tox fails on ImportError in python3.5

Question

I am trying to run tox package on my project which worked fine so far. I am running in Phycharm on Windows 10 Pro 64-bit, tox version 3.15.0 when I run the command:

python -m tox --recreate

tox tests pass for python3.6,3.7,3.8 but not for Python3.5.

This is the error I get when I run:

python -m tox -epy35

GLOB sdist-make: C:\Users\Or\Documents\Studies\TAU\Term2\Project2\Source_code\pylint_upload\setup.py
py35 recreate: C:\Users\Or\Documents\Studies\TAU\Term2\Project2\Source_code\pylint_upload\.tox\py35
py35 installdeps: https://github.com/PyCQA/astroid/tarball/master#egg=astroid-master-2.0, coverage<5.0, mccabe, isort>=4.2.5,<5, pytest, pytest-xdist, pytest-benchmark, pytest-p
rofiling
py35 inst: C:\Users\Or\Documents\Studies\TAU\Term2\Project2\Source_code\pylint_upload\.tox\.tmp\package\4\pylint-2.6.1.dev1.zip
py35 installed: apipkg==1.5,astroid @ https://github.com/PyCQA/astroid/tarball/master,atomicwrites==1.4.0,attrs==20.2.0,colorama==0.4.3,coverage==4.5.4,execnet==1.7.1,gprof2dot=
=2019.11.30,importlib-metadata==2.0.0,iniconfig==1.0.1,isort==4.3.21,lazy-object-proxy==1.4.3,mccabe==0.6.1,packaging==20.4,pathlib2==2.3.5,pluggy==0.13.1,py==1.9.0,py-cpuinfo==
7.0.0,pylint @ file:///C:/Users/Or/Documents/Studies/TAU/Term2/Project2/Source_code/pylint_upload/.tox/.tmp/package/4/pylint-2.6.1.dev1.zip,pyparsing==2.4.7,pytest==6.1.0,pytest
-benchmark==3.2.3,pytest-forked==1.3.0,pytest-profiling==1.7.0,pytest-xdist==2.1.0,six==1.15.0,toml==0.10.1,typed-ast==1.4.1,wrapt==1.12.1,zipp==1.2.0
py35 run-test-pre: PYTHONHASHSEED='454'
py35 run-test: commands[0] | python -Wignore -m coverage run -m pytest --benchmark-disable 'C:\Users\Or\Documents\Studies\TAU\Term2\Project2\Source_code\pylint_upload/tests/'
ImportError while loading conftest 'C:\Users\Or\Documents\Studies\TAU\Term2\Project2\Source_code\pylint_upload\tests\conftest.py'.
..\tests\conftest.py:9: in <module>
    from pylint.testutils import MinimalTestReporter
py35\lib\site-packages\pylint\testutils.py:274: in <module>
    checkers.initialize(linter)
py35\lib\site-packages\pylint\checkers\__init__.py:64: in initialize
    register_plugins(linter, __path__[0])
py35\lib\site-packages\pylint\utils\utils.py:255: in register_plugins
    os.path.join(directory, filename)
py35\lib\site-packages\astroid\modutils.py:284: in load_module_from_file
    return load_module_from_modpath(modpath, path, use_sys)
py35\lib\site-packages\astroid\modutils.py:245: in load_module_from_modpath
    module = imp.load_module(curname, mp_file, mp_filename, mp_desc)
C:\Program Files\Python 3.5\lib\imp.py:234: in load_module
    return load_source(name, filename, file)
C:\Program Files\Python 3.5\lib\imp.py:172: in load_source
    module = _load(spec)
py35\lib\site-packages\pylint\checkers\async.py:16: in <module>
    from pylint.checkers import utils as checker_utils
py35\lib\site-packages\pylint\checkers\utils.py:640: in <module>
    def is_attr_private(attrname: str) -> Optional[Match[str]]:
C:\Program Files\Python 3.5\lib\typing.py:631: in __getitem__
    return Union[arg, type(None)]
C:\Program Files\Python 3.5\lib\typing.py:534: in __getitem__
    dict(self.__dict__), parameters, _root=True)
C:\Program Files\Python 3.5\lib\typing.py:491: in __new__
    for t2 in all_params - {t1} if not isinstance(t2, TypeVar)):
C:\Program Files\Python 3.5\lib\typing.py:490: in <genexpr>
    if any(issubclass(t1, t2)
E   TypeError: issubclass() arg 1 must be a class
ERROR: InvocationError for command 'C:\Users\Or\Documents\Studies\TAU\Term2\Project2\Source_code\pylint_upload\.tox\py35\Scripts\python.EXE' -Wignore -m coverage run -m pytest -
-benchmark-disable 'C:\Users\Or\Documents\Studies\TAU\Term2\Project2\Source_code\pylint_upload/tests/' (exited with code 4)
___________________________________________________________________________________ summary ____________________________________________________________________________________
ERROR:   py35: commands failed

