def get_previous_dataset(self, dataset: xr.Dataset) -> xr.Dataset:
"""Utility method to retrieve the previous set of data for hte same
datastream as the provided dataset from the DatastreamStorage.
:param dataset:
The reference dataset that will be used to search the
DatastreamStore for prior data.
:type dataset: xr.Dataset
:return:
The previous dataset from the DatastreamStorage if it exists,
otherwise None.
:rtype: xr.Dataset
"""
prev_dataset = None
start_date, start_time = DSUtil.get_start_time(dataset)
datastream_name = DSUtil.get_datastream_name(dataset, self.config)
with self.storage.fetch_previous_file(
datastream_name, f"{start_date}.{start_time}"
) as netcdf_file:
if netcdf_file:
prev_dataset = self.storage.handlers.read(
file=netcdf_file, name=netcdf_file
)
return prev_dataset
def test_start_time_is_correct(raw_dataset, dataset, config):
expected = ("20211001", "000000")
time_definition = config.dataset_definition.get_variable("time")
assert DSUtil.get_raw_start_time(raw_dataset, time_definition) == expected
assert DSUtil.get_start_time(dataset) == expected