The Importance of Contract Testing in Microservices

I have heard of systems that spend like 75% of their CPU time just parsing or generating Jason. I think for a lot of use cases, the rest is totally sufficient. The promise of microservices was I only need to focus on my little service. But when combined with other services, then things don't work as expected. And so what sometimes people do to try and look at the emergent behavior of the system is they run end-to-end tests. That's incredibly expensive and annoying. If we wanted to stand up 200 services, we would have just stayed with monolith. So contract testing tries to be sort of a middle layer that says, it's going to give me