Contract testing with OpenAPI

Contract testing is a crucial process in API development that ensures both consumers and providers adhere to a predefined agreement, usually outlined in an API specification like OpenAPI, mitigating risks from API changes. The article discusses how contract testing fits into the testing pyramid, which also includes unit, integration, and end-to-end testing, each serving different purposes and complexities. Contract tests, which verify the interactions between API consumers and providers, are more complex than unit tests but simpler than integration tests, providing early detection of breaking changes. The piece also outlines the implementation of contract testing using OpenAPI and tools like Speakeasy, which can automate test generation and ensure that APIs remain reliable despite evolving requirements. It emphasizes the importance of contract testing for maintaining a stable API ecosystem and the potential for automated test generation to save time and reduce errors.