mockets.io

mockets.io allows you to mock socket.io's sockets, so as to test them. This is a fast and easy solution, as it does not create an actual socket connection, but rather use simpler functions, to allow for fast and easy testing.

Installation

mockets.io is available as an npm package.

// With npm
npm install mockets.io

Usage

These tests assume that you have installed a testing library, such as jest for instance.

For these tests, we'll assume we're in some kind of game website. To play a game, players have to join a lobby, and listen to updates on that lobby.

You're handling your socket events in a facade, GameFacade.

Rooms handling

Because you don't want to send updates to every players when the lobby is updated, you're likely to create a socket.io room and make your player's socket join the socket.io room.

describe('GameFacade', () => {
    let mocketServer: MocketServer;
    let mocketSocket: any;

    beforeEach(() => {
        // Reset server and socket to ensure clean tests
        mocketServer = new MocketServer();
        mocketSocket = mocketServer.createSocket();
    })

    test('GameFacade.joinLobby should make socket join socket.io room', () => {
        expect(mocketSocket.rooms.size).toBe(0);

        // Your own treatment function
        GameFacade.joinLobby(socket);

        expect(mocketSocket.rooms.size).toBe(1);
    })
});

Events handling

Now, you might want to ensure that your sockets are emitting events as well as receiving them.

describe('GameFacade', () => {
    let mocketServer: MocketServer;
    let lobbyHostPlayer: any;
    let anotherPlayer: any;

    beforeEach(() => {
        // Reset server and socket to ensure clean tests
        mocketServer = new MocketServer();
        lobbyHostPlayer = mocketServer.createSocket();
        anotherPlayer = mocketServer.createSocket();
    })

    test('GameFacade.joinLobby should make joining socket emit update to other players', () => {
        expect(anotherPlayer.sentEvents.length).toBe(0);
        expect(lobbyHostPlayer.receivedEvents.length).toBe(0);

        // Your own treatment function
        GameFacade.joinLobby(socket);

        expect(anotherPlayer.sentEvents.length).toBe(1);
        expect(lobbyHostPlayer.receivedEvents.length).toBe(1);
    })
});