Refactor request_factory & response_validator

test-app/app/controllers/application_controller.rb

@@ -4,4 +4,9 @@ class ApplicationController < ActionController::Base
   protect_from_forgery with: :null_session
 
   wrap_parameters format: [ :json ]
+
+  respond_to :json
+  rescue_from 'ActionController::UnknownFormat' do |ex|
+    head :not_acceptable
+  end
 end