### Question:
FreePool implements Pool { public void close() { open = false; } FreePool( int maxSize );  FreePool(); void close(); void join(); synchronized void run( final PoolRunnable runnable );  }### Answer:
@Test public void close1() throws Exception { FreePool p = new FreePool( 2 ); p.close(); }
@Test public void close3() throws Exception { FreePool p = new FreePool( 2 ); p.close(); p.close(); }