Allow specifying the location to report on for check_code_length

[G-Rath]

Is your feature request related to a problem? Please describe.

"I'm always frustrated when..." I'm working on a complex test and suddenly my IDE flags every single line in the block because it's too long:

In the above, the first test is being flagged by RSpec/MultipleExpectations while the second is being flagged by RSpec/ExampleLength - while these cops belong to rubocop-rspec, the latter is literally just calling check_code_length which is a rubocop core method hence I'm opening this issue.

Describe the solution you'd like

I'd like RSpec/ExampleLength to report on the sending node rather than the whole block, so by extension I'd like to be able to somehow control the node check_code_length reports as the location of the offense.

Describe alternatives you've considered

Forking check_code_length in rubocop-rspec - there's not that much code so this doesn't seem like the worst thing in the world, but I expect it would be harder to convince the team to accept such a PR and really this issue could apply to any cop using check_code_length.

I could also disable the cop on the test while I'm working, but that's a bit annoying to have to manage - I've got to do it each time, and then remove it if I manage to shrink the example again.

Additional context

I've got three ideas on how this could be supported without a breaking change:

1. support taking a block which would get called instead of add_offense, and passed the values currently being passed to add_offense; this would allow the most flexibility
   • (I think this is probably the best way to go since its not an error to pass a block to a method that doesn't yield so it'd gracefully fallback on older versions of Rubocop)
2. make location a param with a default value; I think that should be completely not breaking, though it would be annoying having such a complex default value and technically the method would do a bit more work than it does now when node.line_count <= max_length
3. make an internal check_code_length and then expose a couple of public methods with different signatures (including the current "original", + check_code_length_with_location etc); effectively 2. but in a way that makes it easier to avoid breaking changes if the signature needs to change in future

[G-Rath]

@koic fwiw I'm happy to have a crack at this, I just would like to know if maintainers are ok with what I've suggested or have other ideas or etc 🙂

[G-Rath]

So I'm looking into this, and not sure if my preferred "pass a block" idea will work because a block is already being passed to add_offense though I'm not sure what it's doing:

add_offense(location, message: message(length, max_length)) { self.max = length }

From what I understand the block is for autocorrection, but this isn't doing anything autocorrecting-ish - instead its doing an assignment, which looks to end up calling a dynamically created method via RuboCop::ExcludeLimit#exclude_limit that indicates it's about setting values up for --auto-gen-config...

Meanwhile I've also just found #2414 and #2629 which might indicate the current reporting location was intentionally switched to - I suspect that the ecosystem has since changed in a manner that makes it fine to revisit but I'm overall getting the feeling this might be harder to tackle than initially thought.

Any guidance or opinions would be welcome :)