Testing

You will find below some code examples with common testing libraries:

• mocha
• jest
• tape

Example with mocha

Installation: npm i -D mocha chai

// with { "type": "module" } in your package.jsonimport { createServer } from "http";import { io as Client } from "socket.io-client";import { Server } from "socket.io";import { assert } from "chai";
// with { "type": "commonjs" } in your package.json// const { createServer } = require("http");// const { Server } = require("socket.io");// const Client = require("socket.io-client");// const assert = require("chai").assert;
describe("my awesome project", () => {  let io, serverSocket, clientSocket;
  before((done) => {    const httpServer = createServer();    io = new Server(httpServer);    httpServer.listen(() => {      const port = httpServer.address().port;      clientSocket = new Client(`http://localhost:${port}`);      io.on("connection", (socket) => {        serverSocket = socket;      });      clientSocket.on("connect", done);    });  });
  after(() => {    io.close();    clientSocket.close();  });
  it("should work", (done) => {    clientSocket.on("hello", (arg) => {      assert.equal(arg, "world");      done();    });    serverSocket.emit("hello", "world");  });
  it("should work (with ack)", (done) => {    serverSocket.on("hi", (cb) => {      cb("hola");    });    clientSocket.emit("hi", (arg) => {      assert.equal(arg, "hola");      done();    });  });});

Example with jest

Installation: npm i -D jest

const { createServer } = require("http");const { Server } = require("socket.io");const Client = require("socket.io-client");
describe("my awesome project", () => {  let io, serverSocket, clientSocket;
  beforeAll((done) => {    const httpServer = createServer();    io = new Server(httpServer);    httpServer.listen(() => {      const port = httpServer.address().port;      clientSocket = new Client(`http://localhost:${port}`);      io.on("connection", (socket) => {        serverSocket = socket;      });      clientSocket.on("connect", done);    });  });
  afterAll(() => {    io.close();    clientSocket.close();  });
  test("should work", (done) => {    clientSocket.on("hello", (arg) => {      expect(arg).toBe("world");      done();    });    serverSocket.emit("hello", "world");  });
  test("should work (with ack)", (done) => {    serverSocket.on("hi", (cb) => {      cb("hola");    });    clientSocket.emit("hi", (arg) => {      expect(arg).toBe("hola");      done();    });  });});

Example with tape

Installation: npm i -D tape

const { createServer } = require("http");const { Server } = require("socket.io");const Client = require("socket.io-client");const test = require("tape");
let io, serverSocket, clientSocket;
test("setup", (t) => {  const httpServer = createServer();  io = new Server(httpServer);  httpServer.listen(() => {    const port = httpServer.address().port;    clientSocket = new Client(`http://localhost:${port}`);    io.on("connection", (socket) => {      serverSocket = socket;    });    clientSocket.on("connect", t.end);  });});
test("it works", (t) => {  t.plan(1);  clientSocket.on("hello", (arg) => {    t.equal(arg, "world");  });  serverSocket.emit("hello", "world");});
test("it works (with ack)", (t) => {  t.plan(1);  serverSocket.on("hi", (cb) => {    cb("hola");  });  clientSocket.emit("hi", (arg) => {    t.equal(arg, "hola");  });});
test.onFinish(() => {  io.close();  clientSocket.close();});