#![cfg(all(feature = "client-legacy", any(feature = "http1", feature = "http2")))]
#![allow(clippy::unused_io_amount)]
#![allow(clippy::expect_fun_call)]

mod test_utils;

use std::io::{Read, Write};
use std::net::{SocketAddr, TcpListener};
use std::pin::Pin;
use std::sync::atomic::Ordering;
use std::sync::Arc;
use std::task::Poll;
use std::thread;
use std::time::Duration;

use futures_channel::{mpsc, oneshot};
use futures_util::future::{self, FutureExt, TryFutureExt};
use futures_util::stream::StreamExt;
use futures_util::{self, Stream};
use http_body_util::BodyExt;
use http_body_util::{Empty, Full, StreamBody};
use tokio::io::{AsyncReadExt, AsyncWriteExt};

use hyper::body::Bytes;
use hyper::body::Frame;
use hyper::Request;
use hyper_util::client::legacy::connect::{capture_connection, HttpConnector};
use hyper_util::client::legacy::Client;
use hyper_util::rt::{TokioExecutor, TokioIo};

use test_utils::{DebugConnector, DebugStream};

pub fn runtime() -> tokio::runtime::Runtime {
    tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .expect("new rt")
}

fn s(buf: &[u8]) -> &str {
    std::str::from_utf8(buf).expect("from_utf8")
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn drop_body_before_eof_closes_connection() {
    // https://github.com/hyperium/hyper/issues/1353
    let _ = pretty_env_logger::try_init();

    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let rt = runtime();
    let (closes_tx, closes) = mpsc::channel::<()>(10);
    let client = Client::builder(hyper_util::rt::TokioExecutor::new()).build(
        DebugConnector::with_http_and_closes(HttpConnector::new(), closes_tx),
    );
    let (tx1, rx1) = oneshot::channel();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        let body = vec![b'x'; 1024 * 128];
        write!(
            sock,
            "HTTP/1.1 200 OK\r\nContent-Length: {}\r\n\r\n",
            body.len()
        )
        .expect("write head");
        let _ = sock.write_all(&body);
        let _ = tx1.send(());
    });

    let req = Request::builder()
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req).map_ok(move |res| {
        assert_eq!(res.status(), hyper::StatusCode::OK);
    });
    let rx = rx1;
    rt.block_on(async move {
        let (res, _) = future::join(res, rx).await;
        res.unwrap();
        tokio::time::sleep(Duration::from_secs(1)).await;
    });
    rt.block_on(closes.into_future()).0.expect("closes");
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[tokio::test]
async fn drop_client_closes_idle_connections() {
    let _ = pretty_env_logger::try_init();

    let server = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
    let addr = server.local_addr().unwrap();
    let (closes_tx, mut closes) = mpsc::channel(10);

    let (tx1, rx1) = oneshot::channel();

    let t1 = tokio::spawn(async move {
        let mut sock = server.accept().await.unwrap().0;
        let mut buf = [0; 4096];
        sock.read(&mut buf).await.expect("read 1");
        let body = [b'x'; 64];
        let headers = format!("HTTP/1.1 200 OK\r\nContent-Length: {}\r\n\r\n", body.len());
        sock.write_all(headers.as_bytes())
            .await
            .expect("write head");
        sock.write_all(&body).await.expect("write body");
        let _ = tx1.send(());

        // prevent this thread from closing until end of test, so the connection
        // stays open and idle until Client is dropped
        if let Ok(n) = sock.read(&mut buf).await {
            assert_eq!(n, 0);
        }
    });

    let client = Client::builder(TokioExecutor::new()).build(DebugConnector::with_http_and_closes(
        HttpConnector::new(),
        closes_tx,
    ));

    let req = Request::builder()
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req).map_ok(move |res| {
        assert_eq!(res.status(), hyper::StatusCode::OK);
    });
    let rx = rx1;
    let (res, _) = future::join(res, rx).await;
    res.unwrap();

    // not closed yet, just idle
    std::future::poll_fn(|ctx| {
        assert!(Pin::new(&mut closes).poll_next(ctx).is_pending());
        Poll::Ready(())
    })
    .await;

    // drop to start the connections closing
    drop(client);

    // and wait a few ticks for the connections to close
    let t = tokio::time::sleep(Duration::from_millis(100)).map(|_| panic!("time out"));
    futures_util::pin_mut!(t);
    let close = closes.into_future().map(|(opt, _)| opt.expect("closes"));
    future::select(t, close).await;
    t1.await.unwrap();
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[tokio::test]
async fn drop_response_future_closes_in_progress_connection() {
    let _ = pretty_env_logger::try_init();

    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let (closes_tx, closes) = mpsc::channel(10);

    let (tx1, rx1) = oneshot::channel();
    let (_client_drop_tx, client_drop_rx) = std::sync::mpsc::channel::<()>();

    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        // we never write a response head
        // simulates a slow server operation
        let _ = tx1.send(());

        // prevent this thread from closing until end of test, so the connection
        // stays open and idle until Client is dropped
        let _ = client_drop_rx.recv();
    });

    let res = {
        let client = Client::builder(TokioExecutor::new()).build(
            DebugConnector::with_http_and_closes(HttpConnector::new(), closes_tx),
        );

        let req = Request::builder()
            .uri(&*format!("http://{addr}/a"))
            .body(Empty::<Bytes>::new())
            .unwrap();
        client.request(req).map(|_| unreachable!())
    };

    future::select(res, rx1).await;

    // res now dropped
    let t = tokio::time::sleep(Duration::from_millis(100)).map(|_| panic!("time out"));
    futures_util::pin_mut!(t);
    let close = closes.into_future().map(|(opt, _)| opt.expect("closes"));
    future::select(t, close).await;
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[tokio::test]
async fn drop_response_body_closes_in_progress_connection() {
    let _ = pretty_env_logger::try_init();

    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let (closes_tx, closes) = mpsc::channel(10);

    let (tx1, rx1) = oneshot::channel();
    let (_client_drop_tx, client_drop_rx) = std::sync::mpsc::channel::<()>();

