Testing with a Dummy Controller in a Rails Engine

If you have a controller in your dummy app (spec/dummy/app/controllers/dummy_controller.rb) for your Rails engine, you might need to access the list of routes within your spec code. You can do this, surprisingly, with Rails.application.routes.routes!

Using self.included to Include Dependencies

As part of a project I'm working on, I created a mountable engine for extracting all authentication concerns for the app. I created a TestHelper module that includes methods for mocking various aspects required for authentication. These methods require Devise::TestHelpers to function properly, and my goal was for the calling app to not know or care about this dependency. To solve this, I used self.included to automatically include the helper when necessary (in my case, only in controller specs).
Here is the code:

 def self.included(receiver)  
  if defined?(receiver.metadata) && receiver.metadata[:type] == :controller  
   receiver.send :include, Devise::TestHelpers  
  end  
 end