How to enable different version of Pytest with Poetry and resolves

[akomisarek]

Hello,

In the older version of pants we could specify the version of pytest in the Pants config: https://www.pantsbuild.org/2.15/docs/python/goals/test#pytest-version-and-plugins

In recent versions (I think stopping at 2.16) this syntax is no longer supported and we need to rely on the resolvers and install from resolvers.

How do I replicate that setup with Poetry + Pants and how I can provide smaller lockfiles?

1. I can have dev section in my Poetry, where I can add my test dependencies. Can I generate Pants lockfile from this Poetry section somehow easily?
2. I couldn't find answer in that section: https://www.pantsbuild.org/2.21/docs/python/overview/lockfiles#lockfiles-for-tools
3. I am aware of macro "poetry-requirements." I can even pass "resolver" there, but it would just build me a lockfile with the whole universe of dependencies.

I tried the below:

1. In pants.toml I have:

[python.resolves]
pytest = "pytest_lockfile.txt"

[pytest]
args = ["--disable-warnings"]
install_from_resolve = "pytest"

2. In my pyproject.toml I have:

pytest = "7.3.0"
pytest-datafiles = "2.0.1"
testfixtures = "^7.0.4"
... others

3. In BUILD:

poetry_requirements(name="poetry-dev", resolver="pytest") # I guess here I would need to be able to target only my test dependencies..

4. Lockfile generation, generate all the dependencies from the project, which is not what I should use, is it? I would expect just the version of libraries and dependencies for pytest itself
   pants generate-lockfiles --resolve=pytest

Any recommendations?

Thanks!

[benjyw]

So you're not currently using a Pants lockfile, it sounds like?

There is no way to generate Pants requirements from just the dev requirements. But it's not a bad idea to enable that, if you want to add it. See here for the current implementation which always grabs both sections. We could add arguments to the macro to control which groups it looks at. Should be pretty straightforward.

[akomisarek]

Perfect, thanks for your answer. That's what I am thinking :) currently I did workaround and using the requirements.txt file just for test deps and resolve from there. It works now pretty well, but of course would be great to have in one place.

I am familiarising myself with the Pants, might add this when I have a second and will ask for review :)