"All or nothing" is not the point I'm making, it's "any or nothing." Unittests frequently have justifiable value for their effort, even when only providing part

"All or nothing" is not the point I'm making, it's "any or nothing." Unittests frequently have justifiable value for their effort, even when only providing partial coverage. I'm arguing that the effort involved in creating formal proofs for any part of your software is almost never worth the benefits, outside of mission critical applications, when a dozen simple unittests could provide 99.99% confidence. And certainly not worth it enough to become "mainstream", which is the title of the post.