tests for Png & Gif codecs

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

@@ -3,15 +3,33 @@
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
 
+// ReSharper disable InconsistentNaming
 namespace ImageSharp.Tests
 {
     using System.Text;
     using Xunit;
 
     using ImageSharp.Formats;
+    using ImageSharp.PixelFormats;
 
     public class GifDecoderTests
     {
+        private const PixelTypes PixelTypes = Tests.PixelTypes.StandardImageClass | Tests.PixelTypes.RgbaVector | Tests.PixelTypes.Argb32;
+
+        public static readonly string[] TestFiles = { TestImages.Gif.Giphy, TestImages.Gif.Rings, TestImages.Gif.Trans };
+
+        [Theory]
+        [WithFileCollection(nameof(TestFiles), PixelTypes)]
+        public void DecodeAndReSave<TPixel>(TestImageProvider<TPixel> imageProvider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = imageProvider.GetImage())
+            {
+                imageProvider.Utility.SaveTestOutputFile(image, "bmp");
+                imageProvider.Utility.SaveTestOutputFile(image, "gif");
+            }
+        }
+        
         [Fact]
         public void Decode_IgnoreMetadataIsFalse_CommentsAreRead()
         {

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

@@ -9,9 +9,23 @@ namespace ImageSharp.Tests
     using Xunit;
 
     using ImageSharp.Formats;
+    using ImageSharp.PixelFormats;
 
     public class GifEncoderTests
     {
+        private const PixelTypes PixelTypes = Tests.PixelTypes.StandardImageClass | Tests.PixelTypes.RgbaVector | Tests.PixelTypes.Argb32;
+
+        [Theory]
+        [WithTestPatternImages(100, 100, PixelTypes)]
+        public void EncodeGeneratedPatterns<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage())
+            {
+                provider.Utility.SaveTestOutputFile(image, "gif", new GifEncoder());
+            }
+        }
+
         [Fact]
         public void Encode_IgnoreMetadataIsFalse_CommentsAreWritten()
         {

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

@@ -9,9 +9,29 @@ namespace ImageSharp.Tests
     using Xunit;
 
     using ImageSharp.Formats;
+    using ImageSharp.PixelFormats;
 
     public class PngDecoderTests
     {
+        private const PixelTypes PixelTypes = Tests.PixelTypes.StandardImageClass | Tests.PixelTypes.RgbaVector | Tests.PixelTypes.Argb32;
+
+        public static readonly string[] TestFiles =
+            {
+                TestImages.Png.Splash, TestImages.Png.Indexed, TestImages.Png.Interlaced, TestImages.Png.FilterVar,
+                TestImages.Png.ChunkLength1, TestImages.Png.ChunkLength2
+            };
+
+        [Theory]
+        [WithFileCollection(nameof(TestFiles), PixelTypes)]
+        public void DecodeAndReSave<TPixel>(TestImageProvider<TPixel> imageProvider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = imageProvider.GetImage())
+            {
+                imageProvider.Utility.SaveTestOutputFile(image, "bmp");
+            }
+        }
+
         [Fact]
         public void Decode_IgnoreMetadataIsFalse_TextChunckIsRead()
         {

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

@@ -7,6 +7,7 @@ using ImageSharp.Formats;
 
 namespace ImageSharp.Tests
 {
+    using System.Collections.Generic;
     using System.IO;
     using System.Linq;
     using System.Threading.Tasks;
@@ -17,6 +18,29 @@ namespace ImageSharp.Tests
 
     public class PngEncoderTests : FileTestBase
     {
+        private const PixelTypes PixelTypes = Tests.PixelTypes.StandardImageClass | Tests.PixelTypes.RgbaVector | Tests.PixelTypes.Argb32;
+
+        [Theory]
+        [WithTestPatternImages(100, 100, PixelTypes, PngColorType.RgbWithAlpha)]
+        [WithTestPatternImages(100, 100, PixelTypes, PngColorType.Rgb)]
+        [WithTestPatternImages(100, 100, PixelTypes, PngColorType.Palette)]
+        [WithTestPatternImages(100, 100, PixelTypes, PngColorType.Grayscale)]
+        [WithTestPatternImages(100, 100, PixelTypes, PngColorType.GrayscaleWithAlpha)]
+        public void EncodeGeneratedPatterns<TPixel>(TestImageProvider<TPixel> provider, PngColorType pngColorType)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage())
+            {
+                PngEncoderOptions options = new PngEncoderOptions()
+                                                {
+                                                    PngColorType = pngColorType
+                                                };
+                provider.Utility.TestName += "_" + pngColorType;
+
+                provider.Utility.SaveTestOutputFile(image, "png", new PngEncoder(), options);
+            }
+        }
+
         [Theory]
         [WithBlankImages(1, 1, PixelTypes.All)]
         public void WritesFileMarker<TPixel>(TestImageProvider<TPixel> provider)