### Question:
ZkClusterControllerLeaderSelector implements ClusterControllerLeaderSelector, ConnectionStateListener { @Override public void start() { checkNotNull(leaderSelector, "leader selector is not initialized"); leaderSelector.autoRequeue(); leaderSelector.start(); } ZkClusterControllerLeaderSelector(CuratorFramework client,
                                             String zkRootPath); @Override void initialize(ClusterControllerLeader leader); @Override void start(); @Override void close(); @Override void stateChanged(CuratorFramework client, ConnectionState newState);  }### Answer:
@Test(expected = NullPointerException.class) public void testStartBeforeInitialize() { selector.start(); }