fix the unintentionally broken apply_ufunc tests

Author: keewis

xarray/tests/test_units.py

@@ -1,3 +1,4 @@
+import functools
 from itertools import zip_longest
 import operator
 import warnings
@@ -364,7 +365,7 @@ def __repr__(self):
 
 
 def test_apply_ufunc_dataarray(dtype):
-    func = function(
+    func = functools.partial(
         xr.apply_ufunc, np.mean, input_core_dims=[["x"]], kwargs={"axis": -1}
     )
 
@@ -379,7 +380,7 @@ def test_apply_ufunc_dataarray(dtype):
 
 
 def test_apply_ufunc_dataset(dtype):
-    func = function(
+    func = functools.partial(
         xr.apply_ufunc, np.mean, input_core_dims=[["x"]], kwargs={"axis": -1}
     )