> Type systems do not replace testing

They're a good substitute for many of the use cases of testing.

> if a test works after retrying it then it is probably not something that a type system would be able to catch.

Type systems are pretty good at catching incorrect concurrency logic these days, and getting better all the time.

Yes they are not equivalent, but creating languages without a strict type system and the proposition of test driven development are going back and fort in strictness. It is beneficial to have a more strict programming language, but it can be uncomfortable and burdensome. So I find interesting we keep going back and forth in this dimension.