def METHOD_NAME(self) -> None:
    datapipe = _DummyDataReader(int(100000))
    train_datapipe, val_datapipe = idx_split_train_val(datapipe, 0.6)
    self.assertEqual(len(list(train_datapipe)), 100000 * 0.6)
    self.assertEqual(len(list(val_datapipe)), 100000 * 0.4)