Add remote tester bridge for Flutter integration tests

Introduces the flet_integration_test Dart package and RemoteWidgetTester for TCP-based remote control of Flutter integration tests. Updates FletTestApp in Python to support a new 'remote' test mode, allowing tests to be driven without launching a Flet app. Refactors test setup and teardown logic to support both local and remote modes, