public void TestAttachChild()
{
_tree.InsertAsRoot(0);
_tree.InsertAsLc(_tree.Root, 1);
_tree.InsertAsRc(_tree.Root, 2);
//new tree
var newTree = new BinTree <int>();
newTree.InsertAsRoot(5);
_tree.AttachAsLc(_tree.Root, newTree);
Assert.AreEqual(_tree.Size, 3);
Assert.AreEqual(_tree.Root.LChild.Data, 5);
}