feat(test): use random ports for testing

- port is assigned by the OS.

src/lib.rs

@@ -1,16 +1,17 @@
 use actix_web::{web, App, HttpResponse, HttpServer};
 use actix_web::dev::Server;
+use std::net::TcpListener;
 
 async fn healthcheck_route() -> HttpResponse {
     return HttpResponse::Ok().finish()
 }
 
-pub fn run() -> Result<Server, std::io::Error>{
+pub fn run(listener: TcpListener) -> Result<Server, std::io::Error>{
     let server = HttpServer::new(||{
         App::new()
         .route("/health_check", web::get().to(healthcheck_route))
     })
-    .bind("127.0.0.1:8000")?
+    .listen(listener)?
     .run();
 
     Ok(server)

src/main.rs

@@ -1,8 +1,12 @@
+use std::net::TcpListener;
+
 use email_newsletter_api::run;
 
 #[tokio::main]
 async fn main() -> Result<(), std::io::Error>{
+    let listener = TcpListener::bind("127.0.0.1:8000").expect("Failed to bind to port 8000");
+
     // Move the error up the call stack
     // otherwise await for the HttpServer
-    run()?.await
+    run(listener)?.await
 }