Add subscribe method to event extender

src/Extend/Event.php

@@ -16,13 +16,16 @@
 class Event implements ExtenderInterface
 {
     private $listeners = [];
+    private $subscribers = [];
 
     /**
      * Add a listener to a domain event dispatched by flarum or a flarum extension.
      *
      * The listener can either be:
-     *  - a callback function or
+     *  - a callback function
      *  - the class attribute of a class with a public `handle` method, which accepts an instance of the event as a parameter
+     *  - an array, where the first argument is an object or class name, and the second argument is the method on the
+     *    first argument that should be executed as the listener
      *
      * @param string $event
      * @param callable|string $listener
@@ -34,12 +37,36 @@ public function listen(string $event, $listener)
         return $this;
     }
 
+    /**
+     * Add a subscriber for a set of domain events dispatched by flarum or a flarum extension.
+     * Event subscribers are classes that may subscribe to multiple events from within the subscriber class itself,
+     * allowing you to define several event handlers within a single class.
+     *
+     * @see https://laravel.com/docs/6.x/events#writing-event-subscribers
+     *
+     * @param string $subscriber: The class attribute of the subscriber class
+     */
+    public function subscribe(string $subscriber)
+    {
+        $this->subscribers[] = $subscriber;
+
+        return $this;
+    }
+
     public function extend(Container $container, Extension $extension = null)
     {
         $events = $container->make(Dispatcher::class);
 
         foreach ($this->listeners as $listener) {
             $events->listen($listener[0], $listener[1]);
         }
+
+        $app = $container->make('flarum');
+
+        $app->booted(function () use ($events) {
+            foreach ($this->subscribers as $subscriber) {
+                $events->subscribe($subscriber);
+            }
+        });
     }
 }

tests/integration/extenders/EventTest.php

@@ -10,12 +10,14 @@
 namespace Flarum\Tests\integration\extenders;
 
 use Flarum\Extend;
+use Flarum\Foundation\Application;
 use Flarum\Group\Command\CreateGroup;
 use Flarum\Group\Event\Created;
 use Flarum\Tests\integration\RetrievesAuthorizedUsers;
 use Flarum\Tests\integration\TestCase;
 use Flarum\User\User;
-use Illuminate\Contracts\Bus\Dispatcher;
+use Illuminate\Contracts\Bus\Dispatcher as BusDispatcher;
+use Illuminate\Contracts\Events\Dispatcher;
 use Symfony\Component\Translation\TranslatorInterface;
 
 class EventTest extends TestCase
@@ -24,7 +26,7 @@ class EventTest extends TestCase
 
     protected function buildGroup()
     {
-        $bus = $this->app()->getContainer()->make(Dispatcher::class);
+        $bus = $this->app()->getContainer()->make(BusDispatcher::class);
 
         return $bus->dispatch(
             new CreateGroup(User::find(1), ['attributes' => [
@@ -72,6 +74,32 @@ public function custom_listener_works_with_class_with_handle_method_and_can_inje
 
         $this->assertEquals('core.group.admin', $group->name_singular);
     }
+
+    /**
+     * @test
+     */
+    public function custom_subscriber_works()
+    {
+        // Because it injects a translator, this also tests that stuff can be injected into this callback.
+        $this->extend((new Extend\Event)->subscribe(CustomSubscriber::class));
+
+        $group = $this->buildGroup();
+
+        $this->assertEquals('core.group.admin', $group->name_singular);
+    }
+
+    /**
+     * @test
+     */
+    public function custom_subscriber_applied_after_app_booted()
+    {
+        // Because it injects a translator, this also tests that stuff can be injected into this callback.
+        $this->extend((new Extend\Event)->subscribe(CustomSubscriber::class));
+
+        $group = $this->buildGroup();
+
+        $this->assertEquals('booted', $group->name_plural);
+    }
 }
 
 class CustomListener
@@ -88,3 +116,26 @@ public function handle(Created $event)
         $event->group->name_singular = $this->translator->trans('core.group.admin');
     }
 }
+
+class CustomSubscriber
+{
+    protected $bootedAtConstruct;
+    protected $translator;
+
+    public function __construct(Application $app, TranslatorInterface $translator)
+    {
+        $this->bootedAtConstruct = $app->isBooted();
+        $this->translator = $translator;
+    }
+
+    public function subscribe(Dispatcher $events)
+    {
+        $events->listen(Created::class, [$this, 'whenGroupCreated']);
+    }
+
+    public function whenGroupCreated(Created $event)
+    {
+        $event->group->name_singular = $this->translator->trans('core.group.admin');
+        $event->group->name_plural = $this->bootedAtConstruct ? 'booted' : 'not booted';
+    }
+}