make sure the .get_duration altgorithm accepts dates vs time in due/d…

…tstart

CHANGELOG.md

@@ -17,6 +17,7 @@ This project should more or less adhere to [Semantic Versioning](https://semver.
 
 ### Fixed
 
+* `get_duration`: make sure the algorithm doesn't raise an exception comparing dates with timestamps
 * `set_due`: make sure the algorithm doesn't raise an exception comparing naive timestamps with timezone timestamps
 * Code formatting / style fixes.
 * Search method did some logic handling non-conformant servers (loading data from the server if the search response didn't include the icalendar data, ignoring trash from the Google server when it returns data without a VTODO/VEVENT/VJOURNAL component.

caldav/objects.py

@@ -2662,7 +2662,7 @@ def get_duration(self) -> timedelta:
 
         WARNING: this method is likely to be deprecated and moved to
         the icalendar library.  If you decide to use it, please put
-        caldav<2.0 in the requirements.
+        caldav<3.0 in the requirements.
         """
         i = self.icalendar_component
         return self._get_duration(i)
@@ -2671,11 +2671,15 @@ def _get_duration(self, i):
         if "DURATION" in i:
             return i["DURATION"].dt
         elif "DTSTART" in i and self._ENDPARAM in i:
-            ## if we get an exception here it may be that one of the
-            ## timestamps is a date and the other is a datetime.
-            ## This is a breach of the standard.
-            ## We may want to implement a workaround in lib.vcal.fix
-            return i[self._ENDPARAM].dt - i["DTSTART"].dt
+            end = i[self._ENDPARAM].dt
+            start = i["DTSTART"].dt
+            ## We do have a problem here if one is a date and the other is a
+            ## datetime.  This is NOT explicitly defined as a technical
+            ## breach in the RFC, so we need to work around it.
+            if isinstance(end, datetime) != isinstance(start, datetime):
+                start = datetime(start.year, start.month, start.day)
+                end = datetime(end.year, end.month, end.day)
+            return end - start
         elif "DTSTART" in i and not isinstance(i["DTSTART"], datetime):
             return timedelta(days=1)
         else: