Fix: Support events without end

According to RFC5545, an event may have no DTEND nor DURATION property. Set end = start in that case.

icalevents/icalparser.py

@@ -97,8 +97,6 @@ class Event:
         :param uid: UID of new event
         :return: new event
         """
-        duration = self.end - self.start
-
         if not new_start:
             new_start = self.start
 
@@ -109,7 +107,11 @@ class Event:
         ne.summary = self.summary
         ne.description = self.description
         ne.start = new_start
+        
+        if self.end:
+            duration = self.end - self.start
             ne.end = (new_start + duration)
+
         ne.all_day = (self.all_day and (new_start - self.start).seconds == 0)
         ne.uid = uid
 
@@ -131,10 +133,10 @@ def create_event(component, tz=UTC):
     
     if component.get('dtend'):
         event.end = normalize(component.get('dtend').dt, tz=tz)
-    elif component.get('duration'):
+    elif component.get('duration'): # compute implicit end as start + duration
         event.end = event.start + component.get('duration').dt
-    else:
-        raise ValueError("Event has neither end, nor duration property.")
+    else: # compute implicit end as start + 0
+        event.end = event.start
     
     event.summary = str(component.get('summary'))
     event.description = str(component.get('description'))

test/test_data/duration.ics

@@ -6,9 +6,14 @@ DESCRIPTION:Event with duration (1 day), instead of explicit end.
 SUMMARY:Duration Event
 END:VEVENT
 BEGIN:VEVENT
-DTSTART:20180120T100000
+DTSTART:20180115T100000
 DURATION:PT1H
 DESCRIPTION:Event with duration (1 hour), instead of explicit end.
 SUMMARY:Duration Event
 END:VEVENT
+BEGIN:VEVENT
+DTSTART:20180120T120000
+DESCRIPTION:Event without explicit dtend, nor duration property.
+SUMMARY:Short event
+END:VEVENT
 END:VCALENDAR

test/test_icalevents.py

@@ -46,6 +46,10 @@ class ICalEventsTests(unittest.TestCase):
         self.assertEqual(e2.start.hour, 10, "explicit event start")
         self.assertEqual(e2.end.hour, 11, "implicit event end")
 
+        e3 = evs[2]
+        self.assertEqual(e3.start.hour, 12, "explicit event start")
+        self.assertEqual(e3.end.hour, 12, "implicit event end")
+        
     def test_events_recurring(self):
         ical = "test/test_data/recurring.ics"
         start = date(2018, 10, 15)