This upgrade was fairly easy. The thing that will potentially give you more work are tests around ajax requests.

Here are the few detailed notes:

• ActiveModels now includes a none scope by default. So if you have some none scope defined, just remove their definitions.
• The state machine gem has not been updated for Rails 4.1 yet. Rails 4.1 made private the around_validation method in ActiveModels. Since state machine uses this method to inject its own validations, you need an extension for it. I’ve created a file named config/initializers/state_machine.rb and added the following code:
  module StateMachine::Integrations::ActiveModel; public :around_validation; end
• CFRS is also possible in AJAX request. Because of this AJAX requests are checked against it as well as of Rails 4.1. Therefore, in your tests, get :whatever, :format => ‘js’ has to become xhr :get, :whatever, :format => :js