ModuleNotFoundError when tests are in subdirectory of the main package

[Ark-kun]

I git a third-party package with the following structure:

./__init__.py
./conftest.py
./some_code.py
./tests/
./tests/__init__.py
./tests/conftest.py
./tests/test_version.py
./tests/utils/
./tests/utils/__init__.py
./tests/utils/fixtures.py

./tests/conftest.py:

from tests.utils.fixtures import foo

When the CI system runs pytest I get an error:
pytest ./tests/test_version.py

ImportError while loading conftest 'xxx/tests/conftest.py'.
tests/conftest.py:13: in <module>
    from tests.utils.fixtures import foo
E   ModuleNotFoundError: No module named 'tests'

For internal reasons I cannot set PYTHONPATH.

Is there any pytest arg that would help me make this conftest import work?

[agammann]

From the repository root, try:

python -m pytest tests/test_version.py

That form adds the current directory to sys.path, so your top-level tests package is importable by tests/conftest.py. The pytest console command does not necessarily add it. I reproduced your directory layout with from tests.utils.fixtures import foo: pytest tests/test_version.py failed with No module named 'tests', while python -m pytest tests/test_version.py passed on pytest 9.1.1. I also ran the module form on pytest 7.3.1 successfully. This is the difference described in pytest's invocation docs.