In a microservices architecture, services are independently developed, deployed, and scaled. But independence comes with a hidden cost: integration risk . When the orders-service calls the users-service , how do you know the response shape hasn't changed? When the payments-service upgrades its API, how do you catch breaking changes before they reach production? Unit tests won't catch this. E2E tests are too slow and too brittle to run on every deployment. The answer is contract testing , a lightweight, fast, and precise approach to verifying that services can communicate with each other correctly, without the overhead of a shared test environment. This guide covers what contract testing is, how consumer-driven contract testing with Pact works, and how to integrate it into your microservices CI/CD pipeline. What Is Contract Testing? A contract is a formal agreement between two services about what requests and responses look like.…