Can no longer group test cases by non-str attribute

[sshane]

We used to be able to group test cases in xdist by a hashable class attribute (added by parameterized_class), now it assumes that it's always a string. Broken by #1201

https://github.com/commaai/openpilot/blame/fcebb5eb9f8735b6516a70f630c28f297c252c6a/selfdrive/car/tests/test_models.py#L474

test_route is a dataclass

@parameterized_class(('platform', 'test_route'), get_test_cases())
@pytest.mark.xdist_group_class_property('test_route')
class TestCarModel(TestCarModelBase):
  pass

batman@workstation-shane:~/openpilot/selfdrive/car/tests$ pytest -n1 test_models.py 
================================================================================== test session starts ==================================================================================
platform linux -- Python 3.12.4, pytest-8.4.0, pluggy-1.6.0
Using --randomly-seed=3682492429
rootdir: /home/batman/openpilot
configfile: pyproject.toml
plugins: repeat-0.9.4, subtests-0.14.1, timeout-2.4.0, mock-3.14.0, asyncio-0.26.0, randomly-3.16.0, cov-6.1.1, cpp-2.6.0, hypothesis-6.47.5, xdist-3.7.0
asyncio: mode=Mode.STRICT, asyncio_default_fixture_loop_scope=function, asyncio_default_test_loop_scope=function
1 worker [1932 items]  
INTERNALERROR> def worker_internal_error(
INTERNALERROR>         self, node: WorkerController, formatted_error: str
INTERNALERROR>     ) -> None:
INTERNALERROR>         """
INTERNALERROR>         pytest_internalerror() was called on the worker.
INTERNALERROR>     
INTERNALERROR>         pytest_internalerror() arguments are an excinfo and an excrepr, which can't
INTERNALERROR>         be serialized, so we go with a poor man's solution of raising an exception
INTERNALERROR>         here ourselves using the formatted message.
INTERNALERROR>         """
INTERNALERROR>         self._active_nodes.remove(node)
INTERNALERROR>         try:
INTERNALERROR> >           assert False, formatted_error
INTERNALERROR> E           AssertionError: Traceback (most recent call last):
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/main.py", line 289, in wrap_session
INTERNALERROR> E                 session.exitstatus = doit(config, session) or 0
INTERNALERROR> E                                      ^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/main.py", line 342, in _main
INTERNALERROR> E                 config.hook.pytest_collection(session=session)
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_hooks.py", line 512, in __call__
INTERNALERROR> E                 return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
INTERNALERROR> E                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
INTERNALERROR> E                 return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
INTERNALERROR> E                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 167, in _multicall
INTERNALERROR> E                 raise exception
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR> E                 teardown.throw(exception)
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/logging.py", line 788, in pytest_collection
INTERNALERROR> E                 return (yield)
INTERNALERROR> E                         ^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR> E                 teardown.throw(exception)
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/warnings.py", line 99, in pytest_collection
INTERNALERROR> E                 return (yield)
INTERNALERROR> E                         ^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR> E                 teardown.throw(exception)
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/config/__init__.py", line 1450, in pytest_collection
INTERNALERROR> E                 return (yield)
INTERNALERROR> E                         ^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 121, in _multicall
INTERNALERROR> E                 res = hook_impl.function(*args)
INTERNALERROR> E                       ^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/main.py", line 353, in pytest_collection
INTERNALERROR> E                 session.perform_collect()
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/main.py", line 816, in perform_collect
INTERNALERROR> E                 hook.pytest_collection_modifyitems(
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_hooks.py", line 512, in __call__
INTERNALERROR> E                 return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
INTERNALERROR> E                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
INTERNALERROR> E                 return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
INTERNALERROR> E                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 167, in _multicall
INTERNALERROR> E                 raise exception
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR> E                 teardown.throw(exception)
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/cacheprovider.py", line 443, in pytest_collection_modifyitems
INTERNALERROR> E                 res = yield
INTERNALERROR> E                       ^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
INTERNALERROR> E                 teardown.throw(exception)
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/_pytest/cacheprovider.py", line 373, in pytest_collection_modifyitems
INTERNALERROR> E                 res = yield
INTERNALERROR> E                       ^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 121, in _multicall
INTERNALERROR> E                 res = hook_impl.function(*args)
INTERNALERROR> E                       ^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E               File "/home/batman/openpilot/.venv/lib/python3.12/site-packages/xdist/remote.py", line 254, in pytest_collection_modifyitems
INTERNALERROR> E                 item._nodeid = f"{item.nodeid}@{'_'.join(sorted(gnames))}"
INTERNALERROR> E                                                 ^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR> E             TypeError: sequence item 0: expected str instance, CarTestRoute found
INTERNALERROR> E           assert False