@Test
public void getAlreadyAssignedFields_yieldFieldFromClass() {

    ControllerWithFieldBinding controller = new ControllerWithFieldBinding(
            new Button("myButton"));
    Binder binder = new Binder();
    Map<String, Component> assignedFields = binder
            .getAlreadyAssignedFields(controller);
    assertEquals(1, assignedFields.size());
}