TestWaitTerminateMiddleware.php

<?php

namespace Drupal\Core\Test\StackMiddleware;

use Drupal\Core\Lock\LockBackendInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\HttpKernelInterface;

/**
 * Acquire a lock to signal request termination to the test runner.
 */
class TestWaitTerminateMiddleware implements HttpKernelInterface {
  
  /**
   * Constructs a test wait terminate stack middleware object.
   *
   * @param \Symfony\Component\HttpKernel\HttpKernelInterface $httpKernel
   *   The decorated kernel.
   * @param \Drupal\Core\Lock\LockBackendInterface $lock
   *   The lock backend.
   * @param bool $waitForTerminate
   *   Container parameter to toggle this behavior.
   */
  public function __construct(protected HttpKernelInterface $httpKernel, protected LockBackendInterface $lock, protected bool $waitForTerminate = FALSE) {
  }
  
  /**
   * {@inheritdoc}
   */
  public function handle(Request $request, $type = self::MAIN_REQUEST, $catch = TRUE) : Response {
    $result = $this->httpKernel
      ->handle($request, $type, $catch);
    if (!$this->waitForTerminate) {
      return $result;
    }
    // Set a header on the response to instruct the test runner that it must
    // await the lock. Note that the lock acquired here is automatically
    // released from within a shutdown function.
    $this->lock
      ->acquire('test_wait_terminate');
    $result->headers
      ->set('X-Drupal-Wait-Terminate', '1');
    return $result;
  }

}