Chain request headers in WSGI protocol (#296)

Cargo.toml

@@ -36,6 +36,7 @@ futures = "0.3"
 http-body-util = { version = "=0.1" }
 hyper = { version = "=1.3", features = ["http1", "http2", "server"] }
 hyper-util = { version = "=0.1", features = ["server-auto", "tokio"] }
+itertools = "0.13"
 log = "0.4"
 percent-encoding = "=2.3"
 pin-project = "1.1"

src/wsgi/callbacks.rs

@@ -7,6 +7,7 @@ use hyper::{
     http::{request, uri::Authority},
     Version,
 };
+use itertools::Itertools;
 use percent_encoding::percent_decode_str;
 use pyo3::{
     prelude::*,
@@ -51,15 +52,20 @@ fn run_callback(
     let content_type = parts.headers.remove(header::CONTENT_TYPE);
     let content_len = parts.headers.remove(header::CONTENT_LENGTH);
     let mut headers = Vec::with_capacity(parts.headers.len());
-    for (key, val) in &parts.headers {
+    for key in parts.headers.keys() {
         headers.push((
             format!("HTTP_{}", key.as_str().replace('-', "_").to_uppercase()),
-            val.to_str().unwrap_or_default(),
+            parts
+                .headers
+                .get_all(key)
+                .iter()
+                .map(|v| v.to_str().unwrap_or_default())
+                .join(","),
         ));
     }
     if !parts.headers.contains_key(header::HOST) {
         let host = parts.uri.authority().map_or("", Authority::as_str);
-        headers.push(("HTTP_HOST".to_string(), host));
+        headers.push(("HTTP_HOST".to_string(), host.to_string()));
     }
 
     Python::with_gil(|py| {

tests/test_wsgi.py

@@ -10,7 +10,9 @@
 async def test_scope(wsgi_server, threading_mode):
     payload = 'body_payload'
     async with wsgi_server(threading_mode) as port:
-        res = httpx.post(f'http://localhost:{port}/info?test=true', content=payload)
+        res = httpx.post(
+            f'http://localhost:{port}/info?test=true', content=payload, headers=[('test', 'val1'), ('test', 'val2')]
+        )
 
     assert res.status_code == 200
     assert res.headers['content-type'] == 'application/json'
@@ -22,6 +24,7 @@ async def test_scope(wsgi_server, threading_mode):
     assert data['query_string'] == 'test=true'
     assert data['headers']['HTTP_HOST'] == f'localhost:{port}'
     assert data['content_length'] == str(len(payload))
+    assert data['headers']['HTTP_TEST'] == 'val1,val2'
 
 
 @pytest.mark.asyncio