Test invocation fails with Python 3.13.0~alpha2

[befeleme]

In Fedora Linux we try to build the Python libraries with Python 3.13.0 alpha versions.
Trio fails to build in our environment, more concretely the test invocation fail with a traceback below.

+ /usr/bin/pytest --pyargs trio -p trio._tests.pytest_plugin --verbose --skip-optional-imports
Traceback (most recent call last):
  File "/usr/bin/pytest", line 8, in <module>
    sys.exit(console_main())
             ^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 192, in console_main
    code = main()
           ^^^^^^
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 150, in main
    config = _prepareconfig(args, plugins)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 331, in _prepareconfig
    config = pluginmanager.hook.pytest_cmdline_parse(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/pluggy/_hooks.py", line 493, in __call__
    return self._hookexec(self.name, self._hookimpls, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/pluggy/_manager.py", line 115, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/pluggy/_callers.py", line 130, in _multicall
    teardown[0].send(outcome)
  File "/usr/lib/python3.13/site-packages/_pytest/helpconfig.py", line 104, in pytest_cmdline_parse
    config: Config = outcome.get_result()
                     ^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/pluggy/_result.py", line 114, in get_result
    raise exc.with_traceback(exc.__traceback__)
  File "/usr/lib/python3.13/site-packages/pluggy/_callers.py", line 77, in _multicall
    res = hook_impl.function(*args)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 1075, in pytest_cmdline_parse
    self.parse(args)
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 1425, in parse
    self._preparse(args, addopts=addopts)
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 1301, in _preparse
    self.pluginmanager.consider_preparse(args, exclude_only=False)
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 709, in consider_preparse
    self.consider_pluginarg(parg)
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 735, in consider_pluginarg
    self.import_plugin(arg, consider_entry_points=True)
  File "/usr/lib/python3.13/site-packages/_pytest/config/__init__.py", line 781, in import_plugin
    __import__(importspec)
  File "/builddir/build/BUILDROOT/python-trio-0.23.1-1.fc40.x86_64/usr/lib/python3.13/site-packages/trio/__init__.py", line 77, in <module>
    from ._path import Path as Path
  File "/builddir/build/BUILDROOT/python-trio-0.23.1-1.fc40.x86_64/usr/lib/python3.13/site-packages/trio/_path.py", line 201, in <module>
    class Path(metaclass=AsyncAutoWrapperType):
  File "/builddir/build/BUILDROOT/python-trio-0.23.1-1.fc40.x86_64/usr/lib/python3.13/site-packages/trio/_path.py", line 145, in __init__
    type(cls).generate_forwards(cls, attrs)
  File "/builddir/build/BUILDROOT/python-trio-0.23.1-1.fc40.x86_64/usr/lib/python3.13/site-packages/trio/_path.py", line 162, in generate_forwards
    raise TypeError(attr_name, type(attr))
TypeError: ('pathmod', <class 'module'>)

[A5rocks]

Unfortunately it appears that even if we fix this, one of our test deps (cryptography) doesn't support Python 3.13 yet :(

Oh and going up the chain of blockers, it seems that this won't be fixed until the betas.

[befeleme]

I agree it's a very early heads-up at the moment.

FTR, we've built both cryptography 41.0.5 (https://copr.fedorainfracloud.org/coprs/g/python/python3.13/package/python-cryptography/) and cffi (https://copr.fedorainfracloud.org/coprs/g/python/python3.13/package/python-cffi/) with Python 3.13.0. The cffi's main branch already contains fixes for Python 3.13.0.