mutilated pytest stack traces

On Python 2.7, stack traces are garbled when using the fs pytest fixture:

test.py:

def test(fs):
    assert 0

bash:

$ virtualenv venv --no-site-packages
$ . venv/bin/activate
(venv) $ pip install pytest pyfakefs
(venv) $ pytest test.py

Output:

_____________________________________ test ______________________________________

fs = <pyfakefs.fake_filesystem.FakeFilesystem object at 0x10efdbc50>

>   ???
E   assert 0

test.py:2: AssertionError

Output without including fs fixture:

_____________________________________ test ______________________________________

    def test():
>       assert 0
E       assert 0

test.py:2: AssertionError

Any ideas? Sorry if this has already been reported somewhere (I couldn’t find an issue for it).

Python version: 2.7.14 pip version: 10.0.1 virtualenv version: 15.1.0 pip freeze output:

attrs==17.4.0
funcsigs==1.0.2
more-itertools==4.1.0
pluggy==0.6.0
py==1.5.3
pyfakefs==3.4.1
pytest==3.5.1
six==1.11.0

Thanks, Karl

[jmcgeheeiv]

Thank you for the great triage and the Python 3 fix, @mrbean-bremen.

I will give it a try, but like @mrbean-bremen, I am not so experienced with pytest.

[mrbean-bremen]

I seem to have found a solution for this under Python 3 (happened there too), but under Python 2 it still does not work. Not faking the open function fixes it, but that is not an option…