pytest passes, but pre-commit run of pytest hook fails with "0 collected".

[zirpu]

example repo: https://github.com/zirpu/decimal_time

I can run pytest fine, but trying to commit gives me:

test/decimal_time $ git commit -mtest. decimal_time
isort....................................................................Passed
black....................................................................Passed
flake8...................................................................Passed
mypy.....................................................................Passed
pytest...................................................................Failed
hookid: pytest

============================= test session starts ==============================
platform linux -- Python 3.7.3, pytest-5.1.2, py-1.8.0, pluggy-0.12.0
rootdir: /home/allan/projects/zirpu/pykatas/test/decimal_time, inifile: pytest.ini
plugins: cov-2.7.1
collected 0 items

============================ no tests ran in 0.01s =============================

Pytest runs fine with:

======================================================= test session starts =======================================================
platform linux -- Python 3.7.3, pytest-5.0.1, py-1.8.0, pluggy-0.12.0
rootdir: /home/allan/projects/zirpu/pykatas/test/decimal_time, inifile: pytest.ini
collected 4 items                                                                                                                 

test/test_decimal_time.py ....                                                                                              [100%]

==================================================== 4 passed in 0.02 seconds =====================================================

I cannot find a way to get more info from pre-commit and pytest, pointers appreciated.

[asottile]

pre-commit by default passes the changed files as arguments. If you're changing non-test files, then pytest will be invoked as pytest non-test-file.py and will discover zero tests and exit with code 5 (nonzero).

Personally I wouldn't suggest running tests as part of a commit stage as they're often ~slightly too slow. That said, if you want to make this work, you can use pass_filenames: false / always_run: true -- here's an example: https://github.com/pre-commit/pygrep-hooks/blob/eb0a92ce09636b6d72787952ce0f74c5dad996fa/.pre-commit-config.yaml#L47-L53

[zirpu]

ah. thanks. that works.