koa + socket.io

koa-socketio.ts

import { BaseContext } from 'koa'

declare module 'koa' {
  interface BaseContext {
    io: SocketIO.Server
  }
}

export default (io: SocketIO.Server) => async (
  ctx: BaseContext,
  next: () => Promise<any>
) => {
  ctx.io = io
  await next()
}

server.ts

import http from 'http'
import Koa from 'koa'
import bodyParser from 'koa-bodyparser'
import socketIo from 'socket.io'
import koaSocket from './middlewares/koa-socketio'
import setupSocket from './setupSocket'

const app = new Koa()

app.use(bodyParser())

app.use(koaError())
const server = http.createServer(app.callback())
const io = socketIo.listen(server)
app.use(koaSocket(io))

setupSocket(io)

export default server

setupSocket.ts

import socketIo from 'socket.io'

export default (io: socketIo.Server) => {
  io.on('connection', socket => {
    socket.on('some_event', (data: any) => {
      console.log('some_event', data)
    })
  })
}

test.ts

/* eslint-env jest */

import request from 'supertest'
import io from 'socket.io-client'
import server from '../../src/server'

server.listen(9999)

const socket = io.connect('http://localhost:9999', {
  transports: ['websocket']
})

describe('api socket test', () => {
  afterAll(async () => {
    socket.disconnect()
    server.close()
  })
  
  it('example', async () => {
    const data = {sample: 'test'}

    let mockCallback = jest.fn()
    socket.once('some_event', mockCallback)

    res = await request(server)
      .post('/api/some')
      .send(data)
    expect(res.status).toBe(200)

    expect(mockCallback.mock.calls.length).toBe(1)
    expect(mockCallback.mock.calls[0][0]).toEqual(data)
  })
})