Profiles for Python projects

[Zelphir Kaltstahl]

Hi Guix Users!

Today I experimented a little with creating profiles from manifest.scm
file for Python projects. I have the following manifest.scm:

(specifications->manifest
 '("python@3.8.2"
   "python-falcon@2.0.0"
   "python-levenshtein@0.12.0"
   "python-jsonschema@3.2.0"
   "python-pytest@5.3.5"))

I create a profile with that and it works fine:

guix package --manifest="manifest.scm" 
--profile="${GUIX_EXTRA_PROFILES}"/my-env/my-env

Then I do the sourcing:

GUIX_PROFILE="${GUIX_EXTRA_PROFILES}/my-env/my-env"; source 
"${GUIX_PROFILE}/etc/profile"

This also works fine and when I do:

which python3
#
which pytest

I also get a path in the profile I created. So far all seems to just
work. However, then I hit a snag when trying to run the tests of the
project:

LOG_LEVEL="DEBUG" PYTHONPATH="$(pwd)/my_project" python3 -m pytest -m 
"my_test_marker" -s -vvv

I now get the error:

No module named pytest

So it seems, that somehow modules mentioned with

-m <module>

Are not found. If I use PyTest without

python3 -m

in front, it also does not find libraries and I get errors for the
dependencies of the actual project.

Perhaps there is an easy fix for this. Has anyone used a Guix profile
like this before and knows how to make it work?

Regards,
Zelphir