After sending my CV, they answered with a Codility on-line test for me to do. After successfully completing the test(about 80% score), they replied back after a week saying that I was invited to an on-site interview. It had two parts, one with the team leader, in which I was asked several questions about my background and computer science knowledge. The second part of the interview was a bit more technical, they asked me about some Java questions, concurrency topics and I had to go through the third Codility task(the one that I didn't complete 100%)to see if I could spot the mistakes that I did.