Contract Testing

Test API contracts between services to catch breaking changes before deployment.

When to Activate

Setting up Pact consumer-driven contract tests for REST or message-based APIs
Validating OpenAPI specs with Prism mock server or dredd
Checking schema compatibility (JSON Schema, Protobuf, Avro)
Detecting breaking changes in CI with oasdiff
Implementing can-i-deploy gates before deployment
Establishing a safety net between two independently deployed microservices so either team can release without coordinating manually
Adding a CI gate that blocks any pull request that introduces a field removal, rename, or type change to a public REST API
Testing a Kafka event consumer against the exact message schema that the producer publishes, without spinning up the full event pipeline