Sometimes I forget about things I've said that could be useful. 1/ https://twitter.com/rajkatie/status/1353961778691133441

The idea behind this one is that you learn a lot about the quality of a design by trying to test it, but it happens at (at least) two levels. 2/

There are the tests that you write for thing and the tests you write for the thing that uses the thing. 3/

The former tests are valuable because they tell you how easy it is to use the API. The value of the latter tests is that they show you what happens when code uses your API; the effect of that coupling. 4/

If it is hard to write isolated tests for code that uses your API, you want to know. This is a cost you are putting on your users. 5/

This is why this is "the golden rule." Its practice leads you to treat users of your code like you'd want to be treated yourself.

High cohesion and low coupling are great things that we can share. 6/