如何使用 jest/enzyme 模拟 multer 以使用 axios 后模拟调用进行文件上传

我正在测试我的快速路由器axios调用后到后端。我正进入（状态500响应而不是 200，不知道如何嘲笑multer有效地。 对此有什么想法吗？谢谢

路线.jsx

const axios = require('axios')
const router = express.Router()
const multer = require('multer')
const FormData = require('form-data')
const express = require('express')

const upload = multer({ storage: multer.memoryStorage() }).any()

router.post('/', upload, (req, res) => {
  const formData = new FormData()
   const { body } = req 
    req.files.forEach(file => {
      formData.append(
        'files',
        file.buffer,
        {
          filename: file.originalname
        },
        file.originalname
      )
    })


  axios
    .post('/api/endpoint', formData)
    .then(response => {return response
    })
    .catch(e => {
    console.log(e)
    })
})

module.exports = router

下面是我的测试用例

路由.jsx.测试

const axios = require('axios')
const MockAdapter = require('axios-mock-adapter')
const myroute = require('myroute')
const app = express()
const mock = new MockAdapter(axios)
const request = require('supertest')
const express = require('express')
const bodyParser = require('body-parser')
const multer = require('multer')
jest.mock('multer')

multer.mockImplementation(() => {
  return {
    any () {
      return (req, res, next) => {
        req.body = { userName: 'testUser' }
        req.files = [
          {
            originalname: 'sample.name',
            mimetype: 'sample.type',
            path: 'sample.url'
          }
        ]
        return next()
      }
    }
  }
})
app.use(bodyParser.json())

app.use('/', myroute)

describe('sendFiles', () => {
  const url = '/api/endpoint'  

  test('200 response', () => {
    const myMockRes = { mykey: 'myVal' }
    let formData = new FormData()
    const file = new Blob(['somee contents'], { type: 'multipart/form-data' })
    formData.append('files', file)
    formData.append('userName', 'testUser')
    mock.onPost(url).reply(200, myMockRes)
    return (
      request(app)
        .post('/')
        .send({ userName: 'testUser', files: [file] })
        //.expect('Content-Type', /json/)
        .expect(200)
        .then(response => {
          const { data } = response.body
          expect(data).toEqual(myMockRes)
        })
    )
  })


})

error:

TypeError: Cannot read property 'any' of undefined in routes.jsx

const upload = multer({ storage: multer.memoryStorage() }).any()
    

当你使用jest.mock('multer'), Jest 自动模拟模块并返回undefined当它在测试中被调用时。既然我们想嘲笑memoryStorage and any方法也是如此，我们必须通过将工厂作为第二个参数传递给jest.mock https://jestjs.io/docs/en/jest-object#jestmockmodulename-factory-options.

jest.mock('multer', () => {
  const multer = () => ({
    any: () => {
      return (req, res, next) => {
        req.body = { userName: 'testUser' }
        req.files = [
          {
            originalname: 'sample.name',
            mimetype: 'sample.type',
            path: 'sample.url',
            buffer: Buffer.from('whatever'), // this is required since `formData` needs access to the buffer
          },
        ]
        return next()
      }
    },
  })
  multer.memoryStorage = () => jest.fn()
  return multer
})

另一个问题是Blob节点中不存在。您可以使用Buffer.from https://nodejs.org/api/buffer.html#buffer_static_method_buffer_from_string_encoding生成一个缓冲区以在请求中发送。

const file = Buffer.from('whatever')

而且你不需要使用FormData在测试中。

整个代码：

// router.test.js

const axios = require('axios')
const MockAdapter = require('axios-mock-adapter')
const express = require('express')
const app = express()
const mock = new MockAdapter(axios)
const request = require('supertest')

const bodyParser = require('body-parser')

const myroute = require('./router')

jest.mock('multer', () => {
  const multer = () => ({
    any: () => {
      return (req, res, next) => {
        req.body = { userName: 'testUser' }
        req.files = [
          {
            originalname: 'sample.name',
            mimetype: 'sample.type',
            path: 'sample.url',
            buffer: Buffer.from('whatever'),
          },
        ]
        return next()
      }
    },
  })
  multer.memoryStorage = () => jest.fn()
  return multer
})

app.use(bodyParser.json())

app.use('/', myroute)

describe('sendFiles', () => {
  const url = '/api/endpoint'

  test('200 response', () => {
    const myMockRes = { mykey: 'myVal' }
    const file = Buffer.from('whatever')
    mock.onPost(url).reply(200, myMockRes)
    return request(app)
      .post('/')
      .send({ userName: 'testUser', files: [file] })
      .expect(200)
      .then((response) => {
        const { data } = response.body
        expect(data).toEqual(myMockRes)
      })
  })
})