Add tests for #2209

tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs

@@ -470,6 +470,30 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
             Assert.Null(ex);
         }
 
+        // https://github.com/SixLabors/ImageSharp/issues/2209
+        [Theory]
+        [WithFile(TestImages.Png.Issue2209IndexedWithTransparency, PixelTypes.Rgba32)]
+        public void Issue2209_Decode_HasTransparencyIsTrue<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using Image<TPixel> image = provider.GetImage(PngDecoder);
+            image.DebugSave(provider);
+            PngMetadata metadata = image.Metadata.GetPngMetadata();
+            Assert.True(metadata.HasTransparency);
+        }
+
+        // https://github.com/SixLabors/ImageSharp/issues/2209
+        [Theory]
+        [InlineData(TestImages.Png.Issue2209IndexedWithTransparency)]
+        public void Issue2209_Identify_HasTransparencyIsTrue(string imagePath)
+        {
+            var testFile = TestFile.Create(imagePath);
+            using var stream = new MemoryStream(testFile.Bytes, false);
+            IImageInfo imageInfo = Image.Identify(stream);
+            PngMetadata metadata = imageInfo.Metadata.GetPngMetadata();
+            Assert.True(metadata.HasTransparency);
+        }
+
         // https://github.com/SixLabors/ImageSharp/issues/410
         [Theory]
         [WithFile(TestImages.Png.Bad.Issue410_MalformedApplePng, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/TestImages.cs

@@ -125,6 +125,9 @@ namespace SixLabors.ImageSharp.Tests
             // Discussion 1875: https://github.com/SixLabors/ImageSharp/discussions/1875
             public const string Issue1875 = "Png/raw-profile-type-exif.png";
 
+            // Issue 2209: https://github.com/SixLabors/ImageSharp/issues/2209
+            public const string Issue2209IndexedWithTransparency = "Png/issues/Issue_2209.png";
+
             public static class Bad
             {
                 public const string MissingDataChunk = "Png/xdtn0g01.png";

tests/Images/Input/Png/issues/Issue_2209.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:58eae3863a2107bf3359a87492bc95524b54dd091683e333ac73d76f229a1f71
+size 621275