unable to add cmd line option dynamically

[revesansparole]

I want to run pytest with coverage option only when the command is not launched inside pycharm. Previously I just added a hook in conftest.py and it was working well:

def pytest_cmdline_preparse(args):
    if 'PYCHARM_HOSTED' not in os.environ:
        args.append("--cov=waloupkg")

However the latest pytest calls this hook only after pytest-cov hooks have been already called and I'm unable to launch the cov pluggin as demonstrated below. In case 1) I do not get a coverage report while in case 2) I get one (not displayed here).

1. This is what happen when I do not specify '--cov' on the command line expecting my hook to do it for me:

(toto) C:\Users\jchopard\Documents\eval\pkging\waloupkg
>pytest -s
cov: pytest_load_initial_conftests ['--maxfail=2', '-rf', '-s']
mine: pytest_cmdline_preparse
=============================================== test session starts ================================================
platform win32 -- Python 3.7.1, pytest-3.10.0, py-1.7.0, pluggy-0.8.0
rootdir: C:\Users\jchopard\Documents\eval\pkging\waloupkg, inifile: setup.cfg
plugins: cov-2.6.0
collected 1 item

2. This is what happen when I explicitly specify '--cov' on the command line

(toto) C:\Users\jchopard\Documents\eval\pkging\waloupkg
>pytest -s --cov
cov: pytest_load_initial_conftests ['--maxfail=2', '-rf', '-s', '--cov']
cov: __init__
cov: start
mine: pytest_cmdline_preparse
=============================================== test session starts ================================================
platform win32 -- Python 3.7.1, pytest-3.10.0, py-1.7.0, pluggy-0.8.0
rootdir: C:\Users\jchopard\Documents\eval\pkging\waloupkg, inifile: setup.cfg
plugins: cov-2.6.0
collected 1 item

PS: I tried to use pytest_load_initial_conftestsinstead of pytest_cmdline_preparse but the hook was never called.

[revesansparole]

addendum: apparently the problem is not the order but the fact that pytest_configure does not exists anymore in pytest-cov. I tried to add it by hand but pytest is not calling it.

[blueyed]

Try setting PYTEST_ADDOPTS maybe dynamically instead.

[revesansparole]

@blueyed my understanding of the problem is that the --cov option need to be set before the calls to pytest-cov plugin initialisation. I don't see any entry point in the workflow of pytest that would allow me to do that. Am-I missing something?

[blueyed]

What I've meant is to set PYTEST_ADDOPTS="--cov …" dynamically (via a wrapper that you would use in pycharm). Just some idea.

But in general it might sound like some kind of regression (either in pytest or pytest-cov), so it might be useful to know when this stopped working for you? I would guess with pytest-cov 2.6 maybe.

[revesansparole]

I think the problem is both pytest and pytest-cov but I've moved (more like duplicated) the issue in pytest-cov. I'll wait for their solution.

[blueyed]

Well, it is currently mainly me and Bruno there, too.. ;)
It would help to a) link/refer the issues (just mention the others URL), and b) see which version (and commit, using git-bisect) changed the behavior.

[Zac-HD]

Moved to pytest-dev/pytest-cov#241