Add test

src/Graphics/tests/Graphics.Tests/PlatformImageTests.cs

@@ -0,0 +1,52 @@
+using System;
+using System.IO;
+using Xunit;
+
+namespace Microsoft.Maui.Graphics.Tests;
+
+public class PlatformImageTests
+{
+	[Theory]
+	[InlineData(true)]
+	[InlineData(false)]
+	public void PlatformImageFromStreamTest(bool seekable)
+	{
+		byte[] orange1x1pxPngBytes = Convert.FromBase64String("iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQIW2P4v5ThPwAG7wKklwQ/bwAAAABJRU5ErkJggg==");
+		using MemoryStream memoryStream = new(orange1x1pxPngBytes);
+		Stream stream = seekable ? memoryStream : new NonSeekableReadOnlyStream(memoryStream);
+
+		var image = Microsoft.Maui.Graphics.Platform.PlatformImage.FromStream(stream);
+
+		Assert.NotNull(image);
+	}
+
+	    private class NonSeekableReadOnlyStream(Stream stream) : Stream
+	{
+		public override bool CanRead => stream.CanRead;
+
+		public override bool CanSeek => false;
+
+		public override bool CanWrite => false;
+
+		public override long Length => throw new NotSupportedException();
+
+		public override long Position
+		{
+			get { return stream.Position; }
+			set { throw new NotSupportedException(); }
+		}
+
+		public override void Flush() => throw new NotSupportedException();
+
+		public override int Read(byte[] buffer, int offset, int count)
+		{
+			return stream.Read(buffer, offset, count);
+		}
+
+		public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
+
+		public override void SetLength(long value) => throw new NotSupportedException();
+
+		public override void Write(byte[] buffer, int offset, int count) => throw new NotSupportedException();
+	}
+}