Usage You need to tell RuboCop to load the Rails extension. There are three ways to do this: RuboCop configuration file Put this into your .rubocop.yml. require: rubocop-rails Now you can run rubocop and it will automatically load the RuboCop Rails cops together with the standard cops. Command line rubocop --require rubocop-rails Rake task RuboCop::RakeTask.new do |task| task.requires << 'rubocop-rails' end Installation Cops