Summary

For pytest checks:

When argnames and argvalues are passed as keyword arguments to pytest.mark.parametrize, ruff doesn't raise PT006 where it would otherwise (for passing a list instead of a single value).

Details

Steps to reproduce the issue:

• Create a test filetest_something.py, containing two test functions.
  Note that the test functions only expect a single parametrized argument.

  In both cases, the parametrize() decorator is called with a list for argnames and a list of list for argvalues. The difference is that the first one uses positional arguments, and the second one uses keyword arguments.

  import pytest
   
   
  @pytest.mark.parametrize(
      ["contact_type"],
      [["email"], ["phone"]],
  )   
  def test_function_issue_caught_PT006(contact_type: str):...
   
  @pytest.mark.parametrize(
      argnames=["contact_type"],
      argvalues=[["email"], ["phone"]],
  )   
  def test_function_issue_uncaught_PT006(contact_type: str):...

• Run ruff explicitly looking for the PT006 issue:

  $ ruff check test_something.py  --select PT006

• Expected behavior (I think, you'll confirm 😅 ):

  • Ruff raises an issue PT006 with the same message for both test functions: "Use a string for the first argument".

• Actual behavior:

  • Ruff raises an issue only for the first test function (the one with positional arguments):

    $ ruff check test_something.py  --select PT006
    test_something.py:5:5: PT006 [*] Wrong type passed to first argument of `pytest.mark.parametrize`; expected `str`
      | 
    4 | @pytest.mark.parametrize(
    5 |     ["contact_type"],
      |     ^^^^^^^^^^^^^^^^ PT006
    6 |     [["email"], ["phone"]],
    7 | )
      | 
      = help: Use a string for the first argument