mock_controller.rb

  ## TODO wtf!? there must be an easier way...  please help!
  #
    def mock_controller
      require 'action_dispatch/testing/test_request.rb'
      require 'action_dispatch/testing/test_response.rb'
      store = ActiveSupport::Cache::MemoryStore.new
      controller = ApplicationController.new
      controller.perform_caching = true
      controller.cache_store = store
      request = ActionDispatch::TestRequest.new
      response = ActionDispatch::TestResponse.new
      controller.request = request
      controller.response = response
      controller.send(:initialize_template_class, response)
      controller.send(:assign_shortcuts, request, response)
      controller.send(:default_url_options).merge!(DefaultUrlOptions) if defined?(DefaultUrlOptions)
      controller
    end

Don't know if this is actually an improvement, but it's shorter.
https://gist.github.com/909415