@relaycorp/ws-mock
v5.2.13
Published
Mock client and server to unit test the NPM package 'ws'
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@relaycorp/ws-mock
Mock client and server to unit test servers and clients powered by ws
.
Install
npm install @relaycorp/ws-mock
Using the mock client
You'd use a mock client when you need to test a server. You should initialise MockClient
by passing the ws
server to be tested and then call client.connect()
to initiate the connection. From that point you can interact with the server. For example:
test('Challenge should be sent as soon as client connects', async () => {
const client = new MockClient(wsServer);
await client.connect();
const challengeSerialized = await client.receive();
expect(challengeSerialized).toBeInstanceOf(ArrayBuffer);
});
You'll find real-world examples in relaycorp/relaynet-internet-gateway and relaycorp/awala-gateway-desktop.
Using the mock server
You'd use a mock server when you need to test a client. You basically need to initialise MockServer
and replace the default export from ws
with a mock WebSocket. Here's an example with Jest:
let mockServer: MockServer;
beforeEach(() => {
mockServer = new MockServer();
});
jest.mock('ws', () => ({
__esModule: true,
default: jest.fn().mockImplementation(() => mockServer.client),
}));
test('Server message should be played back', async () => {
const clientUnderTest = new ClientUnderTest();
const messageToEcho = 'foo';
await mockServer.use(
clientUnderTest.connectToServerAndInteractWithIt(),
async () => {
await mockServer.send(messageToEcho);
// Check that the client sent the message back to the server:
const clientResponse = await mockServer.receive();
expect(clientResponse).toEqual(messageToEcho);
},
);
});
You'll find real-world examples in relaycorp/relaynet-poweb-js.
Using streams
When using streams in the unit under test, make sure to mock the createWebSocketStream
function in ws
. Here's an example with Jest:
import { createMockWebSocketStream } from '@relaycorp/ws-mock';
import WebSocket from 'ws';
jest
.spyOn(WebSocket, 'createWebSocketStream')
.mockImplementation(createMockWebSocketStream);