How to test node - ember app

I'm wondering how can I make tests to simulate user interactions in my app.

1.- Should I do it separately? (client side - server side)

2.- In Ember's official web page I notice that they're using Qunit to make his test, Is this the best option? Can i use another one? Can I use this in the server side too?

I have many questions on my head right now, so I hope you can explain it to me, or maybe any helpful link.

Thanks you!