fix(jmap): guard create_event against malformed server response; preserve RELATED=END in alarm round-trip

Author: SashankBhamidi

caldav/jmap/async_client.py

@@ -175,6 +175,11 @@ async def create_event(self, calendar_id: str, ical_str: str) -> str:
                 created, _, _, not_created, _, _ = parse_event_set(resp_args)
                 if "new-0" in not_created:
                     self._raise_set_error(session, not_created["new-0"])
+                if "new-0" not in created:
+                    raise JMAPMethodError(
+                        url=session.api_url,
+                        reason="CalendarEvent/set response missing created entry for new-0",
+                    )
                 return created["new-0"]["id"]
 
         raise JMAPMethodError(url=session.api_url, reason="No CalendarEvent/set response")

caldav/jmap/client.py

@@ -254,6 +254,11 @@ def create_event(self, calendar_id: str, ical_str: str) -> str:
                 created, _, _, not_created, _, _ = parse_event_set(resp_args)
                 if "new-0" in not_created:
                     self._raise_set_error(session, not_created["new-0"])
+                if "new-0" not in created:
+                    raise JMAPMethodError(
+                        url=session.api_url,
+                        reason="CalendarEvent/set response missing created entry for new-0",
+                    )
                 return created["new-0"]["id"]
 
         raise JMAPMethodError(url=session.api_url, reason="No CalendarEvent/set response")

caldav/jmap/convert/ical_to_jscal.py

@@ -230,6 +230,8 @@ def _valarm_to_alert(alarm) -> tuple[str, dict]:
         if isinstance(trigger_val, timedelta):
             # Relative trigger — convert to SignedDuration string
             alert["trigger"] = _timedelta_to_duration(trigger_val)
+            if str(trigger_prop.params.get("RELATED", "START")).upper() == "END":
+                alert["relativeTo"] = "end"
         elif isinstance(trigger_val, datetime):
             # Absolute trigger — UTCDateTime string
             alert["trigger"] = trigger_val.strftime("%Y-%m-%dT%H:%M:%SZ")

caldav/jmap/convert/jscal_to_ical.py

@@ -243,7 +243,10 @@ def _alert_to_valarm(alert: dict) -> icalendar.Alarm:
         else:
             try:
                 td = _duration_to_timedelta(trigger_str)
-                alarm.add("trigger", td)
+                trigger = icalendar.vDuration(td)
+                if alert.get("relativeTo") == "end":
+                    trigger.params["RELATED"] = "END"
+                alarm.add("trigger", trigger)
             except ValueError:
                 alarm.add("trigger", timedelta(0))
     else:

tests/test_jmap_unit.py

@@ -1172,6 +1172,20 @@ def test_valarm_absolute(self):
         alert = next(iter(result["alerts"].values()))
         assert alert["trigger"].endswith("Z")
 
+    def test_valarm_related_end(self):
+        ical = _make_ical(
+            "DTSTART:20240615T100000Z\r\n"
+            "SUMMARY:End Alarm Event\r\n"
+            "BEGIN:VALARM\r\n"
+            "ACTION:DISPLAY\r\n"
+            "TRIGGER;RELATED=END:-PT5M\r\n"
+            "END:VALARM\r\n"
+        )
+        result = ical_to_jscal(ical)
+        alert = next(iter(result["alerts"].values()))
+        assert alert["trigger"] == "-PT5M"
+        assert alert.get("relativeTo") == "end"
+
     def test_organizer_attendee(self):
         ical = _make_ical(
             "DTSTART:20240615T100000Z\r\n"
@@ -1367,6 +1381,14 @@ def test_alert_relative(self):
         assert "BEGIN:VALARM" in result
         assert "TRIGGER:-PT15M" in result
 
+    def test_alert_related_end(self):
+        jscal = _minimal_jscal(
+            alerts={"al1": {"trigger": "-PT5M", "action": "display", "relativeTo": "end"}}
+        )
+        result = jscal_to_ical(jscal)
+        assert "RELATED=END" in result
+        assert "-PT5M" in result
+
     def test_participants_organizer(self):
         jscal = _minimal_jscal(
             participants={
@@ -1542,6 +1564,12 @@ def test_create_event_raises_on_failure(self, monkeypatch):
             client.create_event("cal1", self._MINIMAL_ICAL)
         assert exc_info.value.error_type == "invalidArguments"
 
+    def test_create_event_raises_on_malformed_response(self, monkeypatch):
+        resp = self._set_response(created={}, notCreated={})
+        client = _make_client_with_mocked_session(monkeypatch, resp)
+        with pytest.raises(JMAPMethodError):
+            client.create_event("cal1", self._MINIMAL_ICAL)
+
     def test_create_event_passes_calendar_id(self, monkeypatch):
         resp = self._set_response(created={"new-0": {"id": "sv-2"}})
         client, captured = self._capturing_client(monkeypatch, resp)