testing for a controller that does not exist

class StateControllerTest < ActionController::TestCase

   get :index

end

get :index works. However because of recent change in the controller
name I want /mystate/index to go to the same place. I put in a
FourOhFour cathcall controller which redirect user from /mystate/index
to /state/index. It works.

But how do I get that /mystate/index goes to /state/index . The problem
is that I do not have a controller named MystateController anymore.

Any suggestions.