confirm if units satisfy pint.

src/pynxtools/dataconverter/writer.py

@@ -35,7 +35,7 @@
 )
 
 logger = logging.getLogger("pynxtools")  # pylint: disable=C0103
-
+ureg = pint.UnitRegistry()
 
 def does_path_exist(path, h5py_obj) -> bool:
     """Returns true if the requested path exists in the given h5py object."""
@@ -260,7 +260,20 @@ def _put_data_into_hdf5(self):
         def add_units_key(dataset, path):
             units_key = f"{path}/@units"
             units = self.data.get(units_key, None)
-            units = str(units) if isinstance(units, pint.Unit) else units
+            if units is None:
+                return
+            if isinstance(units, pint.Unit):
+                units = str(units)
+            else:
+                try:
+                    ureg.Unit(units)
+                except pint.errors.UndefinedUnitError as exc:
+                    massage = (
+                        f"Units provided for path: '{path}@units' are not valid."
+                        f" Please provide a valid unit."
+                    )
+                    raise InvalidDictProvided(massage) from exc
+
             if units:
                 dataset.attrs["units"] = units