sdk implementation

sdk/src/media/LivekitMediaTrack.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 {
+  ParticipantEvent,
+  type RemoteParticipant,
+  type Room as LivekitRoom,
+  Track,
+  TrackEvent,
+  type TrackPublication,
+} from "livekit-client";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { ObservableScope } from "../../../src/state/ObservableScope";
+import { type AudioMediaTrack } from "../api";
+import { createLivekitMediaTrack } from "./LivekitMediaTrack";
+
+describe("createLivekitMediaTrack", () => {
+  let scope: ObservableScope;
+  beforeEach(() => {
+    scope = new ObservableScope();
+  });
+  afterEach(() => scope.end());
+
+  it("describes the publication", () => {
+    const { participant, publication, room } = fakes();
+    const track = createLivekitMediaTrack(
+      scope,
+      participant,
+      publication as unknown as TrackPublication,
+      room,
+      "camera",
+    );
+    expect(track.kind).toBe("video");
+    expect(track.source).toBe("camera");
+    expect(track.id).toBe("TR_1");
+    expect(track.encrypted$.value).toBe(true);
+  });
+
+  it("attaches elements to the track, even one that arrives later", () => {
+    const { participant, publication, room, emitter } = fakes({
+      track: undefined,
+    });
+    const element = document.createElement("video");
+    const track = createLivekitMediaTrack(
+      scope,
+      participant,
+      publication as unknown as TrackPublication,
+      room,
+      "camera",
+    );
+    track.attach(element);
+    track.attach(element);
+
+    const livekitTrack = fakeTrack();
+    publication.track = livekitTrack;
+    emitter.emit(TrackEvent.Subscribed, livekitTrack);
+    expect(livekitTrack.attach).toHaveBeenCalledTimes(1);
+    expect(livekitTrack.attach).toHaveBeenCalledWith(element);
+
+    track.detach(element);
+    expect(livekitTrack.detach).toHaveBeenCalledWith(element);
+  });
+
+  it("detaches everything when its scope ends", () => {
+    const { participant, publication, room } = fakes();
+    const element = document.createElement("video");
+    const scope = new ObservableScope();
+    const track = createLivekitMediaTrack(
+      scope,
+      participant,
+      publication as unknown as TrackPublication,
+      room,
+      "camera",
+    );
+    track.attach(element);
+    scope.end();
+    expect(publication.track!.detach).toHaveBeenCalledWith(element);
+  });
+
+  it("follows the mute state", () => {
+    const { participant, publication, room, emitter } = fakes();
+    const track = createLivekitMediaTrack(
+      scope,
+      participant,
+      publication as unknown as TrackPublication,
+      room,
+      "camera",
+    );
+    expect(track.muted$.value).toBe(false);
+    publication.isMuted = true;
+    emitter.emit(ParticipantEvent.TrackMuted, publication);
+    expect(track.muted$.value).toBe(true);
+  });
+
+  it("scales a remote member's volume on the participant", () => {
+    const { participant, publication, room } = fakes({
+      kind: Track.Kind.Audio,
+    });
+    const track = createLivekitMediaTrack(
+      scope,
+      participant,
+      publication as unknown as TrackPublication,
+      room,
+      "microphone",
+    ) as AudioMediaTrack;
+    track.setVolume(0.5);
+    expect(participant.setVolume).toHaveBeenCalledWith(
+      0.5,
+      Track.Source.Microphone,
+    );
+  });
+});
+
+type FakeTrack = Track & {
+  attach: ReturnType<typeof vi.fn>;
+  detach: ReturnType<typeof vi.fn>;
+};
+
+type FakePublication = Omit<TrackPublication, "track" | "isMuted"> & {
+  track: FakeTrack | undefined;
+  isMuted: boolean;
+};
+
+function fakeTrack(): FakeTrack {
+  return { attach: vi.fn(), detach: vi.fn() } as unknown as FakeTrack;
+}
+
+function fakes({
+  track = fakeTrack(),
+  kind = Track.Kind.Video,
+}: { track?: FakeTrack | undefined; kind?: Track.Kind } = {}): {
+  participant: RemoteParticipant & { setVolume: ReturnType<typeof vi.fn> };
+  publication: FakePublication;
+  room: LivekitRoom;
+  emitter: EventEmitter;
+} {
+  const emitter = new EventEmitter();
+  const participant = Object.assign(emitter, {
+    isLocal: false,
+    identity: "@alice:example.org:DEVICE",
+    setVolume: vi.fn(),
+    getTrackPublication: (): TrackPublication =>
+      publication as unknown as TrackPublication,
+  }) as unknown as RemoteParticipant & { setVolume: ReturnType<typeof vi.fn> };
+  const publication = Object.assign(emitter, {
+    kind,
+    trackSid: "TR_1",
+    isMuted: false,
+    isEncrypted: true,
+    track,
+  }) as unknown as FakePublication;
+  const room = new EventEmitter() as unknown as LivekitRoom;
+  return { participant, publication, room, emitter };
+}