Add average filter tests

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

@@ -0,0 +1,62 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Png.Filters;
+using SixLabors.ImageSharp.Tests.TestUtilities;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Png
+{
+    public class PngDecoderFilterTests
+    {
+        private static void RunAverageFilterTest()
+        {
+            // arrange
+            byte[] scanline =
+            {
+                3, 39, 39, 39, 0, 4, 4, 4, 0, 1, 1, 1, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2, 0, 2, 2, 2, 0, 4, 4, 4,
+                0, 2, 2, 2, 0, 3, 3, 3, 0, 1, 1, 1, 0, 3, 3, 3, 0, 3, 3, 3, 0, 1, 1, 1, 0, 3, 3, 3, 0, 2, 2, 2, 0,
+                1, 1, 1, 0, 3, 3, 3, 0, 1, 1, 1, 0, 3, 3, 3, 0, 1, 1, 1, 0, 3, 3, 3, 0, 3, 3, 3, 0, 254, 254, 254,
+                0, 6, 6, 6, 14, 71, 71, 71, 157, 254, 254, 254, 28, 251, 251, 251, 0, 4, 4, 4, 0, 2, 2, 2, 0, 11,
+                11, 11, 0, 226, 226, 226, 0, 255
+            };
+
+            byte[] previousScanline =
+            {
+                3, 74, 74, 74, 0, 73, 73, 73, 0, 73, 73, 73, 0, 74, 74, 74, 0, 74, 74, 74, 0, 73, 73, 73, 0, 72, 72,
+                72, 0, 72, 72, 72, 0, 73, 73, 73, 0, 74, 74, 74, 0, 73, 73, 73, 0, 72, 72, 72, 0, 72, 72, 72, 0, 74,
+                74, 74, 0, 72, 72, 72, 0, 73, 73, 73, 0, 75, 75, 75, 0, 73, 73, 73, 0, 74, 74, 74, 0, 72, 72, 72, 0,
+                73, 73, 73, 0, 73, 73, 73, 0, 72, 72, 72, 0, 74, 74, 74, 0, 61, 61, 61, 0, 101, 101, 101, 78, 197,
+                197, 197, 251, 152, 152, 152, 255, 155, 155, 155, 255, 162, 162, 162, 255, 175, 175, 175, 255, 160,
+                160, 160, 255, 139
+            };
+
+            byte[] expected =
+            {
+                3, 76, 76, 76, 0, 78, 78, 78, 0, 76, 76, 76, 0, 76, 76, 76, 0, 77, 77, 77, 0, 77, 77, 77, 0, 76, 76,
+                76, 0, 78, 78, 78, 0, 77, 77, 77, 0, 78, 78, 78, 0, 76, 76, 76, 0, 77, 77, 77, 0, 77, 77, 77, 0, 76,
+                76, 76, 0, 77, 77, 77, 0, 77, 77, 77, 0, 77, 77, 77, 0, 78, 78, 78, 0, 77, 77, 77, 0, 77, 77, 77, 0,
+                76, 76, 76, 0, 77, 77, 77, 0, 77, 77, 77, 0, 73, 73, 73, 0, 73, 73, 73, 14, 158, 158, 158, 203, 175,
+                175, 175, 255, 158, 158, 158, 255, 160, 160, 160, 255, 163, 163, 163, 255, 180, 180, 180, 255, 140,
+                140, 140, 255, 255
+            };
+
+            // act
+            AverageFilter.Decode(scanline, previousScanline, 4);
+
+            // assert
+            Assert.Equal(scanline, expected);
+        }
+
+        [Fact]
+        public void AverageInverse_Works() => RunAverageFilterTest();
+
+#if SUPPORTS_RUNTIME_INTRINSICS
+        [Fact]
+        public void AverageInverse_WithHardwareIntrinsics_Works() => FeatureTestRunner.RunWithHwIntrinsicsFeature(RunAverageFilterTest, HwIntrinsics.AllowAll);
+
+        [Fact]
+        public void AverageInverse__WithoutSSE2_Works() => FeatureTestRunner.RunWithHwIntrinsicsFeature(RunAverageFilterTest, HwIntrinsics.DisableSSE2);
+#endif
+    }
+}

tests/ImageSharp.Tests/Formats/Png/PngFilterTests.cs → tests/ImageSharp.Tests/Formats/Png/PngEncoderFilterTests.cs

@@ -13,7 +13,7 @@ using Xunit.Abstractions;
 namespace SixLabors.ImageSharp.Tests.Formats.Png
 {
     [Trait("Format", "Png")]
-    public partial class PngFilterTests : MeasureFixture
+    public class PngEncoderFilterTests : MeasureFixture
     {
 #if BENCHMARKING
         public const int Times = 1000000;
@@ -21,7 +21,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
         public const int Times = 1;
 #endif
 
-        public PngFilterTests(ITestOutputHelper output)
+        public PngEncoderFilterTests(ITestOutputHelper output)
             : base(output)
         {
         }