deadlock in Tempfile::read_field with TestRequest

[lovasoa]

I was creating a test for a case where a client sends an invalid multipart request without a closing boundary:

use actix_multipart::{
    form::{tempfile::TempFile, FieldReader},
    Multipart,
};
use actix_web::{
    dev::{self, ServiceResponse},
    error::ErrorBadRequest,
    web, App, FromRequest, HttpServer, middleware::Logger,
};
use futures::StreamExt;

async fn test(srv_req: dev::ServiceRequest) -> actix_web::Result<dev::ServiceResponse> {
    let (req, mut pl) = srv_req.into_parts();
    let mut multipart = Multipart::from_request(&req, &mut pl).await?;
    let file_field = multipart.next().await.ok_or(ErrorBadRequest("no file"))??;
    let mut limits = actix_multipart::form::Limits::new(1000, 1000);
    let file_obj = TempFile::read_field(&req, file_field, &mut limits).await?;
    let resp = format!(
        "Loaded file {:?} in {:?}",
        file_obj.file_name,
        file_obj.file.path()
    );
    Ok(ServiceResponse::new(
        req,
        actix_web::HttpResponse::Ok().body(resp),
    ))
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    env_logger::init();
    let srv = HttpServer::new(|| 
            App::new().service(web::service("/").finish(test))
            .wrap(Logger::default())
        )
        .bind("127.0.0.1:8080")?
        .run();
    srv.await
}

#[actix_web::test]
async fn test_problematic_payload() -> std::io::Result<()> {
    use actix_web::test::TestRequest;

    let testrequest = TestRequest::get()
        .insert_header(("content-type", "multipart/form-data;boundary=xxx"))
        .set_payload(
            "--xxx\r\n\
        Content-Disposition: form-data; name=\"my_uploaded_file\"; filename=\"test.txt\"\r\n\
        \r\n\
        Hello World\r\n\
        ", // no closing boundary
        )
        .to_srv_request();
    let resp = test(testrequest).await.unwrap();
    println!("Response: {:?}", resp.response().body());
    Ok(())
}

Expected Behavior

I would have expected the behavior with TestRequest to be the same as the one with the live server.

Current Behavior

When running the live server and testing it manually with

nc -N localhost 8080 << EOF
POST / HTTP/1.1
Host: localhost:8081
User-Agent: curl/7.81.0
Accept: */*
Content-Length: 452
Content-Type: multipart/form-data; boundary=------------------------bf59f5a0357ff623

--------------------------bf59f5a0357ff623
Content-Disposition: form-data; name="my_file"; filename="hosts"
Content-Type: application/octet-stream


hello world
I do not have a closing boundary
EOF

Nothing deadlocks, and I get a proper response:

HTTP/1.1 400 Bad Request
content-length: 30
content-type: text/plain; charset=utf-8
date: Thu, 23 Nov 2023 20:17:20 GMT

Multipart stream is incomplete

But when running the test with cargo test, it simply never returns.