tox cannot find module

Question

I am trying to run tox on a module.

Consider the following python package:

foo
├── tox.ini
├── setup.cfg
│ tests
│ └── test_bar.py
└── src
 ├── data
 │ └── data.csv
 ├── __init__.py
 └── bar.py

Where bar.py has:

import importlib.resources
def get_data_file(file_name):
 return importlib.resources.files("data").joinpath(file_name).read_text()

and test_bar.py has:

import bar
def test_bar():
 data = bar.get_data_file('data.csv')
 assert True

I can use this package as follows:

import bar
data = bar.get_data_file('data.csv')

Moreover, pytest passes.

However, tox returns the following error message in tests/test_bar.py

ModuleNotFoundError: No module named 'bar'

Initial approach

Initially, the package had the following structure:

foo
├── tox.ini
├── setup.cfg
│ tests
│ └── test_bar.py
└── src
 └── foo
 ├── data
 │ └── data.csv
 ├── __init__.py
 └── bar.py
 

This structure is in accordance to PyScaffold, and works with tox. However, since this package only has one module, I was hoping to avoid having to import foo.bar, and instead import bar.

I tried the suggestion from https://github.com/pyscaffold/pyscaffold/discussions/399 i.e. add from .foo import bar or from . import bar in __init__.py.

However, if I then try to import bar, I get ModuleNotFoundError: No module named 'bar'.

Moreover, my understanding is that anything in the src folder is considered to be part of the package. Therefore I figured I should be able to put bar.py directly in src.

In conclusion, I believe to have the following questions:

• Is it best practice to try to aim for import bar instead of import foo.bar, given that I only have 1 module
• If so, is it best practice to put bar.py directly in the src folder
• If so, should I configure tox differently?