pre-commit hook fails but pytest runs fine if called directly

[deadpyxel]

So I've been using pytest to test my applications and everything is working fine. One thing that is not really working as expected are the pre-commit hooks I've setup.
I have the following hooks in my .pre-commit-config.yaml:

repos:
  # ... Other non local commits
  - repo: local
    hooks:
      - id: pytest
        name: pytest
        stages: [commit]
        language: system
        entry: pytest
        types: [python]

      - id: pytest-cov
        name: pytest
        stages: [push]
        language: system
        entry: pytest --cov --cov-fail-under=70
        types: [python]
        pass_filenames: false

While running directly from my virtualenv all tests run fine:

======================================================== test session starts ========================================================
platform linux -- Python 3.8.5, pytest-6.0.2, py-1.9.0, pluggy-0.13.1
rootdir: /home/user/dev/myproject, configfile: setup.cfg
plugins: cov-2.10.1
collected 41 items

tests/test_adapter.py ...............                                                                                         [ 36%]
tests/test_entities.py .....................                                                                                  [ 87%]
tests/test_models.py .....                                                                                                    [100%]

======================================================== 41 passed in 7.96s =========================================================

if I run the pre-commithooks, let's say using pre-commit run --all-files:

Trim Trailing Whitespace.................................................Passed
Fix End of Files.........................................................Passed
Check Yaml...............................................................Passed
Check for added large files..............................................Passed
Debug Statements (Python)................................................Passed
Fix requirements.txt.....................................................Passed
pyupgrade................................................................Passed
flake8...................................................................Passed
Reorder python imports...................................................Passed
mypy.....................................................................Failed
- hook id: mypy
- exit code: 1
# some mypy errors
black....................................................................Passed
pytest...................................................................Failed
- hook id: pytest
- exit code: 5
============================= test session starts ==============================
platform linux -- Python 3.8.5, pytest-6.0.2, py-1.9.0, pluggy-0.13.1
rootdir: /home/user/dev/myproject, configfile: setup.cfg
plugins: cov-2.10.1
collected 21 items

tests/test_entities.py .....................                             [100%]

============================== 21 passed in 0.54s ==============================
============================= test session starts ==============================
platform linux -- Python 3.8.5, pytest-6.0.2, py-1.9.0, pluggy-0.13.1
rootdir: /home/user/dev/myproject, configfile: setup.cfg
plugins: cov-2.10.1
collected 0 items

============================ no tests ran in 0.43s =============================
============================= test session starts ==============================
platform linux -- Python 3.8.5, pytest-6.0.2, py-1.9.0, pluggy-0.13.1
rootdir: /home/user/dev/myproject, configfile: setup.cfg
plugins: cov-2.10.1
collected 15 items

tests/test_adapter.py ...............                                    [100%]

============================== 15 passed in 7.43s ==============================
============================= test session starts ==============================
platform linux -- Python 3.8.5, pytest-6.0.2, py-1.9.0, pluggy-0.13.1
rootdir: /home/user/dev/myproject, configfile: setup.cfg
plugins: cov-2.10.1
collected 5 items

tests/test_models.py .....                                               [100%]

============================== 5 passed in 0.56s ===============================

As you can see, while the tests are passing, it gives this error that is related with that entry saying that could not collect tests, which I find weird since the usual run has not that problem.

My requirements-dev.txt:

-i https://pypi.org/simple
appdirs==1.4.4
aspy.refactor-imports==2.1.1
astpretty==2.0.0
attrs==20.2.0
bandit==1.6.2
black==20.8b1
bump2version==1.0.0
cached-property==1.5.2
cfgv==3.2.0
click==7.1.2
coverage==5.3
distlib==0.3.1
filelock==3.0.12
flake8==3.8.3
flake8-bandit==2.1.2
flake8-black==0.2.1
flake8-bugbear==20.1.4
flake8-expression-complexity==0.0.8
flake8-import-order==0.18.1
flake8-plugin-utils==1.3.1
flake8-polyfill==1.0.2
flake8-pytest-style==1.3.0
gitdb==4.0.5
gitpython==3.1.8
identify==1.5.5
iniconfig==1.0.1
mccabe==0.6.1
more-itertools==8.5.0
mypy==0.782
mypy-extensions==0.4.3
nodeenv==1.5.0
packaging==20.4
pathspec==0.8.0
pbr==5.5.0
pluggy==0.13.1
pre-commit==2.7.1
py==1.9.0
pycodestyle==2.6.0
pyflakes==2.2.0
pyparsing==3.0.0a2
pytest==6.0.2
pytest-cov==2.10.1
python-dotenv==0.14.0
pyyaml==5.3.1
regex==2020.7.14
reorder-python-imports==2.3.5
six==1.15.0
smmap==3.0.4
stevedore==3.2.2
toml==0.10.1
typed-ast==1.4.1
typing-extensions==3.7.4.3
virtualenv==20.0.31

and the pytest section from my setup.cfg:

[coverage:run]
omit = tests/*,main.py

[coverage:report]
show_missing = True

[tool:pytest]
python_files = tests/*.py
markers =
	fast: marks a test as a fast execution test.
	slow: marks a test as a slow execution test.
	db_dependent: marks a test with database dependencies.
	network_dependent: marks a test as network dependent.
	integration: marks a test that is meant to be used as integration testing

I'm not really sure if this is expected, but since the results are different, I believe there's something wrong either with the hook I've setup or with how pytest and pre-commit are talking to each other.

[RonnyPfannschmidt]

Pytest is executed for multi sets of files, some don't provide tests and fail that execution as expected

This needs a reconfigure of the pre-
Commit hook spec

[asottile]

pre-commit passes filenames as positional arguments and will invoke multiple times in parallel

you're likely confused by one of these behaviours and/or not replicating that same behaviour outside pre-commit (the "no tests discovered" is probably pytest not/a/test/file.py another/not/a/test/file.py for example)

you probably want:

    entry: pytest tests
    pass_filenames: false
    always_run: true

See also this stackoverflow post

but also you probably don't want to run pytest as a pre-commit hook

[deadpyxel]

This idea seems to work. I'm sorry I didn't understand how to make this properly.

I was going pre-commit route because this application has no tox config on it, and will run only on py 3.8 for now, so I thought it was not necessary. Maybe I should change my mind. Also, it is not a library, so probably I should rely on CI tools for that. It seems I made things more difficult to myself.

Thanks again for the feedback and instruction.