It's also useful if the team providing the service can provide a fake or a stub with interesting pre-programmed scenarios, this reduces the number of false assu

It's also useful if the team providing the service can provide a fake or a stub with interesting pre-programmed scenarios, this reduces the number of false assumptions someone can make, is sort of a living documentation (assuming people update their fakes). Something like contract testing (Pact etc) can also be useful, although I haven't seen it being used in practice yet.