title: Python Mocking assert_called not working
body: <p>I am able to successfully mock a function, and I am sure that the original is not called.  I added a huge print statement to the original function and when I mock it, this print is not called.  When I turn the mock back on, the print statement is not called.  </p>
  
  <p>However, my assert_called is failing saying it was never called.  Has anyone ever experienced something like this?</p>
  
  <pre><code>class FooTestCase(unittest.TestCase):
  
      @mock.patch('MyObj.helper_function')
      def test_simple(self, mock_hf):
  
          my_obj = MyObj()
  
          # internally, this class imports HelperModule 
          # and the method calls helper_function
          my_obj.do_something()
  
          mock_hf.helper_function.assert_called()
  
          return
  </code></pre>
  
  <p>My error response</p>
  
  <pre><code>AssertionError: Expected 'helper_function' to have been called.
  </code></pre>
  
  <p><strong>Update</strong>
  I just added the following lines right before the assertion</p>
  
  <pre><code>    print mock_cw.method_calls
      print mock_cw.mock_calls
  </code></pre>
  
  <p>method_calls is an empty list, while mock_calls is a list with 1 item which is </p>
  
  <pre><code>[call(arg1_expected_for_helper_fn, arg2_expected_for_helper_fn)]
  </code></pre>
  
  <p>Yet the assert still fails</p>