Return uncategorized commands for a null category in GetCommandsByCategory [patch]

Keybinding.Test/CommandCategoryFilterTests.cs

@@ -0,0 +1,56 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.Keybinding.Test;
+
+using ktsu.Keybinding.Core.Models;
+using ktsu.Keybinding.Core.Services;
+
+[TestClass]
+public class CommandCategoryFilterTests
+{
+	private static readonly string[] UncategorizedIds = ["file.save"];
+	private static readonly string[] EditIds = ["edit.copy"];
+
+	private CommandRegistry _registry = null!;
+
+	[TestInitialize]
+	public void Setup()
+	{
+		_registry = new CommandRegistry();
+		_registry.RegisterCommand(new Command("file.save", "Save"));
+		_registry.RegisterCommand(new Command("edit.copy", "Copy", null, "Edit"));
+	}
+
+	[TestMethod]
+	[DataRow(null)]
+	[DataRow("")]
+	[DataRow("  ")]
+	public void GetCommandsByCategory_BlankCategory_ReturnsOnlyUncategorizedCommands(string? category)
+	{
+		string[] ids = [.. _registry.GetCommandsByCategory(category).Select(c => (string)c.Id)];
+
+		CollectionAssert.AreEquivalent(UncategorizedIds, ids);
+	}
+
+	[TestMethod]
+	[DataRow("Edit")]
+	[DataRow("edit")]
+	[DataRow(" Edit ")]
+	public void GetCommandsByCategory_NamedCategory_ReturnsOnlyThatCategory(string category)
+	{
+		string[] ids = [.. _registry.GetCommandsByCategory(category).Select(c => (string)c.Id)];
+
+		CollectionAssert.AreEquivalent(EditIds, ids);
+	}
+
+	[TestMethod]
+	public void GetCommandsByCategory_PassingACommandsOwnCategoryBack_FindsThatCommand()
+	{
+		foreach (Command command in _registry.GetAllCommands())
+		{
+			Assert.IsTrue(
+				_registry.GetCommandsByCategory(command.Category).Contains(command),
+				$"{command.Id} should be in the group for its own category.");
+		}
+	}
+}

Keybinding/Contracts/ICommandRegistry.cs

@@ -39,7 +39,7 @@ public interface ICommandRegistry
 	/// <summary>
 	/// Gets commands by category
 	/// </summary>
-	/// <param name="category">The category to filter by</param>
+	/// <param name="category">The category to filter by, compared case-insensitively. Null, empty or whitespace selects the uncategorized commands.</param>
 	/// <returns>Collection of commands in the specified category</returns>
 	public IReadOnlyCollection<Command> GetCommandsByCategory(string? category);
 

Keybinding/Services/CommandRegistry.cs

@@ -40,7 +40,7 @@
 	{
 		return string.IsNullOrWhiteSpace(commandId)
 			? throw new ArgumentException("Command ID cannot be null or whitespace", nameof(commandId))
 			: _commands.TryGetValue(commandId.Trim(), out Command? command) ? command : null;
 	}
 
 	/// <inheritdoc/>
@@ -57,9 +57,13 @@
 	{
 		lock (_lock)
 		{
-			string? normalizedCategory = category?.Trim();
+			// Compare explicitly: a null CommandCategory converts to "" rather than null, so passing
+			// it straight to string.Equals made null find nothing while "" found the uncategorized commands.
+			string? wanted = string.IsNullOrWhiteSpace(category) ? null : category.Trim();
 			return _commands.Values
-				.Where(c => string.Equals(c.Category, normalizedCategory, StringComparison.OrdinalIgnoreCase))
+				.Where(c => wanted is null
+					? string.IsNullOrWhiteSpace(c.Category)
+					: string.Equals(c.Category?.ToString(), wanted, StringComparison.OrdinalIgnoreCase))
 				.ToList()
 				.AsReadOnly();
 		}