MockSocket related test_makefile failures with Python 3.13

[kulikjak]

❓ I'm submitting a ...

• 🐞 bug report
• 🐣 feature request
• ❓ question about the decisions made in the repository

🐞 Describe the bug. What is the current behavior?

When running the Cheroot test suite under Python 3.13, test_bytes_read and test_bytes_written fail with the following error (full trace below):

E                   pytest.PytestUnraisableExceptionWarning: Exception ignored in: <function IOBase.__del__ at 0x7fc35010e8e0>
E                   
E                   Traceback (most recent call last):
E                     File "/usr/lib/python3.13/_pyio.py", line 418, in __del__
E                       self.close()
E                       ~~~~~~~~~~^^
E                     File "/usr/lib/python3.13/_pyio.py", line 818, in close
E                       self.raw.close()
E                       ~~~~~~~~~~~~~~^^
E                     File "/usr/lib/python3.13/socket.py", line 789, in close
E                       self._sock._decref_socketios()
E                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
E                   AttributeError: 'MockSocket' object has no attribute '_decref_socketios'

My guess is that this is related the following io changes:
https://docs.python.org/3/whatsnew/3.13.html#io

💡 To Reproduce

Run the test suite with Python 3.13.0.

📋 Details
Full traceback:

=================================== FAILURES ===================================
_______________________________ test_bytes_read ________________________________

cls = <class '_pytest.runner.CallInfo'>
func = <function call_and_report.<locals>.<lambda> at 0x7fc34e78e8e0>
when = 'call'
reraise = (<class '_pytest.outcomes.Exit'>, <class 'KeyboardInterrupt'>)

    @classmethod
    def from_call(
        cls,
        func: Callable[[], TResult],
        when: Literal["collect", "setup", "call", "teardown"],
        reraise: type[BaseException] | tuple[type[BaseException], ...] | None = None,
    ) -> CallInfo[TResult]:
        """Call func, wrapping the result in a CallInfo.
    
        :param func:
            The function to call. Called without arguments.
        :type func: Callable[[], _pytest.runner.TResult]
        :param when:
            The phase in which the function is called.
        :param reraise:
            Exception or exceptions that shall propagate if raised by the
            function, instead of being wrapped in the CallInfo.
        """
        excinfo = None
        start = timing.time()
        precise_start = timing.perf_counter()
        try:
>           result: TResult | None = func()

cls        = <class '_pytest.runner.CallInfo'>
duration   = 0.005907708022277802
excinfo    = <ExceptionInfo PytestUnraisableExceptionWarning('Exception ignored in: <function IOBase.__del__ at 0x7fc35010e8e0>\n\nTraceback (most...s()\n    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^\nAttributeError: \'MockSocket\' object has no attribute \'_decref_socketios\'\n') tblen=12>
func       = <function call_and_report.<locals>.<lambda> at 0x7fc34e78e8e0>
precise_start = 515484.144903254
precise_stop = 515484.150810962
reraise    = (<class '_pytest.outcomes.Exit'>, <class 'KeyboardInterrupt'>)
result     = None
start      = 1730812298.088149
stop       = 1730812298.0940628
when       = 'call'

