Add simple clone test

tests/ImageSharp.Tests/Image/ImageCloneTests.cs

@@ -0,0 +1,36 @@
+using System;
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.PixelFormats;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests
+{
+    public class ImageCloneTests
+    {
+        [Theory]
+        [WithTestPatternImages(9, 9, PixelTypes.Rgba32)]
+        public void CloneAs_ToBgra32(TestImageProvider<Rgba32> provider)
+        {
+            using (Image<Rgba32> image = provider.GetImage())
+            using (Image<Bgra32> clone = image.CloneAs<Bgra32>())
+            {
+                for (int y = 0; y < image.Height; y++)
+                {
+                    Span<Rgba32> row = image.GetPixelRowSpan(y);
+                    Span<Bgra32> rowClone = clone.GetPixelRowSpan(y);
+
+                    for (int x = 0; x < image.Width; x++)
+                    {
+                        Rgba32 rgba = row[x];
+                        Bgra32 bgra = rowClone[x];
+
+                        Assert.Equal(rgba.R, bgra.R);
+                        Assert.Equal(rgba.G, bgra.G);
+                        Assert.Equal(rgba.B, bgra.B);
+                        Assert.Equal(rgba.A, bgra.A);
+                    }
+                }
+            }
+        }
+    }
+}