8.0.0: pytest is failing because it canmot find `tests` module

[kloczek]

I'm packaging your module as an rpm package so I'm using the typical PEP517 based build, install and test cycle used on building packages from non-root account.

• python3 -sBm build -w --no-isolation
• because I'm calling build with --no-isolation I'm using during all processes only locally installed modules
• install .whl file in </install/prefix>
• run pytest with $PYTHONPATH pointing to sitearch and sitelib inside </install/prefix>
• build is performed in env which is cut off from access to the public network (pytest is executed with -m "not network")

Here is pytest output:

lling-8.0.0-2.fc35.x86_64/usr/lib/python3.8/site-packages
+ /usr/bin/pytest -ra -m 'not network'
==================================================================================== test session starts ====================================================================================
platform linux -- Python 3.8.16, pytest-7.2.1, pluggy-1.0.0
rootdir: /home/tkloczko/rpmbuild/BUILD/spelling-8.0.0
plugins: anyio-3.6.2, datadir-1.4.1, regressions-2.4.2, pytest_param_files-0.3.4
collected 6 items / 2 errors

========================================================================================== ERRORS ===========================================================================================
__________________________________________________________________________ ERROR collecting tests/test_builder.py ___________________________________________________________________________
ImportError while importing test module '/home/tkloczko/rpmbuild/BUILD/spelling-8.0.0/tests/test_builder.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib64/python3.8/importlib/__init__.py:127: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests/test_builder.py:16: in <module>
    from tests import helpers  # isort:skip
E   ModuleNotFoundError: No module named 'tests'
___________________________________________________________________________ ERROR collecting tests/test_filter.py ___________________________________________________________________________
ImportError while importing test module '/home/tkloczko/rpmbuild/BUILD/spelling-8.0.0/tests/test_filter.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib64/python3.8/importlib/__init__.py:127: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests/test_filter.py:16: in <module>
    from tests import helpers # isort:skip
E   ModuleNotFoundError: No module named 'tests'
================================================================================== short test summary info ==================================================================================
ERROR tests/test_builder.py
ERROR tests/test_filter.py
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 2 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
===================================================================================== 2 errors in 0.36s =====================================================================================