rustlings/exercises/collections/vec2.rs

// vec2.rs
// A Vec of even numbers is given. Your task is to complete the loop
// so that each number in the Vec is multiplied by 2.
//
// Make me pass the test!
//
// Execute the command `rustlings hint collections2` if you need
// hints.

// I AM NOT DONE

fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
    for i in v.iter_mut() {
        // TODO: Fill this up so that each element in the Vec `v` is
        // multiplied by 2.
    }

    // At this point, `v` should be equal to [4, 8, 12, 16, 20].
    v
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_vec_loop() {
        let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
        let ans = vec_loop(v.clone());

        assert_eq!(
            ans,
            v.iter()
                .map(|x| x * 2)
                .collect::<Vec<i32>>()
        );
    }
}