`pytest.mark.usefixtures()` without argument gets silently ignored

[The-Compiler]

Someone in my pytest training accidentally did:

import pytest

@pytest.mark.usefixtures()
def test_fixt():
    pass

but forgot to pass a fixture name. Because we do:

pytest/src/_pytest/fixtures.py

Lines 1536 to 1539 in 0070151

	def _getusefixturesnames(self, node: nodes.Item) -> Iterator[str]:
	"""Return the names of usefixtures fixtures applicable to node."""
	for mark in node.iter_markers(name="usefixtures"):
	yield from mark.args

That results in the mark being silently ignored. IMHO, this should result in a warning or even error instead.

I think this would be a great beginner issue for someone that never contributed to pytest before. Maybe someone at the upcoming sprint wants to take a look?

[RonnyPfannschmidt]

We should start to warn and consider turning it into a error next major release

[JiajunXu2]

I am currently working on this issue, would it be better to issue a warning or raise an error?

[The-Compiler]

I agree with what Ronny has said above, let's start with a warning

[andydluna]

Hello. I would love to contribute, but I am not sure how to do so. However, my idea is that we can use the already imported warning module and warn the user whenever node.iter_markers(name="usefixtures") is empty. Hopefully someone can implement it and give it a try!

[daria-shaw]

Heya, saw that #12439 has gotten a lil stale (no update since July). Alright if I take a crack at picking it up this weekend if I got time?

[webknjaz]

@daara-s sure! Please pull the original commits into your branch and add yours on top so that we'd credit that author too.