Add test for issue #1891

Author: brianpopow

tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs

@@ -380,6 +380,18 @@ public void TiffDecoder_CanDecode_PackBitsCompressed<TPixel>(TestImageProvider<T
         public void TiffDecoder_CanDecode_JpegCompressed<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider, useExactComparer: false);
 
+        // https://github.com/SixLabors/ImageSharp/issues/1891
+        [Theory]
+        [WithFile(Issues1891, PixelTypes.Rgba32)]
+        public void TiffDecoder_ThrowsException_WithTooManyDirectories<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel> => Assert.Throws<ImageFormatException>(
+                () =>
+                {
+                    using (provider.GetImage(TiffDecoder))
+                    {
+                    }
+                });
+
         [Theory]
         [WithFileCollection(nameof(MultiframeTestImages), PixelTypes.Rgba32)]
         public void DecodeMultiframe<TPixel>(TestImageProvider<TPixel> provider)

tests/ImageSharp.Tests/TestImages.cs

@@ -840,6 +840,7 @@ public static class Tiff
             public const string Flower32BitGrayPredictorLittleEndian = "Tiff/flower-minisblack-32_lsb_deflate_predictor.tiff";
 
             public const string Issues1716Rgb161616BitLittleEndian = "Tiff/Issues/Issue1716.tiff";
+            public const string Issues1891 = "Tiff/Issues/Issue1891.tiff";
 
             public const string SmallRgbDeflate = "Tiff/rgb_small_deflate.tiff";
             public const string SmallRgbLzw = "Tiff/rgb_small_lzw.tiff";

tests/Images/Input/Tiff/Issues/Issue1891.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a2779c7fb2c2ad858e0d7efcfffd594cc6fb2846e0475a2998a3cda50f289b9b
+size 307