cakephp/tests/test_app/TestApp/Application.php

<?php
/**
 * CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 * @link          https://cakephp.org CakePHP(tm) Project
 * @since         3.3.0
 * @license       https://opensource.org/licenses/mit-license.php MIT License
 */
namespace TestApp;

use Cake\Http\BaseApplication;
use Cake\Routing\Middleware\RoutingMiddleware;

class Application extends BaseApplication
{

    public function middleware($middleware)
    {
        $middleware->add(new RoutingMiddleware());
        $middleware->add(function ($req, $res, $next) {
            $res = $next($req, $res);

            return $res->withHeader('X-Middleware', 'true');
        });

        return $middleware;
    }

    /**
     * Routes hook, used for testing with RoutingMiddleware.
     *
     * @param \Cake\Routing\RouteBuilder $routes
     * @return void
     */
    public function routes($routes)
    {
        $routes->scope('/app', function ($routes) {
            $routes->connect('/articles', ['controller' => 'Articles']);
        });
    }
}