IMHO, not understanding testing is a very big hole. It is not like not knowing what the latest and greatest Node.js web framework is. An interviewer could quite

IMHO, not understanding testing is a very big hole. It is not like not knowing what the latest and greatest Node.js web framework is. An interviewer could quite reasonably eliminate someone by not having worked with testing before. Your best bet is to learn about testing well enough to eliminate this hole.