introducing [GroupOutput] + apply it to all filter tests

tests/ImageSharp.Tests/Processing/Processors/Filters/BlackWhiteTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class BlackWhiteTest
     {
         [Theory]

tests/ImageSharp.Tests/Processing/Processors/Filters/BrightnessTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
 {
+    [GroupOutput("Filters")]
     public class BrightnessTest
     {
         public static readonly TheoryData<float> BrightnessValues

tests/ImageSharp.Tests/Processing/Processors/Filters/ColorBlindnessTest.cs

@@ -10,7 +10,8 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
-    public class ColorBlindnessTest : FileTestBase
+    [GroupOutput("Filters")]
+    public class ColorBlindnessTest
     {
         public static readonly TheoryData<ColorBlindness> ColorBlindnessFilters
         = new TheoryData<ColorBlindness>
@@ -26,7 +27,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
         };
 
         [Theory]
-        [WithTestPatternImages(nameof(ColorBlindnessFilters), 100, 100, DefaultPixelType)]
+        [WithTestPatternImages(nameof(ColorBlindnessFilters), 48, 48, PixelTypes.Rgba32)]
         public void ApplyColorBlindnessFilter<TPixel>(TestImageProvider<TPixel> provider, ColorBlindness colorBlindness)
             where TPixel : struct, IPixel<TPixel>
         {
@@ -38,7 +39,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
         }
 
         [Theory]
-        [WithTestPatternImages(nameof(ColorBlindnessFilters), 100, 100, DefaultPixelType)]
+        [WithTestPatternImages(nameof(ColorBlindnessFilters), 48, 48, PixelTypes.Rgba32)]
         public void ApplyColorBlindnessFilterInBox<TPixel>(TestImageProvider<TPixel> provider, ColorBlindness colorBlindness)
             where TPixel : struct, IPixel<TPixel>
         {

tests/ImageSharp.Tests/Processing/Processors/Filters/ContrastTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
 {
+    [GroupOutput("Filters")]
     public class ContrastTest
     {
         public static readonly TheoryData<float> ContrastValues

tests/ImageSharp.Tests/Processing/Processors/Filters/FilterTest.cs

@@ -11,6 +11,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class FilterTest
     {
         // Testing the generic FilterProcessor with more than one pixel type intentionally.

tests/ImageSharp.Tests/Processing/Processors/Filters/GrayscaleTest.cs

@@ -11,6 +11,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class GrayscaleTest
     {
         public static readonly TheoryData<GrayscaleMode> GrayscaleModeTypes

tests/ImageSharp.Tests/Processing/Processors/Filters/HueTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class HueTest
     {
         public static readonly TheoryData<int> HueValues

tests/ImageSharp.Tests/Processing/Processors/Filters/InvertTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
 {
+    [GroupOutput("Filters")]
     public class InvertTest
     {
         [Theory]

tests/ImageSharp.Tests/Processing/Processors/Filters/KodachromeTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class KodachromeTest
     {
         [Theory]

tests/ImageSharp.Tests/Processing/Processors/Filters/LomographTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class LomographTest
     {
         [Theory]

tests/ImageSharp.Tests/Processing/Processors/Filters/OpacityTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
 {
+    [GroupOutput("Filters")]
     public class OpacityTest
     {
         public static readonly TheoryData<float> AlphaValues

tests/ImageSharp.Tests/Processing/Processors/Filters/PolaroidTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class PolaroidTest
     {
         [Theory]

tests/ImageSharp.Tests/Processing/Processors/Filters/SaturateTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class SaturateTest
     {
         public static readonly TheoryData<float> SaturationValues

tests/ImageSharp.Tests/Processing/Processors/Filters/SepiaTest.cs

@@ -9,6 +9,7 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Filters
 {
+    [GroupOutput("Filters")]
     public class SepiaTest
     {
         [Theory]

tests/ImageSharp.Tests/TestUtilities/Attributes/GroupOutputAttribute.cs

@@ -0,0 +1,17 @@
+namespace SixLabors.ImageSharp.Tests
+{
+    using System;
+
+    /// <summary>
+    /// The output produced by this test class should be grouped into the specified subfolder.
+    /// </summary>
+    public class GroupOutputAttribute : Attribute
+    {
+        public GroupOutputAttribute(string subfolder)
+        {
+            this.Subfolder = subfolder;
+        }
+
+        public string Subfolder { get; }
+    }
+}

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

@@ -11,7 +11,9 @@ using Xunit.Abstractions;
 
 namespace SixLabors.ImageSharp.Tests
 {
- 	public interface ITestImageProvider
+    using Castle.Core.Internal;
+
+    public interface ITestImageProvider
     {
         PixelTypes PixelType { get; }
         ImagingTestCaseUtility Utility { get; }
@@ -34,6 +36,7 @@ namespace SixLabors.ImageSharp.Tests
 
         public string TypeName { get; private set; }
         public string MethodName { get; private set; }
+        public string OutputSubfolderName { get; private set; }
 
         public static TestImageProvider<TPixel> TestPattern(
                 int width,
@@ -101,8 +104,9 @@ namespace SixLabors.ImageSharp.Tests
             PixelTypes pixelType = info.GetValue<PixelTypes>("PixelType");
             string typeName = info.GetValue<string>("TypeName");
             string methodName = info.GetValue<string>("MethodName");
+            string outputSubfolderName = info.GetValue<string>("OutputSubfolderName");
 
-            this.Init(typeName, methodName, pixelType);
+            this.Init(typeName, methodName, outputSubfolderName, pixelType);
         }
 
         public virtual void Serialize(IXunitSerializationInfo info)
@@ -110,9 +114,14 @@ namespace SixLabors.ImageSharp.Tests
             info.AddValue("PixelType", this.PixelType);
             info.AddValue("TypeName", this.TypeName);
             info.AddValue("MethodName", this.MethodName);
+            info.AddValue("OutputSubfolderName", this.OutputSubfolderName);
         }
 
