Added test for a bug fixed in issue #665194.

Lib/test/test_email/test_utils.py

@@ -3,6 +3,7 @@ from email import utils
 import test.support
 import time
 import unittest
+import sys
 
 class DateTimeTests(unittest.TestCase):
 
@@ -119,6 +120,17 @@ class LocaltimeTests(unittest.TestCase):
         t2 = utils.localtime(t0.replace(tzinfo=None))
         self.assertEqual(t1, t2)
 
+    # XXX: Need a more robust test for Olson's tzdata
+    @unittest.skipIf(sys.platform.startswith('win'),
+                     "Windows does not use Olson's TZ database")
+    @test.support.run_with_tz('Europe/Kiev')
+    def test_variable_tzname(self):
+        t0 = datetime.datetime(1984, 1, 1, tzinfo=datetime.timezone.utc)
+        t1 = utils.localtime(t0)
+        self.assertEqual(t1.tzname(), 'MSK')
+        t0 = datetime.datetime(1994, 1, 1, tzinfo=datetime.timezone.utc)
+        t1 = utils.localtime(t0)
+        self.assertEqual(t1.tzname(), 'EET')
 
 if __name__ == '__main__':
     unittest.main()