Fix rubocop offenses

test/benchmark/config.ru

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path(['..', 'app'].join(File::SEPARATOR), __FILE__)
 
 run Rails.application

test/support/ruby_2_6_rails_4_2_patch.rb

@@ -2,15 +2,17 @@
 
 if RUBY_VERSION >= '2.6.0'
   if Rails::VERSION::MAJOR < 5
-    class ActionController::TestResponse < ActionDispatch::TestResponse
-      def recycle!
-        # hack to avoid MonitorMixin double-initialize error:
-        @mon_mutex_owner_object_id = nil
-        @mon_mutex = nil
-        initialize
+    module ActionController
+      class TestResponse < ActionDispatch::TestResponse
+        def recycle!
+          # HACK: to avoid MonitorMixin double-initialize error:
+          @mon_mutex_owner_object_id = nil
+          @mon_mutex = nil
+          initialize
+        end
       end
     end
   else
-    puts "Monkeypatch for ActionController::TestResponse no longer needed"
+    puts 'Monkeypatch for ActionController::TestResponse no longer needed'
   end
 end