Detecting when PEP 735 `[dependency-groups]` redirects to package extra(s)

[jamesbraza]

Is your feature request related to a problem? Please describe.

With the rise of uv (circa 2024 to 2025), now the dev extra is common. There is also PEP 735 Dependency Groups that adds standardization here as well. I am getting used to defaults "just working" for both production and development.

Currently optional_dependencies_dev_groups defaults to an empty tuple, requiring every project that uses [project.optional-dependencies] for dev dependencies to explicitly configure optional_dependencies_dev_groups.

Describe the solution you would like

deptry default optional_dependencies_dev_groups to ["dev"] when a dev group exists in [project.optional-dependencies], and otherwise fall back to the prior default of ().

If projects don't want ["dev"] being auto-used, they can specify optional_dependencies_dev_groups = [] to attain the original behavior.

Additional context

N/a

[mkniewallner]

Same thoughts as in #1530 (comment), I'm not sure that we want to change the default since PEP 735 is pretty common nowadays I believe, and deptry allows configuring this for the projects that need an escape hatch. I'm not strongly opposed to it though, maybe @fpgmaas will have a different opinion on that!

[jamesbraza]

So my pyproject.toml actually does follow PEP 735, it has something like this:

[dependency-groups]
dev = ["pkg[dev]"]

(actual usage: https://github.com/Future-House/ldp/blob/v0.45.1/packages/lmi/pyproject.toml#L5-L6)

I think deptry should be able to infer then that dev extra is used by PEP 735, without having to manually configure optional_dependencies_dev_groups.

So maybe then the right ask is not to default optional_dependencies_dev_groups to ["dev"], but to be able to auto-detect when [dependency-groups] re-routes to dev extra.