Summary

Pytest has different semantics for single argnames when using a string or a tuple/list.
With a tuple/list, it expects a one-element sequence as each argvalue, so this is valid:

@pytest.mark.parametrize(("number",), [(0,)])

However, with a string, it just expects a list of the argvalues, so this is valid:

@pytest.mark.parametrize("number", [0])

Rule PT006 updates the first case to look like this:

@pytest.mark.parametrize("number", [(0,)])

which now means that "number" is passed as a tuple and probably breaks the test.

I think the best way to fix this is to flag the error and not fix it when there is one argument.

Version

ruff 0.15.11