title: PHPUnit: expects method meaning
body: <p>When I create a new mock I need to call the expects method. What exactly it does? What about its arguments?</p>
  <pre><code>$todoListMock = $this-&gt;getMock('\Model\Todo_List');
          $todoListMock-&gt;expects($this-&gt;any())
              -&gt;method('getItems')
              -&gt;will($this-&gt;returnValue(array($itemMock)));
  </code></pre>
  <p>I can't find the reason anywhere (I've tried docs). I've read the sources but I can't understand it.</p>