A function to test if all values of a slice are equal (to the first element).

all-eq.rs

fn all_eq<T: Eq>(slice: &[T]) -> bool {
    match slice.split_first() {
        Some((first, others)) => others.iter().all(|x| x == first),
        None => true,
    }
}

#[test]
fn all_eq_easy_eq() {
    assert!(all_eq(&[1, 1, 1, 1, 1]));
}

#[test]
fn all_eq_easy_ne() {
    assert!(all_eq(&[0, 1, 1, 1, 1]) == false);
}

#[test]
fn all_eq_easy_empty_eq() {
    assert!(all_eq::<i32>(&[]));
}

#[test]
fn all_eq_easy_one_val_eq() {
    assert!(all_eq(&[1]));
}