Fix a bug where ConnectionException.toString didn't stringify NSError

pkgs/cupertino_http/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.2.1-wip
+
+* Make `ConnectionException.toString` more helpful.
+
 ## 2.2.0
 
 * Cancel requests when the response stream is cancelled.

pkgs/cupertino_http/example/integration_test/web_socket_test.dart

@@ -0,0 +1,23 @@
+// 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:cupertino_http/cupertino_http.dart';
+import 'package:objective_c/objective_c.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('ConnectionException', () {
+    test('toString', () {
+      expect(
+          ConnectionException(
+                  'failed to connect',
+                  NSError.errorWithDomain_code_userInfo_(
+                      'NSURLErrorDomain'.toNSString(), -999, null))
+              .toString(),
+          'CupertinoErrorWebSocketException: failed to connect '
+          '[The operation couldn’t be completed. '
+          '(NSURLErrorDomain error -999.)]');
+    });
+  });
+}

pkgs/cupertino_http/lib/src/cupertino_web_socket.dart

@@ -18,7 +18,8 @@ class ConnectionException extends WebSocketException {
   ConnectionException(super.message, this.error);
 
   @override
-  String toString() => 'CupertinoErrorWebSocketException: $message $error';
+  String toString() => 'CupertinoErrorWebSocketException: $message '
+      '[${error.localizedDescription.toDartString()}]';
 }
 
 /// A [WebSocket] implemented using the

pkgs/cupertino_http/pubspec.yaml

@@ -1,5 +1,5 @@
 name: cupertino_http
-version: 2.2.0
+version: 2.2.1-wip
 description: >-
   A macOS/iOS Flutter plugin that provides access to the Foundation URL
   Loading System.