ImportPathMismatchError from subprojects with same test folder structure

[soxofaan]

We have a big CI job that runs pytest against a couple (sub)projects checked out side by side. We added a __init__.py file in one of the tests folders to allow for some internal code reuse, and now the whole test suite fails to run with a ImportPathMismatchError.

Minimal reproduction example:

cd some_empty_root_dir
mkdir -p projectA/tests
touch projectA/tests/__init__.py
touch projectA/tests/conftest.py
mkdir -p projectB/tests
touch projectB/tests/__init__.py
touch projectB/tests/conftest.py

So file structure is as follows

$ tree
.
├── projectA
│   └── tests
│       ├── conftest.py
│       └── __init__.py
└── projectB
    └── tests
        ├── conftest.py
        └── __init__.py

Running pytest in each of the subprojects works fine (collected 0 items, but that is expected).

However, when running at the toplevel:

$ pytest
=============================================================================================== test session starts ===============================================================================================
platform linux -- Python 3.11.0, pytest-7.4.0, pluggy-1.2.0
rootdir: /tmp/fruplz
collected 0 items / 1 error                                                                                                                                                                                       

===================================================================================================== ERRORS ======================================================================================================
__________________________________________________________________________________________ ERROR collecting test session __________________________________________________________________________________________
.venv/lib/python3.11/site-packages/_pytest/config/__init__.py:642: in _importconftest
    mod = import_path(conftestpath, mode=importmode, root=rootpath)
.venv/lib/python3.11/site-packages/_pytest/pathlib.py:588: in import_path
    raise ImportPathMismatchError(module_name, module_file, path)
E   _pytest.pathlib.ImportPathMismatchError: ('tests.conftest', '/tmp/fruplz/projectA/tests/conftest.py', PosixPath('/tmp/fruplz/projectB/tests/conftest.py'))
============================================================================================= short test summary info =============================================================================================
ERROR  - _pytest.pathlib.ImportPathMismatchError: ('tests.conftest', '/tmp/fruplz/projectA/tests/conftest.py', PosixPath('/tmp/fruplz/projectB/tests/conftest.py'))
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
================================================================================================ 1 error in 0.04s =================================================================================================

Apparently pytest doesn't like that both projectA/tests/conftest.py and projectB/tests/conftest.py map to tests.conftest.
Is there a workaround for this?

(using pytest 7.4.0)

[giacomorebecchi]

I ran into this issue after updating VSCode, due to an experiment being run on vscode-python (see this issue) For the VSCode test plugin, the solution is simply to deactivate the experiment until they fix the bug.

For the CI/CD processes, instead, I run the pytest command on each subfolder:

pytest ./projectA/tests
pytest ./projectB/tests

By looking at the documentation, another option to avoid multiple commands seems:

pytest --import-mode importlib

However, this seems to break your intention of re-using some code in the tests subfolder.

My personal go-to, while suboptimal, would be to change the structure to:

$ tree
.
├── projectA
│   └── tests
│       └── test_projectA
│           ├── conftest.py
│           └── __init__.py
└── projectB
    └── tests
        └── test_projectB
            ├── conftest.py
            └── __init__.py

@soxofaan I hope this can be of any help!