Api Contract Testing

Helps you set up contract testing between services so you don't break APIs when deploying changes. Instead of running full integration tests, you validate that your service honors the contract consumers expect. Covers Pact for consumer-driven contracts, OpenAPI schema validation, and integration with Pact Broker for sharing contracts across teams. Most valuable in microservices architectures where you need to catch breaking changes before they hit production. The Pact implementation is solid and the reference guides cover both TypeScript and Java. Worth noting that contract tests complement integration tests rather than replace them, since they focus on API shape and format rather than business logic.

skills.sh installs: 926
GitHub stars: 379
last updated: Aug 21, 2026

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Install

$ npx -y skills add aj-geddes/useful-ai-prompts --skill api-contract-testing --agent claude-code

Installs into .claude/skills of the current project.

Files

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:

// tests/pact/user-service.pact.test.ts
import { PactV3, MatchersV3 } from "@pact-foundation/pact";
import { UserService } from "../../src/services/UserService";

const { like, eachLike, iso8601DateTimeWithMillis } = MatchersV3;

SKILL.md on GitHub