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.

[fpgmaas]

I have to admit I am not too familiar with the pattern I see in your repo, but the reason it needs to be an optional dependency group, is so that at a higher-level in the monorepo you can 'gather' the development dependencies with

[dependency-groups]
dev = ["fhlmi[dev]", "ldp[dev]"]

right?

If this is a fairly common pattern in monorepo's, maybe it's worth changing the default. But if this is an edge case then I agree with @mkniewallner that leaving the default empty might be the way to go.

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.

If we were to implement this, I think I'd prefer to go for defaulting optional_dependencies_dev_groups to ["dev"], since that would solve the majority of cases without adding any complexity.

[jamesbraza]

I have to admit I am not too familiar with the pattern I see in your repo, but the reason it needs to be an optional dependency group, is so that at a higher-level in the monorepo you can 'gather' the development dependencies with

[dependency-groups]
dev = ["fhlmi[dev]", "ldp[dev]"]

right?

Yeah the rationale is twofold:

• For developers, uv sync will install everything at the repo root for uv-style workspace monorepos (as you understood)
• pip installers from PyPI can get our dev deps if they want (e.g. pip install ldp[dev])
  • See https://peps.python.org/pep-0735/#dependency-groups-are-not-hidden-extras

If this is a fairly common pattern in monorepo's, maybe it's worth changing the default.

Notably PEP 621 recommends this dev extra pattern: https://peps.python.org/pep-0621/#recommend-that-tools-put-development-related-dependencies-into-a-dev-extra. Since it's encouraged there imo it's worth matching.

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Feel free to ignore this issue. Mainly I am just trying to communicate to deptry that the defaults can be improved, to save me configuration boilerplate.