#[test]
fn iterator_demonstration() {
    let v1 = vec![1, 2, 3];
    let mut v1_iter = v1.iter();
    assert_eq!(v1_iter.next(), Some(&1));
    assert_eq!(v1_iter.next(), Some(&2));
    assert_eq!(v1_iter.next(), Some(&3));
    assert_eq!(v1_iter.next(), None);
    assert_eq!(v1_iter.next(), None);
}

#[test]
fn iterator_sum() {
    let v1 = vec![1, 2, 3];
    let v1_iter = v1.iter();
    let total: i32 = v1_iter.sum();

    assert_eq!(total, 6);
}

#[derive(PartialEq, Debug)]
struct Shoe {
    size: u32,
    style: String,
}

fn shoes_in_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
    shoes.into_iter().filter(|s| s.size == shoe_size).collect()
}

#[test]
fn filters_by_size() {
    let shoes = vec![
        Shoe {
            size: 10,
            style: String::from("sneaker"),
        },
        Shoe {
            size: 13,
            style: String::from("sandal"),
        },
        Shoe {
            size: 10,
            style: String::from("boot"),
        },
    ];

    let in_my_size = shoes_in_size(shoes, 10);

    assert_eq!(
        in_my_size,
        vec![
            Shoe {
                size: 10,
                style: String::from("sneaker"),
            },
            Shoe {
                size: 10,
                style: String::from("boot"),
            },
        ]
    );
}