Web frontend

python-backend/tests/test_player.py

@@ -1,7 +1,9 @@
 """Tests for the shared player behaviour, exercised through FakePlayer.
 
 VlcPlayer adds only the libVLC bindings on top of PlayerBase; it needs a real audio
-device and is covered by the on-device checklist, not here.
+device and is covered by the on-device checklist, not here - except for how it works
+out which track is playing, which is stubbed out at the bottom of this file because
+getting it wrong is invisible until a front-end displays it.
 """
 
 from __future__ import annotations
@@ -13,7 +15,7 @@ import pytest
 
 from musicmouse.bus import EventBus
 from musicmouse.clock import FakeClock
-from musicmouse.devices.player import Player, VlcPlayer
+from musicmouse.devices.player import Player, PlayerBase, VlcPlayer
 from musicmouse.events import (
     Event,
     PlaybackChanged,
@@ -295,3 +297,69 @@ def test_fake_player_satisfies_the_player_protocol(player: FakePlayer) -> None:
 def _vlc_player_satisfies_the_player_protocol(real: VlcPlayer) -> Player:
     """Checked by mypy, not at runtime: VlcPlayer needs libVLC to instantiate."""
     return real
+
+
+# --------------------------------------------------------- track index without libVLC
+
+
+class _FakeMedia:
+    def __init__(self, mrl: str) -> None:
+        self._mrl = mrl
+
+    def get_mrl(self) -> str:
+        return self._mrl
+
+
+class _FakeMediaPlayer:
+    """Just enough of libVLC's media player to exercise index syncing."""
+
+    def __init__(self) -> None:
+        self.media: _FakeMedia | None = None
+
+    def get_media(self) -> _FakeMedia | None:
+        return self.media
+
+
+def _vlc_like(bus: EventBus, playlist: Playlist) -> VlcPlayer:
+    """A VlcPlayer with its libVLC parts stubbed out, without calling __init__."""
+    player = object.__new__(VlcPlayer)
+    PlayerBase.__init__(player, bus)
+    player._media_player = _FakeMediaPlayer()  # type: ignore[assignment]
+    player._playlist = playlist
+    player._mrl_to_index = {f"file://{track.path}": i for i, track in enumerate(playlist.tracks)}
+    return player
+
+
+async def test_the_track_index_is_read_back_off_the_player(bus: EventBus) -> None:
+    """Not taken from the event payload.
+
+    ``MediaListPlayerNextItemSet`` carries a bare int rather than a Media on some
+    libVLC builds, and trusting it left the index pinned at zero: the UI showed track 1
+    of an album that was audibly on track 3.
+    """
+    playlist = Playlist("test", tuple(Track(Path(f"/music/{i}.mp3")) for i in range(3)))
+    player = _vlc_like(bus, playlist)
+    events: list[Event] = []
+    bus.subscribe(TrackChanged, events.append)
+
+    player._media_player.media = _FakeMedia("file:///music/2.mp3")  # type: ignore[attr-defined]
+    player._on_next_item(object())
+    await bus.drain()
+
+    assert player.track_index == 2
+    assert player.current_track is not None
+    assert player.current_track.path.name == "2.mp3"
+    assert len(events) == 1
+
+
+async def test_an_unknown_media_leaves_the_index_alone(bus: EventBus) -> None:
+    playlist = Playlist("test", tuple(Track(Path(f"/music/{i}.mp3")) for i in range(3)))
+    player = _vlc_like(bus, playlist)
+
+    player._media_player.media = None  # type: ignore[attr-defined]
+    player._on_next_item(object())
+    player._media_player.media = _FakeMedia("file:///elsewhere/x.mp3")  # type: ignore[attr-defined]
+    player._on_next_item(object())
+    await bus.drain()
+
+    assert player.track_index == 0