We would like to learn about your use case. For example, if this feature is needed to adopt Narwhals in an open source project, could you please enter the link to it below?

I am adding Narwhals package to Gentoo Linux. It works great, and working with is a pleasure!

Please describe the purpose of the new feature or describe the problem to solve.

For Gentoo packages, we really want to run tests as part of the package building/install process. While using GitHub archives is acceptable, we strongly prefer using source distributions from PyPI, and this is especially important now that PyPI supports signed attestations.

Suggest a solution if possible.

Include all the files needed to run tests in the source distribution.

If you have tried alternatives, please describe them below.

The alternative is to download autogenerated GitHub archives. However, unlike source distributions, they are not signed and they technically don't have 100% guarantee that the file checksum won't change in the future.

Additional information that may help us understand your needs.

No response