Pytest fails on importing package in conftest.py with --cache-clear option

[martinwk]

The bug regards the import of the python package fipy I have installed with conda. If I import the package in the test_.py file, everything runs fine. If I import it in the conftest.py it also works fine. BUT when I add the --cache-clear option test discovery fails.
So this command works: python -m pytest --rootdir "c:\Users\korevma\Repositories\wt_process_models" -s tests_1 although it throws the following warning

============================================================================================================================================= test session starts ==============================================================================================================================================
platform win32 -- Python 3.6.13, pytest-6.2.2, py-1.10.0, pluggy-0.13.1 -- C:\Users\korevma\AppData\Local\Continuum\miniconda3\envs\wt_process_models\python.exe
cachedir: .pytest_cache
rootdir: c:\Users\korevma\Repositories\wt_process_models, configfile: pytest.ini
collected 1 item                                                                                                                                                                                                                                                                                                

tests_1/test_something.py::test_this PASSED

=============================================================================================================================================== warnings summary ===============================================================================================================================================
..\..\AppData\Local\Continuum\miniconda3\envs\wt_process_models\lib\site-packages\future\standard_library\__init__.py:65
  C:\Users\korevma\AppData\Local\Continuum\miniconda3\envs\wt_process_models\lib\site-packages\future\standard_library\__init__.py:65: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
    import imp

-- Docs: https://docs.pytest.org/en/stable/warnings.html
========================================================================================================================================= 1 passed, 1 warning in 1.27s =========================================================================================================================================

while adding the --cache-clear option fails

$ python -m pytest --rootdir "c:\Users\korevma\Repositories\wt_process_models" -s --cache-clear tests_1
Usage: __main__.py [options]

__main__.py: error: no such option: --cache-clear

If I remove the line import fipy from conftest.py python -m pytest --rootdir "c:\Users\korevma\Repositories\wt_process_models" -s --cache-clear tests_1 passes without errors or warnings

conftest.py

import fipy
import pytest


@pytest.fixture
def some_fixture():
    return 123

test_something.py

import pytest
# from wt_process_models import base_classes as bc

def test_this():
    assert True

pytest.ini

[pytest]
testpaths = tests
addopts =
    -r a
    -v
junit_family=legacy

packages and OS versions

platform win32 -- Python 3.6.13, pytest-6.2.2, py-1.10.0, pluggy-0.13.1 -- C:\Users\korevma\AppData\Local\Continuum\miniconda3\envs\wt_process_models\python.exe

pip -list

Package                       Version
----------------------------- ------------
alabaster                     0.7.12
apptools                      5.1.0
APScheduler                   3.7.0
astroid                       2.4.2
atomicwrites                  1.4.0
attrs                         20.3.0
autopep8                      1.5.5
Babel                         2.9.0
backports.functools-lru-cache 1.6.3
brotlipy                      0.7.0
certifi                       2020.12.5
cffi                          1.14.5
chardet                       4.0.0
colorama                      0.4.4
configobj                     5.0.6
cryptography                  3.4.7
cycler                        0.10.0
decorator                     5.0.5
docutils                      0.17
envisage                      4.9.2
et-xmlfile                    1.0.1
FiPy                          3.4.2.1
future                        0.18.2
idna                          2.10
imagesize                     1.2.0
importlib-metadata            3.10.0
importlib-resources           5.1.2
iniconfig                     1.1.1
ipdb                          0.13.4
ipython                       5.8.0
ipython-genutils              0.2.0
isort                         5.8.0
jdcal                         1.4.1
Jinja2                        2.11.3
joblib                        1.0.1
kiwisolver                    1.3.1
lazy-object-proxy             1.4.3
MarkupSafe                    1.1.1
matplotlib                    3.3.4
mayavi                        4.7.1
mccabe                        0.6.1
more-itertools                8.7.0
numpy                         1.19.5
olefile                       0.46
openpyxl                      3.0.6
packaging                     20.9
pandas                        1.1.5
patsy                         0.5.1
pickleshare                   0.7.5
Pillow                        8.1.2
Pint                          0.16.1
pip                           21.0.1
plotly                        4.14.3
pluggy                        0.13.1
prompt-toolkit                1.0.15
py                            1.10.0
pycodestyle                   2.7.0
pycparser                     2.20
pyface                        7.3.0
Pygments                      2.8.1
pyiast                        1.4.3
pylint                        2.6.0
pyOpenSSL                     20.0.1
pyparsing                     2.4.7
PyQt5                         5.12.3
PyQt5-sip                     4.19.18
PyQtChart                     5.12
PyQtWebEngine                 5.12.1
PySocks                       1.7.1
pytest                        6.2.2
python-dateutil               2.8.1
pytz                          2021.1
requests                      2.25.1
retrying                      1.3.3
scikit-learn                  0.23.1
scipy                         1.5.3
seaborn                       0.11.1
setuptools                    46.1.3
simplegeneric                 0.8.1
six                           1.15.0
snowballstemmer               2.1.0
Sphinx                        3.5.3
sphinx-rtd-theme              0.5.1
sphinxcontrib-applehelp       1.0.2
sphinxcontrib-devhelp         1.0.2
sphinxcontrib-htmlhelp        1.0.3
sphinxcontrib-jsmath          1.0.1
sphinxcontrib-qthelp          1.0.3
sphinxcontrib-serializinghtml 1.1.4
statsmodels                   0.12.2
threadpoolctl                 2.1.0
toml                          0.10.2
tornado                       6.1
traitlets                     4.3.3
traits                        6.2.0
traitsui                      7.1.0
typed-ast                     1.4.2
typing-extensions             3.7.4.3
tzlocal                       2.0.0
urllib3                       1.26.4
vtk                           -PKG-VERSION
wcwidth                       0.2.5
wheel                         0.34.2
win-inet-pton                 1.1.0
wincertstore                  0.2
wrapt                         1.11.2
zipp                          3.4.1

[The-Compiler]

Are you really running python -m pytest in the first example? What you see in the second example isn't actually pytest, it's a thing called "pytest" (but totally unrelated to this project) coming from old pylint versions, via logilab-common: #1833 - I suspect you're running things in two different environments.

[asottile]

the warning there comes from some chain of things importing future (which imports the deprecated imp module) -- this is unrelated to pytest

[martinwk]

So this is something that needs to be addressed by the package I rely on, of which I can't do much about it. So best solution is to catch and silent that warning I presume?

[asottile]

yep! here's the docs on that: https://docs.pytest.org/en/stable/warnings.html

though realistically, the dependency should probably be fixed to not need python-future since python2 support is probably not desirable

[martinwk]

Thanks for the link!

I agree that it should this should be solved in the dependency itself, but there is much I can do. There is only so much we can do in a day🙂 I will file a feature request there as well