no parameter defined for test error when overriding a fixture that requests a parametrized fixture

[azmeuk]

python 3.11 - pytest 7.3.1 - archlinux
Related issues #1953 #2043

The situation is a bit convoluted: if a fixture requests a parametrized fixture, and is overridden with different params, then it raises a The requested fixture has no parameter defined for test error.

import pytest


@pytest.fixture(params=["foo"])
def fixture_foo():
    yield None


@pytest.fixture
def fixture_bar(fixture_foo):
    yield None


class TestFoobar:
    @pytest.fixture
    def fixture_bar(self, fixture_bar):
        yield None

    def test_foobar(self, fixture_bar):
        assert True

===================================================== test session starts =====================================================
platform linux -- Python 3.11.3, pytest-7.3.1, pluggy-1.0.0
rootdir: ...
collected 1 item

test_foobar.py E                                                                                                        [100%]

=========================================================== ERRORS ============================================================
__________________________________________ ERROR at setup of TestFoobar.test_foobar ___________________________________________
The requested fixture has no parameter defined for test:
    test_foobar.py::TestFoobar::test_foobar

Requested fixture 'fixture_foo' defined in:
test_foobar.py:5

Requested here:
.../lib/python3.11/site-packages/_pytest/fixtures.py:678
=================================================== short test summary info ===================================================
ERROR test_foobar.py::TestFoobar::test_foobar
====================================================== 1 error in 0.02s =======================================================

I encountered this in a real-life project. I simplified all that I could to make an example demonstrating this behavior. Obviously this example does not seem very relevant, but in my real usecase I do need the overriding fixture_bar to have a param to the main fixture_bar.

The error won't happen if:

• fixture_foo is not parametrized or
• the overriding fixture_bar also have a fixture_foo param

It took me a while to find how to fix the issue, but this second workaround is simple enough. However I could not find any documentation about this.

I suggest to either fix this behavior, or document it.

What do you think?