Add a fake UrlRewriter, since instantiating it in tests happens, but is basically crazysauce

actionpack/lib/action_controller.rb

@@ -36,6 +36,7 @@ module ActionController
 
   autoload :Dispatcher,      'action_controller/deprecated/dispatcher'
   autoload :UrlWriter,       'action_controller/deprecated/url_writer'
+  autoload :UrlReriter,      'action_controller/deprecated/url_writer'
   autoload :Integration,     'action_controller/deprecated/integration_test'
   autoload :IntegrationTest, 'action_controller/deprecated/integration_test'
   autoload :PerformanceTest, 'action_controller/deprecated/performance_test'

actionpack/lib/action_controller/deprecated/url_writer.rb

@@ -6,4 +6,9 @@ module ActionController
       klass.class_eval { include Rails.application.routes.url_helpers }
     end
   end
+
+  class UrlRewriter
+    def initialize(*)
+    end
+  end
 end