[Python] Can a mock side_effect iterator be reset after it has been exhausted?

mock.reset_mock() will not reset a side effect iterator. Is there a way to do this without creating the mock again?

>>> from mock import MagicMock
>>> mock = MagicMock(side_effect = [1,2])
>>> mock(), mock()
(1, 2)
>>> mock()

Traceback (most recent call last):
File "<pyshell#114>", line 1, in <module>
mock()
File "C:\Python27\Lib\site-packages\mock.py", line 955, in __call__
return _mock_self._mock_call(*args, **kwargs)
File "C:\Python27\Lib\site-packages\mock.py", line 1013, in _mock_call
result = next(effect)
StopIteration
>>> mock.reset_mock()
>>> mock()

Traceback (most recent call last):
...
StopIteration
>>> mock = MagicMock(side_effect = [1,2])
>>> mock(), mock()
(1, 2)
>>>


The intent is to re-use the mock in subsequent tests but I suspect that, like a generator, it cannot be restarted.

So (better late than never) after being pointed in the right direction I looked in mock.py and found that side_effect is an iterator object (which cannot be reset once exhausted):

def __set_side_effect(self, value):
value = _try_iter(value)
...

def _try_iter(obj):
...
try:
return iter(obj)
except TypeError:
# XXXX backwards compatibility
# but this will blow up on first call - so maybe we should fail early?
return obj


and def reset_mock() does not address the side efect.

Continue reading...