Add InternalAffairs/ExampleHeredocDelimiter cop

.rubocop.yml

@@ -163,6 +163,10 @@ InternalAffairs/ExampleDescription:
   Include:
     - 'spec/rubocop/cop/**/*.rb'
 
+InternalAffairs/ExampleHeredocDelimiter:
+  Include:
+    - 'spec/rubocop/cop/**/*.rb'
+
 InternalAffairs/UndefinedConfig:
   Include:
     - 'lib/rubocop/cop/**/*.rb'

lib/rubocop/cop/internal_affairs.rb

@@ -3,6 +3,7 @@
 require_relative 'internal_affairs/cop_description'
 require_relative 'internal_affairs/empty_line_between_expect_offense_and_correction'
 require_relative 'internal_affairs/example_description'
+require_relative 'internal_affairs/example_heredoc_delimiter'
 require_relative 'internal_affairs/inherit_deprecated_cop_class'
 require_relative 'internal_affairs/location_line_equality_comparison'
 require_relative 'internal_affairs/method_name_end_with'

lib/rubocop/cop/internal_affairs/example_heredoc_delimiter.rb

@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module InternalAffairs
+      # Use `RUBY` for heredoc delimiter of example Ruby code.
+      #
+      # Some editors may apply better syntax highlighting by using appropriate language names for
+      # the delimiter.
+      #
+      # @example
+      #  # bad
+      #  expect_offense(<<~CODE)
+      #    example_ruby_code
+      #  CODE
+      #
+      #  # good
+      #  expect_offense(<<~RUBY)
+      #    example_ruby_code
+      #  RUBY
+      class ExampleHeredocDelimiter < Base
+        extend AutoCorrector
+
+        EXPECTED_HEREDOC_DELIMITER = 'RUBY'
+
+        MSG = 'Use `RUBY` for heredoc delimiter of example Ruby code.'
+
+        RESTRICT_ON_SEND = %i[
+          expect_correction
+          expect_no_corrections
+          expect_no_offenses
+          expect_offense
+        ].freeze
+
+        # @param node [RuboCop::AST::SendNode]
+        # @return [void]
+        def on_send(node)
+          heredoc_node = heredoc_node_from(node)
+          return unless heredoc_node
+          return if expected_heredoc_delimiter?(heredoc_node)
+          return if expected_heredoc_delimiter_in_body?(heredoc_node)
+
+          add_offense(heredoc_node) do |corrector|
+            autocorrect(corrector, heredoc_node)
+          end
+        end
+
+        private
+
+        # @param corrector [RuboCop::Cop::Corrector]
+        # @param node [RuboCop::AST::StrNode]
+        # @return [void]
+        def autocorrect(corrector, node)
+          [
+            heredoc_openning_delimiter_range_from(node),
+            heredoc_closing_delimiter_range_from(node)
+          ].each do |range|
+            corrector.replace(range, EXPECTED_HEREDOC_DELIMITER)
+          end
+        end
+
+        # @param node [RuboCop::AST::StrNode]
+        # @return [Boolean]
+        def expected_heredoc_delimiter_in_body?(node)
+          node.location.heredoc_body.source.lines.any? do |line|
+            line.strip == EXPECTED_HEREDOC_DELIMITER
+          end
+        end
+
+        # @param node [RuboCop::AST::StrNode]
+        # @return [Boolean]
+        def expected_heredoc_delimiter?(node)
+          heredoc_delimiter_string_from(node) == EXPECTED_HEREDOC_DELIMITER
+        end
+
+        # @param node [RuboCop::AST::SendNode]
+        # @return [RuboCop::AST::StrNode, nil]
+        def heredoc_node_from(node)
+          return unless node.first_argument.respond_to?(:heredoc?)
+          return unless node.first_argument.heredoc?
+
+          node.first_argument
+        end
+
+        # @param node [RuboCop::AST::StrNode]
+        # @return [String]
+        def heredoc_delimiter_string_from(node)
+          node.source[Heredoc::OPENING_DELIMITER, 2]
+        end
+
+        # @param node [RuboCop::AST::StrNode]
+        # @return [Parser::Source::Range]
+        def heredoc_openning_delimiter_range_from(node)
+          match_data = node.source.match(Heredoc::OPENING_DELIMITER)
+          node.location.expression.begin.adjust(
+            begin_pos: match_data.begin(2),
+            end_pos: match_data.end(2)
+          )
+        end
+
+        # @param node [RuboCop::AST::StrNode]
+        # @return [Parser::Source::Range]
+        def heredoc_closing_delimiter_range_from(node)
+          node.location.heredoc_end.end.adjust(
+            begin_pos: -heredoc_delimiter_string_from(node).length
+          )
+        end
+      end
+    end
+  end
+end

spec/rubocop/cop/bundler/duplicated_gem_spec.rb

@@ -31,29 +31,29 @@
 
     context 'and a gem is duplicated in default group' do
       it 'registers an offense' do
-        expect_offense(<<-GEM, 'Gemfile')
+        expect_offense(<<-RUBY, 'Gemfile')
           source 'https://rubygems.org'
           gem 'rubocop'
           gem 'rubocop'
           ^^^^^^^^^^^^^ Gem `rubocop` requirements already given on line 2 of the Gemfile.
-        GEM
+        RUBY
       end
     end
 
     context 'and a duplicated gem is in a git/path/group/platforms block' do
       it 'registers an offense' do
-        expect_offense(<<-GEM, 'Gemfile')
+        expect_offense(<<-RUBY, 'Gemfile')
           gem 'rubocop'
           group :development do
             gem 'rubocop', path: '/path/to/gem'
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Gem `rubocop` requirements already given on line 1 of the Gemfile.
           end
-        GEM
+        RUBY
       end
     end
 
     it 'registers an offense when gem from default group is conditionally duplicated' do
-      expect_offense(<<-GEM, 'Gemfile')
+      expect_offense(<<-RUBY, 'Gemfile')
         gem 'rubocop'
         if Dir.exist? local
           gem 'rubocop', path: local
@@ -62,22 +62,22 @@
           gem 'rubocop', '~> 0.90.0'
           ^^^^^^^^^^^^^^^^^^^^^^^^^^ Gem `rubocop` requirements already given on line 1 of the Gemfile.
         end
-      GEM
+      RUBY
     end
 
     it 'does not register an offense when gem is duplicated within `if-else` statement' do
-      expect_no_offenses(<<-GEM, 'Gemfile')
+      expect_no_offenses(<<-RUBY, 'Gemfile')
         if Dir.exist?(local)
           gem 'rubocop', path: local
           gem 'flog', path: local
         else
           gem 'rubocop', '~> 0.90.0'
         end
-      GEM
+      RUBY
     end
 
     it 'does not register an offense when gem is duplicated within `if-elsif` statement' do
-      expect_no_offenses(<<-GEM, 'Gemfile')
+      expect_no_offenses(<<-RUBY, 'Gemfile')
         if Dir.exist?(local)
           gem 'rubocop', path: local
         elsif ENV['RUBOCOP_VERSION'] == 'master'
@@ -87,11 +87,11 @@
         else
           gem 'rubocop', '~> 0.90.0'
         end
-      GEM
+      RUBY
     end
 
     it 'does not register an offense when gem is duplicated within `case` statement' do
-      expect_no_offenses(<<-GEM, 'Gemfile')
+      expect_no_offenses(<<-RUBY, 'Gemfile')
         case
         when Dir.exist?(local)
           gem 'rubocop', path: local
@@ -100,7 +100,7 @@
         else
           gem 'rubocop', '~> 0.90.0'
         end
-      GEM
+      RUBY
     end
   end
 end