node.js - 如何用 Jest 模拟 s3.upload() - node.js

Question

我尝试用 this 模拟 s3 上传功能指令但是当我使用这种模式时有一个

TypeError: s3.upload is not a function

// upload.test.js
const AWS = require('aws-sdk');
jest.mock('aws-sdk', () => {
  const mS3 = { upload: jest.fn().mockReturnThis(), promise: jest.fn() };
  return { S3: jest.fn(() => mS3) };
});

const s3 = new AWS.S3();
s3.upload({}).promise.mockResolvedValueOnce({ Bucket: 'XXX' });

我也在使用 SQS 并且使用这种模式我有另一个错误:

AWS.SQS is not a constructor

我该如何应对？

// upload.js
const AWS = require('aws-sdk');
const s3 = new AWS.S3();
s3Params = {
        Bucket: S3_BUCKET,
        Key: `example.xml`,
        ACL: 'public-read',
        ContentType: 'application/json',
        Body: Buffer.from(file)
      }
    }
await s3.upload(s3Params).promise();

Answer 1

当使用 Jest .mockReturnValueOnce 时，您需要在该值设置为能够接收您在 mockReturnValueOnce 中定义的值作为响应后执行模拟，

例如模拟S3:

// s3-mock.test.js
let AWS = require('aws-sdk');

jest.mock('aws-sdk', () => {
  let instance = {
    upload: jest.fn().mockReturnThis(),
    promise: jest.fn(),
  };
  return { S3: jest.fn(() => instance) };
});


describe("setup for s3.upload testing", () => {
  let testS3;
  beforeEach(() => {
    testS3 = new AWS.S3();
    testS3.promise.mockReturnValueOnce({ Bucket: 'TestBucketName' });
  })

  test('returns expected upload value', async () => {
    let params = {};
    let result = await testS3.upload(params).promise();
    expect(result).toEqual({ Bucket: 'TestBucketName' });
    expect(result.Bucket).toBe("TestBucketName")
  });
});

和模拟 SQS:

// sqs-mock.test
let AWS = require('aws-sdk');

jest.mock('aws-sdk', () => {
  let instance = {
    sendMessage: jest.fn().mockReturnThis(),
    promise: jest.fn(),
  };
  return { SQS: jest.fn(() => instance) };
});


describe("setup for sqs.sendMessage testing", () => {
  let testSQS;
  beforeEach(() => {
    testSQS = new AWS.SQS();
    testSQS.promise.mockReturnValueOnce({ MessageId: 'TestSQSId' });
  })

  test('returns expected message id', async () => {
    let params = {};
    let result = await testSQS.sendMessage(params).promise();
    expect(result).toEqual({ MessageId: 'TestSQSId' });
    expect(result.MessageId).toBe("TestSQSId")
  });
});

关于 https://github.com/oieduardorabelo/jest-mock-aws-sdk 的工作示例

如您所见，它们是相同的，您还可以在 Jest 中使用手动模拟，文件夹 __mocks__ 包含所有包，并在测试中模拟，请查看以下文档: https://jestjs.io/docs/manual-mocks