title: How to mock an object with OCMock which isn't passed as a parameter to method?
body: <p>I have a method I would like to test with OCMock but not sure how to do that. I need to mock 
  <code>ExtClass</code> which isn't defined as part of my code (external library):</p>
  
  <pre><code>+(NSString *)foo:(NSString *)param
  {
      ExtClass *ext = [[ExtClass alloc] initWithParam:param];
      if ([ext someMethod])
          return @"A";
      else
          return @"B";
  }
  </code></pre>
  
  <p>Thanks in advance!</p>