Issue #2771547 by Lendude, klausi, dawehner, alexpott, pwolanin: In Browser...

    $key = $private_key . filectime(__FILE__) . fileinode(__FILE__);

    $time_diff = REQUEST_TIME - $time;

    $test_hmac = Crypt::hmacBase64($check_string, $key);

    // Since we are making a local request a 5 second time window is allowed,

    // Since we are making a local request a 600 second time window is allowed,

    // and the HMAC must match.

    if ($time_diff >= 0 && $time_diff <= 5 && $hmac === $test_hmac) {

    if ($time_diff >= 0 && $time_diff <= 600 && $hmac === $test_hmac) {

      $test_prefix = $prefix;

    }

    else {

      header($_SERVER['SERVER_PROTOCOL'] . ' 403 Forbidden (SIMPLETEST_USER_AGENT invalid)');

      exit;

    }

  }

  return $test_prefix;

}

<?php

namespace Drupal\FunctionalJavascriptTests\Core\Session;

use Drupal\FunctionalJavascriptTests\JavascriptTestBase;

use Drupal\menu_link_content\Entity\MenuLinkContent;

/**

 * Tests that sessions don't expire.

 *

 * @group session

 */

class SessionTest extends JavascriptTestBase {

  /**

   * {@inheritdoc}

   */

  public static $modules = ['menu_link_content', 'block'];

  /**

   * {@inheritdoc}

   */

  protected function setUp() {

    parent::setUp();

    $account = $this->drupalCreateUser();

    $this->drupalLogin($account);

    $menu_link_content = MenuLinkContent::create([

      'title' => 'Link to front page',

      'menu_name' => 'tools',

      'link' => ['uri' => 'route:<front>'],

    ]);

    $menu_link_content->save();

    $this->drupalPlaceBlock('system_menu_block:tools');

  }

  /**

   * Tests that the session doesn't expire.

   *

   * Makes sure that drupal_valid_test_ua() works for multiple requests

   * performed by the Mink browser. The SIMPLETEST_USER_AGENT cookie must always

   * be valid.

   */

  public function testSessionExpiration() {

    // Visit the front page and click the link back to the front page a large

    // number of times.

    $this->drupalGet('<front>');

    $session_assert = $this->assertSession();

    $page = $this->getSession()->getPage();

    for ($i = 0; $i < 25; $i++) {

      $page->clickLink('Link to front page');

      $session_assert->statusCodeEquals(200);

    }

  }

}