RuboCop GitHub 
This repository provides recommended RuboCop configuration and additional Cops for use on GitHub open source and internal Ruby projects.
Usage
Rubocop 0.68 removed performance cops and 0.72 removed Rails cops. However, upgrading rubocop-github without modification will almost definitely create very many new offenses. The current version of this gem exposes the "legacy" configuration under config/default.yml and config/rails.yml which should be used if and only if the version of rubocop is locked to < 0.68 in your project (which it should be unless you bundle update rubocop). It also exposes an "edge" configuration under config/default_edge.yml and config/rails_edge.yml so that the changes can be tested without introducing breaking changes.
Legacy usage
Gemfile
gem "rubocop", "< 0.68"
gem "rubocop-github".rubocop.yml
inherit_gem:
rubocop-github:
- config/default.yml
- config/rails.ymlEdge usage
Gemfile
gem "rubocop-github"
gem "rubocop-performance", require: false
gem "rubocop-rails", require: false.rubocop.yml
inherit_gem:
rubocop-github:
- config/default_edge.yml
- config/rails_edge.ymlTesting
bundle install
bundle exec rake test
The Cops
All cops are located under lib/rubocop/cop/github, and contain examples/documentation.

