Contract Test

Overview

A contract test verifies the agreement between a consumer and a provider — not their internal behaviour. The consumer defines what it expects from the provider; the provider verifies it can meet those expectations. Contract testing is a design discipline as much as a testing technique.

Required background: Apply auto-test universal principles first. This skill adds contract-scope specifics.

When to Use

• Two services are developed by different teams and must stay compatible
• A breaking API change needs to be detected before deployment
• You need to verify that a consumer only uses what the provider actually offers
• Validating that a published schema (OpenAPI, Avro, Protobuf, JSON Schema) matches actual usage

Not for: verifying business logic inside a service (use unit-test or integration-test). Not for testing that two services produce the right end-user outcome (use e2e-test).

Core Principles