def test_datetime_to_epoch(self):
        """Test convert datetime to epoch."""
        timestamp = pd.Timestamp('2013-01-01 00:00:00.000+00:00')
        cli = DataFrameClient('host', 8086, 'username', 'password', 'db')

        self.assertEqual(
            cli._datetime_to_epoch(timestamp),
            1356998400.0
        )
        self.assertEqual(
            cli._datetime_to_epoch(timestamp, time_precision='s'),
            1356998400.0
        )
        self.assertEqual(
            cli._datetime_to_epoch(timestamp, time_precision='m'),
            1356998400000.0
        )
        self.assertEqual(
            cli._datetime_to_epoch(timestamp, time_precision='ms'),
            1356998400000.0
        )
        self.assertEqual(
            cli._datetime_to_epoch(timestamp, time_precision='u'),
            1356998400000000.0
        )