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: named_rustls_tests.rs
    path of file: ./repos/hickory-dns/bin/tests
    
    the code of the file until where you have to start completion: // Copyright 2015-2017 Benjamin Fry <benjaminfry@me.com>
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// https://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// https://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

#![cfg(not(windows))]
#![cfg(feature = "dns-over-rustls")]

mod server_harness;

use std::env;
use std::fs::File;
use std::io::*;
use std::net::*;
use std::sync::Arc;

use hickory_server::server::Protocol;
use rustls::Certificate;
use rustls::ClientConfig;
use rustls::RootCertStore;
use tokio::net::TcpStream as TokioTcpStream;
use tokio::runtime::Runtime;

use hickory_client::client::*;
use hickory_proto::iocompat::AsyncIoTokioAsStd;
use hickory_proto::rustls::tls_client_connect;

use server_harness::{named_test_harness, query_a};

#[test]
fn test_example_tls_toml_startup() {
    named_test_harness(
        "dns_over_tls_rustls_and_openssl.toml",
        move |socket_ports| {
            let mut cert_der = vec![];
            let tls_port = socket_ports.get_v4(Protocol::Tls);
            let server_path = env::var("TDNS_WORKSPACE_ROOT").unwrap_or_else(|_| "..".to_owned());
            println!("using server src path: {server_path}");

            File::open(format!(
                "{server_path}/tests/test-data/test_configs/sec/example.cert"
            ))
            .expect("failed to open cert")
            .read_to_end(&mut cert_der)
            .expect("failed to read cert");

            let mut io_loop = Runtime::new().unwrap();
            let addr: SocketAddr = ("127.0.0.1", tls_port.expect("no tls_port"))
                .to_socket_addrs()
                .unwrap()
                .next()
                .unwrap();

            let cert = to_trust_anchor(&cert_der);
            let mut root_store = RootCertStore::empty();
            root_store.add(&cert).expect("bad certific
    
fn test_example_tls_toml_startup() {
    named_test_harness(
        "dns_over_tls_rustls_and_openssl.toml",
        move |socket_ports| {
            let mut cert_der = vec![];
            let tls_port = socket_ports.get_v4(Protocol::Tls);
            let server_path = env::var("TDNS_WORKSPACE_ROOT").unwrap_or_else(|_| "..".to_owned());
            println!("using server src path: {server_path}");

            File::open(format!(
                "{server_path}/tests/test-data/test_configs/sec/example.cert"
            ))
            .expect("failed to open cert")
            .read_to_end(&mut cert_der)
            .expect("failed to read cert");

            let mut io_loop = Runtime::new().unwrap();
            let addr: SocketAddr = ("127.0.0.1", tls_port.expect("no tls_port"))
                .to_socket_addrs()
                .unwrap()
                .next()
                .unwrap();

            let cert = to_trust_anchor(&cert_der);
            let mut root_store = RootCertStore::empty();
            root_store.add(&cert).expect("bad certificate");

            let config = ClientConfig::builder()
                .with_safe_defaults()
                .with_root_certificates(root_store)
                .with_no_client_auth();

            let config = Arc::new(config);

            let (stream, sender) = tls_client_connect::<AsyncIoTokioAsStd<TokioTcpStream>>(
                addr,
                "ns.example.com".to_string(),
                config.clone(),
            );
            let client = AsyncClient::new(stream, sender, None);

            let (mut client, bg) = io_loop.block_on(client).expect("client failed to connect");
            hickory_proto::spawn_bg(&io_loop, bg);

            // ipv4 should succeed
            query_a(&mut io_loop, &mut client);

            let addr: SocketAddr = ("127.0.0.1", tls_port.expect("no tls_port"))
                .to_socket_addrs()
                .unwrap()
                .next()
                .unwrap();
            let (stream, sender) = tls_client_connect::<AsyncIoTokioAsStd<TokioTcpStream>>(
                addr,
                "ns.example.com".to_string(),
                config,
            );
            let client = AsyncClient::new(stream, sender, None);

            let (mut client, bg) = io_loop.block_on(client).expect("client failed to connect");
            hickory_proto::spawn_bg(&io_loop, bg);

            // ipv6 should succeed
            query_a(&mut io_loop, &mut client);
        },
    )
}