Multiple conftest and __init__.py across packages breaks pytest path resolving - how to solve it?

[TomaszBorczyk]

I have following project setup:

my_repo
├── README.md
└── my_repo
    ├── app
    │   ├── README.md
    │   ├── app
    │   │   └── __init__.py
    │   ├── poetry.lock
    │   ├── pyproject.toml
    │   └── tests
    │       ├── __init__.py
    │       ├── conftest.py
    │       └── test_app.py
    └── package1
        ├── README.md
        ├── package1
        │   └── __init__.py
        ├── poetry.lock
        ├── pyproject.toml
        └── tests
            ├── __init__.py
            ├── conftest.py
            └── test_package.py

This is a monorepo setup, I am omitting most of the files including pyproject.toml for readability.
All file are empty excep test_*.py, which contain a simple test assert True is True
If I run pytest ./my_repo, then I will get following errors:

❯ pytest ./my_repo 
=================================== test session starts ===================================
platform darwin -- Python 3.9.6, pytest-7.2.1, pluggy-1.0.0
rootdir: /Users/myusername/home/Projects/my_repo
collected 0 items / 1 error                                                               

========================================= ERRORS ==========================================
______________________________ ERROR collecting test session ______________________________
/Library/Python/3.9/site-packages/_pytest/config/__init__.py:635: in _importconftest
    mod = import_path(conftestpath, mode=importmode, root=rootpath)
/Library/Python/3.9/site-packages/_pytest/pathlib.py:556: in import_path
    raise ImportPathMismatchError(module_name, module_file, path)
E   _pytest.pathlib.ImportPathMismatchError: ('tests.conftest', '/Users/myusername/home/Projects/my_repo/my_repo/app/tests/conftest.py', PosixPath('/Users/myusername/home/Projects/my_repo/my_repo/package1/tests/conftest.py'))
================================= short test summary info =================================
ERROR  - _pytest.pathlib.ImportPathMismatchError: ('tests.conftest', '/Users/myusername/home...
!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!
==================================== 1 error in 0.06s =====================================

I understand that this is somehow related to pytest not resolving conftest paths correctly. Removing __init__.py from tests dirs solves the issue, but I cannot do that - tests dirs might have some test utils that I will need to reference from the test folder.

What is curious though is when I move my tests inside the package it runs correctly:

my_repo
├── README.md
└── my_repo
    ├── app
    │   ├── README.md
    │   ├── app
    │   │   ├── __init__.py
    │   │   └── tests
    │   │       ├── __init__.py
    │   │       ├── conftest.py
    │   │       └── test_app.py
    │   ├── poetry.lock
    │   └── pyproject.toml
    └── package1
        ├── README.md
        ├── package1
        │   ├── __init__.py
        │   └── tests
        │       ├── __init__.py
        │       ├── conftest.py
        │       └── test_package.py
        ├── poetry.lock
        └── pyproject.toml

How to solve this issue? I cannot remove init from tests, and neither I want to move tests to the package

[TomaszBorczyk]

I've found a working setup:

my_repo
├── README.md
└── my_repo
    ├── __init__.py
    ├── app
    │   ├── README.md
    │   ├── __init__.py
    │   ├── conftest.py
    │   ├── app
    │   │   └── __init__.py
    │   ├── poetry.lock
    │   ├── pyproject.toml
    │   └── tests
    │       ├── __init__.py
    │       └── test_app.py
    ├── conftest.py
    └── package1
        ├── README.md
        ├── __init__.py
        ├── conftest.py
        ├── package1
        │   └── __init__.py
        ├── poetry.lock
        ├── pyproject.toml
        └── tests
            ├── __init__.py
            └── test_package.py

To make it work:

• conftest.py needs to be outside of tests folder
• both my_repo root and each package (next to pyproject.toml) need to have their __init__.py file
• test folders can (but do not have to) contain their __init__.py file (for example when you will be creating package scoped test configuration)
• you still can have root conftest.py for global setups

[TranKiet97]

could you let me know how to use the conftest.py for global setup. Thanks