rust-closures.rs

#[cfg(test)]
mod tests {
    
    fn counter() -> Box<FnMut() -> i32 + 'static> {
        let mut b = 0;
        let ret = move || { b += 1; b };
        Box::new(ret)
    }

    #[test]
    fn it_works() {
        let mut count = counter();
        assert!(count() == 1);
        assert!(count() == 2);
        assert!(count() == 3);
    }
    
}