How to unit test removeObserver in dealloc

I am trying to write a failing test that would verify removeObserver is called when an object is dealloc'ed however, do to the fact that the object is no longer around, how do I determine this functionality? Am I going about testing this incorrectly? I am using OCMockito for my mocking framework.

Here is what I have so far.

- (void)test_dealloc_NotificationCenterRemoveObserver_ShouldCallRemoveObserver {
    self.mockNotificationCenter = mock([NSNotificationCenter class]);
    self.sut.defaultNotificationCenter = self.mockNotificationCenter;

    self.sut = nil;

    [MKTVerify(self.mockNotificationCenter) removeObserver:anything() name:UIContentSizeCategoryDidChangeNotification object:nil];
}