Add new Style/HashArrayLastItem cop

[fatkodima]

Closes #4286

[bbatsov]

I think we should also mention this in the style guide with a suggestion to use braces for the sake of clarity.

[koic]

Can you open a PR as the rule to the style guide?

[fatkodima]

Changed name to HashAsLastArrayItem, opened rubocop/ruby-style-guide#826 and added link to that.

[marcandre]

Looks good, but will you start using Cop::Base instead of Cop::Cop? In this particular case, I think that instead of having an if such_and_such_a_style three times, it would be more readable if there was a single such if

[fatkodima]

I think that instead of having an if such_and_such_a_style three times, it would be more readable if there was a single such if

Didn't get it. Can you point to code?

[marcandre]

Here's what I had in mind. What do you think of this style?

class HashAsLastArrayItem < Base
  include ConfigurableEnforcedStyle

  def on_hash(node)
    return unless node.parent&.array_type?

    if braces_style?
      check_braces(node)
    else
      check_no_brances(node)
    end
  end

  private

  def check_braces(node)
    return unless node.braces

    add_offense(node, message: 'Wrap hash in `{` and `}`.') do |corrector|
      corrector.wrap(node, '{', '}')
    end
  end

  def check_no_braces(node)
    return if node.braces

    add_offense(node, message: 'Omit the braces around the hash.') do |corrector|
      corrector.remove(node.loc.begin)
      corrector.remove(node.loc.end)
    end
  end

  def braces_style?
    style == :braces
  end
end

[fatkodima]

Ah, got it. Looks nicer 👍
Updated with your suggestions.

[koic]

Thanks!