handling timezone. We assume any timezone naive datetime is in UTC.

Author: seperman

deepdiff/diff.py

@@ -8,6 +8,7 @@
 import difflib
 import logging
 import types
+import datetime
 from enum import Enum
 from copy import deepcopy
 from math import isclose as is_close
@@ -1487,7 +1488,15 @@ def _diff_numbers(self, level, local_tree=None, report_type_change=True):
             if t1_s != t2_s:
                 self._report_result('values_changed', level, local_tree=local_tree)
 
-    def _diff_datetimes(self, level, local_tree=None):
+    def _diff_datetime(self, level, local_tree=None):
+        """Diff DateTimes"""
+        level.t1 = datetime_normalize(self.truncate_datetime, level.t1)
+        level.t2 = datetime_normalize(self.truncate_datetime, level.t2)
+
+        if level.t1 != level.t2:
+            self._report_result('values_changed', level, local_tree=local_tree)
+
+    def _diff_time(self, level, local_tree=None):
         """Diff DateTimes"""
         if self.truncate_datetime:
             level.t1 = datetime_normalize(self.truncate_datetime, level.t1)
@@ -1670,8 +1679,11 @@ def _diff(self, level, parents_ids=frozenset(), _original_type=None, local_tree=
         elif isinstance(level.t1, strings):
             self._diff_str(level, local_tree=local_tree)
 
-        elif isinstance(level.t1, datetimes):
-            self._diff_datetimes(level, local_tree=local_tree)
+        elif isinstance(level.t1, datetime.datetime):
+            self._diff_datetime(level, local_tree=local_tree)
+
+        elif isinstance(level.t1, (datetime.date, datetime.timedelta, datetime.time)):
+            self._diff_time(level, local_tree=local_tree)
 
         elif isinstance(level.t1, uuids):
             self._diff_uuids(level, local_tree=local_tree)

deepdiff/helper.py

@@ -623,12 +623,29 @@ def datetime_normalize(truncate_datetime, obj):
         elif truncate_datetime == 'day':
             obj = obj.replace(hour=0, minute=0, second=0, microsecond=0)
     if isinstance(obj, datetime.datetime):
-        obj = obj.replace(tzinfo=datetime.timezone.utc)
+        if has_timezone(obj):
+            obj = obj.astimezone(datetime.timezone.utc)
+        else:
+            obj = obj.replace(tzinfo=datetime.timezone.utc)
     elif isinstance(obj, datetime.time):
         obj = time_to_seconds(obj)
     return obj
 
 
+def has_timezone(dt):
+    """
+    Function to check if a datetime object has a timezone
+
+    Checking dt.tzinfo.utcoffset(dt) ensures that the datetime object is truly timezone-aware
+    because some datetime objects may have a tzinfo attribute that is not None but still
+    doesn't provide a valid offset.
+
+    Certain tzinfo objects, such as pytz.timezone(None), can exist but do not provide meaningful UTC offset information.
+    If tzinfo is present but calling .utcoffset(dt) returns None, the datetime is not truly timezone-aware.
+    """
+    return dt.tzinfo is not None and dt.tzinfo.utcoffset(dt) is not None
+
+
 def get_truncate_datetime(truncate_datetime):
     """
     Validates truncate_datetime value

tests/test_diff_datetime.py

@@ -1,4 +1,5 @@
-from datetime import date, datetime, time
+import pytz
+from datetime import date, datetime, time, timezone
 from deepdiff import DeepDiff
 
 
@@ -19,8 +20,8 @@ def test_datetime_diff(self):
         expected = {
             "values_changed": {
                 "root['a']": {
-                    "new_value": datetime(2023, 7, 5, 11, 11, 12),
-                    "old_value": datetime(2023, 7, 5, 10, 11, 12),
+                    "new_value": datetime(2023, 7, 5, 11, 11, 12, tzinfo=timezone.utc),
+                    "old_value": datetime(2023, 7, 5, 10, 11, 12, tzinfo=timezone.utc),
                 }
             }
         }
@@ -73,3 +74,27 @@ def test_time_diff(self):
             }
         }
         assert res == expected
+
+    def test_diffs_datetimes_different_timezones(self):
+        dt_utc = datetime(2025, 2, 3, 12, 0, 0, tzinfo=pytz.utc)  # UTC timezone
+        # Convert it to another timezone (e.g., New York)
+        dt_ny = dt_utc.astimezone(pytz.timezone('America/New_York'))
+        assert dt_utc == dt_ny
+        diff = DeepDiff(dt_utc, dt_ny)
+        assert not diff
+
+        t1 = [dt_utc, dt_ny]
+        t2 = [dt_ny, dt_utc]
+        assert not DeepDiff(t1, t2)
+        assert not DeepDiff(t1, t2, ignore_order=True)
+
+        t2 = [dt_ny, dt_utc, dt_ny]
+        assert not DeepDiff(t1, t2, ignore_order=True)
+
+    def test_datetime_within_array_with_timezone_diff(self):
+        d1 = [datetime(2020, 8, 31, 13, 14, 1)]
+        d2 = [datetime(2020, 8, 31, 13, 14, 1, tzinfo=timezone.utc)]
+
+        assert not DeepDiff(d1, d2)
+        assert not DeepDiff(d1, d2, ignore_order=True)
+        assert not DeepDiff(d1, d2, truncate_datetime='second')

tests/test_diff_text.py

@@ -1446,7 +1446,8 @@ def test_ignore_type_in_groups_str_and_datetime(self):
         t1 = [1, 2, 3, 'a', now]
         t2 = [1, 2, 3, 'a', 'now']
         ddiff = DeepDiff(t1, t2, ignore_type_in_groups=[(str, bytes, datetime.datetime)])
-        result = {'values_changed': {'root[4]': {'new_value': 'now', 'old_value': now}}}
+        now_utc = now.replace(tzinfo=datetime.timezone.utc)
+        result = {'values_changed': {'root[4]': {'new_value': 'now', 'old_value': now_utc}}}
         assert result == ddiff
 
     def test_ignore_type_in_groups_float_vs_decimal(self):
@@ -2146,20 +2147,20 @@ def test_diffs_rrules(self):
         assert d == {
             "values_changed": {
                 "root[0]": {
-                    "new_value": datetime.datetime(2011, 12, 31, 0, 0),
-                    "old_value": datetime.datetime(2014, 12, 31, 0, 0),
+                    "new_value": datetime.datetime(2011, 12, 31, 0, 0, tzinfo=datetime.timezone.utc),
+                    "old_value": datetime.datetime(2014, 12, 31, 0, 0, tzinfo=datetime.timezone.utc),
                 },
                 "root[1]": {
-                    "new_value": datetime.datetime(2012, 1, 31, 0, 0),
-                    "old_value": datetime.datetime(2015, 1, 31, 0, 0),
+                    "new_value": datetime.datetime(2012, 1, 31, 0, 0, tzinfo=datetime.timezone.utc),
+                    "old_value": datetime.datetime(2015, 1, 31, 0, 0, tzinfo=datetime.timezone.utc),
                 },
                 "root[2]": {
-                    "new_value": datetime.datetime(2012, 3, 31, 0, 0),
-                    "old_value": datetime.datetime(2015, 3, 31, 0, 0),
+                    "new_value": datetime.datetime(2012, 3, 31, 0, 0, tzinfo=datetime.timezone.utc),
+                    "old_value": datetime.datetime(2015, 3, 31, 0, 0, tzinfo=datetime.timezone.utc),
                 },
                 "root[3]": {
-                    "new_value": datetime.datetime(2012, 5, 31, 0, 0),
-                    "old_value": datetime.datetime(2015, 5, 31, 0, 0),
+                    "new_value": datetime.datetime(2012, 5, 31, 0, 0, tzinfo=datetime.timezone.utc),
+                    "old_value": datetime.datetime(2015, 5, 31, 0, 0, tzinfo=datetime.timezone.utc),
                 },
             },
             "iterable_item_removed": {"root[4]": datetime.datetime(2015, 7, 31, 0, 0)},

tests/test_hash.py

@@ -1,9 +1,10 @@
 #!/usr/bin/env python
 import re
 import pytest
-from pathlib import Path
+import pytz
 import logging
 import datetime
+from pathlib import Path
 from collections import namedtuple
 from functools import partial
 from enum import Enum
@@ -896,6 +897,16 @@ def test_list1(self):
         result = DeepHash(obj, ignore_string_type_changes=True, hasher=DeepHash.sha1hex)
         assert expected_result == result
 
+    def test_datetime_hash(self):
+        dt_utc = datetime.datetime(2025, 2, 3, 12, 0, 0, tzinfo=pytz.utc)  # UTC timezone
+        # Convert it to another timezone (e.g., New York)
+        dt_ny = dt_utc.astimezone(pytz.timezone('America/New_York'))
+        assert dt_utc == dt_ny
+
+        result_utc = DeepHash(dt_utc, ignore_string_type_changes=True, hasher=DeepHash.sha1hex)
+        result_ny = DeepHash(dt_ny, ignore_string_type_changes=True, hasher=DeepHash.sha1hex)
+        assert result_utc[dt_utc] == result_ny[dt_ny]
+
     def test_dict1(self):
         string1 = "a"
         key1 = "key1"