Add job for CI using Prism parser

[bquorning]

Inspired by rubocop/rubocop-capybara#112

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Before submitting the PR make sure the following are checked:

• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Updated documentation.
• Added an entry to the CHANGELOG.md if the new code introduces user-observable changes.
• The build (bundle exec rake) passes (be sure to run this locally, since it may produce updated documentation that you will need to commit).

[pirj]

But ruby-head is prism already, isn’t this sufficient?

[bquorning]

Ah yes, probably so. I'll keep this in draft and look at it again next week.

[Earlopain]

My understanding is that it will still use the plain parser gem, even with ruby-head/ruby-3.4
The prism default is runtime-only. Users need to set it in their config files still, even when targeting ruby 3.3 or higher.

[pirj]

Thanks for the hint, @Earlopain !

I’m good with a separate ci job with prism.
Do we need to turn it on in RuboCop somehow? 🤔

[Earlopain]

As a user, you would set AllCops/ParserEngine. For extensions, this should have you covered: https://github.com/rubocop/rubocop/blob/9f2ffa2270bbc174b2a622350d120b05672a1ce5/lib/rubocop/rspec/cop_helper.rb#L13. I'm not immediatly finding the place where you inherit this, but you probably do somewhere? Since you use the same assertion methods from RuboCop::RSpec::ExpectOffense.

For reference, here's the PR for rubocop-rails and it basically only sets the env variable. rubocop/rubocop-rails#1245. The other changes are for places that construct ProcessedSource themselves but I don't believe that will be the case here.

[Earlopain]

Docs generator is broken with Ruby 2.7, I openend rubocop/rubocop#13388. Probably, you can just run bundle exec rake spec here regardless. I don't think the other tasks really need to run with prism.

[bquorning]

I changed it to run only rake spec and not all of rake. Does it look ok now?

[ydah]

Looks good! Thank you♥