The interview I know is 2 parts. First the HR will send you a test according to the job's technique requirement. And if your performance is satisfied, then you will have another interview with the team leader of the hiring manager. Since it's a very small startup from alaTest, this interview is directly with their CTO.
And because they want to have really senior engineer while their recruiter was selecting junior engineer for them. So the interview didn't last long, since both don't wanna waste the time.