After applying, I was nicely impressed by the quick response. It was one of those positions I found less 90 % matching with my professional background.
Spending enough hours with that test challenge and being happy with my highly professional friend's reviews, I was very optimistic about the next step.
The recruiter sent me the test requirements of a Windows application asking me that they would prefer to do it in MFC. The application was about dynamic figures drawing and movement by a timer.
I found it quite a nice challenge and I did it close to the "art" approach, including design patterns, polymorphism, modern C++, objects manager etc. That kind of solution you're not ashamed to leave it public.
Surprisingly, after their "review" to the test solution I proposed, I got a message that after their analysis my "professional qualifications is not matching" with what are they looking for. So they concluded this after I waste a weekend I would spend with my family, but I am afraid they concluded this while seeing I am not mastering German as they expected and I am not a cheap guy.
During the time I had different hiring experiences and I am sorry to say this is the most unprofessional behavior I ever met. In my opinion, if such situations exist they would be obvious from the very beginning and not wasting others time. But I got unprofessional, wasting the time I would have spent with my family.
Anyhow, this attitude told me more about this company and, in the end, I consider they made me a favor.