contract-testing

Automate consumer-driven contract testing for microservices and API contracts.

6|3|Updated Dec 3, 2025

Search Tags:#api #openapi #schema #contract-testing #pact

Ready to run

npx skills add https://github.com/pacphi/ampel --skill contract-testing-pacphi

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: contract-testing
Source: https://github.com/pacphi/ampel/tree/main/.claude/skills/contract-testing
Command: npx skills add https://github.com/pacphi/ampel --skill contract-testing-pacphi

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Ensures that service contracts between consumers and providers remain stable, preventing breaking changes and coordinating evolution.

Core Features & Use Cases

Consumer-Driven Contracts: Pact-like patterns to define expectations
Provider Verification: Verify providers against consumer contracts
Breaking Change Detection: CI/CD integration to block deployments with breaking changes
Versioning & Deprecation: Semantic versioning for API changes

Quick Start

Define a consumer contract with Pact, then verify the provider against it

Frequently Asked Questions about contract-testing

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I detect breaking changes in API contracts before deployment?▼

Contract testing automatically verifies that API changes remain backward compatible by comparing consumer expectations against provider implementations. CI/CD integration blocks deployments when breaking changes are detected, preventing service disruptions across microservices and distributed teams.

What's the difference between Pact-based testing and OpenAPI schema validation?▼

Pact defines consumer-driven contracts capturing actual interaction expectations, while OpenAPI schema validation checks structural compliance against formal specifications. Both detect incompatibilities; Pact emphasizes consumer needs, OpenAPI ensures schema conformance.

Can I use contract testing across multiple microservices and third-party APIs?▼

Contract testing applies to microservices architectures and third-party API integrations by enforcing agreements between consumers and providers. It verifies provider compliance against consumer contracts and detects breaking changes regardless of service boundaries or deployment scope.

How do I implement semantic versioning with contract testing?▼

Contract testing guides versioning decisions by identifying which API changes are backward compatible or require major version bumps. It enforces semantic versioning discipline by reporting violations and preventing deployments that break established contracts.

Do I need JSON Schema knowledge to define API contracts?▼

Contract testing supports multiple definition formats including Pact patterns, OpenAPI/Swagger schemas, and JSON Schema checks. You can define consumer expectations without deep schema expertise; the framework handles validation across formats.

What happens when a provider fails contract verification?▼

Provider verification reports contract violations, detailing which consumer expectations the provider fails to meet. CI/CD integration prevents deployment of non-compliant providers, ensuring contracts remain enforceable before changes reach production.