TCS Walkin experience

I have attended a TCS interview why there are asking skills other than the skills we are having for eg. I am having experience in automation testing, what they are asking is java programs if they are basics we can answer they are asking like take an Array list of String and the output has to be reverse each string in the array list, 2nd Input automation and output has to be uaotamitno. How can a tester write this type of coding.3rd question is character occurrence code which I have written correctly as I haven't written using getKeys he has rejected me. And no question has been asked related to testing everything is related to java and Agile. One of my friends got selected for the manager round and the interviewer is a developer how can the developer take the interview and they are judging i.e., who don't have the knowledge in testing and telling that you are not up to mark.