### Question:
FastFailFilter { public static boolean checkDBGroupFastFailOpen(String dbGroupName) { boolean ret = false; if (failFastDBGroups.containsKey(dbGroupName)) { ret = (System.currentTimeMillis() <= failFastDBGroups.get(dbGroupName)); if (!ret) { failFastDBGroups.remove(dbGroupName); logger.info(String .format("Fast fail DBGroup [%s] has been removed cause of overdue", dbGroupName)); } } return ret; }  static void update(); static boolean checkDBGroupFastFailOpen(String dbGroupName);  }### Answer:
@Test public void testFastFailFilter() { DALGroup eus = new DALGroup("eus", "eus", "eus"); ZKCache zkCache = new ZKCache("eus"); DBChannelDispatcher holdereus = new DBChannelDispatcher(eus, zkCache); DBChannelDispatcher.getHolders().put("eus", holdereus); SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss"); Calendar cal = Calendar.getInstance(); cal.add(Calendar.SECOND, +3); zkCache.setZkCfg(Constants.MASTER_HEARTBEAT_FASTFAIL_PERIOD, format.format(cal.getTime())); try { Assert.assertTrue(FastFailFilter.checkDBGroupFastFailOpen("eus")); Thread.sleep(4000); Assert.assertFalse(FastFailFilter.checkDBGroupFastFailOpen("eus")); } catch (InterruptedException e) { e.printStackTrace(); } }