@BeforeClass
  public static void setUpBeforeClass() throws Exception {
    TEST_UTIL.startMiniCluster(3);
    TEST_UTIL.createTable(TABLE_NAME, FAMILY);
    TEST_UTIL.waitTableAvailable(TABLE_NAME);
    TEST_UTIL.getAdmin().balancerSwitch(false, true);
    ASYNC_CONN = ConnectionFactory.createAsyncConnection(TEST_UTIL.getConfiguration()).get();
    assertFalse(ASYNC_CONN.isClosed());
  }
Fix an infinite loop in {@link AsyncNonMetaRegionLocator}, see the comments on HBASE-21943 for
more details.
hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableLocateRegionForDeletedTable.java