pylint complains about `fs` fixture name

[AustinScola]

I'm using the pytest pyfakefs fixture in a project. The project is linted with pylint. pylint warns C0103: Argument name "fs" doesn't conform to snake_case naming style (invalid-name). I know that I could add fs to the list of good-names for pylint, but I would prefer not to do that because then the name would be accepted everywhere. I could also add # pylint: disable=invalid-name everywhere I use the fixture, but that isn't very clean.

Could we add another name for the pytest fixture? Something like fake_filesystem?

[mrbean-bremen]

Hm, fs is indeed a bit short, but it's also handy and it's quite clear that it stands for file system. I want to avoid polluting the fixture namespace with aliases that cannot be disabled, so I think the way to go here is to define your own fixture:

conftest.py

@pytest.fixture
def fake_filesystem(fs):  # pylint:disable=invalid-name
    yield fs

and use fake_filesystem everywhere else. We could add this as a default, but at the moment I'm more inclined not to do this.

@jmcgeheeiv - what do you think?

[jmcgeheeiv]

I like @mrbean-bremen's workaround. We could add it to our pytest template, which would avoid polluting the namespace, yet everybody sees it and can use it to avoid the PyLint issue if they like.

[AustinScola]

I like @mrbean-bremen's workaround too. Not polluting the namespace sounds like a good reason. Thanks for the suggestion!

As a side note, something else I thought of is that there might be some weird behavior if both the fs and fake_filesystem fixtures are used in the same unit test?

[mrbean-bremen]

there might be some weird behavior if both the fs and fake_filesystem fixtures are used in the same unit test

No, they will both point to the same fake fs and can be used interchangeably:

def test_both_fixtures(fs, fake_filesystem):
    fake_filesystem.create_file('/var/data/xx1.txt')
    fs.create_file('/var/data/xx2.txt')
    assert os.path.exists('/var/data/xx1.txt')
    assert os.path.exists('/var/data/xx2.txt')
    assert fs == fake_filesystem

[mrbean-bremen]

I'm converting this into a discussion Q/A issue.