diff --git a/EssentialCSharp.Web.Tests/SiteMappingTests.cs b/EssentialCSharp.Web.Tests/SiteMappingTests.cs
index 91b4e7d9..a1287bbd 100644
--- a/EssentialCSharp.Web.Tests/SiteMappingTests.cs
+++ b/EssentialCSharp.Web.Tests/SiteMappingTests.cs
@@ -1,4 +1,9 @@
-using EssentialCSharp.Web.Extensions;
+using System.Globalization;
+using System.Text.Json;
+using EssentialCSharp.Web.Extensions;
+using EssentialCSharp.Web.Services;
+using Microsoft.AspNetCore.Hosting;
+using Moq;
 
 namespace EssentialCSharp.Web.Tests;
 
@@ -146,4 +151,78 @@ public async Task FindPercentComplete_KeyNotFound_ReturnsZeroPercent()
         // Assert
         await Assert.That(percent).IsEqualTo("0.00");
     }
+
+    [Test]
+    public async Task GetTocData_OrdersChaptersAndBuildsNestedItems()
+    {
+        // Arrange
+        string contentRoot = Path.Combine(Path.GetTempPath(), $"essential-csharp-{Guid.NewGuid():N}");
+        string chaptersDirectory = Path.Combine(contentRoot, "Chapters");
+        Directory.CreateDirectory(chaptersDirectory);
+
+        List<SiteMapping> siteMappings =
+        [
+            CreateSiteMapping(2, 1, 1, 0, "chapter-two", "Chapter Two"),
+            CreateSiteMapping(1, 2, 1, 0, "chapter-one-page-two", "Page Two"),
+            CreateSiteMapping(1, 1, 1, 0, "chapter-one", "Chapter One"),
+            CreateSiteMapping(1, 1, 2, 1, "chapter-one-topic", "Topic"),
+            CreateSiteMapping(1, 1, 3, 2, "chapter-one-subtopic", "Subtopic"),
+            CreateSiteMapping(1, 1, 4, 1, "chapter-one-second-topic", "Second Topic")
+        ];
+
+        await File.WriteAllTextAsync(
+            Path.Combine(chaptersDirectory, "sitemap.json"),
+            JsonSerializer.Serialize(siteMappings));
+
+        Mock<IWebHostEnvironment> environment = new();
+        environment.SetupGet(x => x.ContentRootPath).Returns(contentRoot);
+
+        try
+        {
+            // Act
+            SiteMappingService service = new(environment.Object);
+            List<SiteMappingDto> chapters = service.GetTocData().ToList();
+
+            // Assert
+            using (Assert.Multiple())
+            {
+                await Assert.That(chapters.Select(x => x.Key).ToArray()).IsEqualTo(["chapter-one", "chapter-two"]);
+                await Assert.That(chapters[0].Title).IsEqualTo("Chapter 1: Chapter One");
+                await Assert.That(chapters[0].Items.Select(x => x.Key).ToArray())
+                    .IsEqualTo(["chapter-one-topic", "chapter-one-second-topic"]);
+                await Assert.That(chapters[0].Items.First().Items.Select(x => x.Key).ToArray())
+                    .IsEqualTo(["chapter-one-subtopic"]);
+                await Assert.That(chapters[1].Title).IsEqualTo("Chapter 2: Chapter Two");
+            }
+        }
+        finally
+        {
+            Directory.Delete(contentRoot, recursive: true);
+        }
+    }
+
+    private static SiteMapping CreateSiteMapping(
+        int chapterNumber,
+        int pageNumber,
+        int orderOnPage,
+        int indentLevel,
+        string key,
+        string heading) =>
+        new(
+            keys: [key],
+            primaryKey: key,
+            pagePath:
+            [
+                "Chapters",
+                chapterNumber.ToString("D2", CultureInfo.InvariantCulture),
+                "Pages",
+                $"{pageNumber:D2}.html"
+            ],
+            chapterNumber: chapterNumber,
+            pageNumber: pageNumber,
+            orderOnPage: orderOnPage,
+            chapterTitle: heading,
+            rawHeading: heading,
+            anchorId: key,
+            indentLevel: indentLevel);
 }
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