Make Rails/RootPathnameMethods aware of enforced style of Style/StringLiterals

Follow up #872 (comment).

This PR makes `Rails/RootPathnameMethods` aware of enforced style of `Style/StringLiterals`.

Author: koic

changelog/fix_make_rails_root_pathname_methods_aware_of_style_string_literals.md

@@ -0,0 +1 @@
+* [#875](https://github.com/rubocop/rubocop-rails/pull/875): Make `Rails/RootPathnameMethods` aware of enforced style of `Style/StringLiterals`. ([@koic][])

lib/rubocop/cop/rails/root_pathname_methods.rb

@@ -186,11 +186,7 @@ def evidence(node)
         def build_path_glob_replacement(path, method)
           receiver = range_between(path.loc.expression.begin_pos, path.children.first.loc.selector.end_pos).source
 
-          argument = if path.arguments.one?
-                       path.first_argument.source
-                     else
-                       join_arguments(path.arguments)
-                     end
+          argument = path.arguments.one? ? path.first_argument.source : join_arguments(path.arguments)
 
           "#{receiver}.#{method}(#{argument})"
         end
@@ -224,10 +220,18 @@ def join_arguments(arguments)
               "\#{#{arg.source}}"
             end
           end.join('/')
-          quote = include_interpolation?(arguments) || use_interpolation ? '"' : "'"
+          quote = enforce_double_quotes? || include_interpolation?(arguments) || use_interpolation ? '"' : "'"
 
           "#{quote}#{joined_arguments}#{quote}"
         end
+
+        def enforce_double_quotes?
+          string_literals_config['EnforcedStyle'] == 'double_quotes'
+        end
+
+        def string_literals_config
+          config.for_cop('Style/StringLiterals')
+        end
       end
     end
   end

spec/rubocop/cop/rails/root_pathname_methods_spec.rb

@@ -91,6 +91,23 @@
       RUBY
     end
 
+    context 'when double-quoted string literals are preferred' do
+      let(:other_cops) do
+        super().merge('Style/StringLiterals' => { 'EnforcedStyle' => 'double_quotes' })
+      end
+
+      it "registers an offense when using `Dir.glob(Rails.root.join('**', '*.rb'))`" do
+        expect_offense(<<~RUBY)
+          Dir.glob(Rails.root.join('**', '*.rb'))
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Rails.root` is a `Pathname` so you can just append `#glob`.
+        RUBY
+
+        expect_correction(<<~RUBY)
+          Rails.root.glob("**/*.rb")
+        RUBY
+      end
+    end
+
     it "registers an offense when using `Dir.glob(Rails.root.join('**', \"\#{path}\", '*.rb'))`" do
       expect_offense(<<~'RUBY')
         Dir.glob(Rails.root.join('**', "#{path}", '*.rb'))