As it was explained in detail, there will be (after they have screened your cv) online tests first. Afterwards you will be invited for a interview with the manager (which was a pleasant experience, the managers are warm and friendly). If all goes well, you'll have to withstand a day in the assessment which consists of the following: in tray exercise, business case, interview with HR, verification of online tests.
In overall, it was a very interesting experience, the good thing is that they work according the waterfall method (meaning: they select only one person for the assessment, if he/she fails the second on the list gets the opportunity etc.). What left a very good impression on me was the hospitality and warmness of the organisation in a professional way. The only downside I can say about the process is that it takes some time, you have to be patient for some months.