qa: provide tests for RandomizedListenerProvider

Adds RandomizedListenerProviderTest, to test the behavior of the class.
Refactors the internals to use a combination of `shuffle` and `yield
from` instead of looping + `array_rand()`.

Author: weierophinney

src/ListenerProvider/RandomizedListenerProvider.php

@@ -16,6 +16,7 @@
 
 class RandomizedListenerProvider implements ListenerProviderInterface
 {
+    /** @var array<string, callable[]> */
     private $listeners = [];
 
     public function getListenersForEvent(object $event) : iterable
@@ -28,11 +29,9 @@ public function getListenersForEvent(object $event) : iterable
             }
         }
 
-        while (count($listeners)) {
-            $index = array_rand($listeners);
-            yield $listeners[$index];
-            unset($listeners[$index]);
-        }
+        shuffle($listeners);
+
+        yield from $listeners;
     }
 
     public function listen(string $name, callable $listener) : void

test/ListenerProvider/RandomizedListenerProviderTest.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * @see       https://github.com/phly/phly-event-dispatcher for the canonical source repository
+ * @copyright Copyright (c) 2018-2019 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\RandomizedListenerProvider;
+use PhlyTest\EventDispatcher\TestAsset\TestEvent;
+use PHPUnit\Framework\TestCase;
+
+class RandomizedListenerProviderTest extends TestCase
+{
+    public function testRandomizesOrderOfListeners()
+    {
+        $listeners = [];
+        for ($i = 0; $i < 10; $i += 1) {
+            $listeners[] = function (TestEvent $event) {
+            };
+        }
+
+        $provider = new RandomizedListenerProvider();
+        foreach ($listeners as $listener) {
+            $provider->listen(TestEvent::class, $listener);
+        }
+
+        $received = iterator_to_array($provider->getListenersForEvent(new TestEvent()));
+        $this->assertNotSame($listeners, $received);
+    }
+}