Lyra/worker/tests/test_musicbrainz.py

import musicbrainzngs
import pytest

from lyra_worker._musicbrainz import _best_release_group, _with_retry

# Offline unit tests for the pure release-group selection logic. The live resolve()
# path (network) is covered by test_musicbrainz_live.py.


def _rg(title, primary_type, artist=""):
    g = {"id": title.lower(), "title": title, "primary-type": primary_type}
    if artist:
        g["artist-credit"] = [{"artist": {"name": artist, "id": artist.lower()}}]
    return g


def test_prefers_album_over_same_titled_single():
    # Real-world "Off the Wall" bug: MusicBrainz returns the Single release-group
    # first, tied on title with the Album. We must pick the Album so a 10-track
    # download isn't tagged from the 2-track single's tracklist.
    groups = [
        _rg("Off the Wall", "Single", "Michael Jackson"),
        _rg("Off the Wall", "Album", "Michael Jackson"),
    ]
    assert _best_release_group("Michael Jackson", "Off the Wall", groups)["primary-type"] == "Album"


def test_album_preference_is_order_independent():
    groups = [
        _rg("Off the Wall", "Album", "Michael Jackson"),
        _rg("Off the Wall", "Single", "Michael Jackson"),
    ]
    assert _best_release_group("Michael Jackson", "Off the Wall", groups)["primary-type"] == "Album"


def test_closer_title_still_wins_over_album_type():
    # Title similarity dominates the album-type preference (for a single artist).
    groups = [
        _rg("Continuum", "Single", "John Mayer"),
        _rg("Continuum Deluxe Reissue", "Album", "John Mayer"),
    ]
    assert _best_release_group("John Mayer", "Continuum", groups)["title"] == "Continuum"


def test_below_threshold_returns_none():
    groups = [_rg("Something Totally Different", "Album", "Michael Jackson")]
    assert _best_release_group("Michael Jackson", "Off the Wall", groups) is None


def test_empty_groups_returns_none():
    assert _best_release_group("Michael Jackson", "Off the Wall", []) is None


def test_prefers_credited_artist_over_same_titled_other_artist_album():
    # Real-world "Fun Machine" bug: Lake Street Dive's EP is what we followed, but two
    # unrelated bands also have a release group literally titled "Fun Machine" as an Album.
    # All three tie on title (1.0), so the old is_album tiebreak wrongly grabbed a foreign
    # Album. The followed artist must win over title-tied albums by other artists.
    groups = [
        _rg("Fun Machine", "EP", "Lake Street Dive"),
        _rg("Fun Machine", "Album", "Bastards of Melody"),
        _rg("Fun Machine", "Album", "Teledildonics 5000"),
    ]
    best = _best_release_group("Lake Street Dive", "Fun Machine", groups)
    assert best["artist-credit"][0]["artist"]["name"] == "Lake Street Dive"


# --- _with_retry: transient MusicBrainz failures (SSL EOF, 503 rate-limit) ---


def test_retry_returns_value_without_backoff_when_first_call_succeeds():
    sleeps: list[float] = []
    calls = {"n": 0}

    def fn():
        calls["n"] += 1
        return "ok"

    assert _with_retry(fn, sleep=sleeps.append) == "ok"
    assert calls["n"] == 1
    assert sleeps == []  # no backoff when nothing failed


def test_retry_recovers_from_transient_network_error():
    # The real symptom: <urlopen error [SSL: UNEXPECTED_EOF_WHILE_READING]> arrives
    # as musicbrainzngs.NetworkError. A couple of retries clears it.
    sleeps: list[float] = []
    calls = {"n": 0}

    def fn():
        calls["n"] += 1
        if calls["n"] < 3:
            raise musicbrainzngs.NetworkError("SSL: UNEXPECTED_EOF_WHILE_READING")
        return "recovered"

    assert _with_retry(fn, sleep=sleeps.append) == "recovered"
    assert calls["n"] == 3
    assert sleeps == [1.0, 2.0]  # exponential backoff before each retry


def test_retry_recovers_from_transient_response_error():
    # MusicBrainz's own 503 rate-limit surfaces as ResponseError.
    calls = {"n": 0}

    def fn():
        calls["n"] += 1
        if calls["n"] < 2:
            raise musicbrainzngs.ResponseError("503 Service Unavailable")
        return "ok"

    assert _with_retry(fn, sleep=lambda _: None) == "ok"
    assert calls["n"] == 2


def test_retry_reraises_after_exhausting_attempts():
    sleeps: list[float] = []

    def fn():
        raise musicbrainzngs.NetworkError("still down")

    with pytest.raises(musicbrainzngs.NetworkError):
        _with_retry(fn, attempts=4, sleep=sleeps.append)
    assert sleeps == [1.0, 2.0, 4.0]  # 3 backoffs across 4 attempts


def test_retry_does_not_swallow_non_transient_errors():
    calls = {"n": 0}

    def fn():
        calls["n"] += 1
        raise ValueError("bug, not a network blip")

    with pytest.raises(ValueError):
        _with_retry(fn, sleep=lambda _: None)
    assert calls["n"] == 1  # non-transient errors propagate immediately, no retry