I guess the lesson learned is to ask what the interview process looks like before getting involved.
However for this company, I applied online, they sent me a InterviewStreet/HackerRank coding test, and only after I passed that did a recruiter call me, and tell me they wanted me onsite for a week.
This is a huge red flag in my opinion and I would recommend people not agree to this. Why? Because it shows complete disregard for the candidate. "Pass a test and you can speak to an actual human being." Its demeaning. It also shows just how useless many recruiters have become. Part of the job of a recruiter's job and good ones do this, is to get a candidate excited about interviewing with the company and get the preliminary deal breaker questions out of the way to see if it even makes sense to proceed.
Nowadays I just point them at my github. If a body of open source isn't enough to get an interview I'm not interested in working there.
I have no problem with competency testing provided I have already spoken to someone on the team and established contact and registered interest with someone besides a recruiter.
Initially it was a Hackerrank challenge, now its a (100% Javascript) "Full Stack" take home exercise before you even get to speak to anyone technical.
Could you share the name of the company so others might avoid them and avoid wasting their time with such nonsense?