Matlab, Rust.
a simple function and a unit test: pub fn add(left: usize, right: usize) -> usize { left + right } #[cfg(test)] mod tests { use super::*; #[test] fn it_works() { let result = add(2, 2); assert_eq!(result, 4); } } You can run cargo test to see the passing test, and you can run cargo build to compile