The Racket Virtual Machine and Randomized Testing

We present a PLT Redex model of a substantial portion of the Racket virtual machine and bytecode verifier (formerly known as MzScheme), along with lessons learned in developing the model. Inspired by the “warts-and-all” approach of the VLISP project, in which Wand et al. produced a verified implementation of Scheme, our model reflects many of the realities of a production system. Our methodology departs from the VLISP project’s in its approach to validation; instead of producing a proof of correctness, we explore the use of QuickCheck-style randomized testing, finding it a cheap and effective technique for discovering a variety of errors in the model—from simple typos to more fundamental design mistakes.