Add more overflow tests for timedelta64 operations

pandas/_testing/__init__.py

@@ -4,6 +4,7 @@
 from datetime import datetime
 from decimal import Decimal
 from functools import wraps
+from inspect import isclass
 import operator
 import os
 import re
@@ -245,19 +246,21 @@ def box_expected(expected, box_cls, transpose=True):
     Parameters
     ----------
     expected : np.ndarray, Index, Series
-    box_cls : {Index, Series, DataFrame}
+    box_cls : {Index, Series, DataFrame, pd.array, ExtensionArray}
 
     Returns
     -------
     subclass of box_cls
     """
-    if box_cls is pd.array:
+    if box_cls is pd.array or (
+        isclass(box_cls) and issubclass(box_cls, ExtensionArray)
+    ):
         if isinstance(expected, RangeIndex):
             # pd.array would return an IntegerArray
             expected = PandasArray(np.asarray(expected._values))
         else:
             expected = pd.array(expected)
-    elif box_cls is Index:
+    elif isclass(box_cls) and issubclass(box_cls, Index):
         expected = Index._with_infer(expected)
     elif box_cls is Series:
         expected = Series(expected)