Create Publisher.test.ts

sdk/src/media-backend/livekit/Publisher.test.ts

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+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { EventEmitter } from "events";
+import { ConnectionState, type Room as LivekitRoom } from "livekit-client";
+import { logger } from "matrix-js-sdk/lib/logger";
+import { describe, expect, it, vi } from "vitest";
+
+import { Publisher } from "./Publisher";
+
+describe("Publisher", () => {
+  describe("setAudioOutputDevice", () => {
+    it("switches the room's output while the room is still connecting", async () => {
+      const { room, switchActiveDevice } = fakeRoom(ConnectionState.Connecting);
+      const publisher = new Publisher(room, new Map(), logger);
+
+      await publisher.setAudioOutputDevice("speaker");
+      expect(switchActiveDevice).toHaveBeenCalledWith("audiooutput", "speaker");
+    });
+
+    it("leaves a room alone that already plays on the device", async () => {
+      const { room, switchActiveDevice } = fakeRoom(
+        ConnectionState.Connected,
+        "speaker",
+      );
+      const publisher = new Publisher(room, new Map(), logger);
+
+      await publisher.setAudioOutputDevice("speaker");
+      expect(switchActiveDevice).not.toHaveBeenCalled();
+    });
+
+    it("rejects where the room cannot switch", async () => {
+      const { room, switchActiveDevice } = fakeRoom(ConnectionState.Connected);
+      switchActiveDevice.mockRejectedValue(new Error("no setSinkId"));
+      const publisher = new Publisher(room, new Map(), logger);
+
+      await expect(publisher.setAudioOutputDevice("speaker")).rejects.toThrow(
+        "no setSinkId",
+      );
+    });
+  });
+});
+
+/** The slice of a LiveKit room the publisher touches at construction and for the output device. */
+function fakeRoom(
+  state: ConnectionState,
+  activeOutput?: string,
+): { room: LivekitRoom; switchActiveDevice: ReturnType<typeof vi.fn> } {
+  const switchActiveDevice = vi.fn(async () => Promise.resolve(true));
+  const room = {
+    state,
+    options: {},
+    setE2EEEnabled: () => undefined,
+    localParticipant: new EventEmitter(),
+    getActiveDevice: () => activeOutput,
+    switchActiveDevice,
+  } as unknown as LivekitRoom;
+  return { room, switchActiveDevice };
+}