SPIN is a general tool for verifying the correctness of distributed software models in a rigorous and mostly automated fashion. It was written by Gerard J. Holzmann and others in the original Unix group of the Computing Sciences Research Center at Bell Labs, beginning in 1980. The software has been available freely since 1991, and continues to evolve to keep pace with new developments in the field.
http://spinroot.com
Unfortunately Bell Labs use strange non-free copyleft-like license instead of good old GPL. So it could not be included in Debian archive. But as I need Debian package for it, I’ve prepared one and put into my repository.