### Question:
PlainMailboxManager implements MailboxManager { public void sessionNotify( Object event ) throws Exception { if (event == Session.UP) { up = true; } else if (event == Session.DOWN) { up = false; unregisterAll(); } session.sessionNotify( event ); } PlainMailboxManager( TransportMessage transport, String uri,
		Resources resources );  PlainMailboxManager( TransportMessage transport, URL uri,
		Resources resources ); TransportMessage getTransport(); @Override String toString(); boolean sessionMessage( Who sender, Message msg ); void transportMessage( Who recipient, Message msg ); Mailbox transportCall( Who recipient, Message msg ); void register( Mailbox mb ); void unregister( Mailbox mb ); Mailbox getMailbox( Long msgid ); void redeliver( Who sender, Message msg ); int size(); Object sessionQuery( Object query ); void sessionControl( Object control, Object value ); void sessionNotify( Object event ); Object transportQuery( Object query ); void transportControl( Object control, Object value ); void transportNotify( Object event ); SessionMessage getSession(); void setSession( SessionMessage session );  }### Answer:
@Test public void sessionNotify() throws Exception { Object EVENT = "foo"; assertNull( session.what ); assertNull( session.event ); mmgr.sessionNotify( EVENT ); assertSame( What.SESSION_NOTIFY, session.what ); assertSame( EVENT, session.event ); }