Having a single test for a subtle edge case that can be missed is better than a committer and a reviewer both missing that edge case and committing code that breaks it.<p>I can&#x27;t fathom how anyone thinks that documenting the algorithm is better than running the algorithm.  The only possible explanation that occurs to me is sociological and that when someone eventually breaks the code which was only documented, you can heap scorn on those who allowed it to be broken because they weren&#x27;t as smart as you are to be able to see that edge case in hindsight.<p>Which I guess is &#x27;better&#x27;.  I&#x27;d prefer to have a test that fails.  When code breaks an edge case that nobody thought of, I&#x27;d add that edge case to the test suite.  It will never be perfect, but it will work at least some of the time.<p>And assuming that test suites must be perfect and complete to be useful is also incredibly naive and a sign of an immature and fairly novice developer.  Test suites are always imperfect, you must always guard against them and not assume they do everything for you, and yet you need to take the time to build them and maintain them since they make your code quality better when they do catch edge conditions where you weren&#x27;t smart enough to see your own bugs you were introducing.<p>I guess some programmers are just smart enough to never commit buggy code though and don&#x27;t need them...