2 assessment tests. First was online, critical thinking, numerical computation, verbal reasoning and critical thinking questions. Second assessment was at a CBT centre, you are assigned to a centre in Lagos, Abuja, Kano, or Port-Harcourt, depending on your stated address; same type of questions in the first stage but this also includes personality and integrity tests.
If you scale through these, you go through 2 rounds of interviews. First with HR, second with top management. Success in those stages leads to your taking medical tests at a health care facility close enough to you.
Get through all these stages and you get an offer. Was a rather quick process for me though. From application closing to getting an offer within 1 month. One disadvantage might be having to move to Lagos and work from Victoria Island if you're not based there as all tech offices are located on the island.