py38 compatibility, ruff adjustment, better error messages tested

pyproject.toml

@@ -157,6 +157,7 @@ ignore = [
     "PERF401", # Use a list comprehension to create a transformed list
     "ARG002",  # Unused method argument: ...
     "ARG001",  # Unused function argument: ...
+    "UP007",   # Optional -> X | None remove when migrated to py39+
 ]
 extend-safe-fixes = [
     "PT006", # Wrong type passed to first argument of @pytest.mark.parametrize; expected {expected_string}

src/icalendar/cal.py

@@ -7,7 +7,7 @@
 
 import os
 from datetime import date, datetime, timedelta
-from typing import List, Tuple
+from typing import List, Optional, Tuple
 
 import dateutil.rrule
 import dateutil.tz
@@ -511,7 +511,6 @@ def p_get(self : Component):
         if not isinstance(value, value_type):
             raise InvalidCalendar(f"{prop} must be either a date or a datetime, not {value}.")
         return value
-
 
     def p_set(self:Component, value) -> None:
         if value is None:
@@ -524,13 +523,13 @@ def p_set(self:Component, value) -> None:
             for other_prop in self.exclusive:
                 if other_prop != prop:
                     self.pop(other_prop, None)
-    p_set.__annotations__["value"] = p_get.__annotations__["return"] = type_def | None
+    p_set.__annotations__["value"] = p_get.__annotations__["return"] = Optional[type_def]
 
     def p_del(self:Component):
         self.pop(prop)
-    
+
     p_doc = f"""The {prop} property.
-    
+
     {doc}
 
     Accepted values: {', '.join(t.__name__ for t in value_type)}.
@@ -595,7 +594,7 @@ def _get_start_end_duration(self):
         return start, end, duration
 
     @property
-    def DURATION(self) -> timedelta | None:  # noqa: N802
+    def DURATION(self) -> Optional[timedelta]:  # noqa: N802
         """The DURATION of the component.
 
         The "DTSTART" property for a "VEVENT" specifies the inclusive start of the event.
@@ -617,7 +616,7 @@ def DURATION(self) -> timedelta | None:  # noqa: N802
         return None
 
     @DURATION.setter
-    def DURATION(self, value: timedelta | None):  # noqa: N802
+    def DURATION(self, value: Optional[timedelta]):  # noqa: N802
         if value is None:
             self.pop("duration", None)
             return
@@ -663,7 +662,7 @@ def start(self) -> date | datetime:
         return start
 
     @start.setter
-    def start(self, start: date | datetime| None):
+    def start(self, start: Optional[date | datetime]):
         """Set the start."""
         self.DTSTART = start
 

src/icalendar/tests/test_issue_662_component_properties.py

@@ -2,7 +2,11 @@
 from datetime import date, datetime, timedelta
 
 import pytest
-from zoneinfo import ZoneInfo
+
+try:
+    from zoneinfo import ZoneInfo
+except ImportError:
+    from backports.zoneinfo import ZoneInfo  # type: ignore
 
 from icalendar import (
     Event,
@@ -201,9 +205,9 @@ def test_start_and_duration(event, dtstart, duration):
 @pytest.mark.parametrize(
     ("invalid_event", "message"),
     [
-        (invalid_event_end_1, "DTSTART and DTEND must have the same type."),
-        (invalid_event_end_2, "DTSTART and DTEND must have the same type."),
-        (invalid_event_end_3, "DTEND and DURATION cannot be there at the same time."),
+        (invalid_event_end_1, "DTSTART and DTEND must be of the same type, either date or datetime."),
+        (invalid_event_end_2, "DTSTART and DTEND must be of the same type, either date or datetime."),
+        (invalid_event_end_3, "Only one of DTEND and DURATION may be in a VEVENT, not both."),
         (invalid_event_end_4, "When DTSTART is a date, DURATION must be of days or weeks."),
     ]
 )