Testing

@ws-asyncapi/testing gives you an in-memory test harness: connect a fully-typed client to a channel with no sockets, no ports, no listen(). It runs the real dispatcher and the real WebSocketNode implementation over an in-memory pipe, so your tests exercise the actual protocol — RPC, typed errors, events, rooms, broadcast, server→client RPC, streams, and connection-state-recovery all behave exactly as in production.

bash

npm install -D @ws-asyncapi/testing
# peers: ws-asyncapi, @ws-asyncapi/client, @ws-asyncapi/adapter-node

Basic test

import { expect, test } from "bun:test"; // or vitest / jest
import { createTestHarness } from "@ws-asyncapi/testing";
import { chat } from "./server"; // your Channel

test("history RPC", async () => {
    const h = createTestHarness(chat);
    const client = h.connect(); // typed client, inferred from `chat`
    await client.opened;

    const { items } = await client.request("history", { limit: 10 });
    expect(items).toHaveLength(10);

    await h.close();
});

Everything is typed straight from the channel — request, onEvent, call, safeRequest, stream, onRequest all infer their argument and result types, and wrong names or payloads are compile errors.

Multiple clients (fan-out, presence)

const h = createTestHarness(chat);
const a = h.connect();
const b = h.connect();
await Promise.all([a.opened, b.opened]);

const received: unknown[] = [];
b.onEvent("message", (m) => received.push(m));
a.call("say", { text: "hi" }); // broadcasts to the room → b receives it

Streams

for await (const tick of client.stream("prices", { symbol: "ACME" })) {
    // ...
}

Simulating other cluster nodes

The harness drives a real backplane (a fresh LocalBackplane with recovery on, by default). Pass a shared backplane to test cross-node behavior — or publish through h.backplane / point an external emitter at it.

const h = createTestHarness(chat, { backplane, codec });
// h.backplane — publish to it to simulate events from another node

Options

createTestHarness(channel, options?):

Option	Default	Purpose
`codec`	JSON	Wire codec (client and server share it automatically)
`backplane`	fresh `LocalBackplane` (recovery on)	Share one to simulate a cluster
`plugins`	—	Server-level plugins (metrics/tracing)

h.connect(options?) accepts { path?, query?, headers? } — path defaults to the channel address with params filled 1.

Testing ​

Basic test ​

Multiple clients (fan-out, presence) ​

Streams ​

Simulating other cluster nodes ​

Options ​

Next ​