Failing to calculate Period.EffectiveEndTime throw EvaluationOutOfRangeException

This exception is more accurate than System.ArgumentOutOfRangeException

Author: axunonb

Ical.Net.Tests/RecurrenceTests.cs

@@ -3097,7 +3097,7 @@ public void Test4()
             RDATE;TZID=America/Chicago:99991231T221000
             END:VEVENT
             END:VCALENDAR
-            """)]
+            """, true)]
 
     // y10k exceeded due to the event duration
     [TestCase("""
@@ -3108,7 +3108,7 @@ public void Test4()
             RRULE:FREQ=DAILY;BYHOUR=22,23;COUNT=2
             END:VEVENT
             END:VCALENDAR
-            """)]
+            """, false)]
 
     // Events are merged in different places than individual RRULES of a single event
     [TestCase("""
@@ -3120,11 +3120,11 @@ public void Test4()
             DTSTART;TZID=America/Chicago:99991231T221000
             END:VEVENT
             END:VCALENDAR
-            """)]
-    public void Recurrence_WithOutOfBoundsUtc_ShouldFailWithCorrectException(string ical)
+            """, true)]
+    public void Recurrence_WithOutOfBoundsUtc_ShouldFailWithCorrectException(string ical, bool shouldThrow)
     {
         var cal = Calendar.Load(ical)!;
-        Assert.That(() => cal.GetOccurrences().ToList(), Throws.InstanceOf<EvaluationOutOfRangeException>());
+        Assert.That(() => cal.GetOccurrences().ToList(), shouldThrow ? Throws.InstanceOf<EvaluationOutOfRangeException>() : Throws.Nothing);
     }
 
     [Test, Category("Recurrence")]
@@ -3790,7 +3790,7 @@ Type LoadType(string name) =>
 
         if (testCase.ExceptionStep == RecurrenceTestExceptionStep.Enumeration)
         {
-            Assert.That(() => EnumerateOccurrences(), throwsConstraint);
+            Assert.That(() => EnumerateOccurrences().Last().Period.EffectiveEndTime, throwsConstraint);
             return;
         }
 

Ical.Net/DataTypes/Period.cs

@@ -4,6 +4,7 @@
 //
 
 using System;
+using Ical.Net.Evaluation;
 using Ical.Net.Serialization.DataTypes;
 
 namespace Ical.Net.DataTypes;
@@ -164,17 +165,27 @@ public override int GetHashCode()
     /// </summary>
     public virtual CalDateTime? EffectiveEndTime
     {
-        get
-        {
-            var effectiveDuration = EffectiveDuration;
-            return _endTime switch
+        get =>
+            _endTime switch
             {
                 null when _duration is null => null,
                 { } endTime => endTime,
-                _ => effectiveDuration is not null
-                    ? _startTime.Add(effectiveDuration.Value)
-                    : null
+                _ => CalculateEndTime()
             };
+    }
+
+    private CalDateTime CalculateEndTime()
+    {
+        try
+        {
+            // When invoked, _duration is not null, so EffectiveDuration
+            // is guaranteed to be non-null
+            return _startTime.Add(EffectiveDuration!.Value);
+        }
+        catch (ArgumentOutOfRangeException)
+        {
+            // intentionally don't include the outer exception
+            throw new EvaluationOutOfRangeException($"Calculating the end time of the period from start time '{_startTime}' and effective duration '{EffectiveDuration}' resulted in an out-of-range value.");
         }
     }
 
@@ -191,17 +202,15 @@ public virtual CalDateTime? EffectiveEndTime
     /// </summary>
     public virtual Duration? EffectiveDuration
     {
-        get
-        {
-            return _duration switch
+        get =>
+            _duration switch
             {
                 null when _endTime is null => null,
                 { } d => d,
                 _ => _endTime is { } endTime
                     ? endTime.Subtract(_startTime)
                     : null
             };
-        }
     }
 
     internal string? TzId => _startTime.TzId; // same timezone for start and end

Ical.Net/Evaluation/EventEvaluator.cs

@@ -79,10 +79,6 @@ and it may differ from the time span added to the period start time.
                 start: period.StartTime,
                 duration: duration.Value);
 
-            // Ensure that adding the duration to the start time
-            // results in a representable date/time
-            _ = newPeriod.EffectiveEndTime;
-
             return newPeriod;
         }
         catch (ArgumentOutOfRangeException)