Flush() error
	// AddVirtualServer creates the specified virtual server.
	AddVirtualServer(*VirtualServer) error
	// UpdateVirtualServer updates an already existing virtual server.  If the virtual server does not exist, return error.
	UpdateVirtualServer(*VirtualServer) error
	// DeleteVirtualServer deletes the specified virtual server.  If the virtual server does not exist, return error.

	// make sure no destination present when creating new service
	f.Destinations[key] = make([]*utilipvs.RealServer, 0)
	return nil
}

// UpdateVirtualServer is a fake implementation, it updates the VirtualServer in the cache store.
func (f *FakeIPVS) UpdateVirtualServer(serv *utilipvs.VirtualServer) error {
	if serv == nil {
		return fmt.Errorf("failed to update service, service can't be nil")
	}
	key := toServiceKey(serv)

	}
	runner.mu.Lock()
	defer runner.mu.Unlock()
	return runner.ipvsHandle.NewService(svc)
}

// UpdateVirtualServer is part of ipvs.Interface.
func (runner *runner) UpdateVirtualServer(vs *VirtualServer) error {
	svc, err := toIPVSService(vs)
	if err != nil {
		return fmt.Errorf("could not convert local virtual server to IPVS service: %w", err)
	}
	runner.mu.Lock()

	// Update virtual server
	vs12 := &utilipvs.VirtualServer{
		Address:  netutils.ParseIPSloppy("1.2.3.4"),
		Port:     uint16(80),
		Protocol: string("TCP"),
		Flags:    utilipvs.FlagPersistent,
	}
	err = fake.UpdateVirtualServer(vs12)
	if err != nil {
		t.Errorf("Fail to update virtual server, error: %v", err)
	}
	// Check the updated virtual server
	got12, err := fake.GetVirtualServer(vs1)
	if err != nil {

			// IPVS service was changed, update the existing one
			// During updates, service VIP will not go down
			proxier.logger.V(3).Info("IPVS service was changed", "serviceName", svcName)
			if err := proxier.ipvs.UpdateVirtualServer(vs); err != nil {
				proxier.logger.Error(err, "Failed to update IPVS service")
				return err
			}
		}
	}

	// bind service address to dummy interface
	if bindAddr {

}
func (f *fakeIpvs) AddVirtualServer(*utilipvs.VirtualServer) error {
	if f.ipvsErr == "AddVirtualServer" {
		return fmt.Errorf("oops")
	}
	f.vsCreated = true
	return nil
}
func (f *fakeIpvs) UpdateVirtualServer(*utilipvs.VirtualServer) error {
	return nil
}
func (f *fakeIpvs) DeleteVirtualServer(*utilipvs.VirtualServer) error {
	if f.ipvsErr == "DeleteVirtualServer" {
		return fmt.Errorf("oops")
	}
	return nil
}