There was a two-day assessment centre. The first day was group work and an interview with HR; The second day was technical interview, and two technical leads learned more about my professional background.
When meet with HR, questions are mainly about my soft skills. e.g. Describe the most impressive project you have in the university and why? For technical questions, I was asked about data structure, algorithm, database and multi thread etc.
Tips: Be confident and relax during the interview. Have a review about all interesting projects and activities you have and match them with both soft skills and technical skills.