First, a coding test using HackerRank. Some programs to write or complete in limited time (less than 2 hours total).
Then, a video interview with a G-Research employee. I needed to design a program or function while explaining what I was doing to the recruiter. I was quite under stress just before passing this test, but it went well.
Finally, I went to their offices to do also some coding tests, or to describe how I would design a particular program. I could not pass this last test, I do not think I understood perfectly what they were expecting.
Nice experience for me, people were always nice.