How to start testing it ?

[Rustem]

Hello, I just read the source code you made for this awesome project. I want to contribute. However I still could not test how everything is working ? How to launch two parallel processes and emulate message exchange in local network ? Could you please provide me with a guide. I tried to start two separate processes, however friendsdb (leveldb) is locked by first running process:
"Uncaught OpenError: IO error: lock ./friendsdb/LOCK: Resource temporarily unavailable", source: events.js (141). Seems it means that I could not use levledb by multiple instances (processes) on the same machine.