Opt-in cop compatibility in redundant directives

[tdeo]

Add compatibility in Lint/RedundantCopDisableDirective, Lint/RedundantCopEnableDirective and Lint/MissingCopEnableDirective for opt-in cops.

I mean by "opt-in" having a cop which is globally disabled in the configuration, but that we want to enable only on specific parts of a file.

My use-case specifically is the following: we sometimes have large-ish arrays maintaining list of allowed values for an attribute, let's imagine:

allowed_prefixes = %w[
  ab_
  ad_
  bc_
  ...
  zz_
]

I wrote a custom cop that checks that this array remains alphabetically sorted for human readibility. Obviously, I don't want to enable it globally in the codebase as array ordering is important in many use-cases, but would like to enable it specifically on that part with:

# rubocop:enable Pennylane/SortedArray
allowed_prefixes = %w[
  ...
]
# rubocop:disable Pennylane/SortedArray

But rubocop currently reports various offenses with this pattern:

sample.rb:3:18: W: [Correctable] Lint/RedundantCopEnableDirective: Unnecessary enabling of Pennylane/SortedArray.
# rubocop:enable Pennylane/SortedArray
                 ^^^^^^^^^^^^^^^^^^^^^
sample.rb:7:1: W: Lint/MissingCopEnableDirective: Re-enable Pennylane/SortedArray cop with # rubocop:enable after disabling it.
# rubocop:disable Pennylane/SortedArray
^
sample.rb:7:1: W: [Correctable] Lint/RedundantCopDisableDirective: Unnecessary disabling of Pennylane/SortedArray.
# rubocop:disable Pennylane/SortedArray

To be able to implement that, I had to inject both config as well as the cop registry into processed_source, which turns out to be pretty isolated changes in RuboCop::Runner as well as in the CopHelper test module to mimic the behaviour.

I also made a small api change to RuboCop::Registry#enabled as 2 arguments were already available from instance variables, please let me know if that isn't an acceptable change.

I didn't squash commits yet to be able to discuss implementation strategy. I originally (until bf4e4b7) tried to only inject config within CommentConfig instead of ProcessedSource, but things were getting a bit more out of hand.

---

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[tdeo]

Hello dear rubocop team,

I'd love to get some feedback on this - does this functionality make sense to be added into rubocop?

Is the modification to ProcessedSource acceptable or would you prefer some other strategy (I don't have any proposal unfortunately)?

Thanks

[bbatsov]

I've been AFK much of September and I'll need some time to go over all the PRs in our backlog. Sorry about the delay!

[bbatsov]

So, if I understand this feature correctly you want to be using the directives to temporary enable a cop, right? If so - I'm fine with the proposal and I'll only request that this functionality be documented accordingly.

[tdeo]

So, if I understand this feature correctly you want to be using the directives to temporary enable a cop, right? If so - I'm fine with the proposal and I'll only request that this functionality be documented accordingly.

That's exactly the functionality I have in mind, I was calling them "opt-in" cops trying to mean they're disabled by default, but as you're saying "temporarily enabled cops" might be more explicit.

Where would you like to see the documentation? Would a paragraph "Temporarily enabling cops in source code" right after "Disabling cops within source code" here work?

[bbatsov]

Where would you like to see the documentation? Would a paragraph "Temporarily enabling cops in source code" right after "Disabling cops within source code" here work?

Yep, that would be the right place IMO.

[bbatsov]

Thanks!