Add standardize keyword also to dummydatastore in tests

tests/dummy_datastore.py

@@ -301,7 +301,7 @@ def get_standardization_dataarray(self, category: str) -> xr.Dataset:
         return ds_standardization
 
     def get_dataarray(
-        self, category: str, split: str
+        self, category: str, split: str, standardize: bool = False
     ) -> Union[xr.DataArray, None]:
         """
         Return the processed data (as a single `xr.DataArray`) for the given
@@ -340,7 +340,13 @@ def get_dataarray(
 
         """
         dim_order = self.expected_dim_order(category=category)
-        return self.ds[category].transpose(*dim_order)
+
+        da_category = self.ds[category].transpose(*dim_order)
+
+        if standardize:
+            return self._standardize_datarray(da_category, category=category)
+
+        return da_category
 
     @cached_property
     def boundary_mask(self) -> xr.DataArray: