Unit tests are valuable for certain types of code, mainly library code in my experience. For example if you are developing a 3d math library, unit tests will be

Unit tests are valuable for certain types of code, mainly library code in my experience. For example if you are developing a 3d math library, unit tests will be invaluable. Unit tests are less valuable for testing applications because the unit tests end up just being mirrors of your application classes/functions and you have to make changes in 2 places now any time you need to tweak application logic. For applications I think black box tests have the highest ROI. Your application should have a headless mode through which you can send all of your test cases (real life inputs) and verify the output of your app has expected shape/value. As you encounter issues from user feedback, simply add to your list of black box tests. The beauty is that down the road you can "rewrite your app in Rust" or whatever and you'll have a huge set of black box regression tests you can use to validate the rewrite.