return 422 status code for JSON rejection errors (#1173)

* return 422 status code for JSON rejection errors

* return 422 status code for JSON rejection errors

src/controller/mod.rs

@@ -172,6 +172,7 @@ impl<T: Serialize> IntoResponse for Json<T> {
 
 impl IntoResponse for Error {
     /// Convert an `Error` into an HTTP response.
+    #[allow(clippy::cognitive_complexity)]
     fn into_response(self) -> Response {
         match &self {
             Self::WithBacktrace {
@@ -221,6 +222,11 @@ impl IntoResponse for Error {
                 StatusCode::BAD_REQUEST,
                 ErrorDetail::new("Bad Request", &err),
             ),
+            Self::JsonRejection(err) => {
+                tracing::debug!(err = err.body_text(), "json rejection");
+                (err.status(), ErrorDetail::with_reason("Bad Request"))
+            }
+
             _ => (
                 StatusCode::INTERNAL_SERVER_ERROR,
                 ErrorDetail::new("internal_server_error", "Internal Server Error"),

tests/controller/into_response.rs

@@ -1,5 +1,6 @@
 use crate::infra_cfg;
 use loco_rs::{controller, prelude::*, tests_cfg};
+use serde::{Deserialize, Serialize};
 use serial_test::serial;
 
 #[tokio::test]
@@ -162,3 +163,43 @@ async fn custom_error() {
 
     handle.abort();
 }
+
+#[tokio::test]
+#[serial]
+async fn json_rejection() {
+    let ctx = tests_cfg::app::get_app_context().await;
+
+    #[allow(clippy::items_after_statements)]
+    #[derive(Debug, Deserialize, Serialize)]
+    pub struct Data {
+        pub email: String,
+    }
+
+    #[allow(clippy::items_after_statements)]
+    async fn action(Json(_params): Json<Data>) -> Result<Response> {
+        format::json(())
+    }
+
+    let handle = infra_cfg::server::start_with_route(ctx, "/", post(action)).await;
+
+    let client = reqwest::Client::new();
+    let res = client
+        .post(infra_cfg::server::get_base_url())
+        .json(&serde_json::json!({}))
+        .send()
+        .await
+        .expect("Valid response");
+
+    assert_eq!(res.status(), 422);
+
+    let res_text = res.text().await.expect("response text");
+    let res_json: serde_json::Value = serde_json::from_str(&res_text).expect("Valid JSON response");
+
+    let expected_json = serde_json::json!({
+        "error": "Bad Request",
+    });
+
+    assert_eq!(res_json, expected_json);
+
+    handle.abort();
+}