I tend to avoid the term unit-test since there is some disagreement about what "unit" mean. Some think it means testing everything down to the level of individu

I tend to avoid the term unit-test since there is some disagreement about what "unit" mean. Some think it means testing everything down to the level of individual private methods. This will indeed lock you down. And if it paired with extensive "mocking", where you only ever test that method A calls method B when invoked, then yes, you have locked your self down and you wont get a lot of value from the tests. I prefer automated tests of larger units or subsystems, and testing against requirements, protocols and specifications rater than implementation details would change. Of course anything will change over time, but I believe this kind of tests provides higher value and lives longer.