Parametrizing fixtures via pytest.mark.parametrize works without 'indirect'?

[tpapaioa]

One of the projects I work on implements test parametrization in a way I don't see mentioned in the pytest documentation, and I wanted to get some feedback here to make sure I'm not missing something in the documentation where this behavior is discussed, and if there are any potential issues with using parametrization in this way. As mentioned in [1], any parametrization applied to a test will also affect any arguments with the same name on fixtures consumed by the test. You can even pass the scope keyword argument to pytest.mark.parametrize() or metafunc.parametrize() when doing so, and it will work as expected with fixture scope.

Example:

# cat tests/test_parametrize.py 
import pytest

@pytest.fixture(scope='module')
def data_modscope(param):
    return f'Data for {param}'


@pytest.mark.parametrize('param', ['1', '2', '3'], scope='module')
def test_param_data(data_modscope, param):
    assert data_modscope == f'Data for {param}'


@pytest.mark.parametrize('param', ['1'], scope='module')
def test_param_data_2(data_modscope):
    assert data_modscope == 'Data for 1'

# pytest tests/test_parametrize.py 
=== test session starts ===
platform linux -- Python 3.9.2, pytest-6.0.2, py-1.10.0, pluggy-0.13.1
rootdir: /home/tpapaioa/git/pytest_parametrize_tests
collected 4 items                                                                                                                                                                                                                            

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

=== 4 passed in 0.01s ===

This basic pattern has been used for years by the project I mentioned, and we've never had a problem with this functionality (although I see mention of a temporary removal and then reinstatement of this behavior in [1]).

[1] https://stackoverflow.com/questions/18011902/pass-a-parameter-to-a-fixture-function/60148972#60148972

[RonnyPfannschmidt]

Strictly speak its direct parameterization

The fixture just takes the same parameter as the test, so it works

If parameterization was used, the data would be on request, not a fixture

[tpapaioa]

So is there any reason that this behavior isn't documented?

[nicoddemus]

No specific reason, other than nobody really took time to do it, probably because it is rarely used and is a complex behavior which might be hard to explain, probably needing a bunch of examples.

PRs in that direction would definitely be welcome.