    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        write!(
            sock,
            "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n"
        )
        .expect("write head");
        let _ = tx1.send(());

        // prevent this thread from closing until end of test, so the connection
        // stays open and idle until Client is dropped
        let _ = client_drop_rx.recv();
    });

    let rx = rx1;
    let res = {
        let client = Client::builder(TokioExecutor::new()).build(
            DebugConnector::with_http_and_closes(HttpConnector::new(), closes_tx),
        );

        let req = Request::builder()
            .uri(&*format!("http://{addr}/a"))
            .body(Empty::<Bytes>::new())
            .unwrap();
        // notably, haven't read body yet
        client.request(req)
    };

    let (res, _) = future::join(res, rx).await;
    // drop the body
    res.unwrap();

    // and wait a few ticks to see the connection drop
    let t = tokio::time::sleep(Duration::from_millis(100)).map(|_| panic!("time out"));
    futures_util::pin_mut!(t);
    let close = closes.into_future().map(|(opt, _)| opt.expect("closes"));
    future::select(t, close).await;
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[tokio::test]
async fn no_keep_alive_closes_connection() {
    // https://github.com/hyperium/hyper/issues/1383
    let _ = pretty_env_logger::try_init();

    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let (closes_tx, closes) = mpsc::channel(10);

    let (tx1, rx1) = oneshot::channel();
    let (_tx2, rx2) = std::sync::mpsc::channel::<()>();

    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .unwrap();
        let _ = tx1.send(());

        // prevent this thread from closing until end of test, so the connection
        // stays open and idle until Client is dropped
        let _ = rx2.recv();
    });

    let client = Client::builder(TokioExecutor::new())
        .pool_max_idle_per_host(0)
        .build(DebugConnector::with_http_and_closes(
            HttpConnector::new(),
            closes_tx,
        ));

    let req = Request::builder()
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req).map_ok(move |res| {
        assert_eq!(res.status(), hyper::StatusCode::OK);
    });
    let rx = rx1;
    let (res, _) = future::join(res, rx).await;
    res.unwrap();

    let t = tokio::time::sleep(Duration::from_millis(100)).map(|_| panic!("time out"));
    futures_util::pin_mut!(t);
    let close = closes.into_future().map(|(opt, _)| opt.expect("closes"));
    future::select(close, t).await;
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[tokio::test]
async fn socket_disconnect_closes_idle_conn() {
    // notably when keep-alive is enabled
    let _ = pretty_env_logger::try_init();

    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let (closes_tx, closes) = mpsc::channel(10);

    let (tx1, rx1) = oneshot::channel();

    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .unwrap();
        let _ = tx1.send(());
    });

    let client = Client::builder(TokioExecutor::new()).build(DebugConnector::with_http_and_closes(
        HttpConnector::new(),
        closes_tx,
    ));

    let req = Request::builder()
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req).map_ok(move |res| {
        assert_eq!(res.status(), hyper::StatusCode::OK);
    });
    let rx = rx1;

    let (res, _) = future::join(res, rx).await;
    res.unwrap();

    let t = tokio::time::sleep(Duration::from_millis(100)).map(|_| panic!("time out"));
    futures_util::pin_mut!(t);
    let close = closes.into_future().map(|(opt, _)| opt.expect("closes"));
    future::select(t, close).await;
}

#[test]
fn connect_call_is_lazy() {
    // We especially don't want connects() triggered if there's
    // idle connections that the Checkout would have found
    let _ = pretty_env_logger::try_init();

    let _rt = runtime();
    let connector = DebugConnector::new();
    let connects = connector.connects.clone();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    assert_eq!(connects.load(Ordering::Relaxed), 0);
    let req = Request::builder()
        .uri("http://hyper.local/a")
        .body(Empty::<Bytes>::new())
        .unwrap();
    let _fut = client.request(req);
    // internal Connect::connect should have been lazy, and not
    // triggered an actual connect yet.
    assert_eq!(connects.load(Ordering::Relaxed), 0);
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn client_keep_alive_0() {
    let _ = pretty_env_logger::try_init();
    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let rt = runtime();
    let connector = DebugConnector::new();
    let connects = connector.connects.clone();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let (tx1, rx1) = oneshot::channel();
    let (tx2, rx2) = oneshot::channel();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        //drop(server);
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 1");
        let _ = tx1.send(());

        let n2 = sock.read(&mut buf).expect("read 2");
        assert_ne!(n2, 0);
        let second_get = "GET /b HTTP/1.1\r\n";
        assert_eq!(s(&buf[..second_get.len()]), second_get);
        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 2");
        let _ = tx2.send(());
    });

    assert_eq!(connects.load(Ordering::SeqCst), 0);

    let rx = rx1;
    let req = Request::builder()
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req);
    rt.block_on(future::join(res, rx).map(|r| r.0)).unwrap();

    assert_eq!(connects.load(Ordering::SeqCst), 1);

    // sleep real quick to let the threadpool put connection in ready
    // state and back into client pool
    thread::sleep(Duration::from_millis(50));

    let rx = rx2;
    let req = Request::builder()
        .uri(&*format!("http://{addr}/b"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req);
    rt.block_on(future::join(res, rx).map(|r| r.0)).unwrap();

    assert_eq!(
        connects.load(Ordering::SeqCst),
        1,
        "second request should still only have 1 connect"
    );
    drop(client);
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn client_keep_alive_extra_body() {
    let _ = pretty_env_logger::try_init();
    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let rt = runtime();

    let connector = DebugConnector::new();
    let connects = connector.connects.clone();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let (tx1, rx1) = oneshot::channel();
    let (tx2, rx2) = oneshot::channel();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 5\r\n\r\nhello")
            .expect("write 1");
        // the body "hello", while ignored because its a HEAD request, should mean the connection
        // cannot be put back in the pool
        let _ = tx1.send(());

        let mut sock2 = server.accept().unwrap().0;
        let n2 = sock2.read(&mut buf).expect("read 2");
        assert_ne!(n2, 0);
        let second_get = "GET /b HTTP/1.1\r\n";
        assert_eq!(s(&buf[..second_get.len()]), second_get);
        sock2
            .write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 2");
        let _ = tx2.send(());
    });

    assert_eq!(connects.load(Ordering::Relaxed), 0);

    let rx = rx1;
    let req = Request::builder()
        .method("HEAD")
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req);
    rt.block_on(future::join(res, rx).map(|r| r.0)).unwrap();

    assert_eq!(connects.load(Ordering::Relaxed), 1);

    let rx = rx2;
    let req = Request::builder()
        .uri(&*format!("http://{addr}/b"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req);
    rt.block_on(future::join(res, rx).map(|r| r.0)).unwrap();

    assert_eq!(connects.load(Ordering::Relaxed), 2);
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[tokio::test]
async fn client_keep_alive_when_response_before_request_body_ends() {
    let _ = pretty_env_logger::try_init();
    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();

    let (closes_tx, mut closes) = mpsc::channel::<()>(10);
    let connector = DebugConnector::with_http_and_closes(HttpConnector::new(), closes_tx);
    let connects = connector.connects.clone();
    let client = Client::builder(TokioExecutor::new()).build(connector.clone());

    let (tx1, rx1) = oneshot::channel();
    let (tx2, rx2) = oneshot::channel();
    let (_tx3, rx3) = std::sync::mpsc::channel::<()>();

    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 1");
        // after writing the response, THEN stream the body
        let _ = tx1.send(());

        sock.read(&mut buf).expect("read 2");
        let _ = tx2.send(());

        // prevent this thread from closing until end of test, so the connection
        // stays open and idle until Client is dropped
        let _ = rx3.recv();
    });

    assert_eq!(connects.load(Ordering::Relaxed), 0);

    let delayed_body = rx1
        .then(|_| Box::pin(tokio::time::sleep(Duration::from_millis(200))))
        .map(|_| Ok::<_, ()>(Frame::data(&b"hello a"[..])))
        .map_err(|_| -> hyper::Error { panic!("rx1") })
        .into_stream();

    let req = Request::builder()
        .method("POST")
        .uri(&*format!("http://{addr}/a"))
        .body(StreamBody::new(delayed_body))
        .unwrap();
    let res = client.request(req).map_ok(move |res| {
        assert_eq!(res.status(), hyper::StatusCode::OK);
    });

    future::join(res, rx2).await.0.unwrap();
    std::future::poll_fn(|ctx| {
        assert!(Pin::new(&mut closes).poll_next(ctx).is_pending());
        Poll::Ready(())
    })
    .await;

    assert_eq!(connects.load(Ordering::Relaxed), 1);

    drop(client);
    let t = tokio::time::sleep(Duration::from_millis(100)).map(|_| panic!("time out"));
    futures_util::pin_mut!(t);
    let close = closes.into_future().map(|(opt, _)| opt.expect("closes"));
    future::select(t, close).await;
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[tokio::test]
async fn client_keep_alive_eager_when_chunked() {
    // If a response body has been read to completion, with completion
    // determined by some other factor, like decompression, and thus
    // it is in't polled a final time to clear the final 0-len chunk,
    // try to eagerly clear it so the connection can still be used.

    let _ = pretty_env_logger::try_init();
    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let connector = DebugConnector::new();
    let connects = connector.connects.clone();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let (tx1, rx1) = oneshot::channel();
    let (tx2, rx2) = oneshot::channel();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        //drop(server);
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write_all(
            b"\
                HTTP/1.1 200 OK\r\n\
                transfer-encoding: chunked\r\n\
                \r\n\
                5\r\n\
                hello\r\n\
                0\r\n\r\n\
            ",
        )
        .expect("write 1");
        let _ = tx1.send(());

        let n2 = sock.read(&mut buf).expect("read 2");
        assert_ne!(n2, 0, "bytes of second request");
        let second_get = "GET /b HTTP/1.1\r\n";
        assert_eq!(s(&buf[..second_get.len()]), second_get);
        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 2");
        let _ = tx2.send(());
    });

    assert_eq!(connects.load(Ordering::SeqCst), 0);

    let rx = rx1;
    let req = Request::builder()
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let fut = client.request(req);

    let resp = future::join(fut, rx).map(|r| r.0).await.unwrap();
    assert_eq!(connects.load(Ordering::SeqCst), 1);
    assert_eq!(resp.status(), 200);
    assert_eq!(resp.headers()["transfer-encoding"], "chunked");

    // Read the "hello" chunk...
    let chunk = resp.collect().await.unwrap().to_bytes();
    assert_eq!(chunk, "hello");

    // sleep real quick to let the threadpool put connection in ready
    // state and back into client pool
    tokio::time::sleep(Duration::from_millis(50)).await;

    let rx = rx2;
    let req = Request::builder()
        .uri(&*format!("http://{addr}/b"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let fut = client.request(req);
    future::join(fut, rx).map(|r| r.0).await.unwrap();

    assert_eq!(
        connects.load(Ordering::SeqCst),
        1,
        "second request should still only have 1 connect"
    );
    drop(client);
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn connect_proxy_sends_absolute_uri() {
    let _ = pretty_env_logger::try_init();
    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let rt = runtime();
    let connector = DebugConnector::new().proxy();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let (tx1, rx1) = oneshot::channel();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        //drop(server);
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        let n = sock.read(&mut buf).expect("read 1");
        let expected = format!("GET http://{addr}/foo/bar HTTP/1.1\r\nhost: {addr}\r\n\r\n");
        assert_eq!(s(&buf[..n]), expected);

        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 1");
        let _ = tx1.send(());
    });

    let rx = rx1;
    let req = Request::builder()
        .uri(&*format!("http://{addr}/foo/bar"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req);
    rt.block_on(future::join(res, rx).map(|r| r.0)).unwrap();
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn connect_proxy_http_connect_sends_authority_form() {
    let _ = pretty_env_logger::try_init();
    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let rt = runtime();
    let connector = DebugConnector::new().proxy();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let (tx1, rx1) = oneshot::channel();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        //drop(server);
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        let n = sock.read(&mut buf).expect("read 1");
        let expected = format!("CONNECT {addr} HTTP/1.1\r\nhost: {addr}\r\n\r\n");
        assert_eq!(s(&buf[..n]), expected);

