Tox 0% coverage | 易学教程

问题

I have a python project where I use:

pipenv
tox
pytest

and many more.

Basically, I want to add tox to my gitlab pipelines. And almost everything seems to work, calling mypy, flake8 or black from tox works fine. But when I call tox -e py37 (so I want to run the tests) with coverage enabled, the tests are run, I can see their results, but the coverage is 0% (100% only on empty __init__ files etc.) and I get the warning: Coverage.py warning: No data was collected. (no-data-collected).

This is my pytest-relevant part of tox.ini:

[tox]
envlist = flake8,mypy,black,py37

[testenv]
extras = tests
commands=
    pytest --cov -ra --tb=short {posargs}

And this is my .coveragerc:

[run]
branch = True
source =
    foo

omit = 
    foo/__init__.py
    foo/__main__.py
    foo/bar/__init__.py
    foo/baz/__init__.py

[report]
exclude_lines =
    pragma: no cover
    if __name__ == .__main__.
show_missing = True

I have a working setup.py which includes all needed packages: pytest, pytest-cov and many more for style etc. (which works). I also have __init__.py in my tests folder.

Funny thing is, if I call the same command I have in tox.ini from my command line (in pipenv): pytest --cov -ra --tb=short, I get the same results but with normal coverage (in my case it's 100%).

Is there a way to fix it? I don't want my pipelines to show wrong coverage + even if they somehow magically would actually get the right one, I still would want to see it locally.

P.S When I was trying to resolve the issue I called tox with tox --sitepackages -e py37 and I got some errors like test command found but not in testenv. And besides those errors, my coverage was fine then. But then I uninstalled tox, pytest and pytest-cov from my global pip register and now with or without --sitepackages flag I still get 0% coverage

回答1:

The root-cause is that pytest during runnung tox uses the installed sources (under site-packages) while the coverage reporter count the hits files in the working directory (ie. your local git repo).

Solution

Add the tox's virtual-env path to coverage:

[testenv]
pytest --cov={envsitepackagesdir}/foo

For more detail read substitutions for virtualenv-related sections

Work-around

Set PYTHONPATH to working directory (ie. export PYTHONPATH=.). Note, that you need to pass the PYTHONPATH to tox by:

[testenv]
passenv =
    PYTHONPATH

This is easy, but using this way, you don't test the installation, because the tests runs on the files in the working directory.

来源：https://stackoverflow.com/questions/58696476/tox-0-coverage

标签

python

python-3.x

pytest

tox

coverage.py