#17762 Working with `conftest.py` fixtures in a Python monorepo New discussion created by alexey-tereshenkov-aiven In the layout of a monorepo

project1
  tests/
    conftest.py (with project1 specific fixtures)
    test_module.py
project2
  tests/
    conftest.py (with project2 specific fixtures)
    test_module.py
conftest.py (with generic fixtures)

when running tests in

project1/tests

directory,

pytest

visits all ancestor directories until reaching the root collecting all

conftest.py

so that fixtures are available. From the docs:

Pants will also infer dependencies on any confest.py files in the current directory and any ancestor directories, which mirrors how Pytest behaves.

This means that when making changes to the root

conftest.py

, all tests will need to be run because every test depends on that root

conftest.py

. It's possible to disable this behavior:

You can turn off this feature by setting conftests = false in the [python-infer] scope.

However, it seems fair that all subprojects may want to use a generic fixture from the root

conftest.py

. But this negatively affects the dependency management within tests as all tests (some of them maybe slow!) will need to be run every time someone touches the root

conftest.py

(since you don't know whether the fixtures a test uses are actually modified). Importing individual fixtures (so that you would split the root

conftest.py

into individual modules) seems to be discouraged:

pytest

docs suggest you define all your fixtures within one single

conftest.py

file. There is an explicit import approach, but I am not sure what are the cons of this approach?

# tests/conftest.py
import pytest
from fixtures.add import add

I see usage of

pytest_plugins = (
   "fixtures.fixture_1",
   "fixtures.fixture_2",
)

in various repositories, but this doesn't work well with Pants dependency inference (as there are no

import

statements). What kind of approach have you decided to go with? pantsbuild/pants