We’ve been building invariants as part of regular code review assessments for more than 6 years now, but our work with Curvance marks our very first official invariant development project, in which developing and testing invariants is all we did. Changes to the Curvance codebase—like function removals, additions of function parameters, adjustments to arguments and error messages, and renaming of source contracts—often challenged our fuzzing suite by invalidating existing invariants or causing a series of assertion failures.