Add GifGraphicControlExtensionTests

tests/ImageSharp.Tests/Formats/Gif/Sections/GifGraphicControlExtensionTests.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Gif;
+
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Gif
+{
+    public class GifGraphicControlExtensionTests
+    {
+        [Fact]
+        public void TestPackedValue()
+        {
+            Assert.Equal(0, GifGraphicControlExtension.GetPackedValue(DisposalMethod.Unspecified, false, false));
+            Assert.Equal(11, GifGraphicControlExtension.GetPackedValue(DisposalMethod.RestoreToBackground, true, true));
+            Assert.Equal(4, GifGraphicControlExtension.GetPackedValue(DisposalMethod.NotDispose, false, false));
+            Assert.Equal(14, GifGraphicControlExtension.GetPackedValue(DisposalMethod.RestoreToPrevious, true, false));
+        }
+    }
+}

tests/ImageSharp.Tests/Formats/Gif/Sections/GifImageDescriptorTests.cs

@@ -9,7 +9,6 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
 {
     public class GifImageDescriptorTests
     {
-
         [Fact]
         public void TestPackedValue()
         {