PersistedSessionManager implements SessionManager<T> { @Override public void setActiveSession(T session) { if (session == null) { throw new IllegalArgumentException("Session must not be null!"); } restoreAllSessionsIfNecessary(); internalSetSession(session.getId(), session, true); } PersistedSessionManager(PreferenceStore preferenceStore,
            SerializationStrategy<T> serializer, String prefKeyActiveSession,
            String prefKeySession);   PersistedSessionManager(PreferenceStore preferenceStore,
            SerializationStrategy<T> serializer, ConcurrentHashMap<Long, T> sessionMap,
            ConcurrentHashMap<Long, PreferenceStoreStrategy<T>> storageMap,
            PreferenceStoreStrategy<T> activesSessionStorage,
            String prefKeySession); @Override T getActiveSession(); @Override void setActiveSession(T session); @Override void clearActiveSession(); @Override T getSession(long id); @Override void setSession(long id, T session); @Override Map<Long, T> getSessionMap(); @Override void clearSession(long id);  }
@Test public void testSetActiveSession_nullSession() { try { sessionManager.setActiveSession(null); fail(); } catch (Exception e) { assertTrue(e instanceof IllegalArgumentException); } }