check of recurrence id is present

- fixes #15

recurring_ical_events.py

@@ -286,12 +286,15 @@ def between(self, start, stop): # TODO: add parameters from time_span_contains_e
         def add_event(event):
             """Add an event and check if it was edited."""
             same_events = events_by_id[event.get("UID", default_uid)] # TODO: test what comes first
-            recurrence_id = event.get("RECURRENCE-ID", event["DTSTART"]).dt
+            recurrence_id = event.get("RECURRENCE-ID", event["DTSTART"]).dt # TODO: this is still wrong: what if there are different events at the same time?
             other = same_events.get(recurrence_id, None)
             if other: # TODO: test that this is independet of order
-                if event["SEQUENCE"] < other["SEQUENCE"]:
-                    return
-                events.remove(other)
+                event_sequence = event.get("SEQUENCE", None)
+                other_sequence = other.get("SEQUENCE", None)
+                if event_sequence is not None and other_sequence is not None:
+                    if event["SEQUENCE"] < other["SEQUENCE"]:
+                        return
+                    events.remove(other)
             same_events[recurrence_id] = event
             events.append(event)
 

test/test_issue_15.py

@@ -20,5 +20,5 @@ def test_rdate_does_not_double_rrule_entry(calendars):
 
 def test_sequence_is_not_present(calendars):
     events = calendars.issue_15_duplicated_events.at("20130803")
-    assert len(events) == 1
+    assert len(events) == 3