typescript - 如何使用 Jest 和 TypeScript 正确 stub /模拟 AWS SecretManager

Question

我正在尝试使用 Jest 对 aws-sdk SecretsManager 进行单元测试并遇到一些问题，我有一个简单的缓存客户端

import { SecretsManager } from 'aws-sdk';
import { SecretsManagerIntegrationError } from '../errors';
const cache = new Map();

interface SecretsManagerConfig {
  region?: string;
}

export class SecretsManagerClient {
  secretsManager: SecretsManager;

  constructor(config: SecretsManagerConfig) {
    this.secretsManager = new SecretsManager(config);
  }

  async getSecretFromSecretsManager(secretName: string) {
    try {
      const params = { SecretId: secretName };
      const data = await this.secretsManager.getSecretValue(params).promise();

      if (data.SecretString) {
        return JSON.parse(data.SecretString);
      } else {
        return Buffer.from(data.SecretBinary as any, 'base64').toString('ascii');
      }
    } catch (error) {
      throw new SecretsManagerIntegrationError(`Error retrieving secrets: ${error}`);
    }
  }

  async getSecret(secretName: string) {
    if (!cache.get(secretName)) {
      const secret = await this.getSecretFromSecretsManager(secretName);
      cache.set(secretName, secret);
      return secret;
    }

    return cache.get(secretName);
  }
}

在我的测试文件中，我已经这样 mock 了 sdk.. 看起来很冗长，而且 sinon 处理的东西非常直接，这个断言失败了，我不确定为什么..

import { SecretsManagerClient } from '../../src/clients/secretsManagerClient';

jest.mock('aws-sdk', () => {
  return {
    SecretsManager: jest.fn(() => ({
      getSecretValue: jest.fn(() => ({
        promise: jest.fn(() => ({
          SecretString: JSON.stringify('cool-secrets-here'),
        })),
      })),
    })),
  };
});

describe('SecretsManagerClient', () => {
  let secretsManager: SecretsManagerClient;

  beforeEach(() => {
    secretsManager = new SecretsManagerClient({});
  });

  describe('when a cached value does not exist', () => {
    it('queries the secretsManager', async () => {
      const getSecretFromSecretsManager = jest.spyOn(secretsManager, 'getSecretFromSecretsManager');

      await secretsManager.getSecret('cool-secret');

      expect(getSecretFromSecretsManager).toHaveBeenCalledTimes(1);
    });
  });

  <!-- fails --->
  describe('when a cached value exists', () => {
    it('uses the cached value', async () => {
      const getSecretFromSecretsManager = jest.spyOn(secretsManager, 'getSecretFromSecretsManager');

      await secretsManager.getSecret('cool-secret');
      await secretsManager.getSecret('cool-secret');

      expect(getSecretFromSecretsManager).toHaveBeenCalledTimes(1);
    });
  });
});

Answer 1

我已经使用 sinon stub 实现了对 AWS 服务的模拟。代码示例如下。

import AWS from 'aws-sdk'
import sinon from 'sinon'

let sinonSandbox

const beforeEach = (done) => {
   sinonSandbox = sinon.sandbox.create()
   done()
}

const afterEach = done => {
   sinonSandbox.restore()
   done()
} 
lab.test('test name', (done) => {
    sinonSandbox.stub(AWS, 'SecretsManager')
      .returns({
        getSecretValue: () => {
          return {
            SecretValue: 'Secret-Value'
          }
        }
    })
    done()
})

您还可以创建一个 aws-sdk-mock npm 模块来模拟所有 AWS SDK 服务和方法。

它真的很容易使用。只需使用服务、方法和 stub 函数调用 AWS.mock。

AWS.mock('SecretsManager', 'getSecretValue', function(params, callback) {
    callback(null, 'success');
});

然后在测试后通过调用恢复方法:

AWS.restore('SecretsManager', 'getSecretValue');

赛农链接:

Sinon Stub Latest Version

stub-promise-aws-sdk-node-js

aws-sdk-mock 链接:

aws-sdk-mock

https://www.npmjs.com/package/aws-sdk-mock