Mock attributes in Python mock?

Question

I'm having a fairly difficult time using mock in Python:

def method_under_test():     r = requests.post("http://localhost/post")      print r.ok # prints "<MagicMock name='post().ok' id='11111111'>"      if r.ok:        return StartResult()     else:        raise Exception()  class MethodUnderTestTest(TestCase):      def test_method_under_test(self):         with patch('requests.post') as patched_post:             patched_post.return_value.ok = True              result = method_under_test()              self.assertEqual(type(result), StartResult,                 "Failed to return a StartResult.") 

The test actually returns the right value, but r.ok is a Mock object, not True. How do you mock attributes in Python's mock library?

Answer 1

You need to use return_value and PropertyMock:

with patch('requests.post') as patched_post:     type(patched_post.return_value).ok = PropertyMock(return_value=True) 

This means: when calling requests.post, on the return value of that call, set a PropertyMock for the property ok to return the value True.

Answer 2

A compact and simple way to do it is to use new_callable patch's attribute to force patch to use PropertyMock instead of MagicMock to create the mock object. The other arguments passed to patch will be used to create PropertyMock object.

with patch('requests.post.ok', new_callable=PropertyMock, return_value=True) as mock_post:     """Your test"""