I didn't change this conftest.py file at all since it used to work, so I don't think this is the real cause of this error. Also the same command run successfully on my Linux machine on Ubuntu, for the same project. I tried to recreate tox again, tried to clone entire repository and run the test again, also tried this and this.

This is the tox.ini file:

[tox]
minversion = 2.4
envlist = py35, py36, py37, py38, pypy, pylint, benchmark
skip_missing_interpreters = true

[testenv:pylint]
deps =
   git+https://github.com/pycqa/astroid@master
   pytest
commands =
    # This would be greatly simplified by a solution for https://github.com/PyCQA/pylint/issues/352
    pylint -rn --rcfile={toxinidir}/pylintrc --load-plugins=pylint.extensions.docparams, pylint.extensions.mccabe \
    {toxinidir}/pylint \
    {toxinidir}/tests/message/ \
    {toxinidir}/tests/checkers/ \
    {toxinidir}/tests/extensions/ \
    {toxinidir}/tests/utils/ \
    {toxinidir}/tests/acceptance/ \
    {toxinidir}/tests/conftest.py \
    {toxinidir}/tests/test_config.py \
    {toxinidir}/tests/test_func.py \
    {toxinidir}/tests/test_functional.py \
    {toxinidir}/tests/test_import_graph.py \
    {toxinidir}/tests/test_pragma_parser.py \
    {toxinidir}/tests/test_pylint_runners.py \
    {toxinidir}/tests/test_regr.py \
    {toxinidir}/tests/test_self.py \
    {toxinidir}/tests/unittest_config.py \
    {toxinidir}/tests/lint/ \
    {toxinidir}/tests/unittest_pyreverse_diadefs.py \
    {toxinidir}/tests/unittest_pyreverse_inspector.py \
    {toxinidir}/tests/unittest_pyreverse_writer.py \
    {toxinidir}/tests/unittest_reporters_json.py \
    {toxinidir}/tests/unittest_reporting.py

[testenv:formatting]
basepython = python3
deps =
    black==20.8b1
    isort==5.5.2
commands =
    black --check . --exclude="tests/functional/|tests/input|tests/extensions/data|tests/regrtest_data/|tests/data/|venv|astroid|.tox"
    isort . --check-only
changedir = {toxinidir}

[testenv:mypy]
basepython = python3
deps =
    typed-ast>=1.4
    mypy>=0.7,<1.0

commands =
    python -m mypy {toxinidir}/pylint/checkers --ignore-missing-imports {posargs:}

[testenv]
deps =
   https://github.com/PyCQA/astroid/tarball/master#egg=astroid-master-2.0
   coverage<5.0
   mccabe
   # isort 5 is not compatible with Python 3.5
   py35: isort>=4.2.5,<5
   pytest
   pytest-xdist
   pytest-benchmark
   pytest-profiling

setenv =
    COVERAGE_FILE = {toxinidir}/.coverage.{envname}

commands =
    ; Run tests, ensuring all benchmark tests do not run
    python -Wignore -m coverage run -m pytest --benchmark-disable {toxinidir}/tests/ {posargs:}

