It depends on the department and the position you have applied for. But most of them would be programming excercises. The position I applied for is a programming job which requires coding in C++, two coding questions related to data structures were asked during the face-to-face interview.
Interview questions [1]
Question 1
Since it is the university, most of the research assistants will either be Master's or PhD students. So how long I can work in the position and manage my academic activities were particularly asked during the interview.
I applied online. The process took 2 months. I interviewed at LSU (Baton Rouge, LA) in Jan 2017
Interview
There is no interview process for this position. The advisor selection process is just like you interviewing the professors and choosing what professor you want to work for. You list 3 professors and you're more likely to get your number one pick.