> The only real “test” is whether it works in production. Everything else is a poor substitute and gives you false confidence. Tests are like bloom filters[1],

> The only real “test” is whether it works in production. Everything else is a poor substitute and gives you false confidence. Tests are like bloom filters[1], either they fail and you have a bug (either in code or in the test itself), or they pass and you possibly still have bugs. As such they only give you false confidence if you're overly naive. If our tests pass then we know what we know. Doesn't mean we pretend there can't be unknown unknowns, so we still need diligence before rolling out a new version into production. [1]: https://en.wikipedia.org/wiki/Bloom_filter https://en.wikipedia.org/wiki/Bloom_filter