func TestData(dom s5.NarrowDom, needInit bool) { d := dom.Data("foo") if d != "" { panic("before any code has run, no data expected") } dom.SetData("foo", "bar") d = dom.Data("foo") if d != "bar" { panic("expected bar after set") } dom.RemoveData("foo") d = dom.Data("foo") if d != "" { panic("after remove, no data expected") } }