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

// @vitest-environment jsdom
//
// The Plex player's session lifecycle, rendered for real (deep-review round 3 of bug hunt 2026-09).
//
// jsdom has no media pipeline, so the <video> is a small stand-in that behaves like Chrome where it
// matters here: `pause()` fires its `timeupdate` in a LATER task (measured in Chrome — which is how the
// previous item's position used to arrive after the player had already reset it for the next one).
import { describe, it, expect, vi, beforeAll, beforeEach, afterEach } from "vitest";
import { render, cleanup, waitFor, screen, fireEvent, act } from "@testing-library/react";
import { QueryClient, QueryClientProvider } from "@tanstack/react-query";

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

import PlexPlayer from "./PlexPlayer";
import { api, HttpError, type PlexItemDetail } from "../lib/api";
import { qk } from "../lib/queryKeys";
import { notify } from "../lib/notifications";
import { ACTIVE_ACCOUNT_KEY } from "../lib/activeAccount";

type Media = HTMLMediaElement & { _t?: number };

beforeAll(() => {
  class Stub {
    observe() {}
    unobserve() {}
    disconnect() {}
    takeRecords() {
      return [];
    }
  }
  globalThis.ResizeObserver ??= Stub as unknown as typeof ResizeObserver;
  globalThis.IntersectionObserver ??= Stub as unknown as typeof IntersectionObserver;
  const later = (el: HTMLMediaElement, ...types: string[]) =>
    setTimeout(() => types.forEach((ty) => el.dispatchEvent(new Event(ty))), 0);
  Object.defineProperty(HTMLMediaElement.prototype, "currentTime", {
    configurable: true,
    get(this: Media) {
      return this._t ?? 0;
    },
    set(this: Media, v: number) {
      this._t = v;
    },
  });
  Object.defineProperty(HTMLMediaElement.prototype, "play", {
    configurable: true,
    value: () => Promise.resolve(),
  });
  Object.defineProperty(HTMLMediaElement.prototype, "pause", {
    configurable: true,
    value(this: HTMLMediaElement) {
      later(this, "timeupdate", "pause"); // as Chrome does: after the call has returned
    },
  });
  Object.defineProperty(HTMLMediaElement.prototype, "load", {
    configurable: true,
    value(this: Media) {
      this._t = 0;
    },
  });
  Object.defineProperty(HTMLMediaElement.prototype, "seekable", {
    configurable: true,
    get: () => ({ length: 0, end: () => 0 }),
  });
  Object.defineProperty(HTMLMediaElement.prototype, "textTracks", {
    configurable: true,
    get: () => Object.assign([], { addEventListener() {}, removeEventListener() {} }),
  });
});

beforeEach(() => {
  // A signed-in account whose saved subtitle language is English (prefs are per account).
  sessionStorage.setItem(ACTIVE_ACCOUNT_KEY, "7");
  localStorage.setItem("siftlode.plexPlayerPrefs.7", JSON.stringify({ subLang: "en" }));
});

afterEach(() => {
  cleanup();
  vi.restoreAllMocks();
  sessionStorage.clear();
  localStorage.clear();
});

const item = (id: string, position = 0): PlexItemDetail =>
  ({
    id,
    title: `Title ${id}`,
    type: "episode",
    duration_seconds: 3000,
    status: "new",
    position_seconds: position,
    audio_streams: [{ ord: 0, label: "English", language: "en", default: true }],
    subtitle_streams: [{ ord: 0, label: "English", language: "en", text: true }],
    markers: [],
  }) as unknown as PlexItemDetail;

const direct = (id: string) =>
  ({ mode: "direct", url: `/media/${id}`, start_s: 0 }) as Awaited<
    ReturnType<typeof api.plexSession>
  >;

