In a previous post we learned about Spring Cloud Contract. We saw how we can use contracts to implement the server side of the contract. But Spring Cloud Contract also creates a stub based on the contract. The stub server is implemented with Wiremock and Spring Boot. The server can match incoming requests with the contracts and send back the response as defined in the contract. Let’s write an application that is invoking HTTP requests on the server application we wrote before. In the tests that we write for this client application we use the stub that is generated by Spring Cloud Contract. We know the stub is following the contract of the actual server.

Spring Cloud Contract is a project that allows to write a contract for a service using a Groovy DSL. In the contract we describe the expected requests and responses for the service. From this contract a stub is generated that can be used by a client application to test the code that invokes the service. Spring Cloud Contract also generates tests based on the contract for the service implementation. Let’s see how we can use the generated tests for the service implementation for a Ratpack application.