title: Unit Testing in Xcode, does it run the app?
body: <p>I'm running into a strange problem that I haven't run into before.</p>
  
  <p>When you do cmd+U to run your Unit Tests (OCUnit for example) does it actually call the main.m, new up the appDelegate and run the app as if your had pressed cmd+R? </p>
  
  <p>I only ask because I'm using CoreData behind this DataLayer.  I'm mocking out the DataLayer successfully in my tests, but once I implemented a getAll method that is actually calling CoreData, the app/xcode is throwing an exception about the managed object model can't be nil.  Which I understand, but I'm not meaning to actually new up the DataLayer class, and I've put a break point in my mainviewcontroller loadView method where it is calling the DataLayer getAll method.  It shouldn't matter with tests because this is a mock object, but it's apparently calling the real instance.</p>
  
  <p>So back to my question, when pressing cmd+U does it also run the app first then run the tests?</p>