How to system-test real-time react multiplayer game?

I am working on a real-time multiplayer board game built using node and socket.io for the backend and react + redux for the frontend. It's the first time I'm doing a project of this sort, i.e. real-time and multiplayer.

I am unsure on how best to go about integration/system testing. How can I actually automate spinning up, say 10 frontends and having them play a game together? Should I use a testing framework for this and if so, which one would be a good choice and why?