Unit test WPF Bindings

I am trying to unit test my WPF databindings using the test suit provided by Microsoft Team System. I would like to be able to test the bindings without showing the window because most of my tests will be for user controls and not actually on a window. Is this possible or is there a better way to do it? The code below works if I show the window, but if I don't, the bindings don't update.

            Window1_Accessor target = new Window1_Accessor();
            UnitTestingWPF.Window1_Accessor.Person p = new UnitTestingWPF.Window1_Accessor.Person() { FirstName = "Shane" };
            Window1 window = (target.Target as Window1);
            window.DataContext = p;         
            //window.Show(); //Only Works when I actually show the window
            //Is it possible to manually update the binding here, maybe?  Is there a better way?
            Assert.AreEqual("Shane", target.textBoxFirstName.Text);  //Fails if I don't Show() the window because the bindings aren't updated