From d8f1043f3d87a098d1f8042f4ac4cbc4fae57e1b Mon Sep 17 00:00:00 2001 From: zhan7236 <76658920+zhan7236@users.noreply.github.com> Date: Fri, 28 Nov 2025 01:49:22 +0000 Subject: [PATCH] TST: Add regression test for DatetimeIndex.union across DST boundary (#62915) --- pandas/tests/indexes/datetimes/test_setops.py | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/pandas/tests/indexes/datetimes/test_setops.py b/pandas/tests/indexes/datetimes/test_setops.py index 7a68cb867c94e..d6ca4610d1044 100644 --- a/pandas/tests/indexes/datetimes/test_setops.py +++ b/pandas/tests/indexes/datetimes/test_setops.py @@ -757,3 +757,13 @@ def test_intersection_non_nano_rangelike(): freq="D", ) tm.assert_index_equal(result, expected) + + +def test_union_across_dst_boundary(): + # GH#62915 union should work when one index ends at DST boundary + # and the other extends past it + index1 = date_range("2025-10-25", "2025-10-26", freq="D", tz="Europe/Helsinki") + index2 = date_range("2025-10-25", "2025-10-28", freq="D", tz="Europe/Helsinki") + result = index1.union(index2) + expected = date_range("2025-10-25", "2025-10-28", freq="D", tz="Europe/Helsinki") + tm.assert_index_equal(result, expected)