• Ruby 2.6.5
• NodeJS 12.16.x
• Yarn 1.12.x

1. Run bundle install to install the gem dependencies
2. Run yarn to install node dependencies
3. Run bundle exec rails server to launch the app on http://localhost:3002

bundle exec rake

bundle exec rspec

It's best to lint just your app directories and not those belonging to the framework, e.g.

bundle exec rubocop app config lib spec Gemfile --format clang -a

or

bundle exec scss-lint app/webpacker/styles