title: Using OCMock to mock [[UIDevice currentDevice] userInterfaceIdiom]
body: <p>I am learning to use OCMocks with my unit tests and I understand the basics. However, I'm not sure how I could mock calls to class methods. </p>
  
  <p>I'd like to have:</p>
  
  <pre><code>[[UIDevice currentDevice] userInterfaceIdiom]
  </code></pre>
  
  <p>return different (but valid) interface idioms for my test cases.</p>
  
  <pre><code>id mock = [OCMockObject mockForClass:[UIDevice class]];
  
  // Would I use a mock or a stub to have UIDevice mock return
  // currentDevice and then from it, return userInterfaceIdiom
  </code></pre>