websocket: add a wrapper around is_terminated (#3443)

Co-authored-by: Loic <[email protected]>
Co-authored-by: loikki <[email protected]>

axum/src/extract/ws.rs

@@ -96,7 +96,7 @@ use crate::{body::Bytes, response::Response, Error};
 use axum_core::body::Body;
 use futures_util::{
     sink::{Sink, SinkExt},
-    stream::{Stream, StreamExt},
+    stream::{FusedStream, Stream, StreamExt},
 };
 use http::{
     header::{self, HeaderMap, HeaderName, HeaderValue},
@@ -533,6 +533,13 @@ impl WebSocket {
     }
 }
 
+impl FusedStream for WebSocket {
+    /// Returns true if the websocket has been terminated.
+    fn is_terminated(&self) -> bool {
+        self.inner.is_terminated()
+    }
+}
+
 impl Stream for WebSocket {
     type Item = Result<Message, Error>;