        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 1");
        let _ = tx1.send(());
    });

    let rx = rx1;
    let req = Request::builder()
        .method("CONNECT")
        .uri(&*format!("http://{addr}/useless/path"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let res = client.request(req);
    rt.block_on(future::join(res, rx).map(|r| r.0)).unwrap();
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn client_upgrade() {
    use tokio::io::{AsyncReadExt, AsyncWriteExt};

    let _ = pretty_env_logger::try_init();
    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let rt = runtime();

    let connector = DebugConnector::new();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let (tx1, rx1) = oneshot::channel();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write_all(
            b"\
                HTTP/1.1 101 Switching Protocols\r\n\
                Upgrade: foobar\r\n\
                \r\n\
                foobar=ready\
            ",
        )
        .unwrap();
        let _ = tx1.send(());

        let n = sock.read(&mut buf).expect("read 2");
        assert_eq!(&buf[..n], b"foo=bar");
        sock.write_all(b"bar=foo").expect("write 2");
    });

    let rx = rx1;

    let req = Request::builder()
        .method("GET")
        .uri(&*format!("http://{addr}/up"))
        .body(Empty::<Bytes>::new())
        .unwrap();

    let res = client.request(req);
    let res = rt.block_on(future::join(res, rx).map(|r| r.0)).unwrap();

    assert_eq!(res.status(), 101);
    let upgraded = rt.block_on(hyper::upgrade::on(res)).expect("on_upgrade");

    let parts = upgraded.downcast::<DebugStream>().unwrap();
    assert_eq!(s(&parts.read_buf), "foobar=ready");

    let mut io = parts.io;
    rt.block_on(io.write_all(b"foo=bar")).unwrap();
    let mut vec = vec![];
    rt.block_on(io.read_to_end(&mut vec)).unwrap();
    assert_eq!(vec, b"bar=foo");
}

#[cfg(not(miri))]
#[cfg(feature = "server")]
#[test]
fn client_http2_upgrade() {
    use http::{Method, Response, Version};
    use hyper::service::service_fn;
    use tokio::io::{AsyncReadExt, AsyncWriteExt};
    use tokio::net::TcpListener;

    let _ = pretty_env_logger::try_init();
    let rt = runtime();
    let server = rt
        .block_on(TcpListener::bind(SocketAddr::from(([127, 0, 0, 1], 0))))
        .unwrap();
    let addr = server.local_addr().unwrap();
    let mut connector = DebugConnector::new();
    connector.alpn_h2 = true;

    let client = Client::builder(TokioExecutor::new()).build(connector);

    rt.spawn(async move {
        let (stream, _) = server.accept().await.expect("accept");
        let stream = TokioIo::new(stream);
        let mut builder = hyper_util::server::conn::auto::Builder::new(TokioExecutor::new());
        // IMPORTANT: This is required to advertise our support for HTTP/2 websockets to the client.
        builder.http2().enable_connect_protocol();
        builder
            .serve_connection_with_upgrades(
                stream,
                service_fn(|req| async move {
                    assert_eq!(req.headers().get("host"), None);
                    assert_eq!(req.version(), Version::HTTP_2);
                    assert_eq!(
                        req.headers().get(http::header::SEC_WEBSOCKET_VERSION),
                        Some(&http::header::HeaderValue::from_static("13"))
                    );
                    assert_eq!(
                        req.extensions().get::<hyper::ext::Protocol>(),
                        Some(&hyper::ext::Protocol::from_static("websocket"))
                    );

                    let on_upgrade = hyper::upgrade::on(req);
                    tokio::spawn(async move {
                        let upgraded = on_upgrade.await.unwrap();
                        let mut io = TokioIo::new(upgraded);

                        let mut vec = vec![];
                        io.read_buf(&mut vec).await.unwrap();
                        assert_eq!(vec, b"foo=bar");
                        io.write_all(b"bar=foo").await.unwrap();
                    });

                    Ok::<_, hyper::Error>(Response::new(Empty::<Bytes>::new()))
                }),
            )
            .await
            .expect("server");
    });

    let req = Request::builder()
        .method(Method::CONNECT)
        .uri(&*format!("http://{addr}/up"))
        .header(http::header::SEC_WEBSOCKET_VERSION, "13")
        .version(Version::HTTP_2)
        .extension(hyper::ext::Protocol::from_static("websocket"))
        .body(Empty::<Bytes>::new())
        .unwrap();

    let res = client.request(req);
    let res = rt.block_on(res).unwrap();

    assert_eq!(res.status(), http::StatusCode::OK);
    assert_eq!(res.version(), Version::HTTP_2);

    let upgraded = rt.block_on(hyper::upgrade::on(res)).expect("on_upgrade");
    let mut io = TokioIo::new(upgraded);

    rt.block_on(io.write_all(b"foo=bar")).unwrap();
    let mut vec = vec![];
    rt.block_on(io.read_to_end(&mut vec)).unwrap();
    assert_eq!(vec, b"bar=foo");
}

