[flutter_tools] Forward app.webLaunchUrl event from Flutter to DAP clients (#116275)

* [flutter_tools] Forward app.webLaunchUrl event from Flutter to DAP clients

Fixes https://github.com/Dart-Code/Dart-Code/issues/4292.

* Update packages/flutter_tools/lib/src/debug_adapters/flutter_adapter.dart
Co-authored-by: Christopher Fujino <fujino@google.com>

* Another static const instead of final
Co-authored-by: Christopher Fujino <fujino@google.com>

packages/flutter_tools/lib/src/debug_adapters/flutter_adapter.dart

@@ -51,7 +51,7 @@ class FlutterDebugAdapter extends FlutterBaseDebugAdapter {
   bool get supportsRestartRequest => true;
 
   /// A list of reverse-requests from `flutter run --machine` that should be forwarded to the client.
-  final Set<String> _requestsToForwardToClient = <String>{
+  static const Set<String> _requestsToForwardToClient = <String>{
     // The 'app.exposeUrl' request is sent by Flutter to request the client
     // exposes a URL to the user and return the public version of that URL.
     //
@@ -65,6 +65,14 @@ class FlutterDebugAdapter extends FlutterBaseDebugAdapter {
     'app.exposeUrl',
   };
 
+  /// A list of events from `flutter run --machine` that should be forwarded to the client.
+  static const Set<String> _eventsToForwardToClient = <String>{
+    // The 'app.webLaunchUrl' event is sent to the client to tell it about a URL
+    // that should be launched (including a flag for whether it has been
+    // launched by the tool or needs launching by the editor).
+    'app.webLaunchUrl',
+  };
+
   /// Completers for reverse requests from Flutter that may need to be handled by the client.
   final Map<Object, Completer<Object?>> _reverseRequestCompleters = <Object, Completer<Object?>>{};
 
@@ -454,6 +462,17 @@ class FlutterDebugAdapter extends FlutterBaseDebugAdapter {
         _handleAppStarted();
         break;
     }
+
+    if (_eventsToForwardToClient.contains(event)) {
+      // Forward the event to the client.
+      sendEvent(
+        RawEventBody(<String, Object?>{
+          'event': event,
+          'params': params,
+        }),
+        eventType: 'flutter.forwardedEvent',
+      );
+    }
   }
 
   /// Handles incoming reverse requests from `flutter run --machine`.

packages/flutter_tools/test/general.shard/dap/flutter_adapter_test.dart

@@ -121,7 +121,7 @@ void main() {
         await adapter.terminateRequest(MockRequest(), TerminateArguments(restart: false), terminateCompleter.complete);
         await terminateCompleter.future;
 
-        expect(adapter.flutterRequests, contains('app.stop'));
+        expect(adapter.dapToFlutterRequests, contains('app.stop'));
       });
 
       test('does not call "app.stop" on terminateRequest if app was not started', () async {
@@ -145,7 +145,7 @@ void main() {
         await adapter.terminateRequest(MockRequest(), TerminateArguments(restart: false), terminateCompleter.complete);
         await terminateCompleter.future;
 
-        expect(adapter.flutterRequests, isNot(contains('app.stop')));
+        expect(adapter.dapToFlutterRequests, isNot(contains('app.stop')));
       });
     });
 
@@ -210,7 +210,39 @@ void main() {
         await adapter.terminateRequest(MockRequest(), TerminateArguments(restart: false), terminateCompleter.complete);
         await terminateCompleter.future;
 
-        expect(adapter.flutterRequests, contains('app.detach'));
+        expect(adapter.dapToFlutterRequests, contains('app.detach'));
+      });
+    });
+
+    group('forwards events', () {
+      test('app.webLaunchUrl', () async {
+        final MockFlutterDebugAdapter adapter = MockFlutterDebugAdapter(
+          fileSystem: MemoryFileSystem.test(style: fsStyle),
+          platform: platform,
+        );
+
+        // Simulate Flutter asking for a URL to be launched.
+        adapter.simulateStdoutMessage(<String, Object?>{
+          'event': 'app.webLaunchUrl',
+          'params': <String, Object?>{
+            'url': 'http://localhost:123/',
+            'launched': false,
+          }
+        });
+
+        // Allow the handler to be processed.
+        await pumpEventQueue(times: 5000);
+
+        // Find the forwarded event.
+        final Map<String, Object?> message = adapter.dapToClientMessages.singleWhere((Map<String, Object?> data) => data['event'] == 'flutter.forwardedEvent');
+        // Ensure the body of the event matches the original event sent by Flutter.
+        expect(message['body'], <String, Object?>{
+          'event': 'app.webLaunchUrl',
+          'params': <String, Object?>{
+            'url': 'http://localhost:123/',
+            'launched': false,
+          }
+        });
       });
     });
 
@@ -238,7 +270,7 @@ void main() {
         // Allow the handler to be processed.
         await pumpEventQueue(times: 5000);
 
-        final Map<String, Object?> message = adapter.flutterMessages.singleWhere((Map<String, Object?> data) => data['id'] == requestId);
+        final Map<String, Object?> message = adapter.dapToFlutterMessages.singleWhere((Map<String, Object?> data) => data['id'] == requestId);
         expect(message['result'], 'http://mapped-host:123/');
       });
     });

packages/flutter_tools/test/general.shard/dap/mocks.dart

@@ -53,11 +53,15 @@ class MockFlutterDebugAdapter extends FlutterDebugAdapter {
   late List<String> processArgs;
   late Map<String, String>? env;
 
-  /// A list of all messages sent to the `flutter run` processes `stdin`.
-  final List<Map<String, Object?>> flutterMessages = <Map<String, Object?>>[];
+  /// A list of all messages sent from the adapter back to the client.
+  final List<Map<String, Object?>> dapToClientMessages = <Map<String, Object?>>[];
 
-  /// The `method`s of all requests send to the `flutter run` processes `stdin`.
-  List<String> get flutterRequests => flutterMessages
+  /// A list of all messages sent from the adapter to the `flutter run` processes `stdin`.
+  final List<Map<String, Object?>> dapToFlutterMessages = <Map<String, Object?>>[];
+
+  /// The `method`s of all mesages sent to the `flutter run` processes `stdin`
+  /// by the debug adapter.
+  List<String> get dapToFlutterRequests => dapToFlutterMessages
       .map((Map<String, Object?> message) => message['method'] as String?)
       .whereNotNull()
       .toList();
@@ -92,6 +96,8 @@ class MockFlutterDebugAdapter extends FlutterDebugAdapter {
 
   /// Handles messages sent from the debug adapter back to the client.
   void _handleDapToClientMessage(ProtocolMessage message) {
+    dapToClientMessages.add(message.toJson());
+
     // Pretend to be the client, delegating any reverse-requests to the relevant
     // handler that is provided by the test.
     if (message is Event && message.event == 'flutter.forwardedRequest') {
@@ -133,7 +139,7 @@ class MockFlutterDebugAdapter extends FlutterDebugAdapter {
 
   @override
   void sendFlutterMessage(Map<String, Object?> message) {
-    flutterMessages.add(message);
+    dapToFlutterMessages.add(message);
     // Don't call super because it will try to write to the process that we
     // didn't actually spawn.
   }