Check blank percent literal by Layout/SpaceInsidePercentLiteralDelimiters

[r7kamura]

Previously, no particular investigation was made for whitespace in blank percent array literals on Layout/SpaceInsideArrayPercentLiteral.

I will change it in this Pull Request so that they are inspected as well.

# bad
%w[ ]
%w[    ]
%w[
]

# good
%w[]

This is a similar change to:

• Check newline in empty hash brace literal on Layout/SpaceInsideHashLiteralBraces #11032

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edit: At first I tried to change Layout/SpaceInsideArrayPercentLiteral Cop, but after discussion, it was decided to use Layout/SpaceInsidePercentLiteralDelimiters Cop instead.

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Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.

[r7kamura]

I am wondering if we should offer several styles or if they are unnecessary at this time.

[r7kamura]

Perhaps it would be better to implement this in Layout/SpaceInsidePercentLiteralDelimiters cop?

[bbatsov]

I am wondering if we should offer several styles or if they are unnecessary at this time.

I don't think so. I haven't seen much usages of spaces in empty literals in general.

Perhaps it would be better to implement this in Layout/SpaceInsidePercentLiteralDelimiters cop?

Well, it can't be an alternative really - it'd be complimentary to the change here.

[bbatsov]

Perhaps it would be better to implement this in Layout/SpaceInsidePercentLiteralDelimiters cop?

My bad - I misread the cop names. 🤦 I agree that would actually be better, as it's more universal. I'd probably mention in the array literals cop that this additional aspect is control by the other cop, so it's clear we're consistent across the board with respect to the empty literals.

[bbatsov]

There it would also make more sense to have some configuration option like EnforcedStyleForEmptyLiteral.

[bbatsov]

Thanks for tackling this!