/** A session answer the test releases when it wants to. */
function deferred() {
  let resolve!: (v: Awaited<ReturnType<typeof api.plexSession>>) => void;
  const promise = new Promise<Awaited<ReturnType<typeof api.plexSession>>>((r) => (resolve = r));
  return { promise, resolve };
}

function mount(opts: {
  details: Record<string, PlexItemDetail>;
  sessions: Record<string, () => Promise<Awaited<ReturnType<typeof api.plexSession>>>>;
  queue?: string[];
  qc?: QueryClient;
}) {
  vi.spyOn(api, "plexItem").mockImplementation((id: string) => Promise.resolve(opts.details[id]!));
  vi.spyOn(api, "plexSession").mockImplementation((id: string) => opts.sessions[id]!());
  const progress = vi.spyOn(api, "plexProgress").mockResolvedValue(undefined as never);
  const status = vi
    .spyOn(api, "plexSubtitleStatus")
    .mockResolvedValue({ state: "preparing", code: null, gen: 0 });
  const qc = opts.qc ?? new QueryClient({ defaultOptions: { queries: { retry: false } } });
  const first = opts.queue?.[0] ?? Object.keys(opts.details)[0]!;
  const view = render(
    <QueryClientProvider client={qc}>
      <PlexPlayer itemId={first} onClose={() => {}} queue={opts.queue} />
    </QueryClientProvider>,
  );
  return { ...view, progress, status, qc };
}

const video = () => document.querySelector("video") as Media;

async function playingAt(src: string, t: number) {
  await waitFor(() => expect(video()?.getAttribute("src")).toBe(src));
  const v = video();
  v._t = t;
  act(() => void v.dispatchEvent(new Event("timeupdate")));
}

const tick = () => act(() => new Promise((r) => setTimeout(r, 20)));

describe("moving to the next item", () => {
  it("settles the item being left, and gives the next one none of its position", async () => {
    const { progress, status, unmount } = mount({
      details: { A: item("A"), B: item("B", 300) },
      sessions: { A: () => Promise.resolve(direct("A")), B: () => new Promise(() => {}) },
      queue: ["A", "B"],
    });
    await playingAt("/media/A", 1500);
    fireEvent.click(screen.getByLabelText("plex.player.next"));
    await waitFor(() => expect(status.mock.calls.some(([id]) => id === "B")).toBe(true));
    await tick(); // the timeupdate that pause() queued has landed by now
    // B's session has not answered, so where B is is where it was asked to start — not A's 25:00.
    expect(status.mock.calls.filter(([id]) => id === "B").map(([, , at]) => at)).not.toContain(
      1500,
    );
    expect(status.mock.calls.find(([id]) => id === "B")?.[2]).toBe(300);
    // A got its final checkpoint at the position it was left at…
    expect(progress.mock.calls).toContainEqual(["A", 1500, 3000, true]);
    unmount();
    // …and leaving B while it was still loading saved nothing of A's position as B's.
    expect(progress.mock.calls.filter(([id]) => id === "B")).toEqual([]);
  });
});

it("a seek that restarts the session is saved at its target while the new session loads", async () => {
  // seekTo wrote the target into the position ref only — and the restart re-renders at once, which
  // re-syncs that ref from the state: a page-hide during the restart saved the pre-seek spot.
  let calls = 0;
  mount({
    details: { A: item("A") },
    sessions: {
      A: () => (calls++ === 0 ? Promise.resolve(direct("A")) : new Promise(() => {})),
    },
  });
  const beacon = vi.spyOn(api, "plexProgressBeacon").mockImplementation(() => {});
  await playingAt("/media/A", 1500);
  fireEvent.click(screen.getByLabelText("plex.player.forward10"));
  await waitFor(() => expect(api.plexSession).toHaveBeenCalledTimes(2)); // a restart, not a native seek
  await tick();
  act(() => void window.dispatchEvent(new Event("pagehide")));
  expect(beacon).toHaveBeenLastCalledWith("A", 1510, 3000, true);
});

