Add 'text' modifier in code part of doc.

src/metrics/middleware.rs

@@ -3,14 +3,13 @@
 //! # Usage
 //! The actix-web middleware function could be used as following:
 //!
-//! ```rust
+//! ```text
 //! let mut http_server = HttpServer::new(move || {
 //!        App::new()
 //!            //skip
 //!            .wrap(from_fn(metrics_midleware))
 //!            //skip
 //!    })
-//!    .on_connect(http::request_on_connect_handler);
 //! ```
 use std::{
     sync::{Arc, RwLock},

src/metrics/mod.rs

@@ -18,7 +18,7 @@
 //!
 //! Define your metrics under `src/metrics/` and register them with the `Registry` like this:
 //!
-//! ```rust
+//! ```text
 //! pub const HTTP_REQUEST_COUNT: &str = "http_request_count";
 //! pub const HTTP_REQUEST_COUNT_HELP: &str = "Number of HTTP requests received, labeled by method and status";
 //!
@@ -43,7 +43,7 @@
 //!
 //! Register the metrics within the `MetricsManager` struct:
 //!
-//! ```rust
+//! ```text
 //! pub struct MetricsManager {
 //!     pub registry: Arc<Mutex<Registry>>,
 //!     pub http_metrics: Arc<HttpMetrics>,
@@ -63,7 +63,7 @@
 //!
 //! Invoke methods to update metrics where relevant events occur. In this example, retrieve `MetricsManager` from the `app_data` in the Actix Web application:
 //!
-//! ```rust
+//! ```text
 //! if let Some(m) = res.request().app_data::<Data<Arc<RwLock<MetricsManager>>>>() {
 //!     let metrics_manager = m.read().unwrap();
 //!     metrics_manager.http_metrics.increment_request_count(&label);

src/metrics/system_metrics.rs

@@ -180,7 +180,8 @@ mod tests {
         let gauge_map = parse_gauge(resp["metrics"].as_str().unwrap());
         assert_eq!(SYS_METRICS_MAP.len(), gauge_map.len());
 
-        for (_, value) in gauge_map {
+        for (metric, value) in gauge_map {
+            println!("{}:{}", metric, value);
             assert!(value != 0.0);
         }
     }