Merge pull request #634 from ryanpetrello/fix-633

require UTC for UNTIL when DTSTART is timezone-aware

2 files changed, 29 insertions, 0 deletions

diff --git a/dateutil/rrule.py b/dateutil/rrule.py
index 6d6adb1..ef4607a 100644
--- a/dateutil/rrule.py
+++ b/dateutil/rrule.py
@@ -21,6 +21,7 @@ from six.moves import _thread, range
 import heapq
 
 from ._common import weekday as weekdaybase
+from .tz import tzutc, tzlocal
 
 # For warning about deprecation of until and count
 from warnings import warn
@@ -447,6 +448,20 @@ class rrule(rrulebase):
             until = datetime.datetime.fromordinal(until.toordinal())
         self._until = until
 
+        if self._dtstart and self._until:
+            if (self._dtstart.tzinfo is not None) != (self._until.tzinfo is not None):
+                # According to RFC5545 Section 3.3.10:
+                # https://tools.ietf.org/html/rfc5545#section-3.3.10
+                #
+                # > If the "DTSTART" property is specified as a date with UTC
+                # > time or a date with local time and time zone reference,
+                # > then the UNTIL rule part MUST be specified as a date with
+                # > UTC time.
+                raise ValueError(
+                    'RRULE UNTIL values must be specified in UTC when DTSTART '
+                    'is timezone-aware'
+                )
+
         if count is not None and until:
             warn("Using both 'count' and 'until' is inconsistent with RFC 5545"
                  " and has been deprecated in dateutil. Future versions will "
diff --git a/dateutil/test/test_rrule.py b/dateutil/test/test_rrule.py
index 57ec9b3..9ac948d 100644
--- a/dateutil/test/test_rrule.py
+++ b/dateutil/test/test_rrule.py
@@ -2930,6 +2930,20 @@ class RRuleTest(WarningTestMixin, unittest.TestCase):
                           "RRULE:FREQ=YEARLY;"
                           "UNTIL=TheCowsComeHome;BYDAY=1TU,-1TH\n"))
 
+    def testStrUntilMustBeUTC(self):
+        with self.assertRaises(ValueError):
+            list(rrulestr("DTSTART;TZID=America/New_York:19970902T090000\n"
+                          "RRULE:FREQ=YEARLY;"
+                          "UNTIL=19990101T000000;BYDAY=1TU,-1TH\n"))
+
+    def testStrUntilWithTZ(self):
+        NYC = tz.gettz('America/New_York')
+        rr = list(rrulestr("DTSTART;TZID=America/New_York:19970101T000000\n"
+                          "RRULE:FREQ=YEARLY;"
+                          "UNTIL=19990101T000000Z\n"))
+        self.assertEqual(list(rr), [datetime(1997, 1, 1, 0, 0, 0, tzinfo=NYC),
+                                    datetime(1998, 1, 1, 0, 0, 0, tzinfo=NYC)])
+
     def testStrEmptyByDay(self):
         with self.assertRaises(ValueError):
             list(rrulestr("DTSTART:19970902T090000\n"