Write tests. Not too many. Mostly integration
Good lord.  Why integration tests?    I think the biggest thing you can do to write more integration tests is to just stop mocking so much stuff. 

Okay. The biggest problem I see with people trying to write unit tests is that they don’t want to change how they write code. They just want tests for it. It’s like watching an OO person try their hardest to write OO code in a functional language.So they try to write E2E tests which work for about 5 or 6 quarters and then fall apart like a cheap bookcase. If you can find a new job before then, you never have to learn to write good tests!I agree with the author that the trick is to stop using mocks all the time, but you don’t have to write integration tests to get rid of mocks. You have to write better code.Usually if I have a unit test with more than one mock it’s bcause I’m too invested in the current shape of the code and I need to cleave the function in two, or change the structure of he question asked (eg, remake two methods into two other methods).Almost always when I accept that the code is wrong, I end up with clearer code and easier tests.Unit tests run faster, are written faster, and not only can they be fixed faster, they can be deleted and rewritten if the requirements change.  The most painful thing to watch by far is someone spending hours trying to recycle an old test because they spent 3 hours on it last time and they’ll be damned if they’re going to just delete it now.