timeutils: fix newer/older comparison with TZ aware datetime

Blindly replacing the timezone information from a timestamp does not
make it correctly UTC. It just strips information away, and therefore
does not make any valid comparison.

This fixes the comparison function by normalizing the timestamps to UTC
before doing any comparison.

Change-Id: I3a1b1eae497200ca951ccb003dbcc75fb75380fa

oslo_utils/tests/test_timeutils.py

@@ -112,6 +112,11 @@ def test_is_older_than_aware(self):
         self._test_is_older_than(lambda x: x.replace(
             tzinfo=iso8601.iso8601.UTC))
 
+    def test_is_older_than_aware_no_utc(self):
+        self._test_is_older_than(lambda x: x.replace(
+            tzinfo=iso8601.iso8601.FixedOffset(1, 0, 'foo')).replace(
+                hour=7))
+
     def _test_is_newer_than(self, fn):
         strptime = datetime.datetime.strptime
         with mock.patch('datetime.datetime') as datetime_mock:
@@ -138,6 +143,11 @@ def test_is_newer_than_aware(self):
         self._test_is_newer_than(lambda x: x.replace(
             tzinfo=iso8601.iso8601.UTC))
 
+    def test_is_newer_than_aware_no_utc(self):
+        self._test_is_newer_than(lambda x: x.replace(
+            tzinfo=iso8601.iso8601.FixedOffset(1, 0, 'foo')).replace(
+                hour=7))
+
     def test_set_time_override_using_default(self):
         now = timeutils.utcnow_ts()
 

oslo_utils/timeutils.py

@@ -119,19 +119,19 @@ def normalize_time(timestamp):
 def is_older_than(before, seconds):
     """Return True if before is older than seconds."""
     if isinstance(before, six.string_types):
-        before = parse_isotime(before).replace(tzinfo=None)
-    else:
-        before = before.replace(tzinfo=None)
+        before = parse_isotime(before)
+
+    before = normalize_time(before)
 
     return utcnow() - before > datetime.timedelta(seconds=seconds)
 
 
 def is_newer_than(after, seconds):
     """Return True if after is newer than seconds."""
     if isinstance(after, six.string_types):
-        after = parse_isotime(after).replace(tzinfo=None)
-    else:
-        after = after.replace(tzinfo=None)
+        after = parse_isotime(after)
+
+    after = normalize_time(after)
 
     return after - utcnow() > datetime.timedelta(seconds=seconds)