Tests in Rust

Like Go and Elixir, Rust has first-class support for automated tests. Like Elixir, Rust also has support for Doctests, which is great.

Usually, tests are defined in the same file as the code under test. We create a new test module and specify the cfg attribute to conditionally compile the test module only in test mode. Tests are defined using the test attribute, and in them we can use several assertion macros provided by the standard library to assert behavior.

pub fn add(x: i32, y: i32) -> i32 {
    x + y
}
 
#[cfg(test)]
mod tests {
    use super::*;
 
    #[test]
    fn adds_numbers() {
        let result = add(69, 42);
        assert_eq!(result, 111);
    }
}