Fixed: Ignore special folders inside Blackhole watch folders

(cherry picked from commit e79dd6f8e689617b1fd9f96c639ac300669112c5)

src/NzbDrone.Common/Disk/FileSystemLookupService.cs

@@ -17,37 +17,6 @@ namespace NzbDrone.Common.Disk
         private readonly IDiskProvider _diskProvider;
         private readonly IRuntimeInfo _runtimeInfo;
 
-        private readonly HashSet<string> _setToRemove = new HashSet<string>
-                                                        {
-                                                            // Windows
-                                                            "boot",
-                                                            "bootmgr",
-                                                            "cache",
-                                                            "msocache",
-                                                            "recovery",
-                                                            "$recycle.bin",
-                                                            "recycler",
-                                                            "system volume information",
-                                                            "temporary internet files",
-                                                            "windows",
-
-                                                            // OS X
-                                                            ".fseventd",
-                                                            ".spotlight",
-                                                            ".trashes",
-                                                            ".vol",
-                                                            "cachedmessages",
-                                                            "caches",
-                                                            "trash",
-
-                                                            // QNAP
-                                                            ".@__thumb",
-
-                                                            // Synology
-                                                            "@eadir",
-                                                            "#recycle"
-                                                        };
-
         public FileSystemLookupService(IDiskProvider diskProvider, IRuntimeInfo runtimeInfo)
         {
             _diskProvider = diskProvider;
@@ -158,7 +127,7 @@ namespace NzbDrone.Common.Disk
                                            })
                                            .ToList();
 
-            directories.RemoveAll(d => _setToRemove.Contains(d.Name.ToLowerInvariant()));
+            directories.RemoveAll(d => SpecialFolders.IsSpecialFolder(d.Name));
 
             return directories;
         }

src/NzbDrone.Common/Disk/SpecialFolders.cs

@@ -0,0 +1,47 @@
+using System.Collections.Generic;
+
+namespace NzbDrone.Common.Disk;
+
+public static class SpecialFolders
+{
+    private static readonly HashSet<string> _specialFolders = new HashSet<string>
+    {
+        // Windows
+        "boot",
+        "bootmgr",
+        "cache",
+        "msocache",
+        "recovery",
+        "$recycle.bin",
+        "recycler",
+        "system volume information",
+        "temporary internet files",
+        "windows",
+
+        // OS X
+        ".fseventd",
+        ".spotlight",
+        ".trashes",
+        ".vol",
+        "cachedmessages",
+        "caches",
+        "trash",
+
+        // QNAP
+        ".@__thumb",
+
+        // Synology
+        "@eadir",
+        "#recycle"
+    };
+
+    public static bool IsSpecialFolder(string folder)
+    {
+        if (folder == null)
+        {
+            return false;
+        }
+
+        return _specialFolders.Contains(folder.ToLowerInvariant());
+    }
+}

src/NzbDrone.Core.Test/Download/DownloadClientTests/Blackhole/ScanWatchFolderFixture.cs

@@ -95,5 +95,22 @@ namespace NzbDrone.Core.Test.Download.DownloadClientTests.Blackhole
 
             VerifySingleItem(DownloadItemStatus.Completed);
         }
+
+        [TestCase("@eaDir")]
+        [TestCase(".@__thumb")]
+        public void GetItems_should_not_include_special_subfolders(string folderName)
+        {
+            GivenCompletedItem();
+
+            var targetDir = Path.Combine(_completedDownloadFolder, folderName);
+
+            Mocker.GetMock<IDiskProvider>()
+                .Setup(c => c.GetDirectories(_completedDownloadFolder))
+                .Returns(new[] { targetDir });
+
+            var items = Subject.GetItems(_completedDownloadFolder, TimeSpan.FromMilliseconds(50)).ToList();
+
+            items.Count.Should().Be(0);
+        }
     }
 }

src/NzbDrone.Core/Download/Clients/Blackhole/ScanWatchFolder.cs

@@ -52,7 +52,13 @@ namespace NzbDrone.Core.Download.Clients.Blackhole
         {
             foreach (var folder in _diskScanService.FilterPaths(watchFolder, _diskProvider.GetDirectories(watchFolder)))
             {
-                var title = FileNameBuilder.CleanFileName(Path.GetFileName(folder));
+                var folderName = Path.GetFileName(folder);
+                var title = FileNameBuilder.CleanFileName(folderName);
+
+                if (SpecialFolders.IsSpecialFolder(folderName))
+                {
+                    continue;
+                }
 
                 var newWatchItem = new WatchFolderItem
                 {