Controller Testing and Role Based Access Control

I think I have a handle on Unit testing and have set up tests for
approximately 20 of my models. I'm now fooling with Controller testing
and still following the AWDWR book with some success.

I have a Role Based Access Control system...pretty much conceived from
Chad Fowler's Rails Recipes that I've been using for some time now and I
can login and pass the following assertions...

  assert_redirected_to :controller => 'main_tabnav'
   # the redirect from a successful login
  user = User.find(session[:user_id])
  assert_equal 'Low Level User',

So I've created 3 Users in users.yml which will give me 3 levels of RBAC
testing and created the roles_users.yml One of my main purposes for
doing integrated testing is to test out my users/rights/roles mechanics
since I now have over 1500 'rights' and 60 'roles'

My question is one of practical design...

If I want to set up controller tests for which I can plug in 3 different
users and obviously anticipate different results for each user, how can
I accomplish this without creating 3 different test sets for each