describe("a session answer that lands late", () => {
  it("is dropped when the viewer has moved on to another item meanwhile", async () => {
    const slowB = deferred();
    mount({
      details: { A: item("A"), B: item("B"), C: item("C") },
      sessions: {
        A: () => Promise.resolve(direct("A")),
        B: () => slowB.promise,
        C: () => Promise.resolve(direct("C")),
      },
      queue: ["A", "B", "C"],
    });
    await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/A"));
    fireEvent.click(screen.getByLabelText("plex.player.next"));
    await screen.findByText("Title B");
    fireEvent.click(screen.getByLabelText("plex.player.next"));
    await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/C"));
    await act(async () => slowB.resolve(direct("B")));
    await tick();
    expect(video().getAttribute("src")).toBe("/media/C");
  });

  it("is dropped when the player has been closed meanwhile", async () => {
    const slowA = deferred();
    const { unmount } = mount({ details: { A: item("A") }, sessions: { A: () => slowA.promise } });
    await waitFor(() => expect(api.plexSession).toHaveBeenCalled());
    const v = video();
    unmount();
    await act(async () => slowA.resolve(direct("A")));
    await tick();
    expect(v.getAttribute("src")).toBeNull();
  });
});

it("closing the player detaches the <video> it was playing", async () => {
  const { unmount } = mount({
    details: { A: item("A") },
    sessions: { A: () => Promise.resolve(direct("A")) },
  });
  await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/A"));
  const v = video();
  unmount();
  expect(v.getAttribute("src")).toBeNull();
});

describe("the subtitle poll and notice", () => {
  it("asks about where a resumed session was asked to start, before playback has ticked", async () => {
    const { status } = mount({
      details: { A: item("A", 1198) },
      sessions: { A: () => new Promise(() => {}) },
    });
    await waitFor(() => expect(status).toHaveBeenCalled());
    expect(status.mock.calls[0]).toEqual(["A", 0, 1198]);
  });

  it("says a failing poll even while an earlier window is still on screen", async () => {
    const qc = new QueryClient({ defaultOptions: { queries: { retry: false } } });
    qc.setQueryData(qk.plexSubtitle("A", 0), { state: "partial", code: null, gen: 1 });
    const view = mount({
      details: { A: item("A") },
      sessions: { A: () => Promise.resolve(direct("A")) },
      qc,
    });
    view.status.mockRejectedValue(new Error("offline"));
    await waitFor(() => expect(view.status).toHaveBeenCalled());
    await screen.findByText("plex.player.subUnavailable.failed");
    expect(document.querySelector("track")).not.toBeNull(); // the window stays mounted meanwhile
  });

  it("marks which track is selected for assistive tech, not only by colour", async () => {
    mount({ details: { A: item("A") }, sessions: { A: () => new Promise(() => {}) } });
    await screen.findByText("Title A");
    fireEvent.click(screen.getByLabelText("plex.player.tracks"));
    const off = await screen.findByText("plex.player.subOff");
    expect(off.closest("button")?.getAttribute("aria-pressed")).toBe("false");
    const pressed = document.querySelectorAll('[aria-pressed="true"]');
    expect([...pressed].map((b) => b.textContent)).toEqual(["English"]); // the saved subtitle
  });
});

it("shows a toast raised while it is open inside itself, not under its scrim", async () => {
  mount({ details: { A: item("A") }, sessions: { A: () => new Promise(() => {}) } });
  await screen.findByText("Title A");
  act(() => notify({ level: "error", message: "Couldn't mark it watched." }));
  const toast = await screen.findByText("Couldn't mark it watched.");
  let host: Element | null = video();
  while (host && !host.contains(toast)) host = host.parentElement;
  expect(host).not.toBe(document.body); // the player's own host, beside its <video>
});

// --- deep-review round 4 ------------------------------------------------------------------------

/** A session answer that FAILS when the test says so. */
function deferredFailure() {
  let reject!: (e: unknown) => void;
  const promise = new Promise<Awaited<ReturnType<typeof api.plexSession>>>((_r, j) => (reject = j));
  return { promise, reject };
}

const startsAsked = (id: string) =>
  vi
    .mocked(api.plexSession)
    .mock.calls.filter(([i]) => i === id)
    .map(([, at]) => at);

describe("leaving an item that was played through", () => {
  const prefs = (p: object) =>
    localStorage.setItem("siftlode.plexPlayerPrefs.7", JSON.stringify({ subLang: "en", ...p }));

