[EDNA-95] Run pytest on CI

[gromakovsky]

Description

Problem: we have tests for Python code, but CI doesn't run them,
so they may silently break.

Solution: add a new CI step that calls pytest in nix-shell.

Related issue(s)

Resolve https://issues.serokell.io/issue/EDNA-95

✅ Checklist for your Pull Request

Related changes (conditional)

• Tests

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from
    silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • README

Stylistic guide (mandatory)

• My commits comply with the policy used in Serokell.
• My code complies with the style guide.

[gromakovsky]

@mkaito I tried the simplest possible approach that came to my mind and it seems to work. Is it good enough?

Alternatively, I can add some test to analysis/default.nix and then have checks.analysis-test in flake.nix, but I don't know how to define this test. So if you think we should have test in analysis/default.nix, please help me to define it. Currently we just export env built by mkPoetryEnv. AFAIU I should return an object with env = mkPoetryEnv … and test = ???

[mkaito]

Our verification steps should all be encoded as flake checks, as per Elagin. I'd have to look into how Poetry works on Nix, I'm not familiar (yet).

[kirelagin]

That’s exactly how it works, yes, you get the stuff from the Poetry env on your PATH and then run pytest. Just make it into a check instead of running nix-shell in the pipeline config directly.