Add option OnlyFor to the Bundler/GemComment cop.

[ric2b]

This PR adds a boolean option OnlyFor to the Bundler/GemComment cop.

The goal of this option is to require gem comments only if the gem version has an explicit version specifier or other options like required/github/etc, so that the reason for the specifier/options is documented.

I tested it on a project I work on and it worked as expected.

---

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[ric2b]

By the way, I'm also planning on doing a similar PR for parameters that change the source of a gem, such as source:, github:, etc (documented here).

I was thinking it could be a bit more general and work by receiving a list of parameter names that should activate the cop, something like: OnlyIfUsingOptions: ['require', 'github']

Does that make sense to you?

[bbatsov]

I'd also expand the cop summary.

[bbatsov]

You should also mention this in the default config. I'm not sure I like the idea of a boolean option, though - might be a better idea to have some styles like "always", "only gems with some extra params". I like your idea overall, but we have to be careful to make the config both easy to understand and extendable.

[ric2b]

Yeah, making it extensible is a great point.

What do you think of a configuration with three parameters:

• AllGems: Boolean
• GemsWithVersionSpecifiers: Boolean
• GemsWithAnyOfTheseOptions: Array

Where AllGems: true would ignore the other options and apply to all gems. Otherwise the rest of the options would be combined.

As an example:

Bundler/GemComment:
  Enabled: true
  AllGems: false
  GemsWithVersionSpecifiers: true
  GemsWithAnyOfTheseOptions: 
    - github
    - bitbucket

Would only trigger for a gem that has version restrictions OR uses at least one of github: and bitbucket:.

[bbatsov]

The problem with the boolean flags approach is that some of them are not compatible with one another and this makes the configuration harder. A different approach might be to just have a list of things to check - e.g.:

- Check
  - gems_with_version
  - gems_from_source
  - etc

And I guess when empty this can mean "all". Or there can be an enforced style "All" and "Subset" and the second one would consult this extra configuration option. Not sure what's the best approach, but I really don't like the boolean flags, so I'd rather us avoid it.

[ric2b]

My last suggestion would make the options compatible with each other, it's just that gems_with_version would be a separate option because it's not a kwarg.

But I like your suggestion, it makes the configuration more straightforward, just need to treat version specifiers as a special case 👍

[bbatsov]

Fine by me.

[ric2b]

@bbatsov The new version has a single new configuration: OnlyWhenUsingAnyOf.

If it's empty the cop behaves the same as before, checking all gems, otherwise it only registers offenses on gems with one or more of the configured options.

with_version_specifiers can also be passed as an option in to check for version specifiers.

Happy to change the names to whatever you prefer, if you don't think they're clear enough or consistent with rubocop conventions.

[ric2b]

All the tests pass on my machine, the failing test seems completely unrelated to this PR, not sure what to do.

[bbatsov]

I think it's a good idea to summarize in docs somewhere all the common params (https://bundler.io/man/gemfile.5.html) for its easier for people to figure out what's available to them.

[bbatsov]

You should also update VersionChanged to 0.85.

[bbatsov]

Thanks!