import pytest
from unittest.mock import patch
from sqlalchemy.ext.asyncio import create_async_engine
from sqlalchemy import text
from sqlmodel import SQLModel
from app.database import init_db

@pytest.mark.asyncio
async def test_init_db_creates_tables():
    """Verifies that init_db() successfully creates all necessary tables.

    This test uses a patched in-memory SQLite engine to ensure isolation
    and verify the database initialization logic.
    """
    # Use an in-memory SQLite engine for testing to avoid any impact on real data
    test_engine = create_async_engine("sqlite+aiosqlite:///:memory:")
    
    # Patch the engine in app.database so init_db uses our test engine
    with patch("app.database.engine", test_engine):
        await init_db()
        
        # Check if the expected table "sleep_session" exists in the schema
        async with test_engine.connect() as conn:
            result = await conn.execute(text("SELECT name FROM sqlite_master WHERE type='table' AND name='sleep_session';"))
            row = result.fetchone()
            assert row is not None, "Table 'sleep_session' was not created by init_db()"
            assert row[0] == "sleep_session"

    await test_engine.dispose()