Unit test procedures as returned values?

I've been having a fantastic experience working through the Lil Schemer using Schemeunit to test my progress. I have, however, hit a stumbling block. Maybe i'm missing something, but I can't see how to go about testing for correct procedures as my returned values. Anyone have any suggestions? I am not terribly axed to do this in any particular lisp, though I do seem to prefer Scheme so far.