#[cfg(not(miri))]
#[cfg(feature = "http2")]
#[test]
fn alpn_h2() {
    use http::Response;
    use hyper::service::service_fn;
    use tokio::net::TcpListener;

    let _ = pretty_env_logger::try_init();
    let rt = runtime();
    let listener = rt
        .block_on(TcpListener::bind(SocketAddr::from(([127, 0, 0, 1], 0))))
        .unwrap();
    let addr = listener.local_addr().unwrap();
    let mut connector = DebugConnector::new();
    connector.alpn_h2 = true;
    let connects = connector.connects.clone();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    rt.spawn(async move {
        let (stream, _) = listener.accept().await.expect("accept");
        let stream = TokioIo::new(stream);
        hyper::server::conn::http2::Builder::new(TokioExecutor::new())
            .serve_connection(
                stream,
                service_fn(|req| async move {
                    assert_eq!(req.headers().get("host"), None);
                    Ok::<_, hyper::Error>(Response::new(Full::<Bytes>::from("Hello, world")))
                }),
            )
            .await
            .expect("server");
    });

    assert_eq!(connects.load(Ordering::SeqCst), 0);

    let url = format!("http://{addr}/a").parse::<::hyper::Uri>().unwrap();
    let res1 = client.get(url.clone());
    let res2 = client.get(url.clone());
    let res3 = client.get(url.clone());
    rt.block_on(future::try_join3(res1, res2, res3)).unwrap();

    // Since the client doesn't know it can ALPN at first, it will have
    // started 3 connections. But, the server above will only handle 1,
    // so the unwrapped responses futures show it still worked.
    assert_eq!(connects.load(Ordering::SeqCst), 3);

    let res4 = client.get(url.clone());
    rt.block_on(res4).unwrap();

    // HTTP/2 request allowed
    let res5 = client.request(
        Request::builder()
            .uri(url)
            .version(hyper::Version::HTTP_2)
            .body(Empty::<Bytes>::new())
            .unwrap(),
    );
    rt.block_on(res5).unwrap();

    assert_eq!(
        connects.load(Ordering::SeqCst),
        3,
        "after ALPN, no more connects"
    );
    drop(client);
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn capture_connection_on_client() {
    let _ = pretty_env_logger::try_init();

    let rt = runtime();
    let connector = DebugConnector::new();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    thread::spawn(move || {
        let mut sock = server.accept().unwrap().0;
        sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
        sock.set_write_timeout(Some(Duration::from_secs(5)))
            .unwrap();
        let mut buf = [0; 4096];
        sock.read(&mut buf).expect("read 1");
        sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
            .expect("write 1");
    });
    let mut req = Request::builder()
        .uri(&*format!("http://{addr}/a"))
        .body(Empty::<Bytes>::new())
        .unwrap();
    let captured_conn = capture_connection(&mut req);
    rt.block_on(client.request(req)).expect("200 OK");
    assert!(captured_conn.connection_metadata().is_some());
}

#[cfg(not(miri))]
#[cfg(feature = "http1")]
#[test]
fn connection_poisoning() {
    use std::sync::atomic::AtomicUsize;

    let _ = pretty_env_logger::try_init();

    let rt = runtime();
    let connector = DebugConnector::new();

    let client = Client::builder(TokioExecutor::new()).build(connector);

    let server = TcpListener::bind("127.0.0.1:0").unwrap();
    let addr = server.local_addr().unwrap();
    let num_conns: Arc<AtomicUsize> = Default::default();
    let num_requests: Arc<AtomicUsize> = Default::default();
    let num_requests_tracker = num_requests.clone();
    let num_conns_tracker = num_conns.clone();
    thread::spawn(move || loop {
        let mut sock = server.accept().unwrap().0;
        num_conns_tracker.fetch_add(1, Ordering::Relaxed);
        let num_requests_tracker = num_requests_tracker.clone();
        thread::spawn(move || {
            sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
            sock.set_write_timeout(Some(Duration::from_secs(5)))
                .unwrap();
            let mut buf = [0; 4096];
            loop {
                if sock.read(&mut buf).expect("read 1") > 0 {
                    num_requests_tracker.fetch_add(1, Ordering::Relaxed);
                    sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n")
                        .expect("write 1");
                }
            }
        });
    });
    let make_request = || {
        Request::builder()
            .uri(&*format!("http://{addr}/a"))
            .body(Empty::<Bytes>::new())
            .unwrap()
    };
    let mut req = make_request();
    let captured_conn = capture_connection(&mut req);
    rt.block_on(client.request(req)).expect("200 OK");
    assert_eq!(num_conns.load(Ordering::SeqCst), 1);
    assert_eq!(num_requests.load(Ordering::SeqCst), 1);

    rt.block_on(client.request(make_request())).expect("200 OK");
    rt.block_on(client.request(make_request())).expect("200 OK");
    // Before poisoning the connection is reused
    assert_eq!(num_conns.load(Ordering::SeqCst), 1);
    assert_eq!(num_requests.load(Ordering::SeqCst), 3);
    captured_conn
        .connection_metadata()
        .as_ref()
        .unwrap()
        .poison();

    rt.block_on(client.request(make_request())).expect("200 OK");

    // After poisoning, a new connection is established
    assert_eq!(num_conns.load(Ordering::SeqCst), 2);
    assert_eq!(num_requests.load(Ordering::SeqCst), 4);

    rt.block_on(client.request(make_request())).expect("200 OK");
    // another request can still reuse:
    assert_eq!(num_conns.load(Ordering::SeqCst), 2);
    assert_eq!(num_requests.load(Ordering::SeqCst), 5);
}

// -------------------------------------------------------
// Below is our custom code for testing hyper legacy-client behavior with mock connections for PR #184
// We use fully qualified paths for all types and identifiers to make this code
// copy/paste-able without relying on external 'use' statements. Detailed inline
// comments explain the purpose and logic of each section.

