CODEWITHSUNDEEP
javascriptunit-testingsinon
user2609950
user2609950

Reputation: 101

unit test for web socket in javascript

I need to write unit test using sinon to web socket client. the code is as following:

Socket = {
    connect: function ()
    {
        socket = new WebSocket('ws://localhost:12345');
        socket.onopen = function()
        {

            console.log('connected to the server');
        };

        socket.onmessage = function(message)
        {
            console.log('Received:', message.data);
        };

    }
};

Upvotes: 3

Views: 6066

Answers (1)

Lin Du
Lin Du

Reputation: 102257

We need return the socket instance at last in the connect method. Because you assigned two new functions to onopen and onmessage events. It will override the spy or stub methods on the socket object.

Test environment: Node

Here is the unit test solution:

index.js:

const Socket = {
  connect: function() {
    socket = new WebSocket("ws://localhost:12345");
    socket.onopen = function() {
      console.log("connected to the server");
    };

    socket.onmessage = function(message) {
      console.log("Received:", message.data);
    };
    return socket;
  }
};

module.exports = Socket;

index.spec.js:

const sinon = require("sinon");
const { expect } = require("chai");
const Socket = require("./index");

class WebSocket {
  constructor(uri) {}
  onopen() {}
  onmessage() {}
}
global.WebSocket = WebSocket;

describe("17806481", () => {
  it("should test connect correctly", () => {
    const logSpy = sinon.spy(console, "log");
    const socket = Socket.connect();
    const onopenSpy = sinon.spy(socket, "onopen");
    const onmessageSpy = sinon.spy(socket, "onmessage");
    onopenSpy();
    expect(logSpy.firstCall.calledWith("connected to the server")).to.be.true;
    const mMessage = { data: "fake data" };
    onmessageSpy(mMessage);
    expect(logSpy.secondCall.calledWith("Received:", mMessage.data)).to.be.true;
  });
});

Unit test result with 100% coverage for Socket module:

 17806481
connected to the server
Received: fake data
    ✓ should test connect correctly


  1 passing (10ms)

---------------|----------|----------|----------|----------|-------------------|
File           |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
---------------|----------|----------|----------|----------|-------------------|
All files      |      100 |      100 |       75 |      100 |                   |
 index.js      |      100 |      100 |      100 |      100 |                   |
 index.spec.js |      100 |      100 |       60 |      100 |                   |
---------------|----------|----------|----------|----------|-------------------|

Source code: https://github.com/mrdulin/mocha-chai-sinon-codelab/tree/master/src/stackoverflow/17806481

Upvotes: 1

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