Rust iterator implementation

Rust iterator implementation.rs

#[derive(Debug)]
pub struct TestItem {
    val: usize,
}

#[derive(Debug)]
pub struct TestItems<'a> {
    items: &'a Vec<&'a TestItem>,
    idx: usize,
    pos: usize,
}

impl<'a> TestItems<'a> {
    fn new(items: &'a Vec<&'a TestItem>) -> Self {
        Self {
            items,
            idx: 0,
            pos: 0,
        }
    }
}

impl<'a> Iterator for TestItems<'a> {
    type Item = (usize, &'a TestItem);
    fn next(&mut self) -> Option<Self::Item> {
        if self.idx < self.items.len() {
            let item = self.items[self.idx];
            let curr_pos = self.pos; 
            self.idx += 1;
            self.pos += item.val;
            return Some((curr_pos, item));
        }
        None
    }
}


#[cfg(test)]
mod tests {
    #[allow(unused)]
    use crate::{TestItem, TestItems};

    #[test]
    fn test3() {
        let vec = vec![&TestItem { val: 10 }, &TestItem { val: 20 }];
        let test = TestItems::new(&vec);
        println!("test:{:?}", test);
        for item in test {
            println!("- item:{:?}", item);
        }
        println!("test:{:?}", vec);
    }
}