//XXX: can manually run like this:
// $ cargo test --features="http1,http2,server,client-legacy" --test legacy_client -- test_connection_error_propagation test_incomplete_message_error --nocapture
// $ cargo test --all-features --test legacy_client -- --nocapture
// $ cargo test --all-features --test legacy_client

use std::error::Error; // needed for .source() eg. error[E0599]: no method named `source` found for struct `hyper_util::client::legacy::Error` in the current scope

// Helper function to debug byte slices by attempting to interpret them as UTF-8.
// If the bytes are valid UTF-8, they are printed as a string; otherwise, they are
// printed as a raw byte array. This aids in debugging tokio_test::io::Mock mismatches.
fn debug_bytes(bytes: &[u8], label: &str) {
    // Try to convert the byte slice to a UTF-8 string.
    // If successful, print it with the provided label for context.
    if let Ok(s) = std::str::from_utf8(bytes) {
        eprintln!("{}: {}", label, s);
    } else {
        // If the bytes are not valid UTF-8, print them as a raw byte array.
        eprintln!("{}: {:?}", label, bytes);
    }
}

// Struct representing a mock connection for testing hyper client behavior.
// Implements hyper::rt::Read, hyper::rt::Write, and hyper_util::client::legacy::connect::Connection
// traits to simulate I/O operations. Uses tokio_test::io::Mock for controlled I/O behavior.
struct MockConnection {
    // The underlying mock I/O object, wrapped in hyper_util::rt::TokioIo for compatibility.
    inner: hyper_util::rt::TokioIo<tokio_test::io::Mock>,
    // Atomic flag to signal a connection failure, controlling poll_read behavior.
    failed: std::sync::Arc<std::sync::atomic::AtomicBool>,
    // The error to return when failed=true, simulating an I/O failure.
    error: std::sync::Arc<std::io::Error>,
    // Optional channel to signal unexpected writes, used for debugging.
    error_tx: Option<tokio::sync::mpsc::Sender<()>>,
    // Tracks total bytes written, for logging and verification.
    bytes_written: usize,
}

impl MockConnection {
    // Constructor for MockConnection, initializing all fields.
    // Takes a mock I/O object, failure flag, error, and optional error channel.
    fn new(
        mock: tokio_test::io::Mock,
        failed: std::sync::Arc<std::sync::atomic::AtomicBool>,
        error: std::sync::Arc<std::io::Error>,
        error_tx: Option<tokio::sync::mpsc::Sender<()>>,
    ) -> Self {
        MockConnection {
            inner: hyper_util::rt::TokioIo::new(mock),
            failed,
            error,
            error_tx,
            bytes_written: 0,
        }
    }
}

// Implement hyper::rt::Read trait to handle read operations on the mock connection.
// Controls whether an error or mock I/O data is returned based on the failed flag.
impl hyper::rt::Read for MockConnection {
    // Polls the connection for reading, filling the provided buffer.
    // If failed=true, returns the stored error; otherwise, delegates to the mock I/O.
    fn poll_read(
        mut self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
        buf: hyper::rt::ReadBufCursor<'_>,
    ) -> std::task::Poll<std::result::Result<(), std::io::Error>> {
        // Log the current state of the failed flag for debugging.
        eprintln!(
            "poll_read: failed={}",
            self.failed.load(std::sync::atomic::Ordering::SeqCst)
        );
        // Check if the connection is marked as failed.
        // If true, return the stored error immediately to simulate a connection failure.
        if self.failed.load(std::sync::atomic::Ordering::SeqCst) {
            // Log the error being returned for traceability.
            eprintln!("poll_read: returning error: {}", self.error);
            // Create a new io::Error with the same kind and message as the stored error.
            return std::task::Poll::Ready(std::result::Result::Err(std::io::Error::new(
                self.error.kind(),
                self.error.to_string(),
            )));
        }
        // If not failed, delegate to the mock I/O to simulate normal read behavior.
        // This may return EOF (Poll::Ready(Ok(0))) for empty IoBuilder.
        let inner = std::pin::Pin::new(&mut self.inner);
        inner.poll_read(cx, buf)
    }
}

// Implement hyper::rt::Write trait to handle write operations on the mock connection.
// Logs writes and signals unexpected writes via error_tx.
impl hyper::rt::Write for MockConnection {
    // Polls the connection for writing, sending the provided buffer.
    // Logs the write operation and tracks total bytes written.
    fn poll_write(
        mut self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
        buf: &[u8],
    ) -> std::task::Poll<std::result::Result<usize, std::io::Error>> {
        // Log the size of the buffer being written for debugging.
        eprintln!("poll_write: {} bytes", buf.len());
        // Debug the buffer contents as UTF-8 or raw bytes.
        debug_bytes(buf, "poll_write buffer");
        // Delegate the write to the mock I/O object.
        let inner = std::pin::Pin::new(&mut self.inner);
        match inner.poll_write(cx, buf) {
            // If the write succeeds, update the bytes_written counter and log the result.
            std::task::Poll::Ready(std::result::Result::Ok(bytes)) => {
                // Increment the total bytes written for tracking.
                self.bytes_written += bytes;
                // Log the number of bytes written and the running total.
                eprintln!(
                    "poll_write: wrote {} bytes, total={}",
                    bytes, self.bytes_written
                );
                // If error_tx is present, signal an unexpected write (used in error tests).
                // This helps detect writes when the connection should fail early.
                if let Some(tx) = self.error_tx.take() {
                    // Log that an unexpected write is being signaled.
                    eprintln!("poll_write: signaling unexpected write");
                    // Send a message through the channel, ignoring errors if the receiver is closed.
                    let _ = tx.try_send(());
                }
                // Return the successful write result.
                std::task::Poll::Ready(std::result::Result::Ok(bytes))
            }
            // For pending or error results, propagate them directly.
            other => other,
        }
    }

    // Polls the connection to flush any buffered data.
    // Delegates to the mock I/O object.
    fn poll_flush(
        mut self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<std::result::Result<(), std::io::Error>> {
        // Log the flush operation for debugging.
        eprintln!("poll_flush");
        // Delegate the flush to the mock I/O object.
        let inner = std::pin::Pin::new(&mut self.inner);
        inner.poll_flush(cx)
    }

    // Polls the connection to shut down the write side.
    // Delegates to the mock I/O object.
    fn poll_shutdown(
        mut self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<std::result::Result<(), std::io::Error>> {
        // Log the shutdown operation for debugging.
        eprintln!("poll_shutdown");
        // Delegate the shutdown to the mock I/O object.
        let inner = std::pin::Pin::new(&mut self.inner);
        inner.poll_shutdown(cx)
    }
}

