ruff: Fix DTZ001 datetime.datetime() without tzinfo argument.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/lib/export.py

@@ -30,7 +30,6 @@ from scripts.lib.zulip_tools import overwrite_symlink
 from zerver.lib.avatar_hash import user_avatar_path_from_ids
 from zerver.lib.pysa import mark_sanitized
 from zerver.lib.upload import get_bucket
-from zerver.lib.utils import assert_is_not_none
 from zerver.models import (
     AlertWord,
     Attachment,
@@ -434,8 +433,7 @@ def floatify_datetime_fields(data: TableData, table: TableName) -> None:
                 continue
             assert isinstance(dt, datetime.datetime)
             assert not timezone_is_naive(dt)
-            utc_naive = dt.replace(tzinfo=None) - assert_is_not_none(dt.utcoffset())
-            item[field] = (utc_naive - datetime.datetime(1970, 1, 1)).total_seconds()
+            item[field] = dt.timestamp()
 
 
 def listify_bithandler_fields(data: TableData, table: TableName) -> None:

zerver/tests/test_timezone.py

@@ -1,5 +1,5 @@
 import sys
-from datetime import datetime
+from datetime import datetime, timezone
 
 from django.utils.timezone import now as timezone_now
 
@@ -35,7 +35,10 @@ class TimeZoneTest(ZulipTestCase):
         assert not missing, missing
 
         now = timezone_now()
-        dates = [datetime(now.year, 6, 21), datetime(now.year, 12, 21)]
+        dates = [
+            datetime(now.year, 6, 21, tzinfo=timezone.utc),
+            datetime(now.year, 12, 21, tzinfo=timezone.utc),
+        ]
         extra = {*common_timezones.items(), *ambiguous_abbrevs}
         for name in zoneinfo.available_timezones():
             tz = zoneinfo.ZoneInfo(name)