private void assertMaster(ZKWatcher zk, ServerName expectedAddress)
    throws KeeperException, IOException {
    ServerName readAddress = MasterAddressTracker.getMasterAddress(zk);
    assertNotNull(readAddress);
    assertEquals(expectedAddress, readAddress);
  }
Assert there is an active master and that it has the specified address.
@param zk              single Zookeeper watcher
@param expectedAddress the expected address of the master
@throws KeeperException unexpected Zookeeper exception
@throws IOException     if an IO problem is encountered
hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestActiveMasterManager.java