Skip Finder's Icon\r folder-icon file instead of failing it [patch]

IconHelper.Test/ProcessDirectoryTests.cs

@@ -187,6 +187,37 @@ public void SkipsFileManagerMetadataWithoutCountingItAsFailed()
 		Assert.AreEqual(1, Directory.GetFiles(output).Length);
 	}
 
+	[TestMethod]
+	public void TreatsFindersCustomFolderIconFileAsMetadata()
+	{
+		Assert.IsTrue(IconHelper.IsFileManagerMetadata("Icon\r"), "Finder's custom folder icon file is metadata, not an icon.");
+		Assert.IsFalse(IconHelper.IsFileManagerMetadata("Icon"), "Only the CR-suffixed name is Finder's; a plain Icon file is still an input.");
+		Assert.IsFalse(IconHelper.IsFileManagerMetadata("icon\r"), "Finder always writes the name with a capital I.");
+	}
+
+	[TestMethod]
+	public void SkipsFindersCustomFolderIconFileWithoutCountingItAsFailed()
+	{
+		// Windows can't create a file name containing a carriage return, and a folder that held one
+		// would not reach the tool there anyway, so the batch-level check runs on Linux and macOS.
+		if (OperatingSystem.IsWindows())
+		{
+			Assert.Inconclusive("Windows cannot create a file named \"Icon\\r\".");
+		}
+
+		using TempDirectory temp = new();
+		string input = temp.Combine("in");
+		string output = temp.Combine("out");
+		Directory.CreateDirectory(input);
+		File.WriteAllBytes(Path.Join(input, "Icon\r"), []);
+		WritePng(Path.Join(input, "star.png"), 64);
+
+		BatchResult result = IconHelper.ProcessDirectory(ArgumentsFor(input, output), NamedColors.White);
+
+		Assert.AreEqual(new BatchResult(1, 0), result, "Finder's Icon\\r file should be neither written nor failed.");
+		Assert.AreEqual(IconHelper.ExitSuccess, IconHelper.ExitCodeFor(result));
+	}
+
 	[TestMethod]
 	public void ReportsAndSkipsAFileThatCannotBeOpened()
 	{

IconHelper/IconHelper.cs

@@ -190,12 +190,15 @@ internal static BatchResult ProcessDirectory(Arguments args, Color color)
 
 	/// <summary>
 	/// Names that Finder and Explorer drop into any folder they open: dot-files such as .DS_Store and
-	/// ._ AppleDouble files, plus Thumbs.db, ehthumbs.db and desktop.ini. They are not icons, so they
-	/// count as neither written nor failed; counting them as failures made every batch on such a
-	/// folder exit 2 and taught scripts to ignore the code that reports real decode failures.
+	/// ._ AppleDouble files, plus Thumbs.db, ehthumbs.db and desktop.ini, and the "Icon\r" file Finder
+	/// writes when a folder is given a custom icon (its data fork is empty; the icon lives in the
+	/// resource fork). They are not icons, so they count as neither written nor failed; counting them
+	/// as failures made every batch on such a folder exit 2 and taught scripts to ignore the code that
+	/// reports real decode failures.
 	/// </summary>
 	internal static bool IsFileManagerMetadata(string fileName)
 		=> fileName.StartsWith('.')
+		|| fileName.Equals("Icon\r", StringComparison.Ordinal)
 		|| fileName.Equals("Thumbs.db", StringComparison.OrdinalIgnoreCase)
 		|| fileName.Equals("ehthumbs.db", StringComparison.OrdinalIgnoreCase)
 		|| fileName.Equals("desktop.ini", StringComparison.OrdinalIgnoreCase);