copy test from pandas-dev#36582

Author: simonjayhawkins

pandas/tests/arithmetic/test_timedelta64.py

@@ -2137,7 +2137,19 @@ def test_td64arr_pow_invalid(self, scalar_td, box_with_array):
         with pytest.raises(TypeError, match=pattern):
             td1 ** scalar_td
 
-    def test_add_timestamp_to_timedelta(self):
-        # https://github.com/pandas-dev/pandas/issues/35897
-        result = Timestamp.now() + timedelta_range("0s", "1s", periods=31)
-        assert result.freq is None
+
+def test_add_timestamp_to_timedelta():
+    # GH: 35897
+    timestamp = pd.Timestamp.now()
+    result = timestamp + pd.timedelta_range("0s", "1s", periods=31)
+    expected = pd.DatetimeIndex(
+        [
+            timestamp
+            + (
+                pd.to_timedelta("0.033333333s") * i
+                + pd.to_timedelta("0.000000001s") * divmod(i, 3)[0]
+            )
+            for i in range(31)
+        ]
+    )
+    tm.assert_index_equal(result, expected)