title: PHPUnit: assertInstanceOf() not working
body: <p>I need to check if a variable is an object of the User type.
  User is my class <code>$user</code> my object</p>
  
  <pre><code>$this-&gt;assertInstanceOf($user,User);
  </code></pre>
  
  <p>This is not working, I have a use of undefined constant User - assumed 'User'</p>
  
  <p>Thanks in advance for your help</p>