Pytest says 'ModuleNotFoundError' when using tox

Question

I have the following project structure:

root
|- module
  |- module.py
  |- __init__.py
|- tests
   |- unit
      |- some_test.py
   |- integration
      |- another_test.py
|- conftest.py
|- setup.py
|- tox.ini

When I run python3 module/module.py ... it runs as expected.

However, when I execute tox, I get ModuleNotFoundError: No module named 'dateutil'.

In my setup.py I have install_requires=['python-dateutil'] and tox.ini has the following (simplified) contents:

[tox]
envlist   = py{36, 37}
skipsdist = True

[testenv]
deps = pytest
commands = pytest

Does anyone have any insight as to why running tox gives me that the module 'dateutil' cannot be found and how to fix it?

score 13 · Accepted Answer · answered Feb 05 '19 at 15:52

[tox]skipsdist = True prevents tox to run python setup.py sdist so your install_requires is completely ignored.

If you really want to follow the advice to set [tox]skipsdist = True for applications you are also advised to follow all other best practices for packaging applications: use requirements.txt and add

[testenv]
deps =
    -rrequirements.txt

to tox.ini. Or just directly

[testenv]
deps = python-dateutil

score 6 · Answer 2 · answered May 22 '20 at 21:40

6

What helped me:

Add missing modules to the install_requires section of the setup.py
Delete old .tox directory and re-run tox

answered May 22 '20 at 21:40

Fedorov7890

1,173
13
28

2

I'm using flit, but deleting the `.tox` directory and re-running `tox` solved my issue. Thanks! – Dave Johnson Dec 04 '20 at 22:45
exactly, there is even a simple command `python -m tox --recreate` – Kf H. Jan 10 '22 at 22:03

score 2 · Answer 3 · answered Jan 30 '23 at 18:51

If none of the answers dated before my post works, try this answer from Jürgen Gmach, which states the below:

tox version 4 has been released a couple of weeks ago.

There were a couple of breaking changes, see https://tox.wiki/en/latest/faq.html#breaking-changes-in-tox-4

I would recommend to create an issue at https://github.com/tox-dev/tox/issues

In the meantime, to get your CI unblocked, I would recommend to pin tox < 4 in your github actions.

Pytest says 'ModuleNotFoundError' when using tox

3 Answers3