adding tests for the command pattern

Tests/Command/CommandTest.php

@@ -0,0 +1,36 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Tests\Command;
+
+use DesignPatterns\Command\Invoker;
+use DesignPatterns\Command\Receiver;
+use DesignPatterns\Command\HelloCommand;
+
+/**
+ * CommandTest has the role of the Client in the Command Pattern
+ */
+class CommandTest extends \PHPUnit_Framework_TestCase
+{
+
+    protected $invoker;
+    protected $receiver;
+
+    protected function setUp()
+    {
+        // this is the context of the application
+        $this->invoker = new Invoker();
+        $this->receiver = new Receiver();
+    }
+
+    public function testInvocation()
+    {
+        $this->invoker->setCommand(new HelloCommand($this->receiver));
+        $this->expectOutputString('Hello World');
+        $this->invoker->run();
+    }
+
+}