lint: should allow omitting keys: `concepts` and `exercises.concept`

[ee7]

Due to https://github.com/exercism/configlet/commit/66914845a323d2e21ab7d8b00b7219d0777f4c17, fmt removes these key/value pairs when the values are empty. But that causes lint to produce an error.

This behavior was included in 4.0.0-beta.15, which was available for a little less than an hour. But I rolled back (by marking it as a prerelease), so fetch-configlet once again downloads the previous version.

To-do:

• [x] Either:
  • make lint allow these keys to be missing
  • or make fmt not remove these key/value pairs when the value is empty.
• [ ] Ideally, add some new integration tests, where we run configlet lint after configlet fmt makes changes to track-level config.json files
• [ ] Release 4.0.0-beta.16.

Reported by: https://forum.exercism.org/t/configlet-woes-fmt-removed-too-much/7605

@ErikSchierboom what would you prefer here? To change the behavior of lint (and the spec), or change the behavior of fmt?

The lint spec currently says that the keys are required:

• https://github.com/exercism/docs/blob/839596f45ecd8e258bbf1f76a12ac46b20facbe7/building/configlet/lint.md?plain=1#L115
• https://github.com/exercism/docs/blob/839596f45ecd8e258bbf1f76a12ac46b20facbe7/building/configlet/lint.md?plain=1#L179

[ErikSchierboom]

@ErikSchierboom what would you prefer here? To change the behavior of lint (and the spec), or change the behavior of fmt?

I would prefer changing lint and the spec. It is perfectly fine for tracks to not have concepts or concept exercises I feel, and there is little value in them being empty arrays.

[ErikSchierboom]

And in practice they are optional, as we gracefully handle them not being there.

[ErikSchierboom]

Ideally, add some new integration tests, where we run configlet lint after configlet fmt makes changes to track-level config.json files

That's a great idea.

[ee7]

I would prefer changing lint and the spec. It is perfectly fine for tracks to not have concepts or concept exercises I feel, and there is little value in them being empty arrays.

OK. Let's go with that. Maybe later we could also check there aren't any other keys that are currently required, but could be optional.