SixLabors#542: cleanup test file names, fix naming for RadialGradientBrush test files

Author: jongleur1983

tests/ImageSharp.Tests/Drawing/FillEllipticGradientBrushTest.cs

@@ -13,7 +13,7 @@
 namespace SixLabors.ImageSharp.Tests.Drawing
 {
     [GroupOutput("Drawing/GradientBrushes")]
-    public class FillEllipticGradientBrushTests : FileTestBase
+    public class FillEllipticGradientBrushTests
     {
         [Theory]
         [WithBlankImages(10, 10, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/Drawing/FillRadialGradientBrushTests.cs

@@ -7,11 +7,12 @@
 
 namespace SixLabors.ImageSharp.Tests.Drawing
 {
-    public class FillRadialGradientBrushTests : FileTestBase
+    [GroupOutput("Drawing/GradientBrushes")]
+    public class FillRadialGradientBrushTests
     {
         [Theory]
         [WithBlankImages(200, 200, PixelTypes.Rgba32)]
-        public void RadialGradientBrushWithEqualColorsReturnsUnicolorImage<TPixel>(
+        public void WithEqualColorsReturnsUnicolorImage<TPixel>(
             TestImageProvider<TPixel> provider)
             where TPixel : struct, IPixel<TPixel>
         {
@@ -40,7 +41,7 @@ public void RadialGradientBrushWithEqualColorsReturnsUnicolorImage<TPixel>(
         [WithBlankImages(200, 200, PixelTypes.Rgba32, 100, 0)]
         [WithBlankImages(200, 200, PixelTypes.Rgba32, 0, 100)]
         [WithBlankImages(200, 200, PixelTypes.Rgba32, -40, 100)]
-        public void RadialGradientBrushWithDifferentCentersReturnsImage<TPixel>(
+        public void WithDifferentCentersReturnsImage<TPixel>(
             TestImageProvider<TPixel> provider,
             int centerX,
             int centerY)
@@ -57,7 +58,7 @@ public void RadialGradientBrushWithDifferentCentersReturnsImage<TPixel>(
                         new ColorStop<TPixel>(1, NamedColors<TPixel>.Yellow));
 
                 image.Mutate(x => x.Fill(brush));
-                image.DebugSave(provider);
+                image.DebugSave(provider, $"center{centerX:D3},{centerY:D3}");
                 image.CompareToReferenceOutput(provider);
             }
         }