qa: provides tests for AttachableListenerProvider

Creates AttachableListenerProviderTest, and creates tests for various
behaviors.

Author: weierophinney

test/ListenerProvider/AttachableListenerProviderTest.php

@@ -0,0 +1,55 @@
+<?php
+/**
+ * @see       https://github.com/phly/phly-event-dispatcher for the canonical source repository
+ * @copyright Copyright (c) 2019 Matthew Weier O'Phinney (https:/mwop.net)
+ * @license   https://github.com/phly/phly-event-dispatcher/blob/master/LICENSE.md New BSD License
+ */
+
+declare(strict_types=1);
+
+namespace PhlyTest\EventDispatcher\ListenerProvider;
+
+use Phly\EventDispatcher\ListenerProvider\AttachableListenerProvider;
+use PhlyTest\EventDispatcher\TestAsset\TestEvent;
+use PHPUnit\Framework\TestCase;
+use stdClass;
+
+class AttachableListenerProviderTest extends TestCase
+{
+    public function testProviderAllowsListenerRegistrationAndReturnsListenersBasedOnEventType()
+    {
+        $listenerForTestEvent = function (TestEvent $e) {
+        };
+        $listenerForStdclass = function (stdClass $e) {
+        };
+
+        $provider = new AttachableListenerProvider();
+        $provider->listen(TestEvent::class, $listenerForTestEvent);
+        $provider->listen(stdClass::class, $listenerForStdclass);
+
+        $this->assertSame(
+            [$listenerForTestEvent],
+            iterator_to_array($provider->getListenersForEvent(new TestEvent()))
+        );
+
+        $this->assertSame(
+            [$listenerForStdclass],
+            iterator_to_array($provider->getListenersForEvent(new stdClass()))
+        );
+    }
+
+    public function testProviderDoesNotAllowDuplicateRegistration()
+    {
+        $listenerForTestEvent = function (TestEvent $e) {
+        };
+
+        $provider = new AttachableListenerProvider();
+        $provider->listen(TestEvent::class, $listenerForTestEvent);
+        $provider->listen(TestEvent::class, $listenerForTestEvent);
+
+        $this->assertSame(
+            [$listenerForTestEvent],
+            iterator_to_array($provider->getListenersForEvent(new TestEvent()))
+        );
+    }
+}