Fix linear gradient brush test.

tests/ImageSharp.Tests/Drawing/FillLinearGradientBrushTests.cs

@@ -283,10 +283,12 @@ namespace SixLabors.ImageSharp.Tests.Drawing
                 {
                     // it's diagonal, so for any (a, a) on the gradient line, for all (a-x, b+x) - +/- depending on the diagonal direction - must be the same color)
                     TPixel colorOnDiagonal = image[i, i];
+                    
+                    // TODO: This is incorrect. from -0 to < 0 ??
                     int orthoCount = 0;
                     for (int offset = -orthoCount; offset < orthoCount; offset++)
                     {
-                        Assert.Equal(colorOnDiagonal, image[i + horizontalSign * offset, i + verticalSign * offset]);
+                        Assert.Equal(colorOnDiagonal, image[i + (horizontalSign * offset), i + (verticalSign * offset)]);
                     }
                 }
 
@@ -312,20 +314,21 @@ namespace SixLabors.ImageSharp.Tests.Drawing
             int[] stopColorCodes)
             where TPixel : struct, IPixel<TPixel>
         {
-            TPixel[] colors = {
+            TPixel[] colors =
+            {
                 NamedColors<TPixel>.Navy, NamedColors<TPixel>.LightGreen, NamedColors<TPixel>.Yellow,
                 NamedColors<TPixel>.Red
             };
 
             var coloringVariant = new StringBuilder();
-            ColorStop<TPixel>[] colorStops = new ColorStop<TPixel>[stopPositions.Length];
+            var colorStops = new ColorStop<TPixel>[stopPositions.Length];
             for (int i = 0; i < stopPositions.Length; i++)
             {
                 TPixel color = colors[stopColorCodes[i % colors.Length]];
                 float position = stopPositions[i];
 
                 colorStops[i] = new ColorStop<TPixel>(position, color);
-                coloringVariant.AppendFormat(CultureInfo.InvariantCulture, "{0}@{1};", color, position);
+                coloringVariant.AppendFormat(CultureInfo.InvariantCulture, "{0}@{1};", color.ToRgba32().ToHex(), position);
             }
 
             FormattableString variant = $"({startX},{startY})_TO_({endX},{endY})__[{coloringVariant}]";

tests/Images/External

@@ -1 +1 @@
-Subproject commit 03c7fa7582dea75cea0d49514ccb7e1b6dc9e780
+Subproject commit 1a807d17b4cf5ab50558983d4137614cabe96ce3