Using Ruby 2.2.0 with Rails 3.x

Steps for upgrading a Rails 3.x app to Ruby 2.2.0: 1. Install Ruby 2.2.0, e.g. brew update; brew upgrade ruby-build; rbenv install 2.2.0 2. Set app's ruby version to 2.2.0, e.g. rbenv local 2.2.0 3. Update gems that are broken, e.g. bundle update pg eventmachine rubocop 4. Add test-unit to Gemfile to fix "cannot load such file — test/unit/testcase (LoadError)" error: ```ruby gem 'test-unit' ``` 1. Rollback to 2.1 when you notice all warnings, related to e.g. Comparable, or continue with the warnings