def test_custom_sync_engine_only(db: None, node_embeddings: List[TextNode]) -> None:
    """Test that PGVectorStore works correctly with only a custom sync engine."""
    from sqlalchemy import create_engine

    # Create custom sync engine only
    engine = create_engine(
        f"postgresql+psycopg2://{PARAMS['user']}:{PARAMS['password']}@{PARAMS['host']}:{PARAMS['port']}/{TEST_DB}",
        echo=False,
    )

    # Create PGVectorStore with custom sync engine only
    with pytest.raises(ValueError):
        _ = PGVectorStore(
            embed_dim=TEST_EMBED_DIM,
            engine=engine,
        )
Test that PGVectorStore works correctly with only a custom sync engine.
llama-index-integrations/vector_stores/llama-index-vector-stores-postgres/tests/test_postgres.py