pytest test discovery failed with pytest-pep8 installed

Environment data

Version: 1.38.0 Commit: 3db7e09f3b61f915d03bbfa58e258d6eee843f35 Date: 2019-09-03T21:51:09.716Z Electron: 4.2.10 Chrome: 69.0.3497.128 Node.js: 10.11.0 V8: 6.9.427.31-electron.0 OS: Linux x64 4.15.0-36-generic Extension Name: Python Id: ms-python.python Version: 2019.9.34911 Publisher: Microsoft Python version: 3.5/3.6/3.7

Expected behavior

Tests discovered

Actual behavior

Tests discovering failed.

The workaround is to remove --pep8 keyword from pytestArgs property.

Steps to reproduce:

1. clone https://github.com/zztalker/just_for_test ( git clone https://github.com/zztalker/just_for_test)
2. Install requrements (pip install -r requirements.txt), we need only pytest-pep8
3. Open VS Code from folder (code .)
4. Turn on test discovery and add in settings:

{
    "python.testing.pytestArgs": [
        "--pep8",
        "."
    ],
    "python.testing.unittestEnabled": false,
    "python.testing.nosetestsEnabled": false,
    "python.testing.pytestEnabled": true
}

1. Try to discover tests.

Logs

Output for Python Test Log in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

python /home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/run_adapter.py discover pytest -- -s --cache-clear --pep8 .
Test Discovery failed: 
Error: /home/pz/.local/lib/python3.7/site-packages/pep8.py:110: FutureWarning: Possible nested set at position 1
  EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')
============================= test session starts ==============================
platform linux -- Python 3.7.4, pytest-4.6.3, py-1.8.0, pluggy-0.12.0
rootdir: /home/pz/snippets/cool-tests, inifile: pytest.ini
plugins: pep8-1.0.6
DBG parse item <Pep8Item test_pytest1.py> test_pytest1.py None
collected 9 items
<Pep8Item test_pytest1.py>
<Module test_pytest1.py>
  <Function test_pytest1_test1>
  <Function test_pytest1_test2>
  <Function test_even_failed>
  <Function test_odd_failed>
  <Function test_random>
<Pep8Item test_foldered/test_pytest2.py>
<Module test_foldered/test_pytest2.py>
  <Function test_pytest2_test3>
  <Function test_pytest2_test4>
DBG parse item <Pep8Item test_pytest1.py> test_pytest1.py None
INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/_pytest/main.py", line 498, in perform_collect
INTERNALERROR>     session=self, config=self.config, items=items
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/hooks.py", line 289, in __call__
INTERNALERROR>     return self._hookexec(self, self.get_hookimpls(), kwargs)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/manager.py", line 87, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/manager.py", line 81, in <lambda>
INTERNALERROR>     firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 208, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 80, in get_result
INTERNALERROR>     raise ex[1].with_traceback(ex[2])
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 187, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_discovery.py", line 80, in pytest_collection_modifyitems
INTERNALERROR>     test, parents = self.parse_item(item)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_discovery.py", line 65, in parse_item
INTERNALERROR>     return parse_item(item)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_pytest_item.py", line 163, in parse_item
INTERNALERROR>     testroot, relfile = _split_fspath(str(item.fspath), fileid, item)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_pytest_item.py", line 142, in <lambda>
INTERNALERROR>     _split_fspath=(lambda *a: _split_fspath(*a)),
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_pytest_item.py", line 232, in _split_fspath
INTERNALERROR>     relsuffix = fileid[1:]  # Drop (only) the "." prefix.
INTERNALERROR> TypeError: 'NoneType' object is not subscriptable
INTERNALERROR> 
INTERNALERROR> During handling of the above exception, another exception occurred:
INTERNALERROR> 
INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/_pytest/main.py", line 206, in wrap_session
INTERNALERROR>     session.exitstatus = doit(config, session) or 0
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/_pytest/main.py", line 249, in _main
INTERNALERROR>     config.hook.pytest_collection(session=session)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/hooks.py", line 289, in __call__
INTERNALERROR>     return self._hookexec(self, self.get_hookimpls(), kwargs)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/manager.py", line 87, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/manager.py", line 81, in <lambda>
INTERNALERROR>     firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 208, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 80, in get_result
INTERNALERROR>     raise ex[1].with_traceback(ex[2])
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 187, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/_pytest/main.py", line 259, in pytest_collection
INTERNALERROR>     return session.perform_collect()
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/_pytest/main.py", line 501, in perform_collect
INTERNALERROR>     hook.pytest_collection_finish(session=self)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/hooks.py", line 289, in __call__
INTERNALERROR>     return self._hookexec(self, self.get_hookimpls(), kwargs)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/manager.py", line 87, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/manager.py", line 81, in <lambda>
INTERNALERROR>     firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 208, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 80, in get_result
INTERNALERROR>     raise ex[1].with_traceback(ex[2])
INTERNALERROR>   File "/home/pz/.local/lib/python3.7/site-packages/pluggy/callers.py", line 187, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_discovery.py", line 94, in pytest_collection_finish
INTERNALERROR>     test, parents = self.parse_item(item)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_discovery.py", line 65, in parse_item
INTERNALERROR>     return parse_item(item)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_pytest_item.py", line 163, in parse_item
INTERNALERROR>     testroot, relfile = _split_fspath(str(item.fspath), fileid, item)
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_pytest_item.py", line 142, in <lambda>
INTERNALERROR>     _split_fspath=(lambda *a: _split_fspath(*a)),
INTERNALERROR>   File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_pytest_item.py", line 232, in _split_fspath
INTERNALERROR>     relsuffix = fileid[1:]  # Drop (only) the "." prefix.
INTERNALERROR> TypeError: 'NoneType' object is not subscriptable

========================== 1 warnings in 0.02 seconds ==========================

Traceback (most recent call last):
  File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/run_adapter.py", line 18, in <module>
    main(tool, cmd, subargs, toolargs)
  File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/__main__.py", line 90, in main
    parents, result = run(toolargs, **subargs)
  File "/home/pz/.vscode/extensions/ms-python.python-2019.9.34911/pythonFiles/testing_tools/adapter/pytest/_discovery.py", line 35, in discover
    raise Exception('pytest discovery failed (exit code {})'.format(ec))
Exception: pytest discovery failed (exit code 3)

[zztalker]

I believe, that problem in section, and will try to look into code for more details:

<Pep8Item test_pytest1.py>

[kimadeline]

✅ Validated in 2019.12.48501-dev, test discovery doesn’t fail with "python.testing.pytestEnabled": true and the following settings:

 "python.testing.pytestArgs": [
        "--pep8",
        "."
    ],