#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
    }
}

#[derive(Debug)]
pub struct Rectangle {
    length: u32,
    width: u32
}

impl Rectangle {
    pub fn can_hold(&self, other: &Rectangle) -> bool {
        self.length > other.length && self.width > other.width
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
    }

    #[test]
    fn it_panics() {
        panic!("Make this test fail!");
    }
}

Add struct and method for testing
Add struct and method for testing