/usr/lib/python3.13/vendor-packages/_pytest/runner.py:341: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib/python3.13/vendor-packages/_pytest/runner.py:242: in <lambda>
    lambda: runtest_hook(item=item, **kwds), when=when, reraise=reraise
        item       = <Function test_bytes_read>
        kwds       = {}
        runtest_hook = <HookCaller 'pytest_runtest_call'>
/usr/lib/python3.13/vendor-packages/pluggy/_hooks.py:513: in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
        firstresult = False
        kwargs     = {'item': <Function test_bytes_read>}
        self       = <HookCaller 'pytest_runtest_call'>
/usr/lib/python3.13/vendor-packages/pluggy/_manager.py:120: in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
        firstresult = False
        hook_name  = 'pytest_runtest_call'
        kwargs     = {'item': <Function test_bytes_read>}
        methods    = [<HookImpl plugin_name='runner', plugin=<module '_pytest.runner' from '/usr/lib/python3.13/vendor-packages/_pytest/runner.py'>>,
 <HookImpl plugin_name='skipping', plugin=<module '_pytest.skipping' from '/usr/lib/python3.13/vendor-packages/_pytest/skipping.py'>>,
 <HookImpl plugin_name='hypothesispytest', plugin=<module '_hypothesis_pytestplugin' from '/usr/lib/python3.13/vendor-packages/_hypothesis_pytestplugin.py'>>,
 <HookImpl plugin_name='capturemanager', plugin=<CaptureManager _method='fd' _global_capturing=<MultiCapture out=<FDCapture 1 oldfd=5 _state='suspended' tmpfile=<EncodedFile name="<_io.FileIO name=6 mode='rb+' closefd=True>" mode='r+' encoding='utf-8'>> err=<FDCapture 2 oldfd=7 _state='suspended' tmpfile=<EncodedFile name="<_io.FileIO name=8 mode='rb+' closefd=True>" mode='r+' encoding='utf-8'>> in_=<FDCapture 0 oldfd=3 _state='started' tmpfile=<_io.TextIOWrapper name='/dev/null' mode='r' encoding='utf-8'>> _state='suspended' _in_suspended=False> _capture_fixture=None>>,
 <HookImpl plugin_name='logging-plugin', plugin=<_pytest.logging.LoggingPlugin object at 0x7fc34fc08ec0>>,
 <HookImpl plugin_name='unraisableexception', plugin=<module '_pytest.unraisableexception' from '/usr/lib/python3.13/vendor-packages/_pytest/unraisableexception.py'>>,
 <HookImpl plugin_name='threadexception', plugin=<module '_pytest.threadexception' from '/usr/lib/python3.13/vendor-packages/_pytest/threadexception.py'>>]
        self       = <_pytest.config.PytestPluginManager object at 0x7fc352d40590>
/usr/lib/python3.13/vendor-packages/_pytest/threadexception.py:92: in pytest_runtest_call
    yield from thread_exception_runtest_hook()
/usr/lib/python3.13/vendor-packages/_pytest/threadexception.py:68: in thread_exception_runtest_hook
    yield
        cm         = <_pytest.threadexception.catch_threading_exception object at 0x7fc34ea0e210>
/usr/lib/python3.13/vendor-packages/_pytest/unraisableexception.py:95: in pytest_runtest_call
    yield from unraisable_exception_runtest_hook()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    def unraisable_exception_runtest_hook() -> Generator[None]:
        with catch_unraisable_exception() as cm:
            try:
                yield
            finally:
                if cm.unraisable:
                    if cm.unraisable.err_msg is not None:
                        err_msg = cm.unraisable.err_msg
                    else:
                        err_msg = "Exception ignored in"
                    msg = f"{err_msg}: {cm.unraisable.object!r}\n\n"
                    msg += "".join(
                        traceback.format_exception(
                            cm.unraisable.exc_type,
                            cm.unraisable.exc_value,
                            cm.unraisable.exc_traceback,
                        )
                    )
>                   warnings.warn(pytest.PytestUnraisableExceptionWarning(msg))
E                   pytest.PytestUnraisableExceptionWarning: Exception ignored in: <function IOBase.__del__ at 0x7fc35010e8e0>
E                   
E                   Traceback (most recent call last):
E                     File "/usr/lib/python3.13/_pyio.py", line 418, in __del__
E                       self.close()
E                       ~~~~~~~~~~^^
E                     File "/usr/lib/python3.13/_pyio.py", line 818, in close
E                       self.raw.close()
E                       ~~~~~~~~~~~~~~^^
E                     File "/usr/lib/python3.13/socket.py", line 789, in close
E                       self._sock._decref_socketios()
E                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
E                   AttributeError: 'MockSocket' object has no attribute '_decref_socketios'

cm         = <_pytest.unraisableexception.catch_unraisable_exception object at 0x7fc34ea0f390>
err_msg    = 'Exception ignored in'
msg        = ('Exception ignored in: <function IOBase.__del__ at 0x7fc35010e8e0>\n'
 '\n'
 'Traceback (most recent call last):\n'
 '  File "/usr/lib/python3.13/_pyio.py", line 418, in __del__\n'
 '    self.close()\n'
 '    ~~~~~~~~~~^^\n'
 '  File "/usr/lib/python3.13/_pyio.py", line 818, in close\n'
 '    self.raw.close()\n'
 '    ~~~~~~~~~~~~~~^^\n'
 '  File "/usr/lib/python3.13/socket.py", line 789, in close\n'
 '    self._sock._decref_socketios()\n'
 '    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n'
 "AttributeError: 'MockSocket' object has no attribute '_decref_socketios'\n")

(test_bytes_written fails with pretty much the same one)

📋 Environment

• Cheroot version: tested with 10.0.0 and 11.0.0b3
• Python version: 3.13.0
• OS: Oracle Solaris (but this doesn't seem to be platform dependent)

📋 Additional context

The following change fixed the issue for me:

--- cheroot-11.0.0b3/cheroot/test/test_makefile.py
+++ cheroot-11.0.0b3/cheroot/test/test_makefile.py
@@ -30,6 +30,9 @@ class MockSocket:
         """Simulate a send."""
         return len(val)
 
+    def _decref_socketios(self):
+        pass
+
 
 def test_bytes_read():
     """Reader should capture bytes read."""

[kulikjak]

Oh, and when I modify _pyio.py and IOBase in our Python 3.11 to not ignore these cleanup exceptions, it produces the same error as well.