Tests are valuable, but of course they’re never perfect. Certain kinds of programs require them more than others. And no development approach, method, or tool is the best in all cases.

The program with the most tests that I’m aware of is SQLite. I have a feeling Hipp and his team know their code extremely well and that they do a lot of thinking before they change anything. Then they run their massive test suite, which they built because they’re good enough to know that they’re not good enough to think everything through without making errors.

Tests have saved me from a few blunders over the years.