proper passing of keyword args for deep copy, other test fixes

Author: espg

xarray/core/datatree.py

@@ -897,7 +897,7 @@ def encoding(self, value: Mapping) -> None:
         self._encoding = dict(value)
 
     @property
-    def dims(self) -> Mapping[Hashable, int]:
+    def dims(self) -> Frozen[Hashable, int]:
         """Mapping from dimension names to lengths.
 
         Cannot be modified directly, but is updated when adding new variables.

xarray/core/types.py

@@ -149,6 +149,7 @@ def __iter__(self) -> Iterator[Hashable]: ...
 
     def copy(
         self,
+        *,
         deep: bool = False,
     ) -> Self: ...
 

xarray/tests/test_datatree.py

@@ -2907,7 +2907,7 @@ def test_align_mixed_types_raises(self) -> None:
         ds = Dataset(coords={"x": [0, 1]})
 
         with pytest.raises(TypeError, match="Cannot align DataTree"):
-            xr.align(tree, ds)  # type: ignore[arg-type]
+            xr.align(tree, ds)
 
     def test_align_already_aligned(self) -> None:
         tree1 = DataTree.from_dict(