fix datetime util using 3.11 features

bentsku · bentsku · commit 0d8f406ec9d1 · 2025-09-19T11:37:03.000+02:00
diff --git a/localstack-core/localstack/utils/time.py b/localstack-core/localstack/utils/time.py
@@ -1,6 +1,7 @@
 import time
-from datetime import UTC, date, datetime, timezone, tzinfo
+from datetime import date, datetime, timezone, tzinfo
 from typing import Optional
+from zoneinfo import ZoneInfo
 
 TIMESTAMP_FORMAT = "%Y-%m-%dT%H:%M:%S"
 TIMESTAMP_FORMAT_TZ = "%Y-%m-%dT%H:%M:%SZ"
@@ -56,7 +57,7 @@ def parse_timestamp(ts_str: str) -> datetime:
         try:
             value = datetime.strptime(ts_str, ts_format)
             if value.tzinfo is None:
-                value = value.replace(tzinfo=UTC)
+                value = value.replace(tzinfo=ZoneInfo("UTC"))
             return value
         except ValueError:
             pass
diff --git a/tests/unit/test_common.py b/tests/unit/test_common.py
@@ -5,7 +5,7 @@
 import threading
 import time
 import zipfile
-from datetime import UTC, date, datetime
+from datetime import UTC, date, datetime, timedelta
 from zoneinfo import ZoneInfo
 
 import pytest
@@ -57,7 +57,11 @@ def test_isoformat_milliseconds(self):
     )
     def test_parse_timestamp_timezone_aware(self, str_format):
         datetime_obj = common.parse_timestamp(str_format)
-        assert datetime_obj.tzinfo == UTC
+        # we cannot assert that tzinfo is `datetime.UTC` because it is only supported starting Python 3.11
+        # so we assert manually that the returned `tzinfo` is UTC
+        # we are using ZoneInfo("UTC")  in the `parse_timestamp` utility as it is in the import path of the CLI
+        assert datetime_obj.tzinfo is not None
+        assert datetime_obj.utcoffset() == timedelta(0)
 
     def test_base64_to_hex(self):
         env = common.base64_to_hex("Zm9vIGJhcg ==")
