pytest coverage not working after python update to 3.11

Issue: pytest stopped generating coverage

Description: I upgraded python version from 3.6 to 3.11 (Ubuntu 18.04). I followed this https://www.debugpoint.com/install-python-3-11-ubuntu/ in order to do that. Had issues with pip, followed this advice: https://stackoverflow.com/a/72685573/15923186

I have a project with following structure:

test.sh
|-sorting
  |- env (the virtual environment for sorting)
  |- requirements.txt
  |- pyproject.toml
  |- __init__.py
  |- merge_sort.py
  |- tests
     |-__init__.py
     |-test_merge_sort.py
  
|-something_else (etc.)

requirements.txt are following:

attrs==22.1.0
black==22.8.0
click==8.0.4
coverage==6.2
flake8==5.0.4
importlib-metadata==4.2.0
iniconfig==1.1.1
mccabe==0.7.0
mypy-extensions==0.4.3
packaging==21.3
pathspec==0.9.0
platformdirs==2.4.0
pluggy==1.0.0
py==1.11.0
pycodestyle==2.9.1
pyflakes==2.5.0
pyparsing==3.0.9
pytest==7.0.1
pytest-cov==4.0.0
pytest-cover==3.0.0
tomli==1.2.3
typing-extensions==4.1.1
zipp==3.6.0

Pyproject is following:

[tool.pytest.ini_options]
pythonpath = [
  "."
]

The test script is following:

#!/bin/bash

source "$1"/env/bin/activate

cd "$1" || { echo "Project not found!"; exit 1;}

pytest -vv --cov="$1" --cov-report xml --cov-report term

And is invoked like this: ./test.sh sorting

I'm not "reusing" old virtual environments, I double checked. Before running tests I prepared a new one like this (the same as previously when using python 3.6):

python3 -m venv env
source env/bin/activate
pip install -r requirements.txt

Python 3.11 is the default one for python3 command (output below):

> Python 3.11.0 (main, Oct 24 2022, 19:56:01) [GCC 7.5.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>

Result: Nothing displayed, no coverage report generated

Expected result: Coverage report generated and displayed in the terminal

I also tried to run with:

python3 -m pytest -vv --cov="$1" --cov-report xml --cov-report term

No difference.

If I remove

 --cov="$1" --cov-report xml --cov-report term

from the test.sh script I get following output (which is good and expected)

test session starts ================================================================
platform linux -- Python 3.11.0, pytest-7.0.1, pluggy-1.0.0 -- /path/to/the/env/which/is/irrelevant/sorting/env/bin/python3
cachedir: .pytest_cache
rootdir: /home/mysusrname/folder_name/subfolder_name/sorting, configfile: pyproject.toml
plugins: cov-4.0.0
collected 3 items                                                                                                                                  

tests/test_merge_sort.py::test_merge_sort[numbers0] PASSED                                                                                   [ 33%]
tests/test_merge_sort.py::test_merge_sort[numbers1] PASSED                                                                                   [ 66%]
tests/test_merge_sort.py::test_merge_sort[numbers2] PASSED                                                                                   [100%]

3 passed in 0.01s =================================================================

Solution

So I couldn't agree with @Nathan and kept digging and actually my first comment is right and seems to be faster and imho cleaner solution.

After upgrading python like I described and having a requirements.txt with fixed versions:

delete the old virtual environment

remove versions from requirements.txt (example below):

  attrs
  black
  click
  coverage
  flake8
  importlib-metadata
  iniconfig
  mccabe
  mypy-extensions
  packaging
  pathspec
  platformdirs
  pluggy
  py
  pycodestyle
  pyflakes
  pyparsing
  pytest
  pytest-cov
  pytest-cover
  tomli
  typing_extensions
  zipp

after creating a "fresh" venv and sourcing it run pip install --upgrade pip to make sure the pip is up to date
install the packages (utilizing the requirements.txt with NO versions specified in the venv mentioned above) pip install -r requirements.txt
the newest versions supported for your python distro will be used in such case

run pip freeze > requirements.txt to overwrite the requirements file and again have stable version of it with versions of libraries fixed (example corresponding "clean" file below)

  attrs==22.1.0
  black==22.12.0
  click==8.1.3
  coverage==6.5.0
  flake8==6.0.0
  importlib-metadata==5.1.0
  iniconfig==1.1.1
  mccabe==0.7.0
  mypy-extensions==0.4.3
  packaging==22.0
  pathspec==0.10.3
  platformdirs==2.6.0
  pluggy==1.0.0
  py==1.11.0
  pycodestyle==2.10.0
  pyflakes==3.0.1
  pyparsing==3.0.9
  pytest==7.2.0
  pytest-cov==4.0.0
  pytest-cover==3.0.0
  tomli==2.0.1
  typing_extensions==4.4.0
  zipp==3.11.0

Side notes: I don't think having multiple versions of python is convenient to use, nor it is required in most cases actually. Probably one version as a "default"/to go and maybe a new release / release candidate as a second one is enough. Cannot imagine a situation where I need 5 or 6 versions...The venvs manage versions of python libraries and e.g. docker containers (or other virtualization method) can abstract anything else (not necessarily python related). Not to be misunderstood: Is @Nathan 's solution bad? Nope, it's good, but there are some points I disagree with, that's all. Also his comments helped me out to come up with a solution of my own, so upvote from me :)