Easy. It's just a basic phone screen and then a webcam interview with two people. One part is about OOP, so if you can talk about the four pillars in the most basic way you're fine. The other part is behavioral/experience. If you have any programming experience in any language you can always fall back on that if you can't talk much about the questions given. No drug test if you're concerned, but your client can test you (often doesn't) Look at the other glassdoor interviews and you'll get a VERY clear idea of the questions asked. It's really not hard.