Fix cases where multiple files are resolved as a single book

Emby.Server.Implementations/Library/Resolvers/Audio/AudioResolver.cs

@@ -192,7 +192,8 @@ namespace Emby.Server.Implementations.Library.Resolvers.Audio
                     continue;
                 }
 
-                if (resolvedItem.Files.Count == 0)
+                // Until multi-part books are handled letting files stack hides them from browsing in the client
+                if (resolvedItem.Files.Count == 0 || resolvedItem.Extras.Count > 0 || resolvedItem.AlternateVersions.Count > 0)
                 {
                     continue;
                 }

tests/Jellyfin.Server.Implementations.Tests/Library/AudioResolverTests.cs

@@ -40,6 +40,9 @@ public class AudioResolverTests
     [InlineData("chapter 01 part 01.mp3", "chapter 01 part 02.mp3")]
     /* Mismatched chapters, parts, and named files. */
     [InlineData("chapter 01.mp3", "part 2.mp3")]
+    [InlineData("book title.mp3", "chapter name.mp3")] // "book title" resolves as alternate version of book based on directory name
+    [InlineData("01 Content.mp3", "01 Credits.mp3")] // resolves as alternate versions of chapter 1
+    [InlineData("Chapter Name.mp3", "Part 1.mp3")]
     public void Resolve_AudiobookDirectory_NoResult(params string[] children)
     {
         var resolved = TestResolveChildren("/parent/book title", children);