  // The end of the media, in the order the HTML spec mandates: the browser sets `paused`, fires
  // 'pause', and only THEN fires 'ended'. Dispatching a bare 'ended' models a browser that does not
  // exist, and hid the fact that the pause checkpoint goes out before the finish latch is up
  // (deep-review round 5).
  const endMedia = () => {
    const el = video();
    Object.defineProperty(el, "ended", { configurable: true, get: () => true });
    act(() => void el.dispatchEvent(new Event("pause")));
    act(() => void el.dispatchEvent(new Event("ended")));
  };

  it("settles it as watched when it ended, so Prev does not reopen it at its last seconds", async () => {
    prefs({ upNext: false });
    const { qc, progress } = mount({
      details: { A: item("A"), B: item("B") },
      sessions: { A: () => Promise.resolve(direct("A")), B: () => new Promise(() => {}) },
      queue: ["A", "B"],
    });
    vi.spyOn(api, "plexSetState").mockResolvedValue(undefined as never);
    await playingAt("/media/A", 2995);
    endMedia();
    await screen.findByText("Title B");
    await tick();
    const cached = qc.getQueryData<PlexItemDetail>(qk.plexItem("A", "en"));
    expect([cached?.status, cached?.position_seconds]).toEqual(["watched", 0]);
    expect(progress.mock.calls.filter(([id, , , final]) => id === "A" && final)).toEqual([]);
    fireEvent.click(screen.getByLabelText("plex.player.prev"));
    await waitFor(() => expect(startsAsked("A")).toHaveLength(2));
    expect(startsAsked("A")[1]).toBe(0);
  });

  it("sends no checkpoint at the credits when the auto-skip leaves it", async () => {
    // A final checkpoint at the credits raced the watched mark: landing second, it left the row
    // watched WITH a resume point, and pushed that point to Plex right after the scrobble.
    prefs({ autoSkipCredits: true, autoSkipDelay: 0 });
    const withCredits = {
      ...item("A"),
      markers: [{ type: "credits", start_s: 2900, end_s: 2995 }],
    } as unknown as PlexItemDetail;
    const { qc, progress } = mount({
      details: { A: withCredits, B: item("B") },
      sessions: { A: () => Promise.resolve(direct("A")), B: () => new Promise(() => {}) },
      queue: ["A", "B"],
    });
    const setState = vi.spyOn(api, "plexSetState").mockResolvedValue(undefined as never);
    await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/A"));
    // The 'pause' event (and its checkpoint) can land before the player has re-rendered for the
    // next item — here it lands at once.
    video().pause = function (this: HTMLMediaElement) {
      this.dispatchEvent(new Event("pause"));
    };
    await playingAt("/media/A", 2910);
    await screen.findByText("Title B");
    await tick(); // the pause() that go() queued has fired its events by now
    expect(setState).toHaveBeenCalledWith("A", "watched");
    expect(progress.mock.calls.filter(([id, , , final]) => id === "A" && final)).toEqual([]);
    const cached = qc.getQueryData<PlexItemDetail>(qk.plexItem("A", "en"));
    expect([cached?.status, cached?.position_seconds]).toEqual(["watched", 0]);
  });
  it("takes the finish back when the server refuses the watched mark", async () => {
    // The mark was fired and forgotten (`.catch(() => {})`) while the cache was patched to
    // watched / position 0 regardless, and the once-per-id start guard meant the corrected detail
    // arriving later was never used: the episode reopened at 0:00 with a Watched badge the server
    // disagreed with (round 5).
    prefs({ upNext: false });
    const { qc, progress } = mount({
      details: { A: item("A"), B: item("B") },
      sessions: { A: () => Promise.resolve(direct("A")), B: () => new Promise(() => {}) },
      queue: ["A", "B"],
    });
    vi.spyOn(api, "plexSetState").mockRejectedValue(new Error("offline"));
    await playingAt("/media/A", 2995);
    endMedia();
    await screen.findByText("Title B");
    await tick();
    // The cached detail is not left claiming watched: only the server is honest now.
    const cached = qc.getQueryData<PlexItemDetail>(qk.plexItem("A", "en"));
    expect(cached?.status).not.toBe("watched");
    // And the rollback does NOT write the position back. 2995 of 3000 is inside the backend's
    // finish margin, so that checkpoint would have set watched / position 0 and scrobbled to Plex
    // — performing, through a second route, the very write that was just refused, while the error
    // toast said it had failed (round 6). There is no resume point at the end of the media to
    // restore; the cache drop is the whole of the rollback here.
    expect(progress.mock.calls.filter(([id, , , final]) => id === "A" && final)).toEqual([]);
  });

  it("performs the refused mark through no OTHER route while it stays on the finished item", async () => {
    // Round 6 guarded the explicit rollback write, but the same catch lowered the play-through
    // latch — and that latch is the only gate on the 10s interval, the page-hide beacon and
    // `settle`. All three post `absRef`, which on this path IS the end of the media, and the
    // backend reads a position within `_FINISH_MARGIN_S` of the duration as a finish: within ten
    // seconds of the toast saying the mark had failed, the item was watched, its position cleared
    // and a scrobble sent to Plex (deep-review round 7). `upNext` is ON here — the default — so the
    // player STAYS on the finished item and those routes are live; the round-6 test above turns it
    // off, which tears the effect down before any of them can fire.
    prefs({ upNext: true });
    const beacon = vi.spyOn(api, "plexProgressBeacon").mockImplementation(() => {});
    const { qc, progress, unmount } = mount({
      details: { A: item("A"), B: item("B") },
      sessions: { A: () => Promise.resolve(direct("A")), B: () => new Promise(() => {}) },
      queue: ["A", "B"],
    });
    vi.spyOn(api, "plexSetState").mockRejectedValue(new Error("offline"));
    await playingAt("/media/A", 2995);
    endMedia(); // the up-next card is up, the item is finished, and the mark comes back refused
    await tick();
    progress.mockClear();

    // The viewer closes the tab while the failed-mark toast is still up.
    act(() => void window.dispatchEvent(new Event("pagehide")));
    expect(beacon).not.toHaveBeenCalled();

    // The refusal dropped the cached detail — and the open player's own observer refetches it, so
    // by the time the viewer leaves there is an entry again. `settle` must not re-assert watched
    // onto it: only the server is honest about this item now.
    act(() => void qc.setQueryData(qk.plexItem("A", "en"), item("A")));

    // And leaving the player: `settle` must neither post the end position nor re-assert watched.
    unmount();
    await tick();
    expect(progress.mock.calls.filter(([id]) => id === "A")).toEqual([]);
    expect(qc.getQueryData<PlexItemDetail>(qk.plexItem("A", "en"))?.status).not.toBe("watched");
  });

  it("does restore the position when the refused finish came from the credits skip", async () => {
    // The other caller of the same helper captures a MID-episode position, and there the rollback
    // is the point: without it the viewer loses the stretch they watched. One helper, two callers,
    // and only the near-end one must hold back.
    prefs({ upNext: false, autoSkipCredits: true, autoSkipDelay: 0 });
    const withCredits = {
      ...item("A"),
      markers: [{ type: "credits", start_s: 2000, end_s: 2990 }],
    } as unknown as PlexItemDetail;
    const { qc, progress } = mount({
      details: { A: withCredits, B: item("B") },
      sessions: { A: () => Promise.resolve(direct("A")), B: () => new Promise(() => {}) },
      queue: ["A", "B"],
    });
    vi.spyOn(api, "plexSetState").mockRejectedValue(new Error("offline"));
    await playingAt("/media/A", 2010); // inside the credits → auto-skip advances and marks watched
    await screen.findByText("Title B");
    await tick();
    expect(progress.mock.calls.filter(([id, , , final]) => id === "A" && final)).toEqual([
      ["A", 2010, 3000, true],
    ]);
    expect(qc.getQueryData<PlexItemDetail>(qk.plexItem("A", "en"))?.status).not.toBe("watched");
  });

