Add tiny unit test for ThreadedMutex

tests/Sync/ThreadedMutexTest.php

@@ -0,0 +1,51 @@
+<?php
+namespace Icicle\Tests\Concurrent\Sync;
+
+use Icicle\Concurrent\Sync\ThreadedMutex;
+use Icicle\Coroutine;
+use Icicle\Loop;
+use Icicle\Tests\Concurrent\TestCase;
+
+/**
+ * @group threading
+ */
+class ThreadedMutexTest extends TestCase
+{
+    public function testAcquire()
+    {
+        Coroutine\create(function () {
+            $mutex = new ThreadedMutex();
+            $lock = (yield $mutex->acquire());
+            $lock->release();
+            $this->assertTrue($lock->isReleased());
+        });
+
+        Loop\run();
+    }
+
+    public function testAcquireMultiple()
+    {
+        $this->assertRunTimeBetween(function () {
+            Coroutine\create(function () {
+                $mutex = new ThreadedMutex();
+
+                $lock1 = (yield $mutex->acquire());
+                Loop\timer(0.5, function () use ($lock1) {
+                    $lock1->release();
+                });
+
+                $lock2 = (yield $mutex->acquire());
+                Loop\timer(0.5, function () use ($lock2) {
+                    $lock2->release();
+                });
+
+                $lock3 = (yield $mutex->acquire());
+                Loop\timer(0.5, function () use ($lock3) {
+                    $lock3->release();
+                });
+            });
+
+            Loop\run();
+        }, 1.5, 1.65);
+    }
+}