public void ControlTreeTraversal()
{
var p = new Page();
p.Controls.Add(new TextBox() { ID = "t1" });
var ph = new PlaceHolder();
ph.Controls.Add(new TextBox() { ID = "t2" });
ph.Controls.Add(new System.Web.UI.WebControls.Label() { ID = "l1" });
p.Controls.Add(ph);
Assert.AreEqual( 1,
(from c in p.GetChildren<System.Web.UI.WebControls.Label>()
where c.ID == "l1" select c).Count() );
Assert.AreEqual(2,
(from c in p.GetChildren<TextBox>() select c).Count());
var t2 = (from c in p.GetChildren<TextBox>() where c.ID == "t2" select c).Single();
Assert.IsNotNull(t2);
Assert.AreEqual( ph, (from c in t2.GetParents<PlaceHolder>() select c).Single() );
}
