public NodeMgr getNodeMgr() {
        return nodeMgr;
    }
@Test(expected = DdlException.class)
    public void testAddRepeatedFe() throws Exception {
        GlobalStateMgr globalStateMgr = mockGlobalStateMgr();
        globalStateMgr.getNodeMgr().addFrontend(FrontendNodeType.FOLLOWER, "127.0.0.1", 1000);
    }