Issue #3221633 by bircher, lind101, smustgrave, quietone, Zemelia:...

   * {@inheritdoc}

   */

  public function applies(RouteMatchInterface $route_match) {

    return $route_match->getRouteName() == 'system.batch_page';

    return $route_match->getRouteName() == 'system.batch_page.html';

  }

  /**

<?php

declare(strict_types=1);

namespace Drupal\KernelTests\Core\Batch;

use Drupal\Core\Routing\RouteMatch;

use Drupal\KernelTests\KernelTestBase;

use Symfony\Component\HttpFoundation\Request;

/**

 * Tests the BatchNegotiator.

 *

 * @group Batch

 */

class BatchNegotiatorTest extends KernelTestBase {

  /**

   * {@inheritdoc}

   */

  protected static $modules = [

    'system',

  ];

  /**

   * Test that the negotiator applies to the batch route.

   */

  public function testApplies() {

    $request = Request::create('/batch');

    // Use the router to enhance the object so that a RouteMatch can be created.

    $this->container->get('router')->matchRequest($request);

    $routeMatch = RouteMatch::createFromRequest($request);

    // The negotiator under test.

    $negotiator = $this->container->get('theme.negotiator.system.batch');

    $this->assertTrue($negotiator->applies($routeMatch));

  }

}