Holly Cummins discusses how contract tests combine the lightness of unit tests with the confidence of integration tests, and should be part of your development toolkit. Introduction to contract-first: https://www.redhat.com/en/blog/achieving-promise-microservices-one-contract-time A tutorial on doing contract-first using an OpenAPI approach: https://appdev.consulting.redhat.com/tracks/contract-first/ The documentation for the JVM binding for Pact: https://docs.pact.io/implementation_guides/jvm The Pact Quarkus extension: https://github.com/quarkiverse/quarkus-pact The sample code: https://github.com/holly-cummins/pact-quarkus-sweater-demo