TestHttpClientMiddleware.php

<?php

namespace Drupal\Core\Test\HttpClientMiddleware;

use Drupal\Core\Utility\Error;
use Psr\Http\Message\RequestInterface;
use Psr\Http\Message\ResponseInterface;

/**
 * Overrides the User-Agent HTTP header for outbound HTTP requests.
 */
class TestHttpClientMiddleware {

  /**
   * HTTP middleware that replaces the user agent for test requests.
   */
  public function __invoke() {

    // If the database prefix is being used to run the tests in a copied
    // database, then set the User-Agent header to the database prefix so that
    // any calls to other Drupal pages will run the test-prefixed database. The
    // user agent is used to ensure that multiple testing sessions running at
    // the same time won't interfere with each other as they would if the
    // database prefix were stored statically in a file or database variable.
    return function ($handler) {
      return function (RequestInterface $request, array $options) use ($handler) {
        if ($test_prefix = drupal_valid_test_ua()) {
          $request = $request
            ->withHeader('User-Agent', drupal_generate_test_ua($test_prefix));
        }
        return $handler($request, $options)
          ->then(function (ResponseInterface $response) {
          if (!drupal_valid_test_ua()) {
            return $response;
          }
          if (!empty($response
            ->getHeader('X-Drupal-Wait-Terminate')[0])) {
            $lock = \Drupal::lock();
            if (!$lock
              ->acquire('test_wait_terminate')) {
              $lock
                ->wait('test_wait_terminate');
            }
            $lock
              ->release('test_wait_terminate');
          }
          $headers = $response
            ->getHeaders();
          foreach ($headers as $header_name => $header_values) {
            if (preg_match('/^X-Drupal-Assertion-[0-9]+$/', $header_name, $matches)) {
              foreach ($header_values as $header_value) {
                $parameters = unserialize(urldecode($header_value));
                if (count($parameters) === 3) {
                  if ($parameters[1] === 'User deprecated function') {

                    // Fire the same deprecation message to allow it to be
                    // collected by
                    // \Symfony\Bridge\PhpUnit\DeprecationErrorHandler::collectDeprecations().
                    // phpcs:ignore Drupal.Semantics.FunctionTriggerError
                    @trigger_error((string) $parameters[0], E_USER_DEPRECATED);
                  }
                  else {
                    throw new \Exception($parameters[1] . ': ' . $parameters[0] . "\n" . Error::formatBacktrace([
                      $parameters[2],
                    ]));
                  }
                }
                else {
                  throw new \Exception('Error thrown with the wrong amount of parameters.');
                }
              }
            }
          }
          return $response;
        });
      };
    };
  }

}