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Provide a helper to copy args #37
Description
mock will store references in call_args and call_args_list (see https://docs.python.org/3/library/unittest.mock-examples.html#coping-with-mutable-arguments).
I think that pytest-mock could provide a helper based on the example from the doc:
from copy import deepcopy
>>> class CopyingMock(MagicMock):
... def __call__(self, *args, **kwargs):
... args = deepcopy(args)
... kwargs = deepcopy(kwargs)
... return super(CopyingMock, self).__call__(*args, **kwargs)
The following works (by extending the pytest-mock mocker fixture).
@pytest.fixture
def mocker(mocker):
from copy import deepcopy
from mock import MagicMock
class CopyingMock(MagicMock):
def __call__(self, *args, **kwargs):
args = deepcopy(args)
kwargs = deepcopy(kwargs)
return super(CopyingMock, self).__call__(*args, **kwargs)
mocker.CopyingMock = CopyingMock
return mocker
patched = mocker.patch('foo.bar', new_callable=mocker.CopyingMock)
Not sure if that's helpful enough and/or if there could be a mocker_copy fixture instead, which would handle new_callable not only for patch().
Activity
blueyed commentedon Mar 21, 2016
This is how a
mocker_copyfixture could look like:nicoddemus commentedon Mar 21, 2016
Hi @blueyed, thanks for the suggestion. I think adding this functionality to
pytest-mockis a good idea.I've never needed this functionality myself so I can't judge which approach would feel best from the user point of view, but if I have to choose I would rather have the first approach as it doesn't introduce a new fixture to a feature which I believe is not used that much. What do you think?
blueyed commentedon Mar 22, 2016
@nicoddemus
Thanks for considering it.
I've went with the 2nd approach, since it's much easier to use and provides good separation.
You can easily run into this issue when checking calls that happen in a loop and use e.g. a
dictas arg, which gets (re-)assigned in the loop.Please note that the
new_callable=CopyingMockcan still be overridden, andnew_callable=MagicMockwould cause the default behavior again.We could also consider to have this for the current
mockerfixture by default, but that would breakischecks etc and is probably therefore not a good idea.nicoddemus commentedon Mar 22, 2016
I agree.
Are you working on a PR?
blueyed commentedon Mar 22, 2016
@nicoddemus
Nope.
Feel free to take my patch from above.
nicoddemus commentedon Mar 23, 2016
OK, thanks for the suggestion and patch. 😄