Aiohttp: Parameter "loop_factory" should be declared explicitly via indirect or in function itself

Attempting to upgrade from 3.7.2 to 3.8.1 and I started seeing the following in py.test with test discovery:

Parameter "loop_factory" should be declared explicitly via indirect or in function itself

The commonality it turns out were async functions, and it appears to be caused somewhere within aiohttp. I'm not that familiar with asyncio or aiohttp, so I'm happy to debug more with guidance, but I'm hoping someone might have more thoughts here.

Related packages:

aiohttp==3.6.2
pytest==5.4.0
pytest-aiohttp==0.3.0
pytest-cov==2.8.1
pytest-forked==1.1.3
pytest-mock==2.0.0
pytest-responses==0.4.0
pytest-xdist==1.31.0

Some detail around the callstack:

➜  ~/D/zeus (feat/increase-lru-cache) ✗ py.test -x --pdb
=========================================================================================== test session starts ============================================================================================
platform darwin -- Python 3.8.1, pytest-5.4.0, py-1.8.1, pluggy-0.13.1
rootdir: /Users/dcramer/Development/zeus, inifile: setup.cfg
plugins: mock-2.0.0, celery-4.1.1, xdist-1.31.0, aiohttp-0.3.0, forked-1.1.3, responses-0.4.0, cov-2.8.1
collecting 186 items
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> traceback >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
In function "test_health_check":
Parameter "loop_factory" should be declared explicitly via indirect or in function itself
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> entering PDB >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> PDB post_mortem (IO-capturing turned off) >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> /Users/dcramer/Development/zeus/.venv/lib/python3.8/site-packages/_pytest/python.py(1144)_validate_explicit_parameters()
-> fail(msg, pytrace=False)
(Pdb) l
1139                    func_name = self.function.__name__
1140                    msg = (
1141                        'In function "{func_name}":\n'
1142                        'Parameter "{arg}" should be declared explicitly via indirect or in function itself'
1143                    ).format(func_name=func_name, arg=arg)
1144 ->                 fail(msg, pytrace=False)
1145
1146
1147    def _find_parametrized_scope(argnames, arg2fixturedefs, indirect):
1148        """Find the most appropriate scope for a parametrized call based on its arguments.
1149
(Pdb) u
> /Users/dcramer/Development/zeus/.venv/lib/python3.8/site-packages/_pytest/python.py(939)parametrize()
-> self._validate_explicit_parameters(argnames, indirect)
(Pdb) l
934
935             self._validate_if_using_arg_names(argnames, indirect)
936
937             arg_values_types = self._resolve_arg_value_types(argnames, indirect)
938
939  ->         self._validate_explicit_parameters(argnames, indirect)
940
941             # Use any already (possibly) generated ids with parametrize Marks.
942             if _param_mark and _param_mark._param_ids_from:
943                 generated_ids = _param_mark._param_ids_from._param_ids_generated
944                 if generated_ids is not None:
(Pdb) u
> /Users/dcramer/Development/zeus/.venv/lib/python3.8/site-packages/aiohttp/pytest_plugin.py(203)pytest_generate_tests()
-> metafunc.parametrize("loop_factory",
(Pdb) l
198                         "Unknown loop '%s', available loops: %s" % (
199                             name, list(factories.keys())))
200                 else:
201                     continue
202             factories[name] = avail_factories[name]
203  ->     metafunc.parametrize("loop_factory",
204                              list(factories.values()),
205                              ids=list(factories.keys()))
206
207
208     @pytest.fixture