Polymorphic destroy of resource

I have a folder class which has a folder_linkable, which links a
folder id to items via their id and class. If the folder is destroyed,
I want each linking destroyed, and then each item that is linked to
destroyed. I have in the FolderLinking class:

belongs_to :folder_linkable, :polymorphic =>
true, :dependent=> :destroy

but in my unit tests, the items that are connected with
folder_linkable are not destroyed. Does dependent destroy work with

Otherwise, should I overload destroy, destroying the item, and then
deleting the item via the class delete to avoid the recursive destroy?

I ran into the same problem a few days ago and havn’t found a solution
this. I really wonder if this is a bug (or a missing feature) in rails
or if
I’m just missing something.