There was a straightforward Hacker Rank test: solve several problems from Hacker Rank in one hour. If you have played with Hacker Rank for recreation, you will know the kind of problems that can be set. After passing that, I was invited for an on site interview. My recruiter had briefed me to expect a written test followed by an interview, but as with most recruiters, he was incorrect and I was unexpectedly plunged directly into a two man interview. After discussing my current work, I was asked to solve two simple computer science questions on paper. These are the kind of problems you would find on the easy pages of Project Euler. Still, I would advise anyone who applies for these positions: make sure you are very strong on the basics. Even a hint you don't know the fundamentals of computer science inside out, and you will struggle. Afterwards a member of the internal HR team told me I had not been successful, for being too slow in solving the problems. She invited me to apply again in future.

The interview process was thorough and well structured. It focused primarily on data structures and algorithms, and the level was broadly in line with what you would expect for a software engineering interview of this type. I cannot share specific details of the questions, but standard preparation in algorithms, data structures, problem solving, and coding under interview conditions should be sufficient. Overall, it felt rigorous but fair.