node.js - 如何修复 : "TypeError: wsModule.Server is not a constructor" when running tests in Jest

Question

我是 Jest 的新手，我想开始为 Node.js 服务器编写一些集成测试。当我尝试运行测试时，我收到一个 "TypeError: wsModule.Server is not a constructor" 错误。为什么我的测试环境不初始化套接字服务器？

服务器.js:

const app = require('express')();
const server = require('http').Server(app);
const io = require('socket.io')(server); <-- TEST FAILS BECAUSE OF SOCKET MODULE
const router = require('./router/router');
const bodyParser = require('body-parser');
const cors = require('cors');
require('./socket/socket')(io); 

// Allow CORS so our client can consume JSON
app.use(cors())

// Takes the raw requests and turns them into usable properties on req.body
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

// Use our router
app.use('/', router);

server.listen(3000, (req, res) => {
  console.log("listen at 3000!");
});

module.exports = app;

套接字.js:

const userService = require('../services/userService');
const roomService = require('../services/roomService');

module.exports = function (io) {

  io.on("connection", socket => {

    console.log('there has been a connection with: ' + socket.id);

    socket.on('set-username', ({ roomId, username }) => {
      userService.setUsername(roomId, username, socket, io);
    });

    socket.on('start-game', ({ roomId, hostName }) => {
      roomService.startGame(roomId, hostName, socket, io);
    });

});

房间服务.test.js:

const chai = require('chai');
const chaiHttp = require('chai-http');
const server = require('../../server');
const { expect } = chai;
chai.use(chaiHttp);

describe("example", () => {
  test('should run', () => {
    expect(true).to.be.true;
  })
})

Answer 1

测试失败，因为 server.listen 是异步 而您的测试是同步

Why won't my test environment initialize the socket server?

问题是您的测试将在 HTTP 服务器启动之前完成，并且Socket.IO 服务器连接到它。

参见 Testing Asynchronous Code

你可以在 server.js 中注释 server.listen 并导出 server 这样你就可以使用它在测试时告诉 jest 等到服务器启动后再运行其余测试。

服务器.js

- server.listen(3000, (req, res) => { console.log("listen at 3000!"); });
- module.exports = app;

+ module.exports = server

roomService.test.js

const server = require('../../server');

describe("example", () => {
    beforeAll(done => { //pass a callback to tell jest it is async
        //start the server before any test
        server.listen(3000, () => done());
    })

    afterAll(done => { //pass a callback to tell jest it is async
        //close the server after all tests
        server.listening ? server.close(() => done()) : done();
    })

    test('should run', () => {
        expect(true).to.be.true;
    })
})

当然，当你想在开发模式下再次运行你的应用程序时，你必须取消注释。

为了避免在这个文件中注释/取消注释，创建一个单独的模块，你可以在其中启动你的服务器和使其成为应用入口点。

这是你的文件的样子

服务器.js

const app = require('./app');
const server = require('http').Server(app);
const io = require('socket.io')(server);
require('./socket/socket')(io); 
module.exports = server;

开始.js:

const server = require('./server');
server.listen(3000, (req, res) => {
    console.log("listen at 3000!");
});

应用程序.js

const app = require('express')();
const router = require('./router/router');
const bodyParser = require('body-parser');
const cors = require('cors');

app.use(cors())
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use('/', router);

module.exports = app;

使用 start.js 应用程序入口点，您现在可以运行应用程序和测试而无需进行任何更改