We use the UnitTesting module a lot to help keep our code maintainable. It’s only the developers who use it at the moment, and usually the developer who wrote the original SUB writing the test to ensure it works in various cases. It’s useful when working on another developer’s microflows as it can help show any changes you’ve made have not accidentally broken the existing functionality.
The QAs we have concentrate on testing the front end and the end to end process. This can be using a tool like ATS, Selenium, Katalon, etc.
Hope this helps