Merge the EventApplication and PluginApplication interfaces.

They had an awkward relationship that is better expressed by making them
the same. This also lets the pluginEvents() hook be a 'transparent' hook
method similar to routes, middleware and console.

src/Console/CommandRunner.php

@@ -191,13 +191,12 @@ public function run(array $argv, ConsoleIo $io = null)
     protected function bootstrap()
     {
         $this->app->bootstrap();
-        if ($this->app instanceof EventApplicationInterface) {
-            $eventManager = $this->app->events($this->getEventManager());
-            $this->setEventManager($eventManager);
-        }
         if ($this->app instanceof PluginApplicationInterface) {
             $this->app->pluginBootstrap();
-            $this->app->pluginEvents();
+
+            $events = $this->app->events($this->getEventManager());
+            $events = $this->app->pluginEvents($events);
+            $this->setEventManager($events);
         }
     }
 

src/Core/PluginApplicationInterface.php

@@ -14,10 +14,13 @@
  */
 namespace Cake\Core;
 
+use Cake\Event\EventDispatcherInterface;
+use Cake\Event\EventManagerInterface;
+
 /**
  * Interface for Applications that leverage plugins
  */
-interface PluginApplicationInterface
+interface PluginApplicationInterface extends EventDispatcherInterface
 {
     /**
      * Add a plugin to the loaded plugin set.
@@ -62,7 +65,16 @@ public function pluginConsole($commands);
     /**
      * Run events hook for plugins
      *
-     * @return void
+     * @param \Cake\Event\EventManagerInterface $eventManager Event manager instance.
+     * @return \Cake\Event\EventManagerInterface
+     */
+    public function pluginEvents(EventManagerInterface $eventManager);
+
+    /**
+     * Application hook for attaching events to the Application event manager instance.
+     *
+     * @param \Cake\Event\EventManagerInterface $eventManager Event manager instance.
+     * @return \Cake\Event\EventManagerInterface
      */
-    public function pluginEvents();
+    public function events(EventManagerInterface $eventManager);
 }

src/Core/composer.json

@@ -25,6 +25,9 @@
         "php": ">=5.6.0",
         "cakephp/utility": "^3.0.0"
     },
+    "suggest": {
+        "cakephp/event": "To use PluginApplicationInterface or plugin applications."
+    },
     "autoload": {
         "psr-4": {
             "Cake\\Core\\": "."

src/Http/BaseApplication.php

@@ -19,8 +19,6 @@
 use Cake\Core\Plugin;
 use Cake\Core\PluginApplicationInterface;
 use Cake\Core\PluginInterface;
-use Cake\Event\EventApplicationInterface;
-use Cake\Event\EventDispatcherInterface;
 use Cake\Event\EventDispatcherTrait;
 use Cake\Event\EventManager;
 use Cake\Event\EventManagerInterface;
@@ -39,8 +37,6 @@
  */
 abstract class BaseApplication implements
     ConsoleApplicationInterface,
-    EventApplicationInterface,
-    EventDispatcherInterface,
     HttpApplicationInterface,
     PluginApplicationInterface
 {
@@ -81,14 +77,13 @@ abstract public function middleware($middleware);
     /**
      * {@inheritDoc}
      */
-    public function pluginEvents()
+    public function pluginEvents($events)
     {
-        $events = $this->getEventManager();
-
         foreach ($this->plugins->with('events') as $plugin) {
             $events = $plugin->events($events);
         }
-        $this->setEventManager($events);
+
+        return $events;
     }
 
     /**

src/Http/Server.php

@@ -111,13 +111,13 @@ public function run(ServerRequestInterface $request = null, ResponseInterface $r
     protected function bootstrap()
     {
         $this->app->bootstrap();
-        if ($this->app instanceof EventApplicationInterface) {
-            $eventManager = $this->app->events($this->getEventManager());
-            $this->setEventManager($eventManager);
-        }
+
         if ($this->app instanceof PluginApplicationInterface) {
             $this->app->pluginBootstrap();
-            $this->app->pluginEvents();
+
+            $events = $this->app->events($this->getEventManager());
+            $events = $this->app->pluginEvents($events);
+            $this->setEventManager($events);
         }
     }
 

tests/TestCase/Console/CommandRunnerTest.php

@@ -400,7 +400,10 @@ public function testRunCallsPluginHookMethods()
 
         $app->expects($this->at(0))->method('bootstrap');
         $app->expects($this->at(1))->method('pluginBootstrap');
-        $app->expects($this->at(2))->method('pluginEvents');
+        $app->expects($this->at(2))->method('pluginEvents')
+            ->will($this->returnCallback(function ($events) {
+                return $events;
+            }));
 
         $commands = new CommandCollection();
         $app->expects($this->at(3))

tests/TestCase/Http/BaseApplicationTest.php

@@ -122,7 +122,7 @@ public function testPluginEvents()
         $this->assertCount(0, $start->listeners('TestPlugin.load'));
 
         $app->addPlugin(TestPlugin::class);
-        $this->assertNull($app->pluginEvents());
+        $this->assertSame($start, $app->pluginEvents($start));
 
         $after = $app->getEventManager();
         $this->assertSame($after, $start);

tests/TestCase/Http/ServerTest.php

@@ -127,7 +127,10 @@ public function testRunCallingPluginHooks()
         $app->expects($this->at(0))
             ->method('pluginBootstrap');
         $app->expects($this->at(1))
-            ->method('pluginBootstrap');
+            ->method('pluginEvents')
+            ->will($this->returnCallback(function ($events) {
+                return $events;
+            }));
         $app->expects($this->at(2))
             ->method('pluginMiddleware')
             ->with($this->isInstanceOf(MiddlewareQueue::class))