update default units handler to use explicit cache folder

python/nwm_client_new/src/hydrotools/nwm_client_new/NWMClientDefaults.py

@@ -21,6 +21,7 @@
 from pathlib import Path
 from typing import List, Dict
 from enum import Enum
+from pint import UnitRegistry
 
 class MeasurementUnitSystem(Enum):
     """A system of units to define measurements.
@@ -98,7 +99,7 @@ def CROSSWALK(self) -> pd.DataFrame:
     def NWM_TO_US_UNIT_CONVERSION(self) -> Dict[str, Dict[str, float]]:
         """Mapping from NWM units to US standard units and respective conversion factors."""
         # Set up unit handler
-        unit_handler = UnitHandler()
+        unit_handler = UnitHandler(unit_registry=UnitRegistry(cache_folder=Path("hydrotools/pint_cache")))
 
         # Build conversion from NWM to US
         nwm_to_us_mapping = {key: self.SI_TO_US_UNIT_MAPPING[val] for key, val in self.NWM_TO_SI_UNIT_MAPPING.items()}

python/nwm_client_new/tests/test_UnitHandler.py

@@ -2,6 +2,8 @@
 from hydrotools.nwm_client_new import UnitHandler
 import numpy as np
 import pandas as pd
+from tempfile import TemporaryDirectory
+from pint import UnitRegistry
 
 @pytest.fixture
 def setup_unit_handler():
@@ -24,3 +26,13 @@ def test_convert_values(setup_unit_handler):
     )
 
     assert (np.all(np.isclose(s, 0.3048)))
+
+def test_alt_unit_registry():
+    with TemporaryDirectory() as td:
+        uh = UnitHandler.UnitHandler(
+            unit_registry=UnitRegistry(cache_folder=td)
+            )
+        test_conversion_factor(uh)
+        test_convert_values(uh)
+        from pathlib import Path
+        assert next(Path(td).iterdir(), None)