def METHOD_NAME(self):
    query = "SELECT t_ts, t_id, t_instrument, t_exchange, t_price, t_size FROM CRYPTO_TRADES LIMIT 10"
    postgres_url = "postgresql://test:test@postgres:5432/test"
    dh_table = read_sql(conn=postgres_url, query=query)
    self.assertEqual(len(dh_table.columns), 6)
    self.assertEqual(dh_table.size, 10)
    with self.assertRaises(DHError) as cm:
        dh_table = read_sql(conn="garbage", query=query)