Heredoc indentation cop

README.md

Heredoc Indentation Cop

This is a scrappy implementation of a cop that checks the following for heredocs:

• Contents may only be indented in increments of 2 spaces.
• Contents may not be indented using spaces.
• Lines may be at max indented 2 spaces more than the line before, ignoring blank lines.

Usage

1. Copy heredoc_internal_indentation.rb to wherever you want in your project
2. Add the following .rubocop.yml, with the correct require location

require: './heredoc_internal_indentation.rb'

Custom/HeredocInternalIndentation:
  Enabled: true

1. Try running Rubocop normally, and either it works, or you find the bugs I missed.

Oversights

• There are no tests. I just ran it against fixture.rb.
• The offense it tied to the node that opens the heredoc instead of offending line.
• This should probably use the indentation config from the IndentationWidth cop.
• Perhaps the cop should only trigger on certain heredoc delimiters (e.g. SQL).
• The code could probably use refactoring.
• Probably others things. 🤷‍♂️

fixture.rb

<<~ONE_SPACE
  blah
   one space
ONE_SPACE

<<~TWO_SPACES
  blah
    two spaces
TWO_SPACES

<<~THREE_SPACES
  blah
     three spaces
THREE_SPACES

<<~TAB
  blah
  	tab
TAB

<<~OVER_INDENTED
  blah
      over indented
OVER_INDENTED

<<~SKIP_LINE_BUT_FINE
  blah

    fine

  also fine
SKIP_LINE_BUT_FINE


<<~SKIP_LINE_AND_OVERINDENTED
  blah

      over indented
SKIP_LINE_AND_OVERINDENTED

heredoc_internal_indentation.rb

# frozen_string_literal: true

module RuboCop
  module Cop
    module Custom
      class HeredocInternalIndentation < Cop
        include Heredoc

        def on_heredoc(node)
          indentation_and_offsets = node.loc.heredoc_body.source.each_line.with_index.map do |line, index|
            next if line.strip.empty?

            indentation = line[/^\s+/]
            next if indentation.nil? || indentation.empty?

            [indentation, index]
          end.compact

          indentation_and_offsets.each_with_index do |(indentation, line_offset), index|
            add_offense(node, message: 'Heredoc must not be indented using tabs') if indentation.include?("\t")
            add_offense(node, message: "Heredoc must be indented in increments of two spaces") if indentation.length.odd?

            previous_indentation = indentation_and_offsets.fetch(index - 1, nil)&.first
            if previous_indentation && indentation.length > previous_indentation.length + 2
              add_offense(node, message: "Heredoc must be indented in increments of two spaces")
            end
          end
        end
      end
    end
  end
end