integration: add 'NoClient' to 'ClusterV3'

Useful for custom clientv3 settings.

Signed-off-by: Gyu-Ho Lee <[email protected]>

integration/cluster.go

@@ -97,6 +97,7 @@ type ClusterConfig struct {
 	ClientTLS             *transport.TLSInfo
 	DiscoveryURL          string
 	UseGRPC               bool
+	NoClient              bool
 	QuotaBackendBytes     int64
 	MaxTxnOps             uint
 	MaxRequestBytes       uint
@@ -986,14 +987,15 @@ func NewClusterV3(t *testing.T, cfg *ClusterConfig) *ClusterV3 {
 		cluster: NewClusterByConfig(t, cfg),
 	}
 	clus.Launch(t)
-	for _, m := range clus.Members {
-		client, err := NewClientV3(m)
-		if err != nil {
-			t.Fatalf("cannot create client: %v", err)
+	if !cfg.NoClient {
+		for _, m := range clus.Members {
+			client, err := NewClientV3(m)
+			if err != nil {
+				t.Fatalf("cannot create client: %v", err)
+			}
+			clus.clients = append(clus.clients, client)
 		}
-		clus.clients = append(clus.clients, client)
 	}
-
 	return clus
 }