Merge pull request jnunemaker#3 from lenary/messages

Customize transgression messages.

lib/canable.rb

@@ -70,8 +70,8 @@ def can_#{can}?(resource)
           current_user.can_#{can}?(resource)
         end
 
-        def enforce_#{can}_permission(resource)
-          raise Canable::Transgression unless can_#{can}?(resource)
+        def enforce_#{can}_permission(resource, message="")
+          raise(Canable::Transgression, message) unless can_#{can}?(resource)
         end
         private :enforce_#{can}_permission
       EOM

test/test_enforcers.rb

@@ -20,6 +20,10 @@ def show
         def update
           enforce_update_permission(article)
         end
+
+        def edit
+          enforce_update_permission(article, "You Can't Edit This")
+        end
       end
 
       @article                 = mock('article')
@@ -43,5 +47,14 @@ def update
       @controller.current_user = nil
       assert_raises(Canable::Transgression) { @controller.update }
     end
+
+    should "pass message around the stack" do
+      @controller.current_user = nil
+      begin
+        @controller.edit
+      rescue Canable::Transgression => e
+        assert_equal e.message, "You Can't Edit This"
+      end
+    end
   end
 end