  it("records a second viewing when the viewer plays on from the finished frame", async () => {
    // `finished` is a latch that makes every checkpoint a no-op; the only thing that lowers it is
    // the video's own 'play' event. Nothing tested that, so dropping the listener would have
    // discarded a whole rewatch with the gate green (round 5).
    prefs({ upNext: true });
    const { progress } = mount({
      details: { A: item("A"), B: item("B") },
      sessions: { A: () => Promise.resolve(direct("A")), B: () => new Promise(() => {}) },
      queue: ["A", "B"],
    });
    vi.spyOn(api, "plexSetState").mockResolvedValue(undefined as never);
    await playingAt("/media/A", 2995);
    endMedia(); // the up-next card is up; the item is finished
    await tick();
    progress.mockClear();

    // The viewer cancels the card and rewinds: playing again takes the finish back.
    const el = video() as Media;
    Object.defineProperty(el, "ended", { configurable: true, get: () => false });
    act(() => void el.dispatchEvent(new Event("play")));
    el._t = 2400;
    act(() => void el.dispatchEvent(new Event("timeupdate")));
    act(() => void el.dispatchEvent(new Event("pause")));
    await tick();
    expect(progress.mock.calls.filter(([id, , , final]) => id === "A" && final)).toEqual([
      ["A", 2400, 3000, true],
    ]);
  });
});

describe("restarting the session before playback has ticked", () => {
  it("an audio switch or a keyboard seek keeps the resume point", async () => {
    const twoAudio = {
      ...item("A", 1200),
      audio_streams: [
        { ord: 0, label: "English", language: "en", default: true },
        { ord: 1, label: "Magyar", language: "hu", default: false },
      ],
    } as unknown as PlexItemDetail;
    mount({ details: { A: twoAudio }, sessions: { A: () => new Promise(() => {}) } });
    await waitFor(() => expect(startsAsked("A")).toEqual([1200]));
    fireEvent.keyDown(window, { key: "a" });
    fireEvent.keyDown(window, { key: "ArrowRight" });
    await waitFor(() => expect(startsAsked("A")).toHaveLength(3));
    expect(startsAsked("A")).toEqual([1200, 1200, 1210]);
  });
});

it("a seek made while a restart is pending wins over it", async () => {
  let calls = 0;
  const pending = deferred();
  mount({
    details: { A: item("A") },
    sessions: {
      A: () => {
        calls++;
        if (calls === 1) return Promise.resolve(direct("A"));
        return calls === 2 ? pending.promise : new Promise(() => {});
      },
    },
  });
  await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/A"));
  Object.defineProperty(video(), "seekable", { get: () => ({ length: 1, end: () => 100 }) });
  await playingAt("/media/A", 95);
  fireEvent.click(screen.getByLabelText("plex.player.forward10")); // 105: past the buffer → restart
  fireEvent.click(screen.getByLabelText("plex.player.rewind10")); // 95: inside the OLD buffer
  await waitFor(() => expect(startsAsked("A")).toEqual([0, 105, 95]));
  await act(async () => pending.resolve({ mode: "direct", url: "/media/A2", start_s: 0 } as never));
  await tick();
  expect(video().getAttribute("src")).toBe("/media/A"); // the superseded 105 answer never attached
});

it("a direct-play item left before its metadata does not seek the next one", async () => {
  mount({
    details: { A: item("A", 1200), B: item("B") },
    sessions: { A: () => Promise.resolve(direct("A")), B: () => Promise.resolve(direct("B")) },
    queue: ["A", "B"],
  });
  await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/A"));
  fireEvent.click(screen.getByLabelText("plex.player.next"));
  await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/B"));
  act(() => void video().dispatchEvent(new Event("loadedmetadata")));
  expect(video().currentTime).toBe(0); // not A's resume point, 1200
});

