trait Speak {
    fn speak(*self) String;
}

trait Greet : Speak {
    fn greet(*self) String;
}

struct Dog {
    name String,
}

impl Speak for Dog {
    fn speak(*self) String {
        "woof".to_string()
    }
}

impl Greet for Dog {
    fn greet(*self) String {
        "hello".to_string()
    }
}

pub fn test_trait_impl() {
    let d = Dog { name: "Rex".to_string() };
    assert_eq!(d.speak(), "woof");
}

pub fn test_trait_with_requirement() {
    let d = Dog { name: "Buddy".to_string() };
    assert_eq!(d.speak(), "woof");
    assert_eq!(d.greet(), "hello");
}

pub fn run_tests() {
    test_trait_impl();
    test_trait_with_requirement();
}