Mypy checking fails with --disallow-untyped-decorators

[squaresmile]

It looks like the @pytest.mark.parametrize decorator can't pass mypy with --disallow-untyped-decorators. mypy works without the flag.

Following my comment, I made this reproduction repo. I can reproduce this with pytest 6.0.1 and Python 3.6.9 on Linux or Python 3.8.5 on Windows.

> mypy test_mypy.py
test_mypy.py:7: note: Revealed type is 'def (query: builtins.str, result: builtins.str)'
> mypy --disallow-untyped-decorators test_mypy.py
test_mypy.py:3: error: Untyped decorator makes function "test_raw" untyped
test_mypy.py:7: note: Revealed type is 'def (query: builtins.str, result: builtins.str)'

> pip list
Package            Version
------------------ -------
attrs              19.3.0
importlib-metadata 1.7.0
iniconfig          1.0.0
more-itertools     8.4.0
mypy               0.782
mypy-extensions    0.4.3
packaging          20.4
pip                20.1.1
pluggy             0.13.1
py                 1.9.0
pyparsing          2.4.7
pytest             6.0.1
setuptools         49.2.0
six                1.15.0
toml               0.10.1
typed-ast          1.4.1
typing-extensions  3.7.4.2
wheel              0.34.2
zipp               3.1.0

[bluetech]

This is a mypy bug. I proposed a fix here: python/mypy#9232.

I'm afraid there isn't a simple workaround for this in pytest. Hopefully the mypy fix will be merged and released, but until then I suggest turning off disallow-untyped-decorators (at least in your test modules) are adding type: ignore comments.