Here's guile-tap [1] which os based on Mikael Svantesson's work. It is a very basic drop-in library for unit testing using the Test Anything Protocol (TAP). One can also combine it with Automake's tap driver to generate nicely colored output.
[1] https://github.com/wedesoft/guile-tap -- Jan Wedekind http://www.wedesoft.de/
