Full day interview with no breaks, multiple rounds with different people all of which acted elitist and had their own pet questions typical of crap interview style and not reflective of actual job

had 30 mins interview with Project Lead/manager. The discussion went smoothly and the interviewer was a really nice guy and asked python related questions. At last, he said he is going to share a coding test that does not have any deadline. coding test was simple which I completed in 2 days and sent back. The next day I got feedback stating they won't proceed further as my solution does not match their standards. Some of the comments were really disappointing and insulting for e.g. They said: "candidate did not use unittest to test and it shows he does not have knowledge of testing framework". I had used pytest to test the code and used assert to validate the tests. How can you judge me that I don't have knowledge of testing modules just because i did not use 'unittest' library? pytest is equally an acceptable framework which is being used in industry. I think they need to educate their panel who verifies the solutions. moreover, they are looking for a super expert python developer who can work as a tester for them.