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: mod.rs
    path of file: ./repos/diem/language/diem-vm/mvhashmap/src/unit_tests
    
    the code of the file until where you have to start completion: // Copyright (c) The Diem Core Contributors
// SPDX-License-Identifier: Apache-2.0

use super::*;

mod proptest_types;

#[test]
fn create_write_read_placeholder_struct() {
    let ap1 = b"/foo/b".to_vec();
    let ap2 = b"/fo
    
fn create_write_read_placeholder_struct() {
    let ap1 = b"/foo/b".to_vec();
    let ap2 = b"/foo/c".to_vec();
    let ap3 = b"/foo/d".to_vec();

    let data = vec![(ap1.clone(), 10), (ap2.clone(), 10), (ap2.clone(), 20)];

    let (mvtbl, max_dep) = MVHashMap::new_from(data);

    assert_eq!(2, max_dep);

    assert_eq!(2, mvtbl.len());

    // Reads that should go the the DB return Err(None)
    let r1 = mvtbl.read(&ap1, 5);
    assert_eq!(Err(None), r1);

    // Reads at a version return the previous versions, not this
    // version.
    let r1 = mvtbl.read(&ap1, 10);
    assert_eq!(Err(None), r1);

    // Check reads into non-ready structs return the Err(entry)

    // Reads at a higher version return the previous version
    let r1 = mvtbl.read(&ap1, 15);
    assert_eq!(Err(Some(10)), r1);

    // Writes populate the entry
    mvtbl.write(&ap1, 10, Some(vec![0, 0, 0])).unwrap();

    // Write to unexpected entries
    assert!(mvtbl.write(&ap1, 1, Some(vec![0, 0, 0])).is_err());
    assert!(mvtbl.write(&ap3, 10, Some(vec![0, 0, 0])).is_err());

    // Subsequent higher reads read this entry
    let r1 = mvtbl.read(&ap1, 15);
    assert_eq!(Ok(&Some(vec![0, 0, 0])), r1);

    // Set skip works
    assert!(mvtbl.skip(&ap1, 20).is_err());

    mvtbl.skip(&ap2, 20).unwrap();
    // Writes populate the entry
    mvtbl.write(&ap2, 10, Some(vec![0, 0, 0])).unwrap();

    // Higher reads skip this entry
    let r1 = mvtbl.read(&ap2, 25);
    assert_eq!(Ok(&Some(vec![0, 0, 0])), r1);
}