    ; Transform absolute path to relative path
    ; for compatibility with coveralls.io and fix 'source not available' error.
    ; If you can find a cleaner way is welcome
    python -c "import os;cov_strip_abspath = open(os.environ['COVERAGE_FILE'], 'r').read().replace('.tox' + os.sep + os.path.relpath('{envsitepackagesdir}', '{toxworkdir}') + os.sep, '');open(os.environ['COVERAGE_FILE'], 'w').write(cov_strip_abspath)"
changedir = {toxworkdir}


[testenv:spelling]
deps =
   https://github.com/PyCQA/astroid/tarball/master#egg=astroid-master-2.0
   pytest
   pytest-xdist
   pyenchant

commands =
    python -Wi -m pytest {toxinidir}/tests/ {posargs:} -k unittest_spelling

changedir = {toxworkdir}

[testenv:coveralls]
setenv =
    COVERAGE_FILE = {toxinidir}/.coverage
passenv =
    *
deps =
    coverage<5.0
    coveralls
skip_install = true
commands =
    python -m coverage combine
    python -m coverage report --rcfile={toxinidir}/.coveragerc -m
    - coveralls --rcfile={toxinidir}/.coveragerc
changedir = {toxinidir}

[testenv:coverage-erase]
setenv =
    COVERAGE_FILE = {toxinidir}/.coverage
deps =
    coverage<5
skip_install = true
commands =
    python -m coverage erase
changedir = {toxinidir}

[testenv:coverage-html]
setenv =
    COVERAGE_FILE = {toxinidir}/.coverage
deps =
    coverage<5
skip_install = true
commands =
    python -m coverage combine
    python -m coverage html --ignore-errors --rcfile={toxinidir}/.coveragerc
changedir = {toxinidir}

[testenv:docs]
usedevelop = True
changedir = doc/
extras =
  docs
commands =
  sphinx-build -W -b html -d _build/doctrees . _build/html

[testenv:benchmark]
deps =
   https://github.com/PyCQA/astroid/tarball/master#egg=astroid-master-2.0
   coverage<5.0
   mccabe
   pytest
   pytest-xdist
   pygal
   pytest-benchmark

commands =
    ; Run the only the benchmark tests, grouping output and forcing .json output so we
    ; can compare benchmark runs
    python -Wi -m pytest --exitfirst \
                         --failed-first \
                         --benchmark-only \
                         --benchmark-save=batch_files \
                         --benchmark-save-data \
                         --benchmark-autosave \
                         {toxinidir}/tests \
                         --benchmark-group-by="group" \
                         {posargs:}

changedir = {toxworkdir}

And this is conftest.py:

# pylint: disable=redefined-outer-name
# pylint: disable=no-name-in-module
import os

import pytest

from pylint import checkers
from pylint.lint import PyLinter
from pylint.testutils import MinimalTestReporter


@pytest.fixture
def linter(checker, register, enable, disable, reporter):
    _linter = PyLinter()
    _linter.set_reporter(reporter())
    checkers.initialize(_linter)
    if register:
        register(_linter)
    if checker:
        _linter.register_checker(checker(_linter))
    if disable:
        for msg in disable:
            _linter.disable(msg)
    if enable:
        for msg in enable:
            _linter.enable(msg)
    os.environ.pop("PYLINTRC", None)
    return _linter


@pytest.fixture(scope="module")
def checker():
    return None


@pytest.fixture(scope="module")
def register():
    return None


@pytest.fixture(scope="module")
def enable():
    return None


@pytest.fixture(scope="module")
def disable():
    return None


@pytest.fixture(scope="module")
def reporter():
    return MinimalTestReporter

Answer 1

Your reported problem is actual a problem in Python 3.5.0!!

You can check your Python 3.5 version by entering a command like python3.5 --version or just enter python3.5 and have a look at the top of the repl output.

You can resolve the problem by installing the any higher point release of Python 3.5, e.g 3.5.1 or the even the latest one, 3.5.10.

This all said - Python 3.5 is already end of life ( https://www.python.org/downloads/ ). If there is no important reason, please consider to drop support for it.