siftlode/frontend/src/components/PlexPlayer.tabtrap.dom.test.tsx

// @vitest-environment jsdom
//
// The Plex player paints an opaque, full-viewport layer over the whole app — and until deep-review
// round 4 it was the only overlay in the tree with no Tab trap at all. Tab from its transport bar,
// from its menus, or from the debug recorder's pill (which docks in THIS player's toast host) walked
// straight out into the page behind it, where the focus ring is invisible and the next Enter fires
// something the user cannot see. `ui/Modal`, `PlayerModal`, `OnboardingWizard` and `Welcome` all trap;
// the round-3 comment that handed the step prompt's trap to "the dialog below" assumed this one did
// too. Its own file because `layerStack` is module state and these tests push into it.
import { describe, it, expect, vi, beforeAll, afterEach } from "vitest";
import { render, cleanup, waitFor, act } from "@testing-library/react";
import { QueryClient, QueryClientProvider } from "@tanstack/react-query";

vi.mock("react-i18next", async (importOriginal) => ({
  ...(await importOriginal<typeof import("react-i18next")>()),
  useTranslation: () => ({ t: (key: string) => key, i18n: { language: "en" } }),
}));

import PlexPlayer from "./PlexPlayer";
import { api, type PlexItemDetail } from "../lib/api";
import { pushLayer, removeLayer } from "../lib/layerStack";

beforeAll(() => {
  class Stub {
    observe() {}
    unobserve() {}
    disconnect() {}
    takeRecords() {
      return [];
    }
  }
  globalThis.ResizeObserver ??= Stub as unknown as typeof ResizeObserver;
  globalThis.IntersectionObserver ??= Stub as unknown as typeof IntersectionObserver;
  for (const [name, value] of Object.entries({
    play: () => Promise.resolve(),
    pause: () => {},
    load: () => {},
  }))
    Object.defineProperty(HTMLMediaElement.prototype, name, { configurable: true, value });
  Object.defineProperty(HTMLMediaElement.prototype, "seekable", {
    configurable: true,
    get: () => ({ length: 0, end: () => 0 }),
  });
  Object.defineProperty(HTMLMediaElement.prototype, "textTracks", {
    configurable: true,
    get: () => Object.assign([], { addEventListener() {}, removeEventListener() {} }),
  });
});

const behind: HTMLButtonElement[] = [];
afterEach(() => {
  cleanup();
  while (behind.length) behind.pop()!.remove();
  vi.restoreAllMocks();
});

const detail = {
  id: "1",
  title: "Title 1",
  type: "movie",
  duration_seconds: 3000,
  status: "new",
  position_seconds: 0,
  audio_streams: [],
  subtitle_streams: [],
  markers: [],
} as unknown as PlexItemDetail;

async function mount() {
  vi.spyOn(api, "plexItem").mockResolvedValue(detail);
  vi.spyOn(api, "plexSession").mockResolvedValue({
    mode: "direct",
    url: "/media/1",
    start_s: 0,
  } as Awaited<ReturnType<typeof api.plexSession>>);
  vi.spyOn(api, "plexProgress").mockResolvedValue(undefined as never);
  render(
    <QueryClientProvider
      client={new QueryClient({ defaultOptions: { queries: { retry: false } } })}
    >
      <PlexPlayer itemId="1" onClose={() => {}} />
    </QueryClientProvider>,
  );
  await waitFor(() =>
    expect(document.querySelector("video")?.getAttribute("src")).toBe("/media/1"),
  );
}

/** A control on the page the player is painted over — the thing focus used to escape onto. */
function pageBehind() {
  const b = document.createElement("button");
  b.textContent = "on the page behind";
  document.body.insertBefore(b, document.body.firstChild);
  behind.push(b);
  return b;
}

const player = () => document.querySelector<HTMLElement>(".fixed.z-overlay")!;

/** jsdom has no layout, so the trap's visibility filter (`offsetParent`) would see nothing tabbable
 *  anywhere. Give every element one for the duration of a check — the house pattern (PlayerModal,
 *  OnboardingWizard, ui/dialogFocus all do this). */
function withLayout<T>(fn: () => T): T {
  const spy = vi.spyOn(HTMLElement.prototype, "offsetParent", "get").mockReturnValue(document.body);
  try {
    return fn();
  } finally {
    spy.mockRestore();
  }
}

const press = (key: string, shiftKey = false) =>
  act(() => {
    window.dispatchEvent(
      new KeyboardEvent("keydown", { key, shiftKey, bubbles: true, cancelable: true }),
    );
  });

describe("PlexPlayer · Tab stays inside the player", () => {
  it("pulls the focus back in when it is on the page behind", async () => {
    await mount();
    const outside = pageBehind();
    outside.focus();
    expect(document.activeElement).toBe(outside);
    withLayout(() => press("Tab"));
    // Not left on a control under an opaque overlay: the trap takes it into the player.
    expect(document.activeElement).not.toBe(outside);
    expect(player().contains(document.activeElement)).toBe(true);
  });

  it("wraps from the last of its own controls back to the first", async () => {
    await mount();
    const items = [
      ...player().querySelectorAll<HTMLElement>(
        'button:not([disabled]), a[href], [tabindex]:not([tabindex="-1"])',
      ),
    ];
    expect(items.length).toBeGreaterThan(1);
    const first = items[0]!;
    const last = items[items.length - 1]!;
    last.focus();
    withLayout(() => press("Tab"));
    expect(document.activeElement).toBe(first);
    // ...and backwards, which is the direction that used to walk straight out behind the player.
    first.focus();
    withLayout(() => press("Tab", true));
    expect(document.activeElement).toBe(last);
  });

  it("keeps trapping while one of its OWN menus is open", async () => {
    await mount();
    // The settings and track menus are `useDismiss` layers. That hook owns Escape and the
    // outside-press and installs no Tab trap at all — but it used to register as a layer that
    // DOES trap, so the player stood its own trap down for it and Tab walked out past the last
    // control into the nav rail. Measured in a real browser: 30 Tabs, 9 escapes. The menus render
    // inside the player, so the player's trap is the one that must stay on.
    const gear = [...player().querySelectorAll<HTMLElement>("button")].find(
      (b) => b.getAttribute("aria-label") === "plex.player.settings",
    );
    expect(gear).toBeDefined();
    act(() => gear!.click());
    const items = [...player().querySelectorAll<HTMLElement>("button:not([disabled])")];
    // The menu really opened — the trap now has to span its controls too.
    expect(items.length).toBeGreaterThan(12);
    const last = items[items.length - 1]!;
    last.focus();
    withLayout(() => press("Tab"));
    expect(player().contains(document.activeElement)).toBe(true);
    expect(document.activeElement).toBe(items[0]);
  });

  it("leaves the Tab to a dialog opened above it, which traps for itself", async () => {
    await mount();
    const outside = pageBehind();
    outside.focus();
    const above = pushLayer(); // a Modal over the player — the download dialog, say
    try {
      withLayout(() => press("Tab"));
      // The player does not reach past it: the dialog above owns the keyboard and its own trap.
      expect(document.activeElement).toBe(outside);
    } finally {
      removeLayer(above);
    }
  });
});