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: custom_tests.rs
    path of file: ./repos/rusoto/rusoto/services/glacier/src/custom
    
    the code of the file until where you have to start completion: extern crate rusoto_mock;

use crate::generated::*;

use self::rusoto_mock::*;
use rusoto_core::Region;

#[tokio::test]
async fn test_initiate_multipart_part_response() {
    let mock = MockRequestDispatcher::with_status(201)
        .with_header("Location", "/111122223333/vaults/examplevault/multipart-uploads/OW2fM5iVylEpFEMM9_HpKowRapC3vn5sSL39_396UW9zLFUWVrnRHaPjUJddQ5OxSHVXjYtrN47NBZ-khxOjyEXAMPLE")
        .with_header("x-amz-multipart-upload-id", "OW2fM5iVylEpFEMM9_HpKowRapC3vn5sSL39_396UW9zLFUWVrnRHaPjUJddQ5OxSHVXjYtrN47NBZ-khxOjyEXAMPLE");
    let client = GlacierClient::new_with(mock
    
async fn test_upload_multipart_part_response() {
    let mock = MockRequestDispatcher::with_status(204).with_header("x-amz-sha256-tree-hash", "42");
    let client = GlacierClient::new_with(mock, MockCredentialsProvider, Region::UsEast1);

    let upload_part_copy_req = UploadMultipartPartInput {
        account_id: "foo".to_owned(),
        upload_id: "bar".to_owned(),
        vault_name: "baz".to_owned(),
        ..Default::default()
    };
    let result = client
        .upload_multipart_part(upload_part_copy_req)
        .await
        .expect("Should parse empty body");
    assert_eq!(
        result.checksum.unwrap(),
        "42",
        "Should handle checksum in response"
    );
}