-        protected TestImageProvider<TPixel> Init(string typeName, string methodName, PixelTypes pixelTypeOverride)
+        protected TestImageProvider<TPixel> Init(
+            string typeName,
+            string methodName,
+            string outputSubfolerName,
+            PixelTypes pixelTypeOverride)
         {
             if (pixelTypeOverride != PixelTypes.Undefined)
             {
@@ -120,7 +129,8 @@ namespace SixLabors.ImageSharp.Tests
             }
             this.TypeName = typeName;
             this.MethodName = methodName;
-            
+            this.OutputSubfolderName = outputSubfolerName;
+
             this.Utility = new ImagingTestCaseUtility
             {
                 SourceFileOrDescription = this.SourceFileOrDescription,
@@ -129,7 +139,7 @@ namespace SixLabors.ImageSharp.Tests
 
             if (methodName != null)
             {
-                this.Utility.Init(typeName, methodName);
+                this.Utility.Init(typeName, methodName, outputSubfolerName);
             }
 
             return this;
@@ -137,7 +147,9 @@ namespace SixLabors.ImageSharp.Tests
 
         protected TestImageProvider<TPixel> Init(MethodInfo testMethod, PixelTypes pixelTypeOverride)
         {
-            return Init(testMethod?.DeclaringType.Name, testMethod?.Name, pixelTypeOverride);
+            string subfolder = testMethod?.DeclaringType.GetAttribute<GroupOutputAttribute>()?.Subfolder
+                               ?? string.Empty;
+            return this.Init(testMethod?.DeclaringType.Name, testMethod?.Name, subfolder, pixelTypeOverride);
         }
 
         public override string ToString()

tests/ImageSharp.Tests/TestUtilities/ImagingTestCaseUtility.cs

@@ -34,6 +34,8 @@ namespace SixLabors.ImageSharp.Tests
         /// </summary>
         public string TestGroupName { get; set; } = string.Empty;
 
+        public string OutputSubfolderName { get; set; } = string.Empty;
+
         /// <summary>
         /// The name of the test case (by default)
         /// </summary>
@@ -165,41 +167,22 @@ namespace SixLabors.ImageSharp.Tests
                 );
         }
 
-        internal void Init(string typeName, string methodName)
+        internal void Init(string typeName, string methodName, string outputSubfolderName)
         {
             this.TestGroupName = typeName;
             this.TestName = methodName;
+            this.OutputSubfolderName = outputSubfolderName;
         }
-
+        
-        internal void Init(MethodInfo method)
-        {
-            this.Init(method.DeclaringType.Name, method.Name);
-        }
-
-        //private static IImageEncoder GetEncoderByExtension(string extension, bool grayscale)
-        //{
-        //    extension = extension?.TrimStart('.');
-        //    var format = Configuration.Default.FindFormatByFileExtension(extension);
-        //    IImageEncoder encoder = Configuration.Default.FindEncoder(format);
-        //    PngEncoder pngEncoder = encoder as PngEncoder;
-        //    if (pngEncoder != null)
-        //    {
-        //        pngEncoder = new PngEncoder();
-        //        encoder = pngEncoder;
-        //        pngEncoder.CompressionLevel = 9;
-
-        //        if (grayscale)
-        //        {
-        //            pngEncoder.PngColorType = PngColorType.Grayscale;
-        //        }
-        //    }
-
-        //    return encoder;
-        //}
-
         internal string GetTestOutputDir()
         {
             string testGroupName = Path.GetFileNameWithoutExtension(this.TestGroupName);
+
+            if (!string.IsNullOrEmpty(this.OutputSubfolderName))
+            {
+                testGroupName = Path.Combine(this.OutputSubfolderName, testGroupName);
+            }
+
             return TestEnvironment.CreateOutputDirectory(testGroupName);
         }
 

tests/ImageSharp.Tests/TestUtilities/Tests/GroupOutputTests.cs

@@ -0,0 +1,30 @@
+// ReSharper disable InconsistentNaming
+namespace SixLabors.ImageSharp.Tests
+{
+    using System.IO;
+
+    using SixLabors.ImageSharp.PixelFormats;
+
+    using Xunit;
+
+    [GroupOutput("Foo")]
+    public class GroupOutputTests
+    {
+        [Theory]
+        [WithBlankImages(1, 1, PixelTypes.Rgba32)]
+        public void OutputSubfolderName_ValueIsTakeFromGroupOutputAttribute<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            Assert.Equal("Foo", provider.Utility.OutputSubfolderName);
+        }
+        
+        [Theory]
+        [WithBlankImages(1,1, PixelTypes.Rgba32)]
+        public void GetTestOutputDir_ShouldDefineSubfolder<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            string expected = $"{Path.DirectorySeparatorChar}Foo{Path.DirectorySeparatorChar}";
+            Assert.Contains(expected, provider.Utility.GetTestOutputDir());
+        }
+    }
+}

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

@@ -22,6 +22,14 @@ namespace SixLabors.ImageSharp.Tests
 
         private ITestOutputHelper Output { get; }
 
+        [Theory]
+        [WithBlankImages(1, 1, PixelTypes.Rgba32)]
+        public void NoOutputSubfolderIsPresentByDefault<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            Assert.Empty(provider.Utility.OutputSubfolderName);
+        }
+
         [Theory]
         [WithBlankImages(42, 666, PixelTypes.Rgba32 | PixelTypes.Argb32 | PixelTypes.HalfSingle, "hello")]
         public void Use_WithEmptyImageAttribute<TPixel>(TestImageProvider<TPixel> provider, string message)