernelInterface;

/**

 * @coversDefaultClass \Drupal\Core\EventSubscriber\ActiveLinkResponseFilter

    $this->assertSame($expected_html_markup, ActiveLinkResponseFilter::setLinkActiveClass($html_markup, $current_path, $is_front, $url_language, $query));

  }

  /**

   * Tests ActiveLinkResponseFilter only affects HTML responses.

   *

   * @covers ::onResponse

   */

  public function testOnlyHtml() {

    $session = new AnonymousUserSession();

    $language_manager = new LanguageManager(new LanguageDefault([]));

    $request_stack = new RequestStack();

    $request_stack->push(new Request());

    $current_path_stack = new CurrentPathStack($request_stack);

    // Make sure path matcher isn't called and we didn't get to the link logic.

    $path_matcher = $this->prophesize(PathMatcherInterface::class);

    $path_matcher->isFrontPage()->shouldNotBeCalled();

    $subscriber = new ActiveLinkResponseFilter(

      $session,

      $current_path_stack,

      $path_matcher->reveal(),

      $language_manager

    );

    // A link that might otherwise be set 'active'.

    $content = '<a data-drupal-link-system-path="otherpage">Other page</a>';

    // Assert response with non-html content type gets ignored.

    $response = new Response();

    $response->setContent($content);

    $response->headers->get('Content-Type', 'application/json');

    $subscriber->onResponse(new FilterResponseEvent(

      $this->prophesize(KernelInterface::class)->reveal(),

      $request_stack->getCurrentRequest(),

      HttpKernelInterface::MASTER_REQUEST,

      $response

    ));

    $this->assertSame($response->getContent(), $content);

  }

  /**

   * Tests certain response types ignored by the ActiveLinkResponseFilter.

   *

   * @covers ::onResponse

   */

  public function testSkipCertainResponseTypes() {

    $session = new AnonymousUserSession();

    $language_manager = new LanguageManager(new LanguageDefault([]));

    $request_stack = new RequestStack();

    $request_stack->push(new Request());

    $current_path_stack = new CurrentPathStack($request_stack);

    // Ensure path matcher is not called. This also tests that the

    // ActiveLinkResponseFilter ignores the response.

    $path_matcher = $this->prophesize(PathMatcherInterface::class);

    $path_matcher->isFrontPage()->shouldNotBeCalled();

    $subscriber = new ActiveLinkResponseFilter(

      $session,

      $current_path_stack,

      $path_matcher->reveal(),

      $language_manager

    );

    // Test BinaryFileResponse is ignored. Calling setContent() would throw a

    // logic exception.

    $response = new BinaryFileResponse(__FILE__, 200, ['Content-Type' => 'text/html']);

    $subscriber->onResponse(new FilterResponseEvent(

      $this->prophesize(KernelInterface::class)->reveal(),

      $request_stack->getCurrentRequest(),

      HttpKernelInterface::MASTER_REQUEST,

      $response

    ));

    // Test StreamedResponse is ignored. Calling setContent() would throw a

    // logic exception.

    $response = new StreamedResponse(function () {

      echo 'Success!';

    }, 200, ['Content-Type' => 'text/html']);

    $subscriber->onResponse(new FilterResponseEvent(

      $this->prophesize(KernelInterface::class)->reveal(),

      $request_stack->getCurrentRequest(),

      HttpKernelInterface::MASTER_REQUEST,

      $response

    ));

  }

}