TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union

[JoeloBineo]

hello i´am using pytest and when I use pytest versión 8.1.1 crashed the github action and with 8.0.1 my action run fine.
the complete error is next:

i belive that I should considered one point in the upgrade in pytest. can you help me ?

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/cmdline.py", line 858, in do_run
    runner.run()
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/execfile.py", line 255, in run
    sys.exit(1)
SystemExit: 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.10.13/x64/bin/coverage", line 8, in <module>
    sys.exit(main())
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/cmdline.py", line 970, in main
    status = CoverageScript().command_line(argv)
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/cmdline.py", line 681, in command_line
    return self.do_run(options, args)
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/cmdline.py", line 865, in do_run
    self.coverage.save()
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/control.py", line 784, in save
    data = self.get_data()
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/control.py", line 865, in get_data
    self._post_save_work()
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/control.py", line 892, in _post_save_work
    for file_path, plugin_name in self._inorout.find_possibly_unexecuted_files():
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/inorout.py", line 534, in find_possibly_unexecuted_files
    yield from self._find_executable_files(src)
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/inorout.py", line 558, in _find_executable_files
    for file_path, plugin_name in itertools.chain(py_files, plugin_files):
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/inorout.py", line 552, in <genexpr>
    py_files = (
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/site-packages/coverage/files.py", line 542, in find_python_files
    if re.match(r"^[^.#~!$@%^&*()+=,]+\.pyw?$", filename):
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/re.py", line 190, in match
    return _compile(pattern, flags).match(string)
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/re.py", line 304, in _compile
    if not (flags & DEBUG):
  File "/opt/hostedtoolcache/Python/3.10.13/x64/lib/python3.10/enum.py", line 987, in __and__
    if not isinstance(other, (self.__class__, int)):
TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union
Error: Process completed with exit code 1.

[RonnyPfannschmidt]

this looks like a "impossible" error in the stdlib - based on the code shown, value MUST be a tuple of actual types,
the fact that it is not, points to something having gone really wrong, its not clear how to debug this

[manfre-lp]

I ran into a version of this issue.

  File "/app/.venv/lib/python3.11/site-packages/django/core/serializers/json.py", line 85, in default
    if isinstance(o, datetime.datetime):
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

For me, it was a result of mocking datetime.datetime. Removing the mock.patch resolved the issue.