Not to worry. Some test frameworks do not expose them, so people often don’t even to know to want for them. User allover did a respectable job of explaining.

IME (python webdev) most test frameworks do expose some form of this, but I’ve never heard them called “matchers”. So perhaps people know & use them, but not by that name.

I mean expose the ability to write your own. When I first used them, I thought all frameworks allowed this, then bumped into some that didn't, or at least not in the popular version at the time.