[fredsir]

A language that is exceedingly popular and has a great type system and has great tooling for tests is Rust. When using Rust, it’s quite evident why you have to use both and not one or the other.

And when it comes down to it, in theory, proofs are better than tests, and Id say no one would disagree, and in practice, types are proof. Unfortunately, you can’t use types for proving everything, so that is where tests comes in.

Imagine a platform where you could indeed prove everything. I believe, but am not sure, that there is some languages that do this, like Idris.