Thought Machine Front End Developer interview questions

They process starts with an evening event that you have to go to meet team members and listen to founder or CTO, I found the format interesting but time consuming. After that they send you a “three hours” code challenge (which I am sure any senior dev would need around three days to fully complete it), for me it was a fully working and production ready calendar app, I took it as an opportunity to practice and spent 16 hours coding it (it’s a three hours challenge but they give you 48 hours to complete ha ¯\_(ツ)_/¯), I wrote some tests but did not aim for 100% coverage because that would prove nothing about my skillset and the whole challenge was already unrealistic, also, the hard part was in sorting and positioning the events. If you code is good they call you for a three hours interview, first hour to review your code, second algorithms and third systems design, each hour with two different team members. The interviewers were mostly good besides two, first hour was ok but they complained I didn’t test the app much (bummer), second part was a couple of intelligent algorithms to test my JS/FP skills (very nice guys), third hour was hard, one of the interviewers was inexperienced and quite self-centered and focused most of his energy on asking the same systems designs question over and over, he didn’t know how to nudge a candidate right, nor to realise the candidate may not know the answer he is looking for and that instead he should move on and empower the person to solve other challenges. (By the way, even though it was the first time I was exposed to the specific problem I did provide a workable solution which wasn't excellent - hard to excell without research opportunity or good interviewer). I receive a feedback and they decided not to move forward because my app wasn’t fully tested and I failed in advanced systems design.