| > I hope this isn't a dumb question Definitely not : ) > but is there a name for that style of testing and do their exist categories of systems for which it is commonly used I don't know but I guess parallell deployment, production testing (hehe) or something. I guess I learned about it here on HN but I've heard similar approaches elsewhere. Three concrete systems I can think of that has been tested in similar but not identical ways: - trajectory calculation systems for some space probe (I forgot the details) where two separate vendors where tasked with writing software and their software where then run in parallel in a simulation of possible trajectories to root out any bugs. Mentioned as an example to point out an extreme variant of testing, probably by someone here on HN or in something linked to from HN. - a vendor running testing of bag sorting equipment on an airport. Probably told me from a colleague of mine at the time who knew them. AFAIK they'd rerun batches and verify the outputs, making sure the new system produced similar or better results. - an API testing service, probably mentioned here on HN as well, tjat worked by firing three similar requests for each resource and method: two to a deployment of the old system and one to the new. The two that were fired against the old would be used to find parts of the response that changed from request to request (time stamps etc) and the the rest of the response would be used as a template to verify the response from the new system. more generally capturing and reusing production input or running two sets of services in parallel in a data center, - or across datacenters: the existing system as usual and the system under test with only input data. |