A good senior developer should be able to go out to lunch and know if the candidate has the skills and the right cultural match by the end. There's no need for coding tests or whiteboarding problems. I've seen some of the best developers I've worked with in 40 years of coding get turned away by Google and Apple because of their terrible interview processes. The only thing better than going out to lunch is working with the person for a couple of weeks. Ideally this happens on a paid contract basis. Of course our culture makes it more challenging to switch jobs if you want to work together first, but really no other interview process has ever provided good data.