core: fix DatetimeBlock operated with timedelta

Author: holymonson

doc/source/whatsnew/v0.24.0.txt

@@ -440,7 +440,7 @@ Datetimelike
 Timedelta
 ^^^^^^^^^
 
--
+- Bug in :class:`DataFrame` with ``dtype='datetime64[ns]'`` when adding :class:`Timedelta` (:issue:`22007`)
 -
 -
 

pandas/core/internals/__init__.py

@@ -2725,6 +2725,11 @@ def _try_coerce_args(self, values, other):
                                 "naive Block")
             other_mask = isna(other)
             other = other.asm8.view('i8')
+        elif isinstance(other, (Timedelta, timedelta, np.timedelta64)):
+            # should be the same as TimeDeltaBlock._box_func
+            other = Timedelta(other, unit='ns')
+            other_mask = isna(other)
+            other = other.asm8.view('i8')
         elif hasattr(other, 'dtype') and is_datetime64_dtype(other):
             other_mask = isna(other)
             other = other.astype('i8', copy=False).view('i8')

pandas/tests/frame/test_arithmetic.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+import datetime
+
 import pytest
 import numpy as np
 
@@ -211,6 +213,16 @@ def test_df_sub_datetime64_not_ns(self):
                                  pd.Timedelta(days=2)])
         tm.assert_frame_equal(res, expected)
 
+    @pytest.mark.parametrize('other', [
+        pd.Timedelta('1d'),
+        datetime.timedelta(days=1),
+        np.timedelta64(1, 'D')
+    ])
+    def test_timestamp_df_add_timedelta(self, other):
+        expected = pd.DataFrame([pd.Timestamp('2018-01-02')])
+        result = pd.DataFrame([pd.Timestamp('2018-01-01')]) + other
+        tm.assert_frame_equal(result, expected)
+
     @pytest.mark.parametrize('data', [
         [1, 2, 3],
         [1.1, 2.2, 3.3],