Which programming language has your favorite approach to testing?

I’m in a discussion about testing in Gleam and what it should look like in the future.
What languages have your favorite approach to testing? Do you prefer testing shipping with the language or having a choice of frameworks?

I prefer when it’s part of the language. Enough decissions to make. But that’s just not possible with all languages.

That’s why I love to work with Go for so many years. You don’t have to think about any essential tool. Rust is similar nowadays. It just works.