I get an error NameError (undefined local variable or method \"current_user\" for # when I try to use current_user in a
current_user is only available in your controllers and views. There is more than one way to achieve what you want, the easier being supplying it as a parameter to your method.
EDIT
if current_user if accessible in the router, you can pass it to your constraints class by doing constraints: APIRouter.new(current_user). Then you need to define APIRouter#initialize and store the current_user in an instance var that you can use in matches?.
EDIT 2
I just remembered devise allows you to do this in your router :
authenticated :user do
root :to => "main#dashboard"
end
I don't know how to ensure that user.is_test though.
EDIT 3
Last attempt. request.env["warden"].user(:user) should give you a user if one is authenticated.