bpo-29097: Forego fold detection on windows for low timestamp values (GH-2385)
On Windows, passing a negative value to local results in an OSError because localtime_s on Windows does not support negative timestamps. Unfortunately this means that fold detection for timestamps between 0 and max_fold_seconds will result in this OSError since we subtract max_fold_seconds from the timestamp to detect a fold. However, since we know there haven't been any folds in the interval [0, max_fold_seconds) in any timezone, we can hackily just forego fold detection for this time range on Windows.
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 7d4cdac..f647a23 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -70,7 +70,7 @@
if not name.startswith('__') and not name.endswith('__'))
allowed = set(['MAXYEAR', 'MINYEAR', 'date', 'datetime',
'datetime_CAPI', 'time', 'timedelta', 'timezone',
- 'tzinfo'])
+ 'tzinfo', 'sys'])
self.assertEqual(names - allowed, set([]))
def test_divide_and_round(self):
@@ -4955,6 +4955,11 @@
self.assertEqual(t0.fold, 0)
self.assertEqual(t1.fold, 1)
+ def test_fromtimestamp_low_fold_detection(self):
+ # Ensure that fold detection doesn't cause an
+ # OSError for really low values, see bpo-29097
+ self.assertEqual(datetime.fromtimestamp(0).fold, 0)
+
@support.run_with_tz('EST+05EDT,M3.2.0,M11.1.0')
def test_timestamp(self):
dt0 = datetime(2014, 11, 2, 1, 30)