I encountered the problem with implementing this that since the on disk layout was going to change from the previous implementation, I felt like the best way to test any one of the file system functions was to have the whole group of them.  (With the further difficulty, that with the design still in a little bit of flux, and relying on functionality that is not present yet(ie, authoritative state) meant other bits actual final hooks can't be made).

I wound up implementing everything, and testing it via the ruby parser. (Should have thrown together a unit test along those lines...  add in a delete function to be able to 'reset' the filesystem).