--- name: validating-api-contracts-d7df513c92e7 description: 'Validate API contracts using consumer-driven contract testing (Pact, Spring Cloud Contract). Use when performing specialized testing. Trigger with phrases like "validate API contract", "run contract tests", or "check consumer contracts". ' allowed-tools: Read, Write, Edit, Grep, Glob, Bash(test:contract-*) version: 1.24.0 author: Jeremy Longshore license: MIT tags: - testing - api - validating-api compatibility: Designed for Claude Code --- # Contract Test Validator ## Overview Validate API contracts between services using consumer-driven contract testing to prevent breaking changes in microservice architectures. Supports Pact (the industry standard for CDC testing), Spring Cloud Contract (JVM), and OpenAPI-diff for specification comparison. ## Prerequisites - Contract testing framework installed (Pact JS/Python/JVM, or Spring Cloud Contract) - Pact Broker running (or PactFlow SaaS) for contract storage and verification - Consumer and provider services with clearly defined API boundaries - Existing integration points documented (which consumers call which provider endpoints) - CI pipeline configured for both consumer and provider repositories ## Instructions 1. Identify consumer-provider relationships in the system: - Map which services call which APIs (e.g., Frontend calls User API, Order API calls Payment API). - Document each interaction: HTTP method, path, headers, request body, expected response. - Prioritize contracts for the most critical and frequently changing integrations. 2. Write consumer-side contract tests (Pact consumer tests): - Define the expected interaction: method, path, query parameters, headers, request body. - Specify the expected response: status code, headers, and response body structure. - Use matchers for flexible assertions (`like()`, `eachLike()`, `term()`) instead of exact values. - Generate a Pact file (JSON contract) from the consumer test. 3. Publish consumer contracts to the Pact Broker: - Run `pact-broker publish` with the consumer version and branch/tag. - Enable webhooks to trigger provider verification when new contracts are published. - Configure can-i-deploy checks in CI to gate deployments. 4. Write provider-side verification tests: - Configure the Pact verifier to fetch contracts from the Pact Broker. - Set up provider states (test data scenarios matching consumer expectations). - Run verification against the actual provider implementation. - Publish verification results back to the Pact Broker. 5. Handle contract evolution: - Adding new fields: Safe -- consumers using matchers will not break. - Removing fields: Breaking -- coordinate with all consumers before removal. - Changing field types: Breaking -- requires consumer updates first. - Use `can-i-deploy` to check compatibility before releasing either side. 6. For schema-based validation (non-Pact): - Compare OpenAPI spec versions using `openapi-diff` to detect breaking changes. - Flag removed endpoints, changed parameter types, and narrowed response schemas. - Run schema validation tests against the actual API responses. 7. Integrate contract tests into the CI/CD pipeline for both consumers and providers. ## Output - Consumer Pact test files defining expected API interactions - Generated Pact contract files (JSON) in `pacts/` directory - Provider verification test configuration - Pact Broker deployment with published contracts and verification status - CI pipeline integration with `can-i-deploy` deployment gates - Contract evolution report flagging breaking vs. non-breaking changes ## Error Handling | Error | Cause | Solution | |-------|-------|---------| | Provider verification fails | Provider response does not match consumer expectations | Check if the contract is outdated; update consumer tests if the change is intentional; fix provider if regression | | `can-i-deploy` blocks release | Consumer has unverified or failed contracts | Run provider verification; check if the right version tags are published; verify Pact Broker webhook fired | | Pact Broker connection error | Broker URL or credentials misconfigured | Verify `PACT_BROKER_BASE_URL` and `PACT_BROKER_TOKEN` environment variables; check network connectivity | | Provider state not found | Consumer test references a state the provider does not implement | Add the missing provider state setup function; align state names between consumer and provider | | Too many contracts to maintain | Every consumer-provider pair has extensive contracts | Focus on critical interactions; use matchers instead of exact values; consolidate similar interactions | ## Examples **Pact consumer test (JavaScript):** ```typescript import { PactV4 } from '@pact-foundation/pact'; const provider = new PactV4({ consumer: 'Frontend', provider: 'UserAPI' }); describe('User API Contract', () => { it('fetches a user by ID', async () => { await provider .addInteraction() .given('user with ID 1 exists') .uponReceiving('a request for user 1') .withRequest('GET', '/api/users/1', (builder) => { builder.headers({ Accept: 'application/json' }); }) .willRespondWith(200, (builder) => { # HTTP 200 OK builder .headers({ 'Content-Type': 'application/json' }) .jsonBody({ id: like('1'), name: like('Alice'), email: like('alice@example.com'), }); }) .executeTest(async (mockServer) => { const response = await fetch(`${mockServer.url}/api/users/1`); const user = await response.json(); expect(user.name).toBeDefined(); }); }); }); ``` **Provider verification test:** ```typescript import { Verifier } from '@pact-foundation/pact'; describe('User API Provider Verification', () => { it('validates consumer contracts', async () => { await new Verifier({ providerBaseUrl: 'http://localhost:3000', # 3000: 3 seconds in ms pactBrokerUrl: process.env.PACT_BROKER_BASE_URL, pactBrokerToken: process.env.PACT_BROKER_TOKEN, provider: 'UserAPI', publishVerificationResult: true, providerVersion: process.env.GIT_SHA, stateHandlers: { 'user with ID 1 exists': async () => { await db.users.create({ id: '1', name: 'Alice', email: 'alice@example.com' }); }, }, }).verifyProvider(); }); }); ``` **can-i-deploy CI check:** ```bash pact-broker can-i-deploy \ --pacticipant Frontend \ --version $(git rev-parse HEAD) \ --to-environment production \ --broker-base-url $PACT_BROKER_URL \ --broker-token $PACT_BROKER_TOKEN ``` ## Resources - Pact documentation: https://docs.pact.io/ - PactFlow (managed Pact Broker): https://pactflow.io/ - Spring Cloud Contract: https://spring.io/projects/spring-cloud-contract - openapi-diff: https://github.com/OpenAPITools/openapi-diff - Consumer-Driven Contracts: https://martinfowler.com/articles/consumerDrivenContracts.html --- Source attribution: jeremylongshore Original project: https://github.com/jeremylongshore/claude-code-plugins-plus-skills/blob/ab85a061f7bcc039dac13ee193de7a4cd4388571/plugins/testing/contract-test-validator/skills/validating-api-contracts/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice MIT License Copyright (c) 2026 Claude Code Plugin Hub Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. # Mega AI Hub resource metadata Creator / publisher: jeremylongshore Original project: https://github.com/jeremylongshore/claude-code-plugins-plus-skills/blob/ab85a061f7bcc039dac13ee193de7a4cd4388571/plugins/testing/contract-test-validator/skills/validating-api-contracts/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering Roles: Backend Developer, DevOps / SRE, QA / Test Engineer Specialties: API, Backend, Design, DevOps, Word Documents, Frontend, Git, Mobile, Stripe, Testing Tools: Pact Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 1393d4619a414c0ae3124212d655788e752f5bf959a5e939ab10e7fb05f59bfc