Enable NRT for ical.net (top) namespace

Ical.Net.Tests/CalendarEventTest.cs

@@ -417,8 +417,8 @@ public void EventResourcesCanBeZeroedOut()
             Assert.That(e.Resources.Any(r => resources.Contains(r)), Is.False);
         });
 
-        e.Resources = null;
-        //See https://github.com/rianjs/ical.net/issues/208 -- this should be changed later so the collection is really null
+        //See https://github.com/rianjs/ical.net/issues/208
+        e.Resources = Array.Empty<string>();
         Assert.That(e.Resources?.Count, Is.EqualTo(0));
     }
 

Ical.Net.Tests/ComponentTest.cs

@@ -3,9 +3,8 @@
 // Licensed under the MIT license.
 //
 
-using System;
+#nullable enable
 using Ical.Net.CalendarComponents;
-using Ical.Net.DataTypes;
 using NUnit.Framework;
 
 namespace Ical.Net.Tests;
@@ -18,8 +17,11 @@ public void UniqueComponent1()
         var iCal = new Calendar();
         var evt = iCal.Create<CalendarEvent>();
 
-        Assert.That(evt.Uid, Is.Not.Null);
-        Assert.That(evt.Created, Is.Null); // We don't want this to be set automatically
-        Assert.That(evt.DtStamp, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(evt.Uid, Is.Not.Null);
+            Assert.That(evt.Created, Is.Null); // We don't want this to be set automatically
+            Assert.That(evt.DtStamp, Is.Not.Null);
+        });
     }
 }

Ical.Net.Tests/CopyComponentTests.cs

@@ -23,7 +23,7 @@ public class CopyComponentTests
     [Test, TestCaseSource(nameof(CopyCalendarTest_TestCases)), Category("Copy tests")]
     public void CopyCalendarTest(string calendarString)
     {
-        var iCal1 = Calendar.Load(calendarString);
+        var iCal1 = Calendar.Load(calendarString)!;
         var iCal2 = iCal1.Copy<Calendar>();
         SerializationTests.CompareCalendars(iCal1, iCal2);
     }

Ical.Net.Tests/FreeBusyTest.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using Ical.Net.CalendarComponents;
 using Ical.Net.DataTypes;
 using NUnit.Framework;
@@ -18,14 +19,14 @@ public class FreeBusyTest
     [Test, Category("FreeBusy")]
     public void GetFreeBusyStatus1()
     {
-        Calendar cal = new Calendar();
+        var cal = new Calendar();
 
-        CalendarEvent evt = cal.Create<CalendarEvent>();
+        var evt = cal.Create<CalendarEvent>();
         evt.Summary = "Test event";
         evt.Start = new CalDateTime(2010, 10, 1, 8, 0, 0);
         evt.End = new CalDateTime(2010, 10, 1, 9, 0, 0);
 
-        var freeBusy = cal.GetFreeBusy(new CalDateTime(2010, 10, 1, 0, 0, 0), new CalDateTime(2010, 10, 7, 11, 59, 59));
+        var freeBusy = cal.GetFreeBusy(new CalDateTime(2010, 10, 1, 0, 0, 0), new CalDateTime(2010, 10, 7, 11, 59, 59))!;
         Assert.Multiple(() =>
         {
             Assert.That(freeBusy.GetFreeBusyStatus(new CalDateTime(2010, 10, 1, 7, 59, 59)), Is.EqualTo(FreeBusyStatus.Free));
@@ -34,4 +35,4 @@ public void GetFreeBusyStatus1()
             Assert.That(freeBusy.GetFreeBusyStatus(new CalDateTime(2010, 10, 1, 9, 0, 0)), Is.EqualTo(FreeBusyStatus.Free));
         });
     }
-}
+}

Ical.Net.Tests/PeriodListWrapperTests.cs

@@ -187,14 +187,14 @@ public void AddRPeriod_ShouldCreate_DedicatePeriodList()
         var serializer = new CalendarSerializer(cal);
         var serialized = serializer.SerializeToString();
         // Assign the deserialized event
-        cal = Calendar.Load(serialized);
+        cal = Calendar.Load(serialized)!;
         evt = cal.Events[0];
 
         // Assert the serialized string and the deserialized event
         Assert.Multiple(() =>
         {
             // 2 dedicate PeriodList objects
-            Assert.That(evt.RecurrenceDatesPeriodLists, Has.Count.EqualTo(3));
+            Assert.That(evt!.RecurrenceDatesPeriodLists, Has.Count.EqualTo(3));
 
             // First PeriodList has date-only periods
             Assert.That(evt.RecurrenceDatesPeriodLists[0], Has.Count.EqualTo(3));

Ical.Net.Tests/ProgramTest.cs

@@ -40,11 +40,11 @@ public static void TestCal(Calendar cal)
     [Test]
     public void Merge1()
     {
-        var iCal1 = Calendar.Load(IcsFiles.MonthlyCountByMonthDay3);
-        var iCal2 = Calendar.Load(IcsFiles.MonthlyByDay1);
+        var iCal1 = Calendar.Load(IcsFiles.MonthlyCountByMonthDay3)!;
+        var iCal2 = Calendar.Load(IcsFiles.MonthlyByDay1)!;
 
         // Change the UID of the 2nd event to make sure it's different
-        iCal2.Events[iCal1.Events[0].Uid].Uid = "1234567890";
+        iCal2.Events[iCal1.Events[0].Uid!].Uid = "1234567890";
         iCal1.MergeWith(iCal2);
 
         var evt1 = iCal1.Events.First();