Lots of work for chapters. This code will be refactored in a chapter rewrite.

API.Tests/ChapterSortComparerTest.cs

@@ -0,0 +1,19 @@
+using System.Linq;
+using API.Comparators;
+using Xunit;
+
+namespace API.Tests
+{
+    public class ChapterSortComparerTest
+    {
+        [Theory]
+        [InlineData(new[] {1, 2, 0}, new[] {1, 2, 0})]
+        [InlineData(new[] {3, 1, 2}, new[] {1, 2, 3})]
+        [InlineData(new[] {1, 0, 0}, new[] {1, 0, 0})]
+        public void ChapterSortTest(int[] input, int[] expected)
+        {
+            Assert.Equal(expected, input.OrderBy(f => f, new ChapterSortComparer()).ToArray());
+        }
+        
+    }
+}