Overview:
I was referred to Mercari's "Merpay" division. I went straight to the technical "take home assignment". There were two ways that you could perform this take home assignment. 1) Implement as a senior developer. 2) Implement in such a way to teach another junior developer how to develop. I chose the former. This is getting more and more common in the field and I detest these assignments. Generally, companies expect you to spend an exorbitant amount of time on these assignments, then they spend a very little amount of time, if any time, assessing your code. This is difficult to do if you have a full-time job and are looking around for other opportunities. I'm saddened to say that Mercari is the same. I got very little feedback for my 25 - 30 hours sunk into their take home program. I would strongly advise against spending any serious thought or time on this assignment if you value your time. It might be worth it if you have a spare related personal github project that you've done before.
The Assignment:
The assignment was simple in concept but difficult to perfect. It was two screens connecting with GitHub API. There were a lot of different things that needed to be taken into account to make it "senior level" (Which, by the way, implies that you have spent a lot of time in this particular field).
The verdict / feedback:
At first, Mercari responded with a "dear John" email, but I pressed them for specific feedback. When I got feedback, you can tell that it was an afterthought. They didn't spend very much time going over my code at all. They made some general conjectures about it, little of it constructive. Big. Fat. Waste. Of. Time. In my 9 years in the field of iOS development, I've only encountered one other company that has treated candidates so poorly. LinkedIn, Facebook, Microsoft, ect. all have superior interview processes that will, at least, give you something to take away. Mercari is a black-hole, time sink. If this is how they treat their candidates, then I can only imagine how they treat their employees.
Final Thoughts:
Don't even try on their assignment. It's not worth your time. Simply horrible.