@Override
    public StateMachineEngine getStateMachineEngine() {
      return new StateMachineEngine() {
        @Override
        public boolean registerStateModelFactory(String stateModelDef,
            StateModelFactory<? extends StateModel> factory) {
          MockHelixManager.this.stateModelDef = stateModelDef;
          stateModelFactory = factory;
          return true;
        }

        @Override
        public boolean registerStateModelFactory(String stateModelDef, StateModelFactory<? extends StateModel> factory,
            String factoryName) {
          throw new IllegalStateException("Not implemented");
        }

        @Override
        public boolean removeStateModelFactory(String stateModelDef, StateModelFactory<? extends StateModel> factory) {
          return false;
        }

        @Override
        public boolean removeStateModelFactory(String stateModelDef, StateModelFactory<? extends StateModel> factory,
            String factoryName) {
          return false;
        }

        @Override
        public StateModelFactory<? extends StateModel> getStateModelFactory(String stateModelName) {
          return null;
        }

        @Override
        public StateModelFactory<? extends StateModel> getStateModelFactory(String stateModelName, String factoryName) {
          return null;
        }

        @Override
        public MessageHandler createHandler(Message message, NotificationContext context) {
          return null;
        }

        @Override
        public String getMessageType() {
          return null;
        }

        @Override
        public List<String> getMessageTypes() {
          return null;
        }

        @Override
        public void reset() {

        }
      };
    }
A mock implementation of the {@link HelixManager} for exclusive use for testing the {@link HelixParticipant}
ambry-clustermap/src/test/java/com/github/ambry/clustermap/MockHelixManagerFactory.java