VirtualizingStackPanel: fix selection wrapping

src/Avalonia.Controls/VirtualizingStackPanel.cs

@@ -226,7 +226,7 @@ namespace Avalonia.Controls
             {
                 if (toIndex < 0)
                     toIndex = count - 1;
-                else if (toIndex >= count - 1)
+                else if (toIndex >= count)
                     toIndex = 0;
             }
 

tests/Avalonia.Controls.UnitTests/ListBoxTests.cs

@@ -759,6 +759,7 @@ namespace Avalonia.Controls.UnitTests
                 var lbItems = target.GetLogicalChildren().OfType<ListBoxItem>().ToArray();
 
                 var first = lbItems.First();
+                var beforeLast = lbItems[^2];
                 var last = lbItems.Last();
 
                 first.Focus();
@@ -769,6 +770,12 @@ namespace Avalonia.Controls.UnitTests
                 RaiseKeyEvent(target, Key.Up);
                 Assert.Equal(true, last.IsSelected);
 
+                RaiseKeyEvent(target, Key.Up);
+                Assert.Equal(true, beforeLast.IsSelected);
+
+                RaiseKeyEvent(target, Key.Down);
+                Assert.Equal(true, last.IsSelected);
+
                 RaiseKeyEvent(target, Key.Down);
                 Assert.Equal(true, first.IsSelected);