Review your app

1. App should have .ruby-version file
2. Same version should be in Gemfile at the top
3. All gems should be locked on minor version ('~> 5.0.1')
4. Gems should be organized in groups
5. Gems should have short description
6. To know which gem should be update - rub bundle-audit or gem outdated
7. Any keys shouldn't be in config/environments/
8. db/seed.rb should exist.
9. Check how many foreign keys grep -v 'add_index' db/schema.rb | grep '_id' | wc -l  and compare it with grep 'add_index' db/schema.rb | wc -

https://medium.com/planet-argon-tenets/