Why does pytestmark with usefixtures not work in conftest.py?

[jaraco]

I'd like to enable a third-party fixture for all tests in the test suite.

I thought I could do this by adding a pytestmark = pytest.mark.usefixtures(fixturename) to conftest.py, but it turns out that fails to trigger the fixture. I ended up creating an autouse fixture that depends on the desired fixture to make it work, but that feels heavy-handed and creates an extra fixture name that I'd rather not have.

Is there a way to declare to use a fixture to be used for all tests? I asked Gemini, but it offers wrong answers only.

Pytest version is latest (8.3.2).

[RonnyPfannschmidt]

conftests are plugins, not part of the node tree, thats why a marker on them will not propagate (for good reason)

the recommended way to have a fixture happen for all tests is a autouse fixture

[jaraco]

So there is no way to declare to "auto-use a third party fixture" without wrapping it in another fixture?

[RonnyPfannschmidt]

The alternative would be to add the marker to the session, which is hacky in another way

The recommended Way to activate a fixture for everything is to have a autouse fixture depend on it