To someone that has programmed for a good 2 decades and more, the above sounds like what a college student or junior dev that just found out about TDD would say.
Unit test and integration tests are (bad) substitutes for good and modular design, which should piggyback on a strong type system. I've seen it so often that whenever I read comments like the above I feel the need to create an HN account just to reply to them.
Junior devs in charge of major design decisions create damage that goes way beyond their limited reach. Test code is untested code. Test code is brittle code - especially integration tests are. You need tests because you're using a dynamically typed language? Well, stop using that language for anything that is even remotely complex. Your future senior dev self will thank you.