Pact is a code-first consumer-driven contract testing tool
”Pact” is an implementation of “consumer driven contract” testing that allows mocking of responses in the consumer codebase, and verification of the interactions in the provider codebase.
Documentation and 5minutes guide - https://docs.pact.io/5-minute-getting-started-guide
There are https://docs.pact.io/getting_started/matching/gotchas with reference to Postel’s law