TestImageProvider can use custom decoder now

tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.cs

@@ -15,7 +15,7 @@ namespace ImageSharp.Tests
 
     using Xunit;
 
-    public class JpegDecoderTests : TestBase
+    public class JpegDecoderTests
     {
         public static string[] BaselineTestJpegs =
             {
@@ -29,7 +29,7 @@ namespace ImageSharp.Tests
         // TODO: We should make this comparer less tolerant ...
         private static readonly ImageComparer VeryTolerantJpegComparer =
             ImageComparer.Tolerant(0.005f, pixelThresholdInPixelByteSum: 4);
-
+        
         [Theory]
         [WithFileCollection(nameof(BaselineTestJpegs), PixelTypes.Rgba32 | PixelTypes.Rgba32 | PixelTypes.Argb32)]
         public void DecodeBaselineJpeg<TPixel>(TestImageProvider<TPixel> provider)

tests/ImageSharp.Tests/TestUtilities/Factories/GenericFactory.cs

@@ -10,6 +10,8 @@ namespace ImageSharp.Tests
     using ImageSharp.PixelFormats;
 
     /// <summary>
+    /// TODO: Non-generic 'Image' class has been removed. We no longer need the factory pattern here!
+    /// 
     /// Utility class to create specialized subclasses of generic classes (eg. <see cref="Image"/>)
     /// Used as parameter for <see cref="WithMemberFactoryAttribute"/> -based factory methods
     /// </summary>

tests/ImageSharp.Tests/TestUtilities/Factories/ImageFactory.cs

@@ -7,6 +7,9 @@ namespace ImageSharp.Tests
 {
     using ImageSharp.PixelFormats;
 
+    /// <summary>
+    /// TODO: Non-generic 'Image' class has been removed. We no longer need the factory pattern here!
+    /// </summary>
     public class ImageFactory : GenericFactory<Rgba32>
     {
         public override Image<Rgba32> CreateImage(byte[] bytes) => Image.Load<Rgba32>(bytes);

tests/ImageSharp.Tests/TestUtilities/ImageProviders/FileProvider.cs

@@ -8,6 +8,7 @@ namespace ImageSharp.Tests
     using System;
     using System.Collections.Concurrent;
 
+    using ImageSharp.Formats;
     using ImageSharp.PixelFormats;
 
     using Xunit.Abstractions;
@@ -19,10 +20,10 @@ namespace ImageSharp.Tests
         {
             // Need PixelTypes in the dictionary key, because result images of TestImageProvider<TPixel>.FileProvider
             // are shared between PixelTypes.Color & PixelTypes.Rgba32
-            private class Key : Tuple<PixelTypes, string>
+            private class Key : Tuple<PixelTypes, string, Type>
             {
-                public Key(PixelTypes item1, string item2)
+                public Key(PixelTypes pixelType, string filePath, Type customDecoderType = null)
-                    : base(item1, item2)
+                    : base(pixelType, filePath, customDecoderType)
                 {
                 }
             }
@@ -51,10 +52,27 @@ namespace ImageSharp.Tests
                     fn =>
                         {
                             TestFile testFile = TestFile.Create(this.FilePath);
-                            return this.Factory.CreateImage(testFile.Bytes);
+                            return Image.Load<TPixel>(testFile.Bytes);
                         });
 
-                return this.Factory.CreateImage(cachedImage);
+                return cachedImage.Clone();
+            }
+
+            public override Image<TPixel> GetImage(IImageDecoder decoder)
+            {
+                Guard.NotNull(decoder, nameof(decoder));
+
+                Key key = new Key(this.PixelType, this.FilePath, decoder.GetType());
+
+                Image<TPixel> cachedImage = cache.GetOrAdd(
+                    key,
+                    fn =>
+                        {
+                            TestFile testFile = TestFile.Create(this.FilePath);
+                            return Image.Load<TPixel>(testFile.Bytes, decoder);
+                        });
+
+                return cachedImage.Clone();
             }
 
             public override void Deserialize(IXunitSerializationInfo info)

tests/ImageSharp.Tests/TestUtilities/ImageProviders/TestImageProvider.cs

@@ -8,6 +8,7 @@ namespace ImageSharp.Tests
     using System;
     using System.Reflection;
 
+    using ImageSharp.Formats;
     using ImageSharp.PixelFormats;
 
     using Xunit.Abstractions;
@@ -82,6 +83,11 @@ namespace ImageSharp.Tests
         /// </summary>
         public abstract Image<TPixel> GetImage();
 
+        public virtual Image<TPixel> GetImage(IImageDecoder decoder)
+        {
+            throw new NotSupportedException($"Decoder specific GetImage() is not supported with {this.GetType().Name}!");
+        }
+
         /// <summary>
         /// Returns an <see cref="Image{TPixel}"/> instance to the test case with the necessary traits.
         /// </summary>

tests/ImageSharp.Tests/TestUtilities/Tests/TestImageProviderTests.cs

@@ -3,12 +3,17 @@
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
 
+// ReSharper disable InconsistentNaming
 namespace ImageSharp.Tests
 {
     using System;
+    using System.IO;
 
+    using ImageSharp.Formats;
     using ImageSharp.PixelFormats;
 
+    using Moq;
+
     using Xunit;
     using Xunit.Abstractions;
 
@@ -85,6 +90,35 @@ namespace ImageSharp.Tests
             this.Output.WriteLine(fn);
         }
 
+        private class TestDecoder : IImageDecoder
+        {
+            public int InvocationCount { get; private set; } = 0;
+
+            public Image<TPixel> Decode<TPixel>(Configuration configuration, Stream stream)
+                where TPixel : struct, IPixel<TPixel>
+            {
+                this.InvocationCount++;
+                return new Image<TPixel>(42, 42);
+            }
+        }
+
+
+        [Theory]
+        [WithFile(TestImages.Bmp.F, PixelTypes.Rgba32)]
+        public void GetImage_WithCustomDecoder_ShouldUtilizeCache<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            Assert.NotNull(provider.Utility.SourceFileOrDescription);
+
+            var decoder = new TestDecoder();
+
+            provider.GetImage(decoder);
+            Assert.Equal(1, decoder.InvocationCount);
+
+            provider.GetImage(decoder);
+            Assert.Equal(1, decoder.InvocationCount);
+        }
+
         public static string[] AllBmpFiles => TestImages.Bmp.All;
 
         [Theory]
@@ -96,7 +130,7 @@ namespace ImageSharp.Tests
             Image<TPixel> image = provider.GetImage();
             provider.Utility.SaveTestOutputFile(image, "png");
         }
-
+        
         [Theory]
         [WithSolidFilledImages(10, 20, 255, 100, 50, 200, PixelTypes.Rgba32 | PixelTypes.Argb32)]
         public void Use_WithSolidFilledImagesAttribute<TPixel>(TestImageProvider<TPixel> provider)