Tests fail with python3.8, latest version pulled from master (Linux Mint / Ubuntu)

Hello,

Trying to update the (unofficial) Ubuntu 20.04 package on my PPA to a newer version, I got an error in the tests. I reproduced it at home (Linux Mint), just running python3.8 -m pytest: (NB I tried also with the 4.3.3 release (pointing git’s HEAD to 3bc6f0c Release 4.3.3) and got the exact same output)

$ python3.8 -m pytest
============================= test session starts ==============================
platform linux -- Python 3.8.5, pytest-4.6.9, py-1.9.0, pluggy-0.13.1
rootdir: /home/nico/.local/dev/pyfakefs
plugins: cov-2.8.1, mock-1.10.4, pyfakefs-4.2.dev0
collected 2024 items                                                           

pyfakefs/pytest_tests/pytest_check_failed_plugin_test.py s               [  0%]
pyfakefs/pytest_tests/pytest_fixture_param_test.py x..                   [  0%]
pyfakefs/pytest_tests/pytest_fixture_test.py x..                         [  0%]
pyfakefs/pytest_tests/pytest_plugin_test.py ...                          [  0%]
pyfakefs/tests/dynamic_patch_test.py .....                               [  0%]
pyfakefs/tests/example_test.py .......s                                  [  1%]
pyfakefs/tests/fake_filesystem_glob_test.py .........                    [  1%]
pyfakefs/tests/fake_filesystem_shutil_test.py ...............s...sssssss [  2%]
ssssssssssssss...........sssssssssss                                     [  4%]
pyfakefs/tests/fake_filesystem_test.py ................................. [  6%]
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pyfakefs/tests/fake_filesystem_unittest_test.py ........................ [ 18%]
.x...............................x..........................             [ 20%]
pyfakefs/tests/fake_filesystem_vs_real_test.py ......................... [ 22%]
..                                                                       [ 22%]
pyfakefs/tests/fake_open_test.py ....................................... [ 24%]
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pyfakefs/tests/fake_os_test.py ......................................... [ 38%]
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ssssss.......sss                                                         [ 85%]
pyfakefs/tests/fake_pathlib_test.py ....s.ssssssssssssss.s......ssssssss [ 86%]
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ssssssssssssss.....................................sssssssssssssssssssss [ 94%]
ssssssssssssssss.....                                                    [ 95%]
pyfakefs/tests/fake_stat_time_test.py .......sssssss........ssssssss.... [ 96%]
...sssssss........ssssssss.....sssss......ssssss                         [ 99%]
pyfakefs/tests/fake_tempfile_test.py ........                            [ 99%]
pyfakefs/tests/mox3_stubout_test.py .........                            [100%]

=================================== FAILURES ===================================
___________________ FakeOsModuleTest.test_open_existing_pipe ___________________

self = <pyfakefs.tests.fake_os_test.FakeOsModuleTest testMethod=test_open_existing_pipe>

    def test_open_existing_pipe(self):
        if self.is_pypy:
            raise unittest.SkipTest('Does not work correctly with PyPy')
        read_fd, write_fd = self.os.pipe()
        with self.open(write_fd, 'wb') as f:
>           self.assertEqual(4, f.write(b'test'))

pyfakefs/tests/fake_os_test.py:2709: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <pyfakefs.fake_filesystem.FakePipeWrapper object at 0x7fe042b61d30>
contents = b'test'

    def write(self, contents):
        """Write to the real pipe."""
>       return os.write(self.fd, contents)
E       OSError: [Errno 9] Bad file descriptor

pyfakefs/fake_filesystem.py:5156: OSError
======== 1 failed, 1212 passed, 807 skipped, 4 xfailed in 6.16 seconds =========
Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/usr/lib/python3/dist-packages/pytest.py", line 102, in <module>
    raise SystemExit(pytest.main())
  File "/usr/lib/python3/dist-packages/_pytest/config/__init__.py", line 82, in main
    return config.hook.pytest_cmdline_main(config=config)
  File "/home/nico/.local/lib/python3.8/site-packages/pluggy/hooks.py", line 286, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "/home/nico/.local/lib/python3.8/site-packages/pluggy/manager.py", line 93, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "/home/nico/.local/lib/python3.8/site-packages/pluggy/manager.py", line 84, in <lambda>
    self._inner_hookexec = lambda hook, methods, kwargs: hook.multicall(
  File "/home/nico/.local/lib/python3.8/site-packages/pluggy/callers.py", line 208, in _multicall
    return outcome.get_result()
  File "/home/nico/.local/lib/python3.8/site-packages/pluggy/callers.py", line 80, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/home/nico/.local/lib/python3.8/site-packages/pluggy/callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "/usr/lib/python3/dist-packages/_pytest/main.py", line 243, in pytest_cmdline_main
    return wrap_session(config, _main)
  File "/usr/lib/python3/dist-packages/_pytest/main.py", line 238, in wrap_session
    config._ensure_unconfigure()
  File "/usr/lib/python3/dist-packages/_pytest/config/__init__.py", line 732, in _ensure_unconfigure
    fin()
  File "/usr/lib/python3/dist-packages/_pytest/capture.py", line 127, in stop_global_capturing
    self._global_capturing.stop_capturing()
  File "/usr/lib/python3/dist-packages/_pytest/capture.py", line 532, in stop_capturing
    self.in_.done()
  File "/usr/lib/python3/dist-packages/_pytest/capture.py", line 611, in done
    _attempt_to_close_capture_file(self.tmpfile)
  File "/usr/lib/python3/dist-packages/_pytest/capture.py", line 850, in _attempt_to_close_capture_file
    f.close()
OSError: [Errno 9] Bad file descriptor

Environment details

Python 3.8.5 (default, Jul 28 2020, 12:59:40) 
[GCC 9.3.0]
pyfakefs 4.4dev

[nicolashainaux]

Many thanks for investigating this so quickly and efficiently 👍 Moreover, the warnings are gone, too. I should be able to package a newer version, then.

[mrbean-bremen]

Ok, after updating to Ubuntu 20.04.1 and installing Python 3.8.6 I still cannot reproduce the warnings, so I’m going to ignore them for now, as they also don’t show up in CI. Closing this as fixed - feel free to reopen it if needed. Thanks again for the report!