class TestHttpClientMiddleware

class TestHttpClientMiddleware {
    
    /**
     * {@inheritdoc}
     *
     * HTTP middleware that replaces the user agent for simpletest requests.
     */
    public function __invoke() {
        // If the database prefix is being used by SimpleTest 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 SimpleTest 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 $response) use ($request) {
                    if (!drupal_valid_test_ua()) {
                        return $response;
                    }
                    $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) {
                                // Call \Drupal\simpletest\WebTestBase::error() with the parameters from
                                // the header.
                                $parameters = unserialize(urldecode($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().
                                        @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;
                });
            };
        };
    }

}