Assertions - Rust Programming

Assertions verify expected results. Real test functions use #[test] with cargo test; this example checks inline with assert_eq!.

Program

Play the program to verify a double function and confirm all checks pass.

unit_tests.rs

fn double(n: i32) -> i32 {
    n * 2
}

fn main() {
    assert_eq!(double(2), 4);
    assert_eq!(double(0), 0);
    println!("all checks passed");
}

assert_eq! `assert_eq!(a, b)` panics if the values differ.

function under test `double` is the code being checked.

cargo test Real tests live in `#[test]` functions run by `cargo test`.