Pact 实战指南

原创于 2025-03-31 16:24:21 发布

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Pact 实战指南

Pact 是一个消费者驱动的契约测试工具，用于确保服务之间的交互符合预期。下面我将介绍 Pact 的核心概念和实战应用。

1. Pact 核心概念

消费者(Consumer): 使用服务的应用
提供者(Provider): 提供服务的应用
契约(Contract): 描述消费者与提供者之间交互的规范
模拟服务(Mock Service): Pact 为消费者测试提供的模拟提供者

2. 实战步骤

2.1 消费者端测试

// 以JavaScript为例
const { Pact } = require('@pact-foundation/pact');
const { getUser } = require('./consumer');

describe('User Service', () => {
  const provider = new Pact({
    consumer: 'UserWeb',
    provider: 'UserService',
    port: 1234,
    log: path.resolve(process.cwd(), 'logs', 'pact.log'),
    dir: path.resolve(process.cwd(), 'pacts'),
    logLevel: 'INFO',
  });

  beforeAll(() => provider.setup());
  afterEach(() => provider.verify());
  afterAll(() => provider.finalize());

  describe('get user', () => {
    beforeAll(() => {
      return provider.addInteraction({
        state: 'a user with id 1 exists',
        uponReceiving: 'a request for user with id 1',
        withRequest: {
          method: 'GET',
          path: '/users/1',
          headers: { 'Accept': 'application/json' }
        },
        willRespondWith: {
          status: 200,
          headers: { 'Content-Type': 'application/json' },
          body: {
            id: 1,
            name: 'John Doe',
            email: 'john@example.com'
          }
        }
      });
    });

    it('returns the correct user', async () => {
      const response = await getUser(1);
      expect(response).toEqual({
        id: 1,
        name: 'John Doe',
        email: 'john@example.com'
      });
    });
  });
});

2.2 提供者端验证

const { Verifier } = require('@pact-foundation/pact');
const path = require('path');

describe('Pact Verification', () => {
  it('validates the expectations of UserWeb', () => {
    const opts = {
      providerBaseUrl: 'http://localhost:3000',
      pactUrls: [
        path.resolve(__dirname, '../pacts/userweb-userservice.json')
      ],
      providerStatesSetupUrl: 'http://localhost:3000/setup'
    };

    return new Verifier().verifyProvider(opts)
      .then(output => {
        console.log('Pact Verification Complete!');
        console.log(output);
      });
  });
});