No more TmxSerializer, now different readers for each file format

DotTiled.Tests/Assert/AssertImage.cs

@@ -0,0 +1,21 @@
+namespace DotTiled.Tests;
+
+public static partial class DotTiledAssert
+{
+  internal static void AssertImage(Image? expected, Image? actual)
+  {
+    if (expected is null)
+    {
+      Assert.Null(actual);
+      return;
+    }
+
+    // Attributes
+    Assert.NotNull(actual);
+    Assert.Equal(expected.Format, actual.Format);
+    Assert.Equal(expected.Source, actual.Source);
+    Assert.Equal(expected.TransparentColor, actual.TransparentColor);
+    Assert.Equal(expected.Width, actual.Width);
+    Assert.Equal(expected.Height, actual.Height);
+  }
+}