### Question:
TraceeSessionListener implements HttpSessionListener { @Override public final void sessionDestroyed(HttpSessionEvent httpSessionEvent) { backend.remove(TraceeConstants.SESSION_ID_KEY); } @SuppressWarnings("unused")  TraceeSessionListener(); protected  TraceeSessionListener(TraceeBackend backend); @Override final void sessionCreated(HttpSessionEvent httpSessionEvent); @Override final void sessionDestroyed(HttpSessionEvent httpSessionEvent);  }### Answer:
@Test public void cleanupSessionOnDestroy() { unit.sessionDestroyed(mock(HttpSessionEvent.class)); verify(backend).remove(SESSION_ID_KEY); }