it("a refetch of the playing item's detail does not restart it", async () => {
  // react-query refetches it on reconnect, and the in-player info panel invalidates it after a
  // watched toggle — each one restarted the film at the last saved checkpoint.
  const details = { A: item("A", 100) };
  const { qc } = mount({ details, sessions: { A: () => Promise.resolve(direct("A")) } });
  await playingAt("/media/A", 1500);
  details.A = item("A", 1490);
  await act(async () => {
    await qc.invalidateQueries({ queryKey: qk.plexItem("A") });
  });
  await tick();
  expect(vi.mocked(api.plexItem).mock.calls.length).toBeGreaterThan(1); // it did refetch
  expect(startsAsked("A")).toEqual([100]);
});

describe("a session request that fails", () => {
  it("is not reported when it has been superseded", async () => {
    const slowB = deferredFailure();
    mount({
      details: { A: item("A"), B: item("B"), C: item("C") },
      sessions: {
        A: () => Promise.resolve(direct("A")),
        B: () => slowB.promise,
        C: () => Promise.resolve(direct("C")),
      },
      queue: ["A", "B", "C"],
    });
    await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/A"));
    fireEvent.click(screen.getByLabelText("plex.player.next"));
    await screen.findByText("Title B");
    fireEvent.click(screen.getByLabelText("plex.player.next"));
    await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/C"));
    await act(async () => slowB.reject(new HttpError(404)));
    await tick();
    expect(screen.queryByText("plex.player.errNotFound")).toBeNull();
  });

  it("keeps following the old stream when a seek-restart fails", async () => {
    let calls = 0;
    const { progress, unmount } = mount({
      details: { A: item("A") },
      sessions: {
        A: () =>
          calls++ === 0 ? Promise.resolve(direct("A")) : Promise.reject(new HttpError(500)),
      },
    });
    await playingAt("/media/A", 1500);
    fireEvent.click(screen.getByLabelText("plex.player.forward10"));
    await screen.findByText("plex.player.errGeneric");
    await playingAt("/media/A", 1600); // the old stream plays on
    unmount();
    expect(progress.mock.calls).toContainEqual(["A", 1600, 3000, true]);
  });

  it("saves nothing of the previous item's position when moving to the next one fails", async () => {
    const { progress, unmount } = mount({
      details: { A: item("A"), B: item("B") },
      sessions: {
        A: () => Promise.resolve(direct("A")),
        B: () => Promise.reject(new HttpError(404)),
      },
      queue: ["A", "B"],
    });
    await playingAt("/media/A", 1500);
    fireEvent.click(screen.getByLabelText("plex.player.next"));
    await screen.findByText("plex.player.errNotFound");
    await tick();
    await playingAt("/media/A", 1600); // A's media, still attached, ticks once more
    unmount();
    expect(progress.mock.calls.filter(([id]) => id === "B")).toEqual([]);
  });
});

it("a session answer that lands while the next item's detail is still loading is dropped", async () => {
  const slowB = deferred();
  mount({
    details: { A: item("A"), B: item("B"), C: item("C") },
    sessions: {
      A: () => Promise.resolve(direct("A")),
      B: () => slowB.promise,
      C: () => Promise.resolve(direct("C")),
    },
    queue: ["A", "B", "C"],
  });
  await waitFor(() => expect(video()?.getAttribute("src")).toBe("/media/A"));
  const real = vi.mocked(api.plexItem).getMockImplementation()!;
  vi.mocked(api.plexItem).mockImplementation((id: string, lang?: string) =>
    id === "C" ? new Promise(() => {}) : real(id, lang),
  );
  fireEvent.click(screen.getByLabelText("plex.player.next"));
  await waitFor(() => expect(startsAsked("B")).toHaveLength(1));
  fireEvent.click(screen.getByLabelText("plex.player.next"));
  await tick();
  await act(async () => slowB.resolve(direct("B")));
  await tick();
  expect(video().getAttribute("src")).not.toBe("/media/B");
});