Add an interface for the Application.

I wasn't too happy about the coupling between Console and Http, and this
new interface lets us not have that. Instead Http and Console will
depend on Core (which they already do). I contemplated adding
a ConsoleApplication and HttpApplication interface as well, but thought
that might be a bit much.

src/Console/CommandRunner.php

@@ -20,7 +20,7 @@
 use Cake\Console\Exception\StopException;
 use Cake\Console\Shell;
 use Cake\Event\EventManagerTrait;
-use Cake\Http\BaseApplication;
+use Cake\Core\ApplicationInterface;
 use Cake\Shell\HelpShell;
 use Cake\Shell\VersionShell;
 use RuntimeException;
@@ -35,7 +35,7 @@ class CommandRunner
     /**
      * The application console commands are being run for.
      *
-     * @var \Cake\Http\BaseApplication
+     * @var \Cake\Core\ApplicationInterface
      */
     protected $app;
 
@@ -56,10 +56,10 @@ class CommandRunner
     /**
      * Constructor
      *
-     * @param \Cake\Http\BaseApplication $app The application to run CLI commands for.
+     * @param \Cake\Core\ApplicationInterface $app The application to run CLI commands for.
      * @param string $root The root command name to be removed from argv.
      */
-    public function __construct(BaseApplication $app, $root = 'cake')
+    public function __construct(ApplicationInterface $app, $root = 'cake')
     {
         $this->app = $app;
         $this->root = $root;

src/Core/ApplicationInterface.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
+ * Copyright 2005-2011, Cake Software Foundation, Inc. (https://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * 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         3.5.0
+ * @license       https://opensource.org/licenses/mit-license.php MIT License
+ */
+namespace Cake\Core;
+
+/**
+ * An interface defining the methods that the
+ * console runner/http server depend on.
+ */
+interface ApplicationInterface
+{
+    /**
+     * Load all the application configuration and bootstrap logic.
+     *
+     * Override this method to add additional bootstrap logic for your application.
+     *
+     * @return void
+     */
+    public function bootstrap();
+
+    /**
+     * Define the routes for an application.
+     *
+     * Use the provided RouteBuilder to define an application's routing.
+     *
+     * @param \Cake\Routing\RouteBuilder $routes A route builder to add routes into.
+     * @return void
+     */
+    public function routes($routes);
+
+    /**
+     * Define the console commands for an application.
+     *
+     * @param \Cake\Console\CommandCollection $commands The CommandCollection to add commands into.
+     * @return \Cake\Console\CommandCollection The updated collection.
+     */
+    public function console($commands);
+
+    /**
+     * Define the HTTP middleware layers for an application.
+     *
+     * @param \Cake\Http\MiddlewareQueue $middleware The middleware queue to set in your App Class
+     * @return \Cake\Http\MiddlewareQueue
+     */
+    public function middleware($middleware);
+}

src/Http/BaseApplication.php

@@ -14,6 +14,7 @@
  */
 namespace Cake\Http;
 
+use Cake\Core\ApplicationInterface;
 use Cake\Routing\DispatcherFactory;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
@@ -25,7 +26,7 @@
  * and ensuring that middleware is attached. It is also invoked as the last piece
  * of middleware, and delegates request/response handling to the correct controller.
  */
-abstract class BaseApplication
+abstract class BaseApplication implements ApplicationInterface
 {
 
     /**
@@ -50,19 +51,15 @@ public function __construct($configDir)
     abstract public function middleware($middleware);
 
     /**
-     * Load all the application configuration and bootstrap logic.
-     *
-     * Override this method to add additional bootstrap logic for your application.
-     *
-     * @return void
+     * {@inheritDoc}
      */
     public function bootstrap()
     {
         require_once $this->configDir . '/bootstrap.php';
     }
 
     /**
-     * Define the routes for an application.
+     * {@inheritDoc}
      *
      * By default this will load `config/routes.php` for ease of use and backwards compatibility.
      *

src/Http/Server.php

@@ -14,6 +14,7 @@
  */
 namespace Cake\Http;
 
+use Cake\Core\ApplicationInterface;
 use Cake\Event\EventDispatcherTrait;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
@@ -29,7 +30,7 @@ class Server
     use EventDispatcherTrait;
 
     /**
-     * @var \Cake\Http\BaseApplication
+     * @var \Cake\Core\ApplicationInterface
      */
     protected $app;
 
@@ -41,9 +42,9 @@ class Server
     /**
      * Constructor
      *
-     * @param \Cake\Http\BaseApplication $app The application to use.
+     * @param \Cake\Core\ApplicationInterface $app The application to use.
      */
-    public function __construct(BaseApplication $app)
+    public function __construct(ApplicationInterface $app)
     {
         $this->setApp($app);
         $this->setRunner(new Runner());
@@ -108,10 +109,10 @@ public function emit(ResponseInterface $response, EmitterInterface $emitter = nu
     /**
      * Set the application.
      *
-     * @param BaseApplication $app The application to set.
+     * @param Cake\Core\ApplicationInterface $app The application to set.
      * @return $this
      */
-    public function setApp(BaseApplication $app)
+    public function setApp(ApplicationInterface $app)
     {
         $this->app = $app;
 
@@ -121,7 +122,7 @@ public function setApp(BaseApplication $app)
     /**
      * Get the current application.
      *
-     * @return \Cake\Http\BaseApplication The application that will be run.
+     * @return \Cake\Core\ApplicationInterface The application that will be run.
      */
     public function getApp()
     {