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.json
import { 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;
      io.on("connection", (socket) => {
        serverSocket = socket;
      });
      clientSocket = new Client(`http://localhost:${port}`);
      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;
      io.on("connection", (socket) => {
        serverSocket = socket;
      });
      clientSocket = new Client(`http://localhost:${port}`);
      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;
    io.on("connection", (socket) => {
      serverSocket = socket;
    });
    clientSocket = new Client(`http://localhost:${port}`);
    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();
});