This is either a standalone question or a follow-up to a previous question. If you previously told the Amazon interviewer about the QA processes you use, you should now discuss your testing and debugging processes. During an interview, you should always anticipate follow-up questions whenever you answer an interviewer's question. This is why you should keep your answers short and direct. It creates an opportunity for the interviewer to dive deeper into the topic if they have a specific interest in it or move on to a new line of questioning.