👋 Welcome to pusher-js-mock

Mock Pusher.js in your JavaScript tests with ease.

Installing ⏬

Using yarn:

``
yarn add --dev pusher-js-mock
`

Or using npm:

`
npm install -D pusher-js-mock
`

Usage 🛠

- Emitting an event 📶
- Listening for an event 👂
- Emitting an event from connection 📶
- Listening for an event from connection 👂
- Stubbing Pusher when imported from pusher-js package 📦
- Stubbing Pusher when used as a global variable 🌍
- Mocking presence channels
- Using custom authorizer
- Pusher events emitted by presence channels
- Using with Vitest

For more detailed examples, check out examples directory
inside the project!

Also, you can check out the
Docs for even more information.

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If you need to mock a Pusher object in your tests that can
subscribe to channel, it's best to use PusherMock.

`javascript
import { PusherMock } from "pusher-js-mock";

// initializing PusherMock
const pusher = new PusherMock();

// subscribing to a Pusher channel
const channel = pusher.subscribe("my-channel");

// emitting an event
channel.emit("event-name");
`

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If you want to check whether your callback is getting called properly, you can
bind a callback to your channel, and then emit an event.

`javascript
import { PusherMock } from "pusher-js-mock";

describe("listening for an event", () => {
// initializing PusherMock
const pusher = new PusherMock();

// subscribing to a Pusher channel
const channel = pusher.subscribe("my-channel");

// define and attach a listener
const listener = jest.fn();
channel.bind("event-name", listener);

// emitting an event
channel.emit("event-name");

// Expect listener to have been called
expect(listener).toHaveBeenCalled();
});
`

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The connection within pusher is mocked and can be used much like a channel channel. There's no need to subscribe to subscription as it's subscribed by default on pusher.

`javascript
import { PusherMock } from "pusher-js-mock";

// initializing PusherMock
const pusher = new PusherMock();

// emitting connection event
pusher.connection.emit("event-name");
`

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As with channels, you can also listen to connection for events.

`javascript
import { PusherMock } from "pusher-js-mock";

describe("listening for an event", () => {
// initializing PusherMock
const pusher = new PusherMock();

// define and attach a listener
const listener = jest.fn();
pusher.connection.bind("event-name", listener);

// emitting an event
pusher.connection.emit("event-name");

// Expect listener to have been called
expect(listener).toHaveBeenCalled();
});
`

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If you're using Pusher in your code in this or similar manner:

`javascript
import Pusher from "pusher-js";
`

You will need to mock Pusher in a specific way.

I suggest you use Jest to test your code.
To do this in Jest, you'll need something like this:

`javascript
jest.mock("pusher-js", () => {
const Pusher = require("pusher-js-mock").PusherMock;
return Pusher;
});
`

If you have tips on how to mock this using other testing frameworks, please
submit an issue or a pull request.

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This shows how to stub a pusher if you're attaching it to window object in your
project. If you're attaching a PusherFactory to a window object like this in
your code:

`javascript
window.PusherFactory = {
pusherClient: function(pusherKey) {
return new Pusher(pusherKey);
}
};
`

It's best for you to use PusherFactoryMock.

`javascript
import { PusherFactoryMock } from "pusher-js-mock";

// initialize instance of PusherFactoryMock
const pusherFactoryMock = new PusherFactoryMock();
// replace it with the object that is attached to a window
window.PusherFactory = pusherFactoryMock;

// get the Pusher client reference
pusher = pusherFactoryMock.pusherClient();
`

This way you'll just replace your PusherFactory with PusherFactoryMock.

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This package also supports using presence channels for multiple clients. The
mock will automatically detect when presence- is in the channel name and
return a presence channel with channel.members filled out as expected. You
can pass in IDs and info via a custom authorizer, just as you would with the
real package.

#### Using custom authorizer

If you want, you can pass in a custom authorizer when creating a Pusher client.

`js
// create-client.js
import Pusher from "pusher-js";
import { getAuthSomehow } from "./getAuthSomehow";

export const createClient = ({ id, info }) =>
new Pusher("APP_KEY", {
cluster: "APP_CLUSTER",
// see https://github.com/pusher/pusher-js#authorizer-function
authorizer: ({ name }) => ({
authorize: (socketId, callback) => {
const auth = getAuthSomehow(id, info);
callback(false, auth);
}
})
});

export default createClient;
`

`js
// create-client.spec.js
import createClient from "../create-client";

// mock the authorize function and pusher
jest.mock("pusher-js", () => require("pusher-js-mock"));
jest.mock("../getAuthSomehow", () => ({
getAuthSomehow: (id, info) => ({ id, info })
}));

it("should create a presence channel", async () => {
// arrange: create pusher client
const pusher = createClient({ id: "my-id", info: { role: "moderator" } });

// act: required to ensure pusher events are called, i.e. pusher:member_added
const presenceChannel = await pusher.subscribe("presence-channel");

// assert: presenceChannel has the properties we expect it to.
expect(presenceChannel.members.myID).toBe("my-id");
expect(presenceChannel.members.me).toEqual({
id: "my-id",
info: { role: "moderator" }
});
expect(presenceChannel.members.members).toEqual({
"my-id": { role: "moderator" }
});
});
`

Check out a code example of using presence channels

#### Pusher events emitted by presence channels

The mocked Pusher instance will also emit pusher internal events
pusher:subscription_succeeded, pusher:member_added and
pusher:member_removed to the relevant clients:

`js
it("should emit presence-channel events", async () => {
const client = createClient({ id: "my-id" });
const channel = client.subscribe("presence-channel");
const listener = jest.fn();

/**
* On bind, pusher:subscription_succeded will trigger
* for the client subscribing. Other clients will be
* notified via pusher:member_added as below.
*/
await channel.bind("pusher:subscription_succeeded", listener);
expect(listener).toHaveBeenCalledTimes(1);

/**
* Create and subscribe a new client that will trigger the
* pusher:member_added event. This only gets triggered for
* clients are not the client subscribing
*/
channel.bind("pusher:member_added", listener);
const otherClient = createClient({ id: "your-id" });
await otherClient.subscribe("presence-channel");
expect(listener).toHaveBeenCalledTimes(2);

/**
* Unsubscribe the otherClient to trigger pusher:member_removed.
* This only gets triggered for clients that are not the client
* unsubscribing.
*/
channel.bind("pusher:member_removed", listener);
await otherClient.unsubscribe("presence-channel");
expect(listener).toHaveBeenCalledTimes(3);
});
`

$3

You can mock Pusher.js in Vitest environment like this:

`js
vi.mock("pusher-js", () => {
return {
__esModule: true,
default: require("pusher-js-mock").PusherMock
};
});
``

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Photo by Octavian Rosca on Unsplash