In the Bitcoin project we found and reported several bugs in OpenSSL based on similar harsnesses that compared our code with similar functions in OpenSSL (where

In the Bitcoin project we found and reported several bugs in OpenSSL based on similar harsnesses that compared our code with similar functions in OpenSSL (where they exist). It's a pretty powerful technique at least in problem domains where fully specified behavior is a realistic expectation. Mutation testing-- where you break the code and confirm that your tests fail-- is also pretty powerful in those same domains.