Additional gif test cases

src/ImageSharp/Formats/Gif/README.md

@@ -1,4 +1,6 @@
-Encoder/Decoder adapted and extended from:
+Encoder/Decoder adapted and extended from:
 
-https://github.com/yufeih/Nine.Imaging/
-https://imagetools.codeplex.com/
+- [Nine.Imaging](https://github.com/yufeih/Nine.Imaging/)
+- [imagetools.codeplex](https://imagetools.codeplex.com/)
+
+A useful set of gif test images can be found at [pygif](https://github.com/robert-ancell/pygif/tree/master/test-suite)

tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs

@@ -2,11 +2,9 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Collections.Generic;
 using System.IO;
 using Microsoft.DotNet.RemoteExecutor;
 
-using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Formats.Gif;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.Metadata;
@@ -30,32 +28,6 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
             TestImages.Gif.Giphy, TestImages.Gif.Kumin
         };
 
-        public static readonly string[] BasicVerificationFiles =
-        {
-            TestImages.Gif.Cheers,
-            TestImages.Gif.Rings,
-
-            // previously DecodeBadApplicationExtensionLength:
-            TestImages.Gif.Issues.BadAppExtLength,
-            TestImages.Gif.Issues.BadAppExtLength_2,
-
-            // previously DecodeBadDescriptorDimensionsLength:
-            TestImages.Gif.Issues.BadDescriptorWidth
-        };
-
-        private static readonly Dictionary<string, int> BasicVerificationFrameCount =
-        new Dictionary<string, int>
-        {
-            [TestImages.Gif.Cheers] = 93,
-            [TestImages.Gif.Issues.BadDescriptorWidth] = 36,
-        };
-
-        public static readonly string[] BadAppExtFiles =
-        {
-            TestImages.Gif.Issues.BadAppExtLength,
-            TestImages.Gif.Issues.BadAppExtLength_2
-        };
-
         [Theory]
         [WithFileCollection(nameof(MultiFrameTestFiles), PixelTypes.Rgba32)]
         public void Decode_VerifyAllFrames<TPixel>(TestImageProvider<TPixel> provider)
@@ -100,15 +72,12 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
         }
 
         [Theory]
-        [WithFileCollection(nameof(BasicVerificationFiles), PixelTypes.Rgba32)]
-        public void Decode_VerifyRootFrameAndFrameCount<TPixel>(TestImageProvider<TPixel> provider)
+        [WithFile(TestImages.Gif.Cheers, PixelTypes.Rgba32, 93)]
+        [WithFile(TestImages.Gif.Rings, PixelTypes.Rgba32, 1)]
+        [WithFile(TestImages.Gif.Issues.BadDescriptorWidth, PixelTypes.Rgba32, 36)]
+        public void Decode_VerifyRootFrameAndFrameCount<TPixel>(TestImageProvider<TPixel> provider, int expectedFrameCount)
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            if (!BasicVerificationFrameCount.TryGetValue(provider.SourceFileOrDescription, out int expectedFrameCount))
-            {
-                expectedFrameCount = 1;
-            }
-
             using (Image<TPixel> image = provider.GetImage())
             {
                 Assert.Equal(expectedFrameCount, image.Frames.Count);
@@ -153,6 +122,35 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
             }
         }
 
+        [Theory]
+        [WithFile(TestImages.Gif.ZeroSize, PixelTypes.Rgba32)]
+        [WithFile(TestImages.Gif.ZeroWidth, PixelTypes.Rgba32)]
+        [WithFile(TestImages.Gif.ZeroHeight, PixelTypes.Rgba32)]
+        public void Decode_WithInvalidDimensions_DoesThrowException<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            System.Exception ex = Record.Exception(
+                () =>
+                {
+                    using Image<TPixel> image = provider.GetImage(GifDecoder);
+                });
+            Assert.NotNull(ex);
+            Assert.Contains("Width or height should not be 0", ex.Message);
+        }
+
+        [Theory]
+        [WithFile(TestImages.Gif.MaxWidth, PixelTypes.Rgba32, 65535, 1)]
+        [WithFile(TestImages.Gif.MaxHeight, PixelTypes.Rgba32, 1, 65535)]
+        public void Decode_WithMaxDimensions_Works<TPixel>(TestImageProvider<TPixel> provider, int expectedWidth, int expectedHeight)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage(GifDecoder))
+            {
+                Assert.Equal(expectedWidth, image.Width);
+                Assert.Equal(expectedHeight, image.Height);
+            }
+        }
+
         [Fact]
         public void CanDecodeIntermingledImages()
         {
@@ -172,6 +170,20 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
             }
         }
 
+        // https://github.com/SixLabors/ImageSharp/issues/405
+        [Theory]
+        [WithFile(TestImages.Gif.Issues.BadAppExtLength, PixelTypes.Rgba32)]
+        [WithFile(TestImages.Gif.Issues.BadAppExtLength_2, PixelTypes.Rgba32)]
+        public void Issue405_BadApplicationExtensionBlockLength<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage())
+            {
+                image.DebugSave(provider);
+                image.CompareFirstFrameToReferenceOutput(ImageComparer.Exact, provider);
+            }
+        }
+
         [Theory]
         [WithFile(TestImages.Gif.Giphy, PixelTypes.Rgba32)]
         [WithFile(TestImages.Gif.Kumin, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/TestImages.cs

@@ -397,6 +397,13 @@ namespace SixLabors.ImageSharp.Tests
             public const string Ratio1x4 = "Gif/base_1x4.gif";
             public const string LargeComment = "Gif/large_comment.gif";
 
+            // Test images from https://github.com/robert-ancell/pygif/tree/master/test-suite
+            public const string ZeroSize = "Gif/image-zero-size.gif";
+            public const string ZeroHeight = "Gif/image-zero-height.gif";
+            public const string ZeroWidth = "Gif/image-zero-width.gif";
+            public const string MaxWidth = "Gif/max-width.gif";
+            public const string MaxHeight = "Gif/max-height.gif";
+
             public static class Issues
             {
                 public const string BadAppExtLength = "Gif/issues/issue405_badappextlength252.gif";