Add a useful stringificiation to WebSocketConnectionClosed (#1764)

Author: brianquinlan

pkgs/web_socket/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.0.1-wip
+
+- Fix a bug where `WebSocketException`/`WebSocketConnectionClosed` did not
+  have a useful string representation.
+
 ## 1.0.0
 
 - First non-experimental release; no semantic changes from version `0.1.6`.

pkgs/web_socket/lib/src/web_socket.dart

@@ -98,6 +98,15 @@ class WebSocketException implements Exception {
 /// [WebSocket.close] is called when the [WebSocket] is closed.
 class WebSocketConnectionClosed extends WebSocketException {
   WebSocketConnectionClosed([super.message = 'Connection Closed']);
+
+  @override
+  String toString() {
+    if (message.isEmpty) {
+      return 'WebSocketConnectionClosed';
+    } else {
+      return 'WebSocketConnectionClosed: $message';
+    }
+  }
 }
 
 /// The interface for WebSocket connections.

pkgs/web_socket/pubspec.yaml

@@ -3,7 +3,7 @@ description: >-
   Any easy-to-use library for communicating with WebSockets
   that has multiple implementations.
 repository: https://github.com/dart-lang/http/tree/master/pkgs/web_socket
-version: 1.0.0
+version: 1.0.1-wip
 
 environment:
   sdk: ^3.4.0

pkgs/web_socket/test/exceptions_test.dart

@@ -0,0 +1,43 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:test/test.dart';
+import 'package:web_socket/web_socket.dart';
+
+void main() {
+  group('WebSocketException', () {
+    test('no message', () async {
+      final exception = WebSocketException();
+      expect(exception.message, isEmpty);
+      expect(exception.toString(), 'WebSocketException');
+    });
+
+    test('with message', () async {
+      final exception = WebSocketException('bad connection');
+      expect(exception.message, 'bad connection');
+      expect(exception.toString(), 'WebSocketException: bad connection');
+    });
+  });
+
+  group('WebSocketConnectionClosed', () {
+    test('no message', () async {
+      final exception = WebSocketConnectionClosed();
+      expect(exception.message, 'Connection Closed');
+      expect(
+          exception.toString(), 'WebSocketConnectionClosed: Connection Closed');
+    });
+
+    test('empty message', () async {
+      final exception = WebSocketConnectionClosed('');
+      expect(exception.message, isEmpty);
+      expect(exception.toString(), 'WebSocketConnectionClosed');
+    });
+
+    test('with message', () async {
+      final exception = WebSocketConnectionClosed('bad connection');
+      expect(exception.message, 'bad connection');
+      expect(exception.toString(), 'WebSocketConnectionClosed: bad connection');
+    });
+  });
+}