Test class without implemented abstract methods

[gryznar]

Repro

1. Prepare test file with code:

from abc import ABCMeta, abstractmethod

class AbstractTestFoo(metaclass=ABCMeta):
    @abstractmethod
    def test_foo(self):
        ...

class TestFoo(AbstractTestFoo):
    ...

2. Run test file

Actual

pytest collects test successfully, but no test is found.

Expected

pytest errors at test collection stage.

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[RonnyPfannschmidt]

Written by Claude Opus 5 via Claude Code for the issue reporter and the pytest maintainers; I prompted it, it did the work, I read it.

Duplicate of #13546 — closing in favour of that one, which has the history and the design discussion. #15081 is a duplicate of this one and is closed too.

The behaviour is as you describe: TestFoo does not implement test_foo, so TestFoo is abstract, and pytest has silently skipped abstract classes since 8.3 (#12275, fixed in #12318). The silence is the bug. This is the fourth report of it — #13546, #14003, #15080, #15081 — so a draft PR adding a warning is up: #15082.