Poetry and Pytest-cov with Sonar: how to reconcile the references?

Question

I'm migrating all my modules to Poetry and I have a problem.

Before with a python setup.py test I was able to run my tests with the correct coverage information.

Now I'm moving to poetry, so my best option is poetry run pytest or otherwise poetry install; pytest. In both cases, I have to specify the source location in Sonar to collect the coverage data. Here I would naturally just pass my src folder, but clearly the references will be wrong because pytest is running using the code installed in the environment by poetry, not on the local code as it used to happen before, so the references will be mismatched. No amount of tinkering seems to be working.

So, is there a way with poetry to use the local references instead of the environment references when running with pytest? Or should I give up and use some weird trick with inspect to retrieve the path of the installed package in the site-packages folder?

Answer 1

Your current setup where pytest is run against the installed package instead of the source files is vastly preferable, since it simulates the behavior of the code as it will behave in use. Path errors, files that were not correctly marked/moved for install, or any other thing that can go wrong during deployment will be encountered right away at no cost whatsoever.

It also helps giving a more accurate coverage, since e.g. any build files that are not part of the package will be ignored. All that you need in order to tell coverage to look at the package instead of your source files is to tell it exactly that. Having this in your .coveragerc should be enough:

[run]
source = sample_project

Given a project structure like this^[1]

.
├── .coveragerc
├── src
│   └── sample_project
│       ├── __init__.py
│       └── util.py
└── tests
    ├── __init__.py
    └── test_util.py

Running pytest --cov tests/ looks inside the installed package correctly:

Test session starts (platform: linux, Python 3.7.2, pytest 3.10.1, pytest-sugar 0.9.2)
rootdir: /home/user/dev/sample_project, inifile:
plugins: sugar-0.9.2, cov-2.7.1
collecting ... 
 tests/test_util.py ✓                                                  100% ██████████

----------- coverage: platform linux, python 3.7.2-final-0 -----------
Name                 Stmts   Miss  Cover
----------------------------------------
tests/__init__.py        0      0   100%
tests/test_util.py       6      0   100%
----------------------------------------
TOTAL                    6      0   100%


Results (0.10s):
       1 passed

---

^{[1] _{It might be important to split off the source code in a directory to avoid name shadowing (the import mechanism will prefer a local package foo in its PYTHONPATH which the working directory is always part of over an installed package foo). From your description, it seems that you're already doing that. If you aren't, consider setting up your project again with poetry new and its optional --src flag enabled.}}