[8.x] Added Event::assertAttached to EventFake class

src/Illuminate/Support/Testing/Fakes/EventFake.php

@@ -7,6 +7,7 @@
 use Illuminate\Support\Arr;
 use Illuminate\Support\Traits\ReflectsClosures;
 use PHPUnit\Framework\Assert as PHPUnit;
+use ReflectionFunction;
 
 class EventFake implements Dispatcher
 {
@@ -284,4 +285,36 @@ public function until($event, $payload = [])
     {
         return $this->dispatch($event, $payload, true);
     }
+
+    /**
+     * Assert if an event has a listener attached to it.
+     *
+     * @param string $expectedEvent
+     * @param string $expectedListener
+     * @return void
+     */
+    public function assertAttached($expectedEvent, $expectedListener)
+    {
+        foreach ($this->dispatcher->getListeners($expectedEvent) as $listenerClosure) {
+            $reflection = new ReflectionFunction($listenerClosure);
+            $actualListener = $reflection->getStaticVariables()['listener'];
+
+            if ($actualListener === $expectedListener) {
+                PHPUnit::assertTrue(true);
+
+                return;
+            }
+
+            if ($actualListener instanceof Closure && $expectedListener === Closure::class) {
+                PHPUnit::assertTrue(true);
+
+                return;
+            }
+        }
+
+        PHPUnit::assertTrue(
+            false,
+            sprintf('Event %s does not have the %s listener attached to it', $expectedEvent, print_r($expectedListener, true))
+        );
+    }
 }

tests/Integration/Events/EventFakeTest.php

@@ -2,6 +2,7 @@
 
 namespace Illuminate\Tests\Integration\Events;
 
+use Closure;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Schema\Blueprint;
 use Illuminate\Support\Facades\Event;
@@ -126,6 +127,20 @@ public function testNonFakedHaltedEventGetsProperlyDispatchedAndReturnsResponse(
 
         Event::assertNotDispatched(NonImportantEvent::class);
     }
+
+    public function testAssertAttached()
+    {
+        Event::fake();
+        Event::listen('event', 'listener');
+        Event::subscribe(PostEventSubscriber::class);
+        Event::listen(function (NonImportantEvent $event) {
+            // do something
+        });
+
+        Event::assertAttached('event', 'listener');
+        Event::assertAttached('post-created', [PostEventSubscriber::class, 'handlePostCreated']);
+        Event::assertAttached(NonImportantEvent::class, Closure::class);
+    }
 }
 
 class Post extends Model
@@ -138,6 +153,21 @@ class NonImportantEvent
     //
 }
 
+class PostEventSubscriber
+{
+    public function handlePostCreated($event)
+    {
+    }
+
+    public function subscribe($events)
+    {
+        $events->listen(
+            'post-created',
+            [PostEventSubscriber::class, 'handlePostCreated']
+        );
+    }
+}
+
 class PostObserver
 {
     public function saving(Post $post)