fix: VTODO with only COMPLETED/CREATED

Doing time filtering on a VTODO with a COMPLETED, but no DTSTART, DUE,
or CREATED, things would crash.

This was discovered a bit ad-hoc while importing some slightly broken
icalendar data into a calendar, and Claude had a go on fixing it.

Also, I reread RFC4791 section 9.9 and had Claude reread it again, and
now I think all the corner cases are covered according to the RFC.

prompt: (work on some unrelated stuff and asking Claude to investigate the crash)
(I rewrote Clauds work completely)
prompt: tests are broken with my last changes, but please verify if the
correct thing is asserted. As I understand the relevant RFC-section, a
VTODO with CREATED set but no other time-related properties should match
if and only if the search interval covers the CREATED timestamp.
followup-prompt: and read through section 9.9 in the caldav RFC as well.
(claude concluded my new code was not in accordance with the RFC, the
pre-existing assert in the test code is in accordance with the RFC, and the
code section was rewritten for the second time)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tobixen

src/icalendar_searcher/filters.py

@@ -85,38 +85,47 @@ def _check_range(
                 ## problem for full-day events is at least simplified.
 
         elif comp_name == "VTODO":
-            ## There is a long matrix for VTODO in the RFC, and it
-            ## may seem complicated, but it isn't that bad:
+            ## There is a long matrix for VTODO in the RFC4701,
+            ## section 9.9, and it may seem complicated, but it isn't
+            ## that bad:
 
             ## * A task with DTSTART and DURATION is equivalent with a
             ##   task with DTSTART and DUE.  This complexity is
             ##   already handled by the icalendar library, so all rows
-            ##   in the matrix where VTODO has the DURATION property?"
-            ##   is Y may be removed.
+            ##   in the matrix where "VTODO has the DURATION property?"
+            ##   is "Y" may be removed.
             ##
-            ## * If either DUE or DTSTART is set, use it.
-            if comp_end and not comp_start:
-                comp_start = comp_end
-            if comp_start and not comp_end:
-                comp_end = comp_start
-
-            ## * If both created/completed is set and
-            ##   comp_start/comp_end is not set, then use those instead
-            if not comp_start:
+            ## * The matrix says that if NEITHER DTSTART, DUE nor DURATION
+            ##   is given, then CREATED and COMPLETED serve as the time bounds.
+            ##   When both are present, treat them as a [CREATED, COMPLETED] range.
+            ##   When only COMPLETED is present, treat it as a point event.
+            ##   When only CREATED is present, the RFC condition is just (end > CREATED)
+            ##   — the task is open-ended from CREATED onward, so comp_end = DATE_MAX_DT.
+            if not comp_start and not comp_end:
                 if "CREATED" in component:
                     comp_start = _normalize_dt(component["CREATED"].dt)
                 if "COMPLETED" in component:
                     comp_end = _normalize_dt(component["COMPLETED"].dt)
+                if comp_start and not comp_end:
+                    comp_end = _normalize_dt(DATE_MAX_DT)
+
+            ## * If only COMPLETED is given (no DTSTART/DUE/CREATED), treat as a point event
+            if comp_end and not comp_start:
+                comp_start = comp_end
+            ## * If only DTSTART is given (no DUE/DURATION), treat as a zero-duration event
+            if comp_start and not comp_end:
+                comp_end = comp_start
 
-            ## * A task may have a DUE before the DTSTART.  The
-            ##   complicated OR-logic in the table may be eliminated
+            ## * A task may have the end before the start.  The
+            ##   complicated OR-logic in the matrix may be eliminated
             ##   by swapping start/end if necessary:
             if comp_end and comp_start and comp_end < comp_start:
                 tmp = comp_start
                 comp_start = comp_end
                 comp_end = tmp
 
-            ## * A task with no timestamps is considered to be done "at any or all days".
+            ## * A task with no timestamps is considered to be done "at any or all days",
+            ##   and should always be found when doing a date search:
             if not comp_end and not comp_start:
                 comp_start = _normalize_dt(DATE_MIN_DT)
                 comp_end = _normalize_dt(DATE_MAX_DT)
@@ -159,7 +168,9 @@ def _check_completed_filter(
             pre-resolved value from check_component() to avoid mutating self.
         :return: True if the component should be included, False if it should be filtered out
         """
-        include_completed = _include_completed if _include_completed is not None else self.include_completed
+        include_completed = (
+            _include_completed if _include_completed is not None else self.include_completed
+        )
         if include_completed:
             return True
 

tests/test_check_component.py

@@ -179,3 +179,27 @@ def test_yule_tree2() -> None:
             searcher.add_property_filter(*prop_filter)
             assert not searcher._check_property_filters(cal.subcomponents[0])
             assert not searcher.check_component(cal)
+
+
+@pytest.mark.parametrize("rrule", [None, "RRULE:FREQ=DAILY\n"])
+def test_vtodo_no_dtstart_range_check(rrule: str | None) -> None:
+    """
+    A VTODO with no DTSTART/DUE/CREATED must not crash on a time-range search,
+    whether or not it has an RRULE.
+    """
+    rrule_line = rrule or ""
+    data = f"""BEGIN:VCALENDAR
+VERSION:2.0
+BEGIN:VTODO
+COMPLETED:20231001T105204Z
+DTSTAMP:20231001T124832Z
+{rrule_line}STATUS:COMPLETED
+SUMMARY:g\xe5 tur
+UID:d432d0a2-6058-11ee-97c8-982cbcdd642c
+END:VTODO
+END:VCALENDAR"""
+    cal = Calendar.from_ical(data)
+    end = datetime(2026, 5, 28, 0, 0, 0)
+    searcher = Searcher(todo=True, end=end, include_completed=True)
+    result = searcher.check_component(cal)
+    assert bool(result)