Tests pass, but staggered_race spews RuntimeError: coroutine ignored GeneratorExit

[musicinmybrain]

Describe the bug
A clear and concise description of what the bug is.

When running tests for v2.4.2, the tests pass, but staggered_race spews a traceback RuntimeError: coroutine ignored GeneratorExit. Maybe this is OK, and is just a minor issue with test teardown, but it looks concerning.

To Reproduce
Steps to reproduce the behavior:

$ gh repo clone aio-libs/aiohappyeyeballs
$ cd aiohappyeyeballs
$ git checkout v2.4.2
$ python3.12 -m venv _e
$ . _e/bin/activate
(_e) $ pip install -e .
(_e) $ pip install pytest pytest-cov pytest-asyncio
(_e) $ python -m pytest

I’m also able to reproduce this on other CPython versions – I tried 3.10, 3.11, and 3.13.

Additional context

================================================================================== 26 passed, 1 skipped, 1 xfailed in 0.70s ===================================================================================
Exception ignored in: <coroutine object test_handling_system_exit at 0x7f0f23a9a570>
Traceback (most recent call last):
  File "/usr/lib64/python3.12/unittest/mock.py", line 1410, in patched
    return await func(*newargs, **newkeywargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/tests/test_impl.py", line 1440, in test_handling_system_exit
    await start_connection(
  File "/home/ben/src/forks/aiohappyeyeballs/src/aiohappyeyeballs/impl.py", line 88, in start_connection
    sock, _, _ = await staggered.staggered_race(
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: coroutine ignored GeneratorExit   
Task was destroyed but it is pending!
task: <Task pending name='Task-55' coro=<test_handling_system_exit() done, defined at /usr/lib64/python3.12/unittest/mock.py:1405> wait_for=<Future pending cb=[Task.task_wakeup()]>>
Task exception was never retrieved
future: <Task finished name='Task-56' coro=<staggered_race.<locals>.run_one_coro() done, defined at /home/ben/src/forks/aiohappyeyeballs/src/aiohappyeyeballs/_staggered.py:70> exception=SystemExit()>
Traceback (most recent call last):
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/runner.py", line 341, in from_call
    result: TResult | None = func()
                             ^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/runner.py", line 242, in <lambda>
    lambda: runtest_hook(item=item, **kwds), when=when, reraise=reraise
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 182, in _multicall
    return outcome.get_result()
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_result.py", line 100, in get_result
    raise exc.with_traceback(exc.__traceback__) 
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 167, in _multicall
    teardown.throw(outcome._exception)
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/threadexception.py", line 92, in pytest_runtest_call
    yield from thread_exception_runtest_hook()  
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/threadexception.py", line 68, in thread_exception_runtest_hook
    yield
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 167, in _multicall
    teardown.throw(outcome._exception)
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/unraisableexception.py", line 95, in pytest_runtest_call
    yield from unraisable_exception_runtest_hook()
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/unraisableexception.py", line 70, in unraisable_exception_runtest_hook
    yield
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 167, in _multicall
    teardown.throw(outcome._exception)
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/logging.py", line 846, in pytest_runtest_call
    yield from self._runtest_for(item, "call")  
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/logging.py", line 829, in _runtest_for
    yield
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 167, in _multicall
    teardown.throw(outcome._exception)
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/capture.py", line 880, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 167, in _multicall
    teardown.throw(outcome._exception)
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/skipping.py", line 257, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/runner.py", line 174, in pytest_runtest_call
    item.runtest()
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pytest_asyncio/plugin.py", line 457, in runtest
    super().runtest()
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/python.py", line 1627, in runtest
    self.ihook.pytest_pyfunc_call(pyfuncitem=self)
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 182, in _multicall
    return outcome.get_result()
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_result.py", line 100, in get_result
    raise exc.with_traceback(exc.__traceback__) 
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/_pytest/python.py", line 159, in pytest_pyfunc_call
    result = testfunction(**testargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/_e/lib64/python3.12/site-packages/pytest_asyncio/plugin.py", line 929, in inner
    _loop.run_until_complete(task)
  File "/usr/lib64/python3.12/asyncio/base_events.py", line 674, in run_until_complete
    self.run_forever()
  File "/usr/lib64/python3.12/asyncio/base_events.py", line 641, in run_forever
    self._run_once()
  File "/usr/lib64/python3.12/asyncio/base_events.py", line 1986, in _run_once
    handle._run()
  File "/usr/lib64/python3.12/asyncio/events.py", line 88, in _run
    self._context.run(self._callback, *self._args)
  File "/home/ben/src/forks/aiohappyeyeballs/src/aiohappyeyeballs/_staggered.py", line 76, in run_one_coro
    result = await coro_fn()
             ^^^^^^^^^^^^^^^
  File "/home/ben/src/forks/aiohappyeyeballs/src/aiohappyeyeballs/impl.py", line 165, in _connect_sock
    await loop.sock_connect(sock, address)
  File "/home/ben/src/forks/aiohappyeyeballs/tests/test_impl.py", line 1395, in _sock_connect
    raise SystemExit
SystemExit

[bdraco]

We are using the new staggered_race implementation in cpython main since cpython is debating if they are going to break compatibility in the next 3.12 patch release in python/cpython#124639

When we vendored the staggered_race code, and I added tests for it throwing SystemExit since we noticed the coverage was missing.

I marked the test as xfail because it fails on all versions of staggered_race, and since it is not a regression I left it to be investigated so we can come up with a minimal reproducer and determine if its a problem with our testing or open a cpython bug report

[musicinmybrain]

I don’t see the RuntimeError anymore in 2.4.3 with #101. All I have now is:

tests/test_staggered_cpython.py::StaggeredTests::test_first_error_second_successful
  /usr/lib64/python3.12/asyncio/base_events.py:726: ResourceWarning: unclosed event loop <_UnixSelectorEventLoop running=False closed=False debug=False>
    _warn(f"unclosed event loop {self!r}", ResourceWarning, source=self)
  Enable tracemalloc to get traceback where the object was allocated.
  See https://docs.pytest.org/en/stable/how-to/capture-warnings.html#resource-warnings for more info.