@Test
public void testFindComponentById_componentDoesntExistInTree_nullReturned() {

    @SuppressWarnings("serial")
    Layout layout = new VerticalLayout() {
        {
            Button b = new Button();
            b.setId("button");
            addComponent(b);
        }
    };
    Component c = Clara.findComponentById(layout, "foobar");
    assertNull(c);
}