### Question:
HBaseClient { public static HBaseClient getInstance() { if (instance == null) { synchronized (HBaseClient.class) { if (instance == null) { instance = new HBaseClient(); } } } return instance; } private  HBaseClient(); private  HBaseClient(String quorum); static HBaseClient getInstance(); static HBaseClient getInstance(String quorum); void insert(HBaseConfig config, Event event); void update(HBaseConfig config, Event event); void delete(HBaseConfig config, Event event); void close();  }### Answer:
@Test public void test_HBaseClient() { HBaseClient client = HBaseClient.getInstance(); Assert.assertNotNull(client); }