Use inflector to avoid conflicts.

test/devise_test.rb

@@ -58,9 +58,6 @@ class DeviseTest < ActiveSupport::TestCase
     assert_equal :fruits, Devise::CONTROLLERS[:kivi]
     Devise::ALL.delete(:kivi)
     Devise::CONTROLLERS.delete(:kivi)
-
-    assert_nothing_raised(Exception) { Devise.add_module(:authenticatable_again, :model => 'devise/model/authenticatable') }
-    assert defined?(Devise::Models::AuthenticatableAgain)
   end
   
   test 'should complain when comparing empty or different sized passes' do