It started by a phone call interview, asking you to introduce yourself as usual, and why you're interested in the job vacancy you applied for.
If you passed, you'll get invited to a written technical exam. You will answer questions related to software engineering, and specifically software testing, and some basic algorithms. If you have a good foundation, you'll crash it.
If you passed the exam, they'll call you for an on-site interview. It's more exhaustive, putting you in real situations, asking you about your previous projects, along with some basic definitions. Overall, It was comfortable, and the interviewers were very helpful.