Websocket server doesn't seem to be connecting

I’ve got a project where a node micro service is connected to a rails actioncable websocket.

I’m trying to speck the websocket connection part (regardless of the fact it’s an actioncable websocket behind the scenes) by using jest and jest-websocket-mock and mock-socket.

My ActionCable class connection method looks like this

// lib/classes/action_cable.js
const WebSocket = require('ws');
class ActionCable {
  constructor(url, opts) {
    this.cableURL = url;
    this.origin = opts.origin || 'http://localhost:3000';
    this.headers = opts.headers || {};
    this.connection = null;
    this.connect = null;
  }
  _connect() {
    if (!this.connect) {
      this.connect = new Promise((resolve, reject) => {
        this.connection = new WebSocket(this.cableURL, undefined, { origin: this.origin, headers: this.headers });

        this.connection.onerror = (err) => {
          reject(err);
        };
        this.connection.onclose = () => {
          reject(new Error('Connection closed'));
        };
        this.connection.onopen = () => {
          resolve(this.connection)
        };
      });
    }
    return this.connect;
  }
}

and in my jest test I’ve got this

// tests/classes/action_cable.test.js
import ActionCable from '../../lib/classes/action_cable.js';
import WS from "jest-websocket-mock";
import { Server } from 'mock-socket';

let actioncableInstance = false;

beforeEach(() => {
  actioncableInstance = new ActionCable('ws://localhost:1234', { origin: 'http://localhost:4321' });
});

describe('_connect', () => {
  let WSServer = false;

  beforeEach(() => {
    WSServer = new WS('ws://localhost:1234');
  });
  afterEach(() => {
    WS.clean();
  });

  describe('when WebSocket server refuses the connection', () => {

    beforeEach(() => {
      WSServer.on('connection', (socket) => {
        console.log('received stuff');
        socket.close({ wasClean: false, code: 1003, reason: "NOPE" });
      });
    });

    test('rejects with error and calls _disconnected', async () => {
      expect.assertions(1);
      await expect(actioncableInstance._connect()).rejects;
    });
  });
});

I’ve got a mocks file that seems to no cause errors when I have it like this

// tests/__mocks__/ws.js
const WebSocket = require('mock-socket').WebSocket;

module.exports = WebSocket;

my project tree looks like this

lib
  | classes
    | action_cable.js
tests
  | __mocks__
    | ws.js
  | classes
    | action_cable.test.js

I’m guessing I’ve got something configured wrong but I fail to see what after half a day of trying to get my test to work for this simple case (I haven’t even begun the other cases but I think once I get the connection refused case going I’ll be able to move on to the rest). But in case there’s something else I’m getting a timeout error from my test Async callback was not invoked within the 5000ms timeout specified by jest.setTimeout.Timeout

For a little context this is part of a bigger library of functions I’ve got for general NodeJS usage so I’m not running anything part of a NodeJS framework.

Any help or insight would be appreciated !

[romgain]

Oh wow, thanks for your write up!!

The fact that mock-socket uses timeouts really makes it harder to write some tests ☹️

Would you be open to raising a quick PR that would add a small warning about mock timers to the readme?

Thanks again!

[jwoodrow]

Got it ! maybe this should be added somewhere in the readme but basically everything I said was wrong. The issue was that in this specific test I had this setup for another test jest.useFakeTimers(); removing the line allows the client to connect to the server.

I realised this when I simply created a new action_cable_2.js and action_cable_2.test.js file using the code I provided to you (that didn’t have the jest.useFakeTimers(); line since I didn’t think it was relevant to this test [no timers to test in this function]) and noticed it simply ran (not with the right error but it was running as intended).

Now I do still have an issue that I can’t seem to find any documentation on how to emulate a connection refused (like an origin header not allowed on the server) I wan work around that but if ever you have an idea of how to do this I’d be open to hearing it. I’ll close my ticket for now since I found the issue with my tests.

Thanks for checking in on my issue !