It was a basic HR interview, and the employee was quite friendly. Explained everything smoothly and didn't raise a question mark in my head. There were some basic technical questions as well which were not difficult to answer.

They were very positive after seeing my CV, and in the HR interview, they also stated that all my qualifications were sufficient. I even answered a few technical questions correctly. Despite sounding optimistic and submitting a workable test case exactly as they requested, I received a rejection email without even an explanation. What I find unprofessional is why, if a rejection is going to happen, it's so definitive and positive at the beginning. Similarly, rejecting a working test case without any explanation, even though it was exactly what was requested, is very unprofessional.