test: add TableTreeNode unit test (#364)

Co-authored-by: alex chow <zhouchuanglin@gmail.com>

Author: ArgoZhang

test/UnitTest/Components/TableTreeNodeTest.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Argo Zhang (argo@163.com). All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+// Website: https://www.blazor.zone or https://argozhang.github.io/
+
+using BootstrapBlazor.Shared;
+
+namespace UnitTest.Components;
+
+public class TableTreeNodeTest
+{
+    [Fact]
+    public void Parent_Ok()
+    {
+        var node = new TableTreeNode<Foo>(new Foo() { Name = "Test" });
+        var target = (IExpandableNode<Foo>)node;
+        Assert.Null(target.Parent);
+    }
+}