Is fs basically like a tempdir scoped to each test function?

[jamesbraza]

The following code runs:

import pytest

def test_a(fs):
    with open("hi.txt", mode="w"):
        pass

def test_b(fs):
    with pytest.raises(FileNotFoundError, match="hi.txt"):
        with open("hi.txt"):
            pass

So just to confirm, can one think of each fs fixture as being a temporary OS (similar in concept to a temporary directory in /tmp)?

Why I am asking is because if the answer is yes, I think I don't need with tempfile.TemporaryDirectory() in my test files any more.

[mrbean-bremen]

Yes, this is exactly what it is. There are module and session-scoped variants (fs_module and fs_session), but the standard fs fixture basically creates a new empty (except for the temp dir) in-memory filesystem at each test start.

[jamesbraza]

Okay, this clears me up! Thank you for the speedy response 👌