Creating a pyproject.toml makes pytest fail with "E ImportError: attempted relative import with no known parent package"

[dofdary]

Hello, I encountered an odd issue in my python project.
Where adding a "pyproject.toml" file somewhere in the project makes pytest unable to set the correct 'root module'.

I made the following minimal reproductible example :

$ ls -R
src

./src:
program

./src/program:
code.py tests

./src/program/tests:
conftest.py  test_code.py

We have top level module src, containing the module program that we want to test.

The tests for program are located in program/tests

In conftest.py we have:

from ..code import foo

Simulating the fact that the tests will import symbols from the code they are testing.

When I run python -m pytest --import-mode=importlib src/program

Everything is fine :)

But when I add a pyproject.toml to my program project:

$ touch src/program/pyproject.toml
$ python -m pytest --import-mode=importlib src/program
ImportError while loading conftest '/Users/me/Documents/git/pytest/src/program/tests/conftest.py'.
src/program/tests/conftest.py:1: in <module>
    from ..code import foo
E   ImportError: attempted relative import beyond top-level package

Things don't work out anymore (here the pyproject.toml is empty, but I've tried with semantically correct ones too).

I get this ImportError

I have this error with versions 8.3.5 and 8.5.3, did not test any other version.

I think this might not be a bug, just that pytest is doing something to determine what is the top-level package, and that the presence of a pyproject mess that up.

Could someone tell me if there is any way to make this works?

My curent getaround is deleting the pyproject.toml from the filesystem just before running pytest...

[mrbean-bremen]

Is there a reason why you want to put pyproject.toml into the source path instead of the project root? I'm pretty sure it is expected at project root, though I couldn't find this in the packaging documentation.

(though it is mentioned in the Good Integration Practices section of the pytest documentation)

[mrbean-bremen]

After digging around a bit, I found that the root dir in pytest is indeed defined by the location of pyproject.toml or other ini files, if they exist. So while the location of pyproject.toml seems not to be defined in the packaging guide, at least pytest assumes that it is in the root dir.