pass action and subject through AccessDenied exception when :through isn't found - closes #366

lib/cancan/controller_resource.rb

@@ -159,7 +159,7 @@ module CanCan
         elsif @options[:shallow]
           resource_class
         else
-          raise AccessDenied # maybe this should be a record not found error instead?
+          raise AccessDenied.new(nil, authorization_action, resource_class) # maybe this should be a record not found error instead?
         end
       else
         resource_class

spec/cancan/controller_resource_spec.rb

@@ -235,7 +235,10 @@ describe CanCan::ControllerResource do
     resource = CanCan::ControllerResource.new(@controller, :through => :category)
     lambda {
       resource.load_resource
-    }.should raise_error(CanCan::AccessDenied)
+    }.should raise_error(CanCan::AccessDenied) { |exception|
+      exception.action.should == :show
+      exception.subject.should == Project
+    }
     @controller.instance_variable_get(:@project).should be_nil
   end