From 37c971851019cafce9c5477b700131a03804a9b7 Mon Sep 17 00:00:00 2001
From: BDisp <bd.bdisp@gmail.com>
Date: Wed, 12 Nov 2025 15:40:05 +0000
Subject: [PATCH] Prevents Runes throwing if Grapheme is null

---
 Terminal.Gui/Drawing/Cell.cs                  |  2 +-
 .../Drawing/CellTests.cs                      | 23 ++++++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/Terminal.Gui/Drawing/Cell.cs b/Terminal.Gui/Drawing/Cell.cs
index c3f613038..96670e296 100644
--- a/Terminal.Gui/Drawing/Cell.cs
+++ b/Terminal.Gui/Drawing/Cell.cs
@@ -44,7 +44,7 @@ public record struct Cell (Attribute? Attribute = null, bool IsDirty = false, st
     ///     In the case where <see cref="Grapheme"/> has more than one rune it is a combining sequence that is normalized to a
     ///     single Text which may occupies 1 or 2 columns.
     /// </remarks>
-    public IReadOnlyList<Rune> Runes => Grapheme.EnumerateRunes ().ToList ();
+    public IReadOnlyList<Rune> Runes => string.IsNullOrEmpty (Grapheme) ? [] : Grapheme.EnumerateRunes ().ToList ();
 
     /// <inheritdoc/>
     public override string ToString ()
diff --git a/Tests/UnitTestsParallelizable/Drawing/CellTests.cs b/Tests/UnitTestsParallelizable/Drawing/CellTests.cs
index 3ee2dea54..c3bc4786a 100644
--- a/Tests/UnitTestsParallelizable/Drawing/CellTests.cs
+++ b/Tests/UnitTestsParallelizable/Drawing/CellTests.cs
@@ -1,4 +1,6 @@
-namespace UnitTests_Parallelizable.DrawingTests;
+using System.Text;
+
+namespace UnitTests_Parallelizable.DrawingTests;
 
 public class CellTests
 {
@@ -7,11 +9,30 @@ public class CellTests
     {
         var c = new Cell ();
         Assert.True (c is { });
+        Assert.Empty (c.Runes);
         Assert.Null (c.Attribute);
         Assert.False (c.IsDirty);
         Assert.Null (c.Grapheme);
     }
 
+    [Theory]
+    [InlineData (null, new uint [] { })]
+    [InlineData ("", new uint [] { })]
+    [InlineData ("a", new uint [] { 0x0061 })]
+    [InlineData ("👩‍❤️‍💋‍👨", new uint [] { 0x1F469, 0x200D, 0x2764, 0xFE0F, 0x200D, 0x1F48B, 0x200D, 0x1F468 })]
+    public void Runes_From_Grapheme (string grapheme, uint [] expected)
+    {
+        // Arrange
+        var c = new Cell { Grapheme = grapheme };
+
+        // Act
+        Rune [] runes = expected.Select (u => new Rune (u)).ToArray ();
+
+        // Assert
+        Assert.Equal (grapheme, c.Grapheme);
+        Assert.Equal (runes, c.Runes);
+    }
+
     [Fact]
     public void Equals_False ()
     {