create a Test folder for each pattern

Behavioral/Mediator/Tests/MediatorTest.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace DesignPatterns\Tests\Mediator\Tests;
+
+use DesignPatterns\Behavioral\Mediator\Mediator;
+use DesignPatterns\Behavioral\Mediator\Subsystem\Database;
+use DesignPatterns\Behavioral\Mediator\Subsystem\Client;
+use DesignPatterns\Behavioral\Mediator\Subsystem\Server;
+
+/**
+ * MediatorTest tests hello world
+ */
+class MediatorTest extends \PHPUnit_Framework_TestCase
+{
+
+    protected $client;
+
+    protected function setUp()
+    {
+        $media = new Mediator();
+        $this->client = new Client($media);
+        $media->setColleague(new Database($media), $this->client, new Server($media));
+    }
+
+    public function testOutputHelloWorld()
+    {
+        // testing if Hello World is output :
+        $this->expectOutputString('Hello World');
+        // as you see, the 3 components Client, Server and Database are totally decoupled
+        $this->client->request();
+        // Anyway, it remains complexity in the Mediator that's why the pattern
+        // Observer is preferable in mnay situations.
+    }
+}