The type system does help a lot, but I find the tests matter more for the next engineer(s) who need to touch your code. Modifying code you didn't write and don'

The type system does help a lot, but I find the tests matter more for the next engineer(s) who need to touch your code. Modifying code you didn't write and don't 100% understand while being sure you didn't break existing features is priceless.