### Question:
DefaultNotificationCenter implements NotificationCenter { @Override public void unsubscribe(String messageName, NotificationObserver observer) { removeObserversForMessageName(messageName, observer, globalObservers); }  @Override void subscribe(String messageName, NotificationObserver observer); @Override void unsubscribe(String messageName, NotificationObserver observer); @Override void unsubscribe(NotificationObserver observer); @Override void publish(String messageName, Object... payload); @Override void publish(Object channel, String messageName, Object[] payload); @Override void subscribe(Object channel, String messageName, NotificationObserver observer); @Override void unsubscribe(Object channel, String messageName, NotificationObserver observer); @Override void unsubscribe(Object channel, NotificationObserver observer); @Override void clear();  }### Answer:
@Test public void removeObserverThatWasNotRegisteredYet() { defaultCenter.unsubscribe(TEST_NOTIFICATION, observer1); }