You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: lru.rs
    path of file: ./repos/rust-analyzer/crates/salsa/tests
    
    the code of the file until where you have to start completion: //! Test setting LRU actually limits the number of things in the database;
use std::sync::{
    atomic::{AtomicUsize, Ordering},
    Arc,
};

#[derive(Debug, PartialEq, Eq)]
struct HotPotato(u32);

static N_POTATOES: AtomicUsize = AtomicUsize::new(0);

impl HotPotato {
    fn new(id: u32) -> HotPotato {
        N_POTATOES.fetch_add(1, Ordering::SeqCst);
        HotPotato(id)
    }
}

impl Drop for HotPotato {
    fn drop(&mut self) {
        N_POTATOES.fetch_sub(1, Ordering::SeqCst);
    }
}

#[salsa::query_group(QueryGroupStorage)]
trait QueryGroup: salsa::Database {
    fn get(&self, x: u32) -> Arc<HotPotato>;
    fn get_volatile(&self, x: u32) -> usize;
}

fn get(_db: &dyn QueryGroup, x: u32) -> Arc<HotPotato> {
    Arc::new(HotPotato::new(x))
}

fn get_volatile(db: &dyn QueryGroup, _x: u32) -> usize {
    static COUNTER: AtomicUsize = AtomicUsize::new(0);
    db.salsa_runtime().report_untracked_read();
    COUNTER.fetch_add(1, Ordering::SeqCst)
}

#[salsa::database(QueryGroupStorage)]
#[derive(Default)]
st
    
fn lru_works() {
    let mut db = Database::default();
    GetQuery.in_db_mut(&mut db).set_lru_capacity(32);
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 0);

    for i in 0..128u32 {
        let p = db.get(i);
        assert_eq!(p.0, i)
    }
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 32);

    for i in 0..128u32 {
        let p = db.get(i);
        assert_eq!(p.0, i)
    }
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 32);

    GetQuery.in_db_mut(&mut db).set_lru_capacity(32);
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 32);

    GetQuery.in_db_mut(&mut db).set_lru_capacity(64);
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 32);
    for i in 0..128u32 {
        let p = db.get(i);
        assert_eq!(p.0, i)
    }
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 64);

    // Special case: setting capacity to zero disables LRU
    GetQuery.in_db_mut(&mut db).set_lru_capacity(0);
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 64);
    for i in 0..128u32 {
        let p = db.get(i);
        assert_eq!(p.0, i)
    }
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 128);

    drop(db);
    assert_eq!(N_POTATOES.load(Ordering::SeqCst), 0);
}