Verify API contracts between services to ensure compatibility and prevent breaking changes. Use for contract testing, Pact, API contract validation, schema validation, and consumer-driven contracts.

API Contract Testing Table of Contents [Overview]( overview) [When to Use]( when to use) [Quick Start]( quick start) [Reference Guides]( reference guides) [Best Practices]( best practices) Overview Contract testing verifies that APIs honor their contracts between consumers and providers. It ensures that service changes don't break dependent consumers without requiring full integration tests. Contract tests validate request/response formats, data types, and API behavior independently. When to Use Testing microservices communication Preventing breaking API changes Validating API versioning Testing consumer provider contracts Ensuring backward compatibility Validating OpenAPI/Swagger specifications Testing third party API integrations Catching contract violations in CI Quick Start Minimal working example: Reference Guides Detailed implementations in the references/ directory: Guide Contents [Pact for Consumer Driven Contracts](references/pact for consumer driven contracts.md) Pact for Consumer Driven Contracts [OpenAPI Schema Validation](references/openapi schema validation.md) OpenAPI Schema Validation [JSON Schema Validation](references/json schema validation.md) JSON Schema Validation [REST Assured for Java](references/rest assured for java.md) REST Assured for Java [Contract Testing with Postman](references/contract testing with postman.md) Contract Testing with Postman [Pact Broker Integration](references/pact broker integration.md) Pact Broker Integration Best Practices ✅ DO Test contracts from consumer perspective Use matchers for flexible matching Validate schema structure, not specific values Version your contracts Test error responses Use Pact broker for contract sharing Run contract tests in CI Test backward compatibility ❌ DON'T Test business logic in contract tests Hard code specific values in contracts Skip error scenarios Test UI in contract tests Ignore contract versioning Deploy without contract verification Test implementation details Mock contract tests

api-contract-testing