fix(dock): enforce tree invariants, sync selection, and fix AOT warnings

src/Test/Ghost.UnitTest/DockingModelTest.cs

@@ -0,0 +1,123 @@
+using Ghost.Editor.Core.Controls.Internal.Docking;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Ghost.UnitTest;
+
+[TestClass]
+public class DockingModelTest
+{
+    [TestMethod]
+    public void TestAddChild_SetsParent()
+    {
+        var group = new DockGroupNode();
+        var child = new DockPanelNode();
+
+        group.AddChild(child);
+
+        Assert.AreEqual(group, child.Parent);
+        Assert.IsTrue(group.Children.Contains(child));
+    }
+
+    [TestMethod]
+    public void TestAddChild_RemovesFromOldParent()
+    {
+        var group1 = new DockGroupNode();
+        var group2 = new DockGroupNode();
+        var child = new DockPanelNode();
+
+        group1.AddChild(child);
+        group2.AddChild(child);
+
+        Assert.AreEqual(group2, child.Parent);
+        Assert.IsFalse(group1.Children.Contains(child));
+        Assert.IsTrue(group2.Children.Contains(child));
+    }
+
+    [TestMethod]
+    public void TestAddChild_PreventsCycle()
+    {
+        var group1 = new DockGroupNode();
+        var group2 = new DockGroupNode();
+
+        group1.AddChild(group2);
+        bool thrown = false;
+        try
+        {
+            group2.AddChild(group1);
+        }
+        catch (InvalidOperationException)
+        {
+            thrown = true;
+        }
+        Assert.IsTrue(thrown);
+    }
+
+    [TestMethod]
+    public void TestRemoveChild_ClearsParent()
+    {
+        var group = new DockGroupNode();
+        var child = new DockPanelNode();
+
+        group.AddChild(child);
+        group.RemoveChild(child);
+
+        Assert.IsNull(child.Parent);
+        Assert.IsFalse(group.Children.Contains(child));
+    }
+
+    [TestMethod]
+    public void TestPanel_SelectionSync_IndexToItem()
+    {
+        var panel = new DockPanelNode();
+        var item1 = new object();
+        var item2 = new object();
+
+        panel.Items.Add(item1);
+        panel.Items.Add(item2);
+
+        panel.SelectedIndex = 1;
+        Assert.AreEqual(item2, panel.SelectedItem);
+
+        panel.SelectedIndex = 0;
+        Assert.AreEqual(item1, panel.SelectedItem);
+
+        panel.SelectedIndex = -1;
+        Assert.IsNull(panel.SelectedItem);
+    }
+
+    [TestMethod]
+    public void TestPanel_SelectionSync_ItemToIndex()
+    {
+        var panel = new DockPanelNode();
+        var item1 = new object();
+        var item2 = new object();
+
+        panel.Items.Add(item1);
+        panel.Items.Add(item2);
+
+        panel.SelectedItem = item2;
+        Assert.AreEqual(1, panel.SelectedIndex);
+
+        panel.SelectedItem = item1;
+        Assert.AreEqual(0, panel.SelectedIndex);
+
+        panel.SelectedItem = null;
+        Assert.AreEqual(-1, panel.SelectedIndex);
+    }
+
+    [TestMethod]
+    public void TestPanel_CollectionChanged_UpdatesSelection()
+    {
+        var panel = new DockPanelNode();
+        var item1 = new object();
+        
+        panel.Items.Add(item1);
+        Assert.AreEqual(0, panel.SelectedIndex);
+        Assert.AreEqual(item1, panel.SelectedItem);
+
+        panel.Items.Remove(item1);
+        Assert.AreEqual(-1, panel.SelectedIndex);
+        Assert.IsNull(panel.SelectedItem);
+    }
+}