Update test coverage for start validation and improve types

ical/list.py

@@ -17,12 +17,12 @@
     RecurIterable,
     SortableItem,
     SortableItemValue,
-    SortedItemIterable,
 )
 from .types.recur import RecurrenceId
 
 
 _LOGGER = logging.getLogger(__name__)
+_SortableTodoItem = SortableItem[datetime.datetime | datetime.date | None, Todo]
 
 
 class RecurAdapter:
@@ -41,9 +41,7 @@ def __init__(self, todo: Todo, tzinfo: datetime.tzinfo | None = None):
         self._duration = todo.computed_duration
         self._tzinfo = tzinfo
 
-    def get(
-        self, dtstart: datetime.datetime | datetime.date
-    ) -> SortableItem[datetime.datetime | datetime.date | None, Todo]:
+    def get(self, dtstart: datetime.datetime | datetime.date) -> _SortableTodoItem:
         """Return a lazy sortable item."""
 
         recur_id_dt = dtstart
@@ -87,20 +85,18 @@ def _pick_todo(todos: list[Todo], tzinfo: datetime.tzinfo) -> Todo:
     next todo that is incomplete and has the latest due date.
     """
     # For a recurring todo, the dtstart is after the last due date. Therefore
-    # we can stort items by dtstart and pick the last one that hasn't happened    
-    iters = []
+    # we can stort items by dtstart and pick the last one that hasn't happened
+    iters: list[Iterable[_SortableTodoItem]] = []
     for todo in todos:
         if not (recur := todo.as_rrule()):
             iters.append([SortableItemValue(todo.dtstart, todo)])
             continue
         iters.append(RecurIterable(RecurAdapter(todo, tzinfo=tzinfo).get, recur))
 
     root_iter = MergedIterable(iters)
-    
+
     # Pick the first todo that hasn't started yet based on its dtstart
     now = datetime.datetime.now(tzinfo)
-    last: Todo | None = None
-
     it = iter(root_iter)
     last = next(it, None)
     if not last:

ical/todo.py

@@ -14,6 +14,7 @@
 
 from .alarm import Alarm
 from .component import ComponentModel, validate_until_dtstart, validate_recurrence_dates
+from .exceptions import CalendarParseError
 from .iter import RulesetIterable
 from .parsing.property import ParsedProperty
 from .types import (
@@ -229,8 +230,12 @@ def as_rrule(self) -> Iterable[datetime.datetime | datetime.date] | None:
 
         This is only valid for events where `recurring` is True.
         """
-        if not (self.rrule or self.rdate) or not self.computed_duration:
+        if not self.rrule and not self.rdate:
             return None
+        if not self.start:
+            raise CalendarParseError("Event must have a start date to be recurring")
+        if not self.due:
+            raise CalendarParseError("Event must have a due date to be recurring")
         return RulesetIterable(
             self.start,
             [self.rrule.as_rrule(self.start)] if self.rrule else [],
@@ -247,7 +252,7 @@ def validate_one_due_or_duration(cls, values: dict[str, Any]) -> dict[str, Any]:
 
     @root_validator
     def validate_duration_requires_start(cls, values: dict[str, Any]) -> dict[str, Any]:
-        """Validate that only one of duration or end date may be set."""
+        """Validate that a duration requires the dtstart."""
         if values.get("duration") and not values.get("dtstart"):
             raise ValueError("Duration requires that dtstart is specified")
         return values

tests/test_todo.py

@@ -4,12 +4,14 @@
 
 import datetime
 import zoneinfo
+from typing import Any
 from unittest.mock import patch
 
 import pytest
 
 from ical.exceptions import CalendarParseError
 from ical.todo import Todo
+from ical.types.recur import Recur
 
 
 def test_empty() -> None:
@@ -53,3 +55,35 @@ def test_duration() -> None:
         "ical.util.local_timezone", return_value=zoneinfo.ZoneInfo("America/Regina")
     ):
         assert todo.start_datetime.isoformat() == "2022-08-07T06:00:00+00:00"
+
+
+@pytest.mark.parametrize(
+    ("params"),
+    [
+        ({}),
+        (
+            {
+                "start": datetime.datetime(2022, 9, 6, 6, 0, 0),
+            }
+        ),
+        (
+            {
+                "due": datetime.datetime(2022, 9, 6, 6, 0, 0),
+            }
+        ),
+        (
+            {
+                "duration": datetime.timedelta(hours=1),
+            }
+        ),
+    ],
+)
+def test_validate_rrule_required_fields(params: dict[str, Any]) -> None:
+    """Test that a Todo with an rrule requires a dtstart."""
+    with pytest.raises(CalendarParseError):
+        event = Todo(
+            summary="Event 1",
+            rrule=Recur.from_rrule("FREQ=WEEKLY;BYDAY=WE,MO,TU,TH,FR;COUNT=3"),
+            **params,
+        )
+        event.as_rrule()