In practice, including a unit test for any nontrivial regex in your application is very helpful. You can demonstrate which sorts of strings are expected to match and, maybe more importantly, which ones are not expected to match. The same goes for testing the capture group contents.

It may feel silly to have a whole unit test for a one-line regex, but that one line can be really dense. If you wrote a function to parse the string without regex, that function would be complex enough to warrant a unit test, after all.

Introducing regressions when tweaking a regex in your application is also a big risk which unit tests can help mitigate.