@Test
public synchronized void pop() {

    disablePushAnimation(child1, child2);
    uut.push(child1, new CommandListenerAdapter());
    uut.push(child2, new CommandListenerAdapter() {
        @Override
        public void onSuccess(String childId) {
            assertContainsOnlyId(child2.getId(), child1.getId());
            uut.pop(Options.EMPTY, new CommandListenerAdapter());
            assertContainsOnlyId(child1.getId());
        }
    });
}