fix(render) :: test a page made only of header components (#1432)

A page with only header components (ie :: `status_code` and `cookie`) never opens a body. Adds a test for this.

Co-authored-by: Ophir LOJKINE <contact@ophir.dev>

Author: 81reap

tests/cookies/header_only_response.sql

@@ -0,0 +1,2 @@
+select 'status_code' as component, 204 as status;
+select 'cookie' as component, 'session' as name, 'abc123' as value;

tests/cookies/mod.rs

@@ -1,4 +1,5 @@
 use crate::common::req_path;
+use actix_web::http::StatusCode;
 use actix_web::http::header::SET_COOKIE;
 
 async fn set_cookie_header(path: &str) -> String {
@@ -30,6 +31,15 @@ async fn zero_turns_off_a_cookie_protection() {
     assert!(header.contains("Path=/admin"), "{header}");
 }
 
+#[actix_web::test]
+async fn a_page_made_only_of_header_components_still_sends_them() {
+    let resp = req_path("/tests/cookies/header_only_response.sql")
+        .await
+        .unwrap();
+    assert_eq!(resp.status(), StatusCode::NO_CONTENT);
+    assert!(resp.headers().contains_key(SET_COOKIE));
+}
+
 #[actix_web::test]
 async fn a_log_row_does_not_end_the_header_phase() {
     let header = set_cookie_header("/tests/cookies/log_before_cookie.sql").await;