Add PixelPool tests

src/ImageSharp/Image/PixelPool{TColor}.cs

@@ -36,15 +36,7 @@ namespace ImageSharp
         /// <param name="array">The array to return to the buffer pool.</param>
         public static void ReturnPixels(TColor[] array)
         {
-            try
+            ArrayPool.Return(array, true);
-            {
-                ArrayPool.Return(array, true);
-            }
-            catch
-            {
-                // Do nothing.
-                // Hacky but it allows us to attempt to return non-pooled arrays and arrays that have already been returned
-            }
         }
     }
 }

tests/ImageSharp.Tests/Image/PixelPoolTests.cs

@@ -0,0 +1,74 @@
+// <copyright file="PixelPoolTests.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Tests
+{
+    using System.Linq;
+
+    using Xunit;
+
+    /// <summary>
+    /// Tests the <see cref="PixelAccessor"/> class.
+    /// </summary>
+    public class PixelPoolTests
+    {
+        [Fact]
+        public void PixelPoolRentsMinimumSize()
+        {
+            Color[] pixels = PixelPool<Color>.RentPixels(1024);
+
+            Assert.True(pixels.Length >= 1024);
+        }
+
+        [Fact]
+        public void PixelPoolRentsEmptyArray()
+        {
+            for (int i = 16; i < 1024; i += 16)
+            {
+                Color[] pixels = PixelPool<Color>.RentPixels(i);
+
+                Assert.True(pixels.All(p => p == default(Color)));
+
+                PixelPool<Color>.ReturnPixels(pixels);
+            }
+
+            for (int i = 16; i < 1024; i += 16)
+            {
+                Color[] pixels = PixelPool<Color>.RentPixels(i);
+
+                Assert.True(pixels.All(p => p == default(Color)));
+
+                PixelPool<Color>.ReturnPixels(pixels);
+            }
+        }
+
+        [Fact]
+        public void PixelPoolDoesNotThrowWhenReturningNonPooled()
+        {
+            Color[] pixels = new Color[1024];
+
+            PixelPool<Color>.ReturnPixels(pixels);
+
+            Assert.True(pixels.Length >= 1024);
+        }
+
+        [Fact]
+        public void PixelPoolCleansRentedArray()
+        {
+            Color[] pixels = PixelPool<Color>.RentPixels(256);
+
+            for (int i = 0; i < pixels.Length; i++)
+            {
+                pixels[i] = Color.Azure;
+            }
+
+            Assert.True(pixels.All(p => p == Color.Azure));
+
+            PixelPool<Color>.ReturnPixels(pixels);
+
+            Assert.True(pixels.All(p => p == default(Color)));
+        }
+    }
+}