// Implement hyper_util::client::legacy::connect::Connection trait to provide connection metadata.
// Required for hyper to use MockConnection as a valid connection.
impl hyper_util::client::legacy::connect::Connection for MockConnection {
    // Returns metadata about the connection.
    // In this case, a default Connected object indicating a new connection.
    fn connected(&self) -> hyper_util::client::legacy::connect::Connected {
        hyper_util::client::legacy::connect::Connected::new()
    }
}

// Struct representing a mock connector for creating MockConnection instances.
// Implements tower_service::Service to integrate with hyper’s client.
#[derive(Clone)]
struct MockConnector {
    // The IoBuilder used to create mock I/O objects for each connection.
    io_builder: tokio_test::io::Builder,
    // Optional error to simulate a connection failure, passed to MockConnection.
    conn_error: Option<std::sync::Arc<std::io::Error>>,
}

impl MockConnector {
    // Constructor for MockConnector, initializing the IoBuilder and optional error.
    fn new(
        io_builder: tokio_test::io::Builder,
        conn_error: Option<std::sync::Arc<std::io::Error>>,
    ) -> Self {
        MockConnector {
            io_builder,
            conn_error,
        }
    }
}

// Implement tower_service::Service for MockConnector to create MockConnection instances.
// Takes a hyper::Uri and returns a future resolving to a MockConnection.
impl tower_service::Service<hyper::Uri> for MockConnector {
    type Response = crate::MockConnection;
    type Error = std::io::Error;
    type Future = std::pin::Pin<
        Box<
            dyn std::future::Future<Output = std::result::Result<Self::Response, Self::Error>>
                + Send,
        >,
    >;

    // Polls the connector to check if it’s ready to handle a request.
    // Always ready, as we don’t have resource constraints.
    fn poll_ready(
        &mut self,
        _cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<std::result::Result<(), Self::Error>> {
        std::task::Poll::Ready(std::result::Result::Ok(()))
    }

    // Creates a new MockConnection for the given URI.
    // Configures the connection based on io_builder and conn_error.
    fn call(&mut self, _req: hyper::Uri) -> Self::Future {
        // Clone the IoBuilder to create a fresh mock I/O object.
        let mut io_builder = self.io_builder.clone();
        // Clone the optional connection error for this call.
        let conn_error = self.conn_error.clone();
        // Return a pinned future that creates the MockConnection.
        Box::pin(async move {
            // Build the mock I/O object from the IoBuilder.
            // This defines the I/O behavior (e.g., EOF for empty builder).
            let mock = io_builder.build();
            // Create an atomic flag to track connection failure, initially false.
            let failed = std::sync::Arc::new(std::sync::atomic::AtomicBool::new(false));
            // Set the default error for non-failure cases.
            // Used when conn_error is None, simulating a clean EOF or connection close.
            let error = if let Some(ref err) = conn_error {
                err.clone()
            } else {
                std::sync::Arc::new(std::io::Error::new(
                    std::io::ErrorKind::BrokenPipe,
                    "connection closed",
                ))
            };
            // Create an mpsc channel for signaling unexpected writes, if conn_error is set.
            // This helps debug cases where writes occur despite an expected failure.
            let error_tx = if conn_error.is_some() {
                // Create a channel with a buffer of 1 for signaling writes.
                let (tx, mut rx) = tokio::sync::mpsc::channel::<()>(1);
                // Spawn a task to log unexpected writes when received.
                tokio::spawn(async move {
                    // Wait for a message indicating a write occurred.
                    if rx.recv().await.is_some() {
                        // Log the unexpected write for debugging.
                        eprintln!("Unexpected write occurred");
                    }
                });
                Some(tx)
            } else {
                None
            };
            // If a connection error is provided, mark the connection as failed.
            // This causes poll_read to return the error immediately.
            if let Some(err_clone) = conn_error {
                // Set the failed flag to true atomically.
                failed.store(true, std::sync::atomic::Ordering::SeqCst);
                // Log the simulated error for traceability.
                eprintln!("Simulated conn task error: {}", err_clone);
            }
            // Create and return the MockConnection with all configured components.
            std::result::Result::Ok(crate::MockConnection::new(mock, failed, error, error_tx))
        })
    }
}

// Test for connection error propagation with PR #184.
// Simulates a connection failure by setting failed=true and returning a custom io::Error.
// Verifies the error propagates through hyper’s client as a hyper::Error(Io, ...).
#[cfg(feature = "http1")]
#[tokio::test]
async fn test_connection_error_propagation_pr184() {
    // Define the error message for the simulated connection failure.
    // Reused for creating the error and verifying the result.
    let err_str = "mock connection failure";
    // Create an io::Error with Other kind and the custom message.
    // Wrapped in Arc for sharing across threads and MockConnection.
    let io_error = std::sync::Arc::new(std::io::Error::new(std::io::ErrorKind::Other, err_str));
    // Create an empty IoBuilder, as no I/O is expected.
    // The error triggers before any reads or writes occur.
    let io_builder = tokio_test::io::Builder::new();
    // Create a MockConnector with the error to simulate a failed connection.
    // The error will set failed=true in MockConnection.
    let connector = crate::MockConnector::new(io_builder, Some(io_error.clone()));
    // Build the hyper client with TokioExecutor and our connector.
    // pool_max_idle_per_host(0) disables connection pooling for a fresh connection.
    let client = hyper_util::client::legacy::Client::builder(hyper_util::rt::TokioExecutor::new())
        .pool_max_idle_per_host(0)
        .build::<_, http_body_util::Empty<hyper::body::Bytes>>(connector);
    // Build a GET request to a mock URI with custom headers.
    // Uses mixed-case headers to match your style, ensuring case-insensitive handling.
    let request = hyper::Request::builder()
        .uri("http://mocked")
        .header("hoSt", "mocked")
        .header("conNection", "close")
        .body(http_body_util::Empty::<hyper::body::Bytes>::new())
        .expect("failed to build request");
    // Send the request and capture the result.
    // Expect it to fail due to the simulated connection error.
    let result = client.request(request).await;
    // Extract the error, as the request should fail.
    let err = result.expect_err("expected request to fail");
    // Log the full error for debugging, including its structure.
    // Matches your detailed logging style for traceability.
    eprintln!("Actually gotten error is: {:?}", err);
    // Downcast the error to a hyper::Error to verify its type.
    // Expect a hyper::Error wrapping an io::Error from MockConnection.
    let hyper_err = err
        .source()
        .and_then(|e| e.downcast_ref::<hyper::Error>())
        .expect("expected hyper::Error");
    // Downcast the hyper::Error’s source to an io::Error.
    // Verify it matches the simulated error from MockConnection.
    let io_err = hyper_err
        .source()
        .and_then(|e| e.downcast_ref::<std::io::Error>())
        .expect(&format!("expected io::Error but got {:?}", hyper_err));
    // Verify the io::Error has the expected kind (Other).
    assert_eq!(io_err.kind(), std::io::ErrorKind::Other);
    // Verify the io::Error’s message matches err_str.
    assert_eq!(io_err.to_string(), err_str);
}

