discovery-by-llm/backend/tests/test_recommendation_api.py

"""HTTP contract tests for recommendation and playlist routes."""

import time
from collections.abc import AsyncGenerator

import pytest
from fastapi.testclient import TestClient
from pydantic import TypeAdapter

from app.adapters.spotify.auth import TokenSet
from app.adapters.spotify.errors import SpotifyAuthenticationError
from app.adapters.spotify.session import SessionStore, SpotifySession
from app.api.routes import SESSION_COOKIE_NAME
from app.api.schemas import StreamEvent
from app.domain.models import ConversationTurn, CreatedPlaylist, PreviousRecommendation, Track
from app.main import create_app
from app.pipeline.event import PipelineDoneEvent, PipelineMetadataEvent, PipelineTrackEvent
from app.ports.protocols import MusicCatalog


class FakePipeline:
    """Emit one complete deterministic stream."""

    async def stream(
        self,
        session_id: str,
        request_id: str,
        catalog: MusicCatalog,
        query: str,
        history: tuple[ConversationTurn, ...],
        previous_recommendations: tuple[PreviousRecommendation, ...],
    ) -> AsyncGenerator[PipelineMetadataEvent | PipelineTrackEvent | PipelineDoneEvent]:
        """Yield metadata, one track, and completion."""
        yield PipelineMetadataEvent(request_id, "A focused test request.", 35)
        yield PipelineTrackEvent(1, _track(), "It fits the requested focus.")
        yield PipelineDoneEvent(1, 4)


class FakePlaylistWriter:
    """Capture playlist writes without external calls."""

    def __init__(self, error: Exception | None = None) -> None:
        """Create an empty write trace."""
        self.error = error
        self.name: str | None = None
        self.track_uris: list[str] = []

    async def create_playlist(self, name: str, description: str) -> CreatedPlaylist:
        """Record the prefixed name and return a stable playlist."""
        if self.error is not None:
            raise self.error
        self.name = name
        return CreatedPlaylist("playlist", "https://open.spotify.com/playlist/playlist")

    async def add_tracks_to_playlist(self, playlist_id: str, track_uris: list[str]) -> None:
        """Record the ordered track URIs."""
        self.track_uris = track_uris


def test_recommendations_stream_lines_validate_against_frozen_schemas(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    async def fail_if_polled(request: object) -> bool:
        raise AssertionError("Request disconnect state must not be polled")

    monkeypatch.setattr("starlette.requests.Request.is_disconnected", fail_if_polled)
    app = create_app()
    with TestClient(app) as client:
        _authenticate(client, session_store=app.state.session_store)
        app.state.recommendation_pipeline = FakePipeline()

        response = client.post(
            "/api/recommendations",
            json={"schema_version": 1, "query": "focused electronic music"},
        )

    adapter: TypeAdapter[StreamEvent] = TypeAdapter(StreamEvent)
    events = [adapter.validate_json(line) for line in response.text.splitlines()]
    assert response.status_code == 200
    assert response.headers["content-type"] == "application/x-ndjson"
    assert [event.type for event in events] == ["metadata", "track", "done"]


def test_recommendations_require_a_valid_session_without_seed() -> None:
    with TestClient(create_app()) as client:
        response = client.post(
            "/api/recommendations",
            json={"schema_version": 1, "query": "focused electronic music"},
        )

    assert response.status_code == 401
    assert response.json() == {"detail": "Not authenticated"}


def test_playlist_endpoint_prefixes_name_and_adds_tracks() -> None:
    app = create_app()
    writer = FakePlaylistWriter()
    with TestClient(app) as client:
        _authenticate(client, session_store=app.state.session_store)
        app.state.spotify_client_factory = lambda session: writer

        response = client.post(
            "/api/playlists",
            json={
                "schema_version": 1,
                "name": "Night drive",
                "track_uris": ["spotify:track:track"],
            },
        )

    assert response.status_code == 200
    assert response.json() == {"url": "https://open.spotify.com/playlist/playlist"}
    assert writer.name == "discovery-by-llm Night drive"
    assert writer.track_uris == ["spotify:track:track"]


def test_playlist_authentication_failure_signals_relogin() -> None:
    app = create_app()
    writer = FakePlaylistWriter(SpotifyAuthenticationError("expired"))
    with TestClient(app) as client:
        _authenticate(client, session_store=app.state.session_store)
        app.state.spotify_client_factory = lambda session: writer

        response = client.post(
            "/api/playlists",
            json={
                "schema_version": 1,
                "name": "Night drive",
                "track_uris": ["spotify:track:track"],
            },
        )

    assert response.status_code == 401
    assert response.json() == {"detail": "Spotify authentication expired"}


def _authenticate(client: TestClient, session_store: SessionStore) -> None:
    session_id = session_store.create(
        SpotifySession(
            tokens=TokenSet("access", "refresh", time.monotonic() + 3600),
            account_id="account",
            display_name="Listener",
        )
    )
    client.cookies.set(SESSION_COOKIE_NAME, session_id)


def _track() -> Track:
    return Track(
        id="track",
        uri="spotify:track:track",
        title="Test Track",
        artists=("Test Artist",),
        album_name="Test Album",
        album_art_url=None,
        external_url="https://open.spotify.com/track/track",
    )