Hypothesis integration raises internal error when collecting `RuleBasedStateMachine`

[Zac-HD]

Initially reported in HypothesisWorks/hypothesis#3850

The bug can be reproduced by installing pytest_asyncio and hypothesis, then trying to run the following test:

from hypothesis.stateful import RuleBasedStateMachine
class StatefulTest(RuleBasedStateMachine):
    def __init__(self):
        super().__init__()
 
TestStorage = StatefulTest.TestCase

INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   ...
INTERNALERROR>   File ".../python3.11/site-packages/pytest_asyncio/plugin.py", line 371, in pytest_collection_modifyitems
INTERNALERROR>     and _hypothesis_test_wraps_coroutine(function)
INTERNALERROR>         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
INTERNALERROR>   File ".../python3.11/site-packages/pytest_asyncio/plugin.py", line 377, in _hypothesis_test_wraps_coroutine
INTERNALERROR>     return _is_coroutine(function.hypothesis.inner_test)
INTERNALERROR>                          ^^^^^^^^^^^^^^^^^^^
INTERNALERROR> AttributeError: 'function' object has no attribute 'hypothesis'

To fix this, we should avoid assuming that the .hypothesis attribute exists in

pytest-asyncio/pytest_asyncio/plugin.py

Lines 482 to 487 in 463ce98

	@staticmethod
	def _can_substitute(item: Function) -> bool:
	func = item.obj
	return getattr(
	func, "is_hypothesis_test", False
	) and asyncio.iscoroutinefunction(func.hypothesis.inner_test)

As a fix, I'd suggest:

        return (
            getattr(func, "is_hypothesis_test", False)
            and getattr(func, "hypothesis", None)
            and asyncio.iscoroutinefunction(func.hypothesis.inner_test)
        )

Note that there's no simple to support async stateful testing; the hypothesis-trio project is essentially a fork of our upstream stateful testing module with async handling injected in many places. My suggestion therefore continues to treat asyncio stateful tests as out of scope, since I don't think there's sufficient demand to be worth the maintainence burden.

[eivindjahren]

It seems that this is no longer an issue in pytest-asyncio==0.23.3. I suggest closing the issue.

[seifertm]

Thanks for the cross-reference to the Hypothesis issue and for the improvement suggestion. I amended the check for Hypothesis tests as suggested.

Pytest-asyncio v0.23 had lots issues with test collection, unfortunately. These caused an INTERNALERROR in pytest at collection time.