There are good and bad tests.... ;) Good = actually tests something, precisely, properly, doesn't take an age to run. Enough of these in CI, and a deploy is far

There are good and bad tests.... ;) Good = actually tests something, precisely, properly, doesn't take an age to run. Enough of these in CI, and a deploy is far less likely to break prod. Bad = author didn't really know what they were trying to test, mocks fall out of date with reality (if they ever reflected it in the first place), other problems such as repetitive code and anything which tempts people to short circuit rather than keeping tests up to date, e:g tests that take far longer to write than the code they test. Shout out for pytest-cases as a library that can reduce repetition and save time. I've been in this game long enough to remember the days before massive automated test suites. Quality software did indeed get shipped in those days too. It took longer, with less regular releases. It took an army of skilled QA people with thorough test plans. You can do good or bad testing whether its today's TDD or yesterday's manual QA.