def test_RR_works(self):
        self.dsd.calculate_RR()
        self.assertIsNotNone(
            self.dsd.fields["rain_rate"],
            "Rain Rate is not in fields after calculate_RR()",
        )
        self.assertEqual(
            len(self.dsd.fields["rain_rate"]["data"]),
            5,
            "Wrong number of time samples in rain rate",
        )