Single interview, plus selection test. Test was unlimited time, but a high pass mark. Only 4 questions. General aptitude for programming, not language specific.
Meaning it isn't something you can prepare for, or look up answers in advance. But is based on solid computer science concepts, so a good mark means you are suited to that kind of work.
Interview questions [1]
Question 1
Asked to describe my current role. And highlight where serious problems were being addressed. E.g. dealing with performance or data volume issues.