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

时间:2018-10-16 19:17:21

标签: javascript unit-testing express jestjs

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

因此,第一步,我将get()的功能移到了自己的文件中:

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)
}

首先,我不确定是否可以正确拆分代码-考虑进行单元测试。

对我来说,唯一需要通过调用/set-status?id=1&value=50完成的操作是为pwmWrite()定义并存储在{{ 1}}。

第二点:如果这是正确的方法,我不明白如何编写jestJS单元测试来检查是否已调用new Gpio-该函数在异步函数内部。

这是我的尝试,但我无法测试pwmWrite的内部调用:

locals

1 个答案:

答案 0 :(得分:2)

您非常亲密,只是缺少了一些东西。

您需要在Expect语句之前调用方法setStatusgetStatus, 并且您丢失了req.queryres上的模拟,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();
});

getStatus在需要setStatus之前需要被模拟,因为它是在那里使用的