TST: GH 27185 Test to check df with timedelta & Int NA sums correctly (#47354)

* TST: GH 27185 Adding test to check df with timedelta and int obj sums as expected

* TST: updating the test with nan NaT and check whole object

Author: aamnv

pandas/tests/reductions/test_reductions.py

@@ -198,6 +198,18 @@ def test_numpy_reduction_with_tz_aware_dtype(self, tz_aware_fixture, func):
         result = getattr(np, func)(expected, expected)
         tm.assert_series_equal(result, expected)
 
+    def test_nan_int_timedelta_sum(self):
+        # GH 27185
+        df = DataFrame(
+            {
+                "A": Series([1, 2, NaT], dtype="timedelta64[ns]"),
+                "B": Series([1, 2, np.nan], dtype="Int64"),
+            }
+        )
+        expected = Series({"A": Timedelta(3), "B": 3})
+        result = df.sum()
+        tm.assert_series_equal(result, expected)
+
 
 class TestIndexReductions:
     # Note: the name TestIndexReductions indicates these tests