expressJS/jestJS:如何拆分get()函数来编写简单的jest单元测试？

Question

如何在expressJS应用程序中定义get()路由,以便进行简单的单元测试？

因此,作为第一步,我get()在自己的文件中移动了函数:

index.js

const express = require('express')
const socketIo = require('socket.io')
const Gpio = require('pigpio').Gpio

const app = express()
const server = http.createServer(app)
const io = socketIo(server)

const setStatus = require('./lib/setStatus.js')

app.locals['target1'] = new Gpio(1, { mode: Gpio.OUTPUT })

app.get('/set-status', setStatus(app, io))

LIB/setStatus.js

const getStatus = require('./getStatus.js')

module.exports = (app, io) => {
  return (req, res) => {
    const { id, value } = req.query // id is in this example '1'
    req.app.locals['target' + id].pwmWrite(value))
    getStatus(app, io)
    res.send({ value }) // don't need this
  }
}

LIB/getStatus.js

const pins = require('../config.js').pins

module.exports = async (app, socket) => {
  const res = []
  pins.map((p, index) => {
    res.push(app.locals['target' + (index + 1)].getPwmDutyCycle())
  })
  socket.emit('gpioStatus', res)
}

所以首先我不太确定,如果我正确地拆分代码 - 考虑进行单元测试.

对我来说,通过调用必须完成的唯一事情/set-status?id=1&value=50是调用pwmWrite()(我猜)对象,该对象由expressJS 定义new Gpio并存储在locals其中.

而对于第二种:如果这应该是正确的方法,我不明白如何编写一个jestJS单元测试来检查是否pwmWrite已被调用 - 这是在异步函数内部.

这是我的尝试,但我无法测试pwmWrite的内部调用:

test('should call pwmWrite() and getStatus()', async () => {
  const app = {}
  const io = { emit: jest.fn() }
  const req = {
    app: {
      locals: {
        target1: { pwmWrite: jest.fn() }
        }
      }
    }
  }
  expect.assertions(1)
  expect(req.app.locals.target1.pwmWrite).toHaveBeenCalled()
  await expect(getStatus(app, io)).toHaveBeenCalled()
})

Answer 1

你们非常接近，只是缺少一些东西。

您需要在期望语句之前调用方法setStatusand getStatus，并且您缺少对req.queryand 的模拟res，因为getStatus使用了它们。

test('should call pwmWrite() and getStatus()', async () => {
  const app = {}
  const io = {};
  const req = {
    query: {
      id: '1',
      name: 'foo'
    },
    app: {
      locals: {
          target1: { pwmWrite: jest.fn() }
      }
    }
  };
  const res = { send: jest.fn() };

  // Mock getStatus BEFORE requiring setStatus
  jest.mock('./getStatus');

  //OBS Use your correct module paths
  const setStatus = require('./setStatus');
  const getStatus = require('./getStatus');


  // Call methods
  setStatus(app, io)(req, res);

  expect.assertions(2);

  // Get called in setStatus
  expect(req.app.locals.target1.pwmWrite).toHaveBeenCalled();

  // See if mocked getStatus has been called
  await expect(getStatus).toHaveBeenCalled();
});

在 require 之前需要getStatus进行模拟setStatus，因为它在那里使用