v8.2.0 raises Can't instantiate abstract class when a test class implements an abstract class #12275
Description
Before, we could have a test class inheriting from an ABC (and unittest.TestCase), now it errors because pytest is trying to instantiate the ABC itself. Running pytest should only instantiate the child test class (which indeed implements all the abstract methods of its ABC parent).
This issue does not appear in v8.1.2 and was likely introduced in #12089.
Minimal example:
from abc import ABC, abstractmethod from unittest import TestCase class Base(TestCase, ABC): @abstractmethod def foo(self): ... class Tests(Base): def foo(self): ... def test(self): ...Output:
(test) tests 🔥pytest test.py ============================================================================= test session starts ============================================================================== platform darwin -- Python 3.9.19, pytest-8.2.0, pluggy-1.5.0 rootdir: ... configfile: pytest.ini plugins: env-1.1.3 collected 1 item / 1 error ==================================================================================== ERRORS ==================================================================================== ________________________________________________________________ ERROR collecting test.py ________________________________________________________________ /Users/martin/miniconda3/envs/test/lib/python3.9/site-packages/_pytest/runner.py:341: in from_call result: Optional[TResult] = func() /Users/martin/miniconda3/envs/test/lib/python3.9/site-packages/_pytest/runner.py:389: in collect return list(collector.collect()) /Users/martin/miniconda3/envs/test/lib/python3.9/site-packages/_pytest/unittest.py:90: in collect self.session._fixturemanager.parsefactories(self.newinstance(), self.nodeid) /Users/martin/miniconda3/envs/test/lib/python3.9/site-packages/_pytest/unittest.py:75: in newinstance return self.obj("runTest") E TypeError: Can't instantiate abstract class Base with abstract method foo =========================================================================== short test summary info ============================================================================ ERROR test.py::Base - TypeError: Can't instantiate abstract class Base with abstract method foo !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! =============================================================================== 1 error in 0.04s =============================================================================== pip list:
Package Version -------------- ------- exceptiongroup 1.2.1 iniconfig 2.0.0 packaging 24.0 pip 23.3.1 pluggy 1.5.0 pytest 8.2.0 pytest-env 1.1.3 setuptools 68.2.2 tomli 2.0.1 wheel 0.41.2 Thanks for your work in general, it's a great package.