title: What is the proper way to detect if unit tests are running at runtime in Xcode?
body: <p>When I'm running unit tests, I'd like to skip some code (e.g. I don't want <code>[[UIApplication sharedApplication] openURL:..]</code> to run). I'm looking for a runtime check if I'm currently running units tests or not.</p>
  
  <p>I know I have seen code that checks the Objective-C runtime if unit tests are running but am not able to find it anymore.</p>