In my county we do L&A (logic and accuracy) testing. Both parties are involved everything is signed off and documented. I know this isn't forensic level, but what more would one want? We complete a test deck using ballot markers, test all races in all precincts. Tabulate them and output a print that checks against the test deck produced. All of this is held in archives and reviewable by the public. Machines are zeroed and sealed and will not be touched until election day.