python-pytest-cases: `pytest` run fails if `test/` folder is moved outside of the `pytest_cases/` folder (packaging scenario)

After install in install prefix I’m trying to test installed resources using pytest. Maybe I’m doing something wrong but this is what I’ve got:

+ PYTHONPATH=/home/tkloczko/rpmbuild/BUILDROOT/python-pytest-cases-3.6.1-2.fc35.x86_64/usr/lib64/python3.8/site-packages:/home/tkloczko/rpmbuild/BUILDROOT/python-pytest-cases-3.6.1-2.fc35.x86_64/usr/lib/python3.8/site-packages
+ PYTHONDONTWRITEBYTECODE=1
+ /usr/bin/pytest -ra
=========================================================================== test session starts ============================================================================
platform linux -- Python 3.8.9, pytest-6.2.4, py-1.10.0, pluggy-0.13.1 -- /usr/bin/python3
cachedir: .pytest_cache
hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('/home/tkloczko/rpmbuild/BUILD/pytest-cases-3.6.1/.hypothesis/examples')
rootdir: /home/tkloczko/rpmbuild/BUILD/pytest-cases-3.6.1, configfile: setup.cfg, testpaths: pytest_cases/tests/
plugins: cases-3.6.1, forked-1.3.0, shutil-1.7.0, virtualenv-1.7.0, expect-1.1.0, httpbin-1.0.0, xdist-2.2.1, flake8-1.0.7, timeout-1.4.2, betamax-0.8.1, freezegun-0.4.2, case-1.5.3, isort-1.3.0, aspectlib-1.5.2, asyncio-0.15.1, toolbox-0.5, xprocess-0.17.1, aiohttp-0.3.0, checkdocs-2.7.0, mock-3.6.1, rerunfailures-9.1.1, requests-mock-1.9.3, Faker-8.4.0, cov-2.12.1, pyfakefs-4.5.0, hypothesis-6.13.14
collected 0 items / 1 error

================================================================================== ERRORS ==================================================================================
______________________________________________________________________ ERROR collecting test session _______________________________________________________________________
/usr/lib64/python3.8/importlib/__init__.py:127: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
<frozen importlib._bootstrap>:1014: in _gcd_import
    ???
<frozen importlib._bootstrap>:991: in _find_and_load
    ???
<frozen importlib._bootstrap>:961: in _find_and_load_unlocked
    ???
<frozen importlib._bootstrap>:219: in _call_with_frames_removed
    ???
<frozen importlib._bootstrap>:1014: in _gcd_import
    ???
<frozen importlib._bootstrap>:991: in _find_and_load
    ???
<frozen importlib._bootstrap>:973: in _find_and_load_unlocked
    ???
E   ModuleNotFoundError: No module named 'pytest_cases.tests'
========================================================================= short test summary info ==========================================================================
ERROR  - ModuleNotFoundError: No module named 'pytest_cases.tests'
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
============================================================================= 1 error in 0.38s =============================================================================

And indeed there is no /home/tkloczko/rpmbuild/BUILDROOT/python-pytest-cases-3.6.1-2.fc35.x86_64/usr/lib/python3.8/site-packages/pytest_cases/tests directory in installed resourrces.