No, my clients wouldn't work with me then... On a serious note, I find it hard to write the tests at the beginning for a code that I'm not sure how/what is gon

No, my clients wouldn't work with me then... On a serious note, I find it hard to write the tests at the beginning for a code that I'm not sure how/what is gonna do. What do I mean by that? Well, as all you probably have experienced, requirements change during development, sometimes 3rd party/microservices/db constraints don't let us achieve what we want. We have to come up with hacky/silly solutions that would require us to rewrite most of the tests that we wrote. A lot of times I don't even know how to code the stuff I'm required to build. How am I supposed to write tests in that kind of situations? I think it would be like building abstractions for problems that I don't know very well yet.