You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: client_watchers_service_test.go
    path of file: ./repos/sharingan/grpc-server/v1.33.2/xds/internal/client
    
    the code of the file until where you have to start completion: /*
 *
 * Copyright 2020 gRPC authors.
 *
 * Licens
    
func (s) TestServiceWatchEmptyRDS(t *testing.T) {
	apiClientCh, cleanup := overrideNewAPIClient()
	defer cleanup()

	client, err := New(clientOpts(testXDSServer, true))
	if err != nil {
		t.Fatalf("failed to create client: %v", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	c, err := apiClientCh.Receive(ctx)
	if err != nil {
		t.Fatalf("timeout when waiting for API client to be created: %v", err)
	}
	apiClient := c.(*testAPIClient)

	serviceUpdateCh := testutils.NewChannel()
	client.WatchService(testLDSName, func(update ServiceUpdate, err error) {
		serviceUpdateCh.Send(serviceUpdateErr{u: update, err: err})
	})
	if _, err := apiClient.addWatches[ListenerResource].Receive(ctx); err != nil {
		t.Fatalf("want new watch to start, got error %v", err)
	}
	client.NewListeners(map[string]ListenerUpdate{testLDSName: {RouteConfigName: testRDSName}})
	if _, err := apiClient.addWatches[RouteConfigResource].Receive(ctx); err != nil {
		t.Fatalf("want new watch to start, got error %v", err)
	}

	client.NewRouteConfigs(map[string]RouteConfigUpdate{})
	u, err := serviceUpdateCh.Receive(ctx)
	if err != nil {
		t.Fatalf("failed to get serviceUpdate: %v", err)
	}
	uu := u.(serviceUpdateErr)
	if !cmp.Equal(uu.u, ServiceUpdate{}) {
		t.Errorf("unexpected serviceUpdate: %v, want %v", uu.u, ServiceUpdate{})
	}
	if uu.err == nil {
		t.Errorf("unexpected serviceError: <nil>, want error watcher timeout")
	}
}