Add test for Visualization to_json
Add test for Visualization to_json

chiu/vincent,qiwsir/vincent,JPO1/vincent,myusuf3/vincent,springcoil/vincent,xunyou/vincent,xunyou/vincent,taohaoge/vincent,wrobstory/vincent,JPO1/vincent,qiwsir/vincent,myusuf3/vincent,wrobstory/vincent,KAPPS-/vincent,CrazyGuo/vincent,KAPPS-/vincent,chiu/vincent,springcoil/vincent,taohaoge/vincent,CrazyGuo/vincent