Type checking `pytest.param`

[jamesbraza]

Imagine I have some code like this:

import pytest


@pytest.mark.parametrize(
    "arg",
    [
        pytest.param("1", id="good"),
        pytest.param(2, id="bad"),
    ],
)
def test_arg(arg: str) -> None:
    assert arg

Currently with Python 3.11, mypy==1.16.0 and pytest-mypy==1.0.1 won't flag that the second pytest.param actually has a type mismatch (int vs str).

It would be super useful to flag this as a latent TypeError when using pytest --mypy.

[dmtucker]

Hey there 👋 Unfortunately, this isn't something this plugin can deliver. Pytest and/or Mypy need to support it...
For example, if we just run mypy on your file, it can't detect this:

$ pipenv install pytest-mypy
$ pipenv run mypy sscce.py 
Success: no issues found in 1 source file

Either Pytest needs to ship type-aware parametrizations, or Mypy needs to be enhanced to detect this.
(I would guess the former, perhaps as part of pytest-dev/pytest#3834? I'd be interested to get pytest-dev's thoughts on this.)