Updated: Fixed typo in the last paragraph.
Today, I was curious to see this behavior of Mock() objects when using mock:
>>> from mock import Mock >>> m = Mock() >>> m.i_dont_exist <Mock name='mock.i_dont_exist' id='139841609578768'> >>> m.i_dont_exist() <Mock name='mock.i_dont_exist()' id='139841609106896'>
The above is expected, since I have not declared a spec when creating the Mock() object, so even when you call a non-existent method or get/set a non-existent attribute, you will not get a AttributeError.
However, I was suprised by the following:
>>> m.assert_not_calledd Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/asaha/.local/share/virtualenvs/606fc8723c1a01b/lib/python2.7/site-packages/mock/mock.py", line 721, in _ _getattr__ raise AttributeError(name) AttributeError: assert_not_calledd
And the following as well:
>>> m.assert_foo Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/asaha/.local/share/virtualenvs/606fc8723c1a01b/lib/python2.7/site-packages/mock/mock.py", line 721, in __getattr__ raise AttributeError(name) AttributeError: assert_foo
I guessed that there is likely a check explicitly for non-existent attributes starting with assert, and if it finds so, it will raise a AttributeError. If you look at the __getattr__ method in mock.py, you will see that this is pretty much what is happening. The exact lines are below:
if not self._mock_unsafe: # self._mock_unsafe is by default False if name.startswith(('assert', 'assret')): # It comes here and an AttributeError is raised raise AttributeError(name)
This is certainly a good thing, since I have often seen assert_called_once in codebases, and is fairly easy to overlook.