// Test for consistent IncompleteMessage error with or without PR #184.
// Simulates a connection that returns EOF immediately, causing hyper’s HTTP/1.1 parser
// to fail with IncompleteMessage due to no response data.
// Uses MockConnector with conn_error=None to keep failed=false, ensuring EOF behavior.
#[cfg(feature = "http1")]
#[tokio::test]
async fn test_incomplete_message_error_pr184() {
    // Create an empty IoBuilder to simulate a connection with no data.
    // No write or read expectations, so poll_read returns EOF (Poll::Ready(Ok(0))).
    // This triggers IncompleteMessage in hyper’s parser.
    let io_builder = tokio_test::io::Builder::new();
    // Create MockConnector with no error (conn_error=None).
    // Keeps failed=false in MockConnection, so poll_read delegates to the mock’s EOF.
    let connector = crate::MockConnector::new(io_builder, None);
    // Build the hyper client with TokioExecutor and our connector.
    // pool_max_idle_per_host(0) disables pooling for a fresh connection.
    let client = hyper_util::client::legacy::Client::builder(hyper_util::rt::TokioExecutor::new())
        .pool_max_idle_per_host(0)
        .build::<_, http_body_util::Empty<hyper::body::Bytes>>(connector);
    // Build a GET request to a mock URI with headers.
    // Uses mixed-case headers to match test_connection_error_propagation_pr184.
    // Empty body ensures focus on response parsing failure.
    let request = hyper::Request::builder()
        .uri("http://mocked")
        .header("hoSt", "mocked")
        .header("conNection", "close")
        .body(http_body_util::Empty::<hyper::body::Bytes>::new())
        .expect("failed to build request");
    // Send the request and capture the result.
    // Expect failure due to EOF causing IncompleteMessage.
    let result = client.request(request).await;
    // Extract the error, as the request should fail.
    // Without PR #184, expect ChannelClosed; with PR #184, expect IncompleteMessage.
    let err = result.expect_err("expected request to fail");
    // Log the full error for debugging, matching your style.
    eprintln!("Actually gotten error is: {:?}", err);
    // Downcast to hyper::Error to verify the error type.
    // Expect IncompleteMessage (with PR #184) or ChannelClosed (without).
    let hyper_err = err
        .source()
        .and_then(|e| e.downcast_ref::<hyper::Error>())
        .expect("expected hyper::Error");
    // Verify the error is IncompleteMessage when PR #184 is applied.
    // This checks the parser’s failure due to EOF.
    assert!(
        hyper_err.is_incomplete_message(),
        "expected IncompleteMessage, got {:?}",
        hyper_err
    );
    // Confirm no io::Error is present, as this is a parsing failure, not I/O.
    // Ensures we’re testing the correct error type.
    assert!(
        hyper_err
            .source()
            .and_then(|e| e.downcast_ref::<std::io::Error>())
            .is_none(),
        "expected no io::Error, got {:?}",
        hyper_err
    );
}

// Test for a successful HTTP/1.1 connection using a mock connector.
// Simulates a server that accepts a request and responds with a 200 OK.
// Verifies the client correctly sends the request and receives the response.
#[cfg(feature = "http1")]
#[tokio::test]
async fn test_successful_connection() {
    // Define the expected server response: a valid HTTP/1.1 200 OK with no body.
    let response = b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n";
    // Define the expected client request, including headers and CRLF termination.
    // This ensures the client sends the correct request format.
    let expected_request = b"GET / HTTP/1.1\r\nhost: mocked\r\nconnection: close\r\n\r\n";
    // Create an IoBuilder to simulate the server’s I/O behavior.
    // Expect the client to write the request and read the response.
    let mut io_builder = tokio_test::io::Builder::new();
    // Configure the IoBuilder to expect the request and provide the response.
    io_builder.write(expected_request).read(response);
    // Finalize the IoBuilder for use in the connector.
    let io_builder = io_builder;
    // Create a MockConnector with no error (conn_error=None).
    // Ensures failed=false, allowing normal I/O operations.
    let connector = crate::MockConnector::new(io_builder, None);
    // Build the hyper client with TokioExecutor and our connector.
    // pool_max_idle_per_host(0) ensures a fresh connection.
    let client = hyper_util::client::legacy::Client::builder(hyper_util::rt::TokioExecutor::new())
        .pool_max_idle_per_host(0)
        .build::<_, http_body_util::Empty<hyper::body::Bytes>>(connector);
    // Build a GET request to a mock URI with headers.
    // Uses mixed-case headers to match your style and verify case-insensitive handling.
    let request = hyper::Request::builder()
        .uri("http://mocked")
        .header("hOst", "mocked")
        .header("coNnection", "close")
        .body(http_body_util::Empty::<hyper::body::Bytes>::new())
        .expect("failed to build request");
    // Send the request and capture the response.
    // Expect a successful response due to the configured IoBuilder.
    let response = client
        .request(request)
        .await
        .expect("request should succeed");
    // Verify the response status is 200 OK.
    assert_eq!(response.status(), 200);
}
