From 2d11ab5977ad1394db01c76a79f94c17628a84a7 Mon Sep 17 00:00:00 2001
From: Michael <5672750+mibac138@users.noreply.github.com>
Date: Wed, 5 Jan 2022 13:31:39 +0100
Subject: [PATCH] Add `ServiceConfig::configure` (#1988)

Co-authored-by: Rob Ede <robjtede@icloud.com>
---
 CHANGES.md    |  2 ++
 src/config.rs | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/CHANGES.md b/CHANGES.md
index ec09de2ac..c379c1545 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -3,10 +3,12 @@
 ## Unreleased - 2021-xx-xx
 ### Added
 - `GuardContext::header` [#2569]
+- `ServiceConfig::configure` to allow easy nesting of configuration functions. [#1988]
 
 ### Changed
 - `HttpResponse` can now be used as a `Responder` with any body type. [#2567]
 
+[#1988]: https://github.com/actix/actix-web/pull/1988
 [#2567]: https://github.com/actix/actix-web/pull/2567
 [#2569]: https://github.com/actix/actix-web/pull/2569
 
diff --git a/src/config.rs b/src/config.rs
index d68374387..2482ee6c4 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -215,6 +215,17 @@ impl ServiceConfig {
         self
     }
 
+    /// Run external configuration as part of the application building process
+    ///
+    /// Counterpart to [`App::configure()`](crate::App::configure) that allows for easy nesting.
+    pub fn configure<F>(&mut self, f: F) -> &mut Self
+    where
+        F: FnOnce(&mut ServiceConfig),
+    {
+        f(self);
+        self
+    }
+
     /// Configure route for a specific path.
     ///
     /// Counterpart to [`App::route()`](crate::App::route).
@@ -264,7 +275,7 @@ mod tests {
 
     use super::*;
     use crate::http::{Method, StatusCode};
-    use crate::test::{call_service, init_service, read_body, TestRequest};
+    use crate::test::{assert_body_eq, call_service, init_service, read_body, TestRequest};
     use crate::{web, App, HttpRequest, HttpResponse};
 
     // allow deprecated `ServiceConfig::data`
@@ -363,4 +374,22 @@ mod tests {
         let resp = call_service(&srv, req).await;
         assert_eq!(resp.status(), StatusCode::OK);
     }
+
+    #[actix_rt::test]
+    async fn nested_service_configure() {
+        fn cfg_root(cfg: &mut ServiceConfig) {
+            cfg.configure(cfg_sub);
+        }
+
+        fn cfg_sub(cfg: &mut ServiceConfig) {
+            cfg.route("/", web::get().to(|| async { "hello world" }));
+        }
+
+        let srv = init_service(App::new().configure(cfg_root)).await;
+
+        let req = TestRequest::with_uri("/").to_request();
+        let res = call_service(&srv, req).await;
+        assert_eq!(res.status(), StatusCode::OK);
+        assert_body_eq!(res, b"hello world");
+    }
 }