Regression tests for metadata-tab session restore

The path-based restore (SessionSettings.ActiveTreeViewPath +
FindNodeByPath) already round-trips through the metadata sub-tree's
stable ToString() values — these tests pin that down: selecting
TypeDef and a debug-only Document table both save paths whose final
segments resolve back to the originating node, including the second
"Metadata: Debug Metadata (Embedded)" hop into the embedded PDB
sub-tree.

Assisted-by: Claude:claude-opus-4-7:Claude Code

ILSpy.Tests/Metadata/MetadataTabSessionRestoreTests.cs

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+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System.Linq;
+using System.Threading.Tasks;
+
+using Avalonia.Headless.NUnit;
+
+using AwesomeAssertions;
+
+using ILSpy;
+using ILSpy.AppEnv;
+using ILSpy.Commands;
+using ILSpy.Metadata;
+using ILSpy.Metadata.CorTables;
+using ILSpy.TreeNodes;
+using ILSpy.ViewModels;
+using ILSpy.Views;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests.Metadata;
+
+[TestFixture]
+public class MetadataTabSessionRestoreTests
+{
+	[AvaloniaTest]
+	public async Task Selecting_A_Metadata_Table_Saves_Its_Path_And_Round_Trips_Through_FindNodeByPath()
+	{
+		// SessionSettings.ActiveTreeViewPath records the selection on every change so a
+		// restart (or a tree-path lookup) can land back on the same node. The metadata
+		// sub-tree's ToString() values must be stable for that round-trip to work.
+
+		var window = AppComposition.Current.GetExport<MainWindow>();
+		window.Show();
+		var vm = (MainWindowViewModel)window.DataContext!;
+		await vm.AssemblyTreeModel.WaitForAssembliesAsync(minimumCount: 1);
+
+		var coreLibName = typeof(object).Assembly.GetName().Name!;
+		var assemblyNode = vm.AssemblyTreeModel.FindNode<AssemblyTreeNode>(coreLibName);
+		assemblyNode.EnsureLazyChildren();
+		var metadataNode = assemblyNode.Children.OfType<MetadataTreeNode>().Single();
+		metadataNode.EnsureLazyChildren();
+		var tablesNode = metadataNode.Children.OfType<MetadataTablesTreeNode>().Single();
+		tablesNode.EnsureLazyChildren();
+		var typeDefNode = tablesNode.Children.OfType<TypeDefTableTreeNode>().Single();
+
+		vm.AssemblyTreeModel.SelectNode(typeDefNode);
+
+		var settings = AppComposition.Current.GetExport<SettingsService>().SessionSettings;
+		var savedPath = settings.ActiveTreeViewPath;
+		savedPath.Should().NotBeNull("selecting a tree node must populate SessionSettings.ActiveTreeViewPath");
+		savedPath!.Should().EndWith(new[] { "Metadata: Metadata", "Tables", "TypeDef" },
+			"the saved path mirrors the metadata sub-tree's stable ToString chain");
+
+		// Round-trip the saved path through the tree's lookup helper — what the restart
+		// code path uses. The walked node must be the very same TypeDef table node.
+		var restored = vm.AssemblyTreeModel.FindNodeByPath(savedPath, returnBestMatch: false);
+		ReferenceEquals(restored, typeDefNode).Should().BeTrue(
+			"FindNodeByPath must resolve the saved path back to the original metadata-table node");
+	}
+
+	[AvaloniaTest]
+	public async Task Embedded_PDB_Metadata_Path_Round_Trips_Through_FindNodeByPath()
+	{
+		// Embedded PDB sub-trees nest a second MetadataTreeNode under DebugDirectoryTreeNode.
+		// The path-restore must walk through both Metadata folders and land on a debug-only
+		// table.
+
+		var window = AppComposition.Current.GetExport<MainWindow>();
+		window.Show();
+		var vm = (MainWindowViewModel)window.DataContext!;
+		await vm.AssemblyTreeModel.WaitForAssembliesAsync(minimumCount: 1);
+
+		var testDllPath = typeof(ICSharpCode.Decompiler.Metadata.MetadataFile).Assembly.Location;
+		var registry = AppComposition.Current.GetExport<MainMenuCommandRegistry>();
+		var openCommand = registry.Commands
+			.Single(c => c.Metadata.Header == nameof(ICSharpCode.ILSpy.Properties.Resources._Open))
+			.CreateExport().Value;
+		openCommand.Execute(testDllPath);
+
+		await Waiters.WaitForAsync(() =>
+			vm.AssemblyTreeModel.AssemblyList!.GetAssemblies().Any(a =>
+				string.Equals(a.FileName, testDllPath, System.StringComparison.OrdinalIgnoreCase)));
+		var loaded = vm.AssemblyTreeModel.AssemblyList!.GetAssemblies()
+			.First(a => string.Equals(a.FileName, testDllPath, System.StringComparison.OrdinalIgnoreCase));
+		await loaded.GetLoadResultAsync();
+
+		var assemblyNode = vm.AssemblyTreeModel.FindNode<AssemblyTreeNode>(loaded.ShortName);
+		assemblyNode.EnsureLazyChildren();
+		var metadataNode = assemblyNode.Children.OfType<MetadataTreeNode>().Single();
+		metadataNode.EnsureLazyChildren();
+		var debugDirectoryNode = metadataNode.Children.OfType<DebugDirectoryTreeNode>().Single();
+		debugDirectoryNode.EnsureLazyChildren();
+		var embeddedPdbNode = debugDirectoryNode.Children.OfType<MetadataTreeNode>().Single();
+		embeddedPdbNode.EnsureLazyChildren();
+		var pdbTables = embeddedPdbNode.Children.OfType<MetadataTablesTreeNode>().Single();
+		pdbTables.EnsureLazyChildren();
+		var documentTable = pdbTables.Children.OfType<global::ILSpy.Metadata.DebugTables.DocumentTableTreeNode>().Single();
+
+		vm.AssemblyTreeModel.SelectNode(documentTable);
+
+		var settings = AppComposition.Current.GetExport<SettingsService>().SessionSettings;
+		var savedPath = settings.ActiveTreeViewPath;
+		savedPath!.Should().Contain("Metadata: Debug Metadata (Embedded)",
+			"the embedded PDB's MetadataTreeNode title must appear in the saved path so a restart can re-walk into it");
+		savedPath.Should().EndWith(new[] { "Document" });
+
+		var restored = vm.AssemblyTreeModel.FindNodeByPath(savedPath, returnBestMatch: false);
+		ReferenceEquals(restored, documentTable).Should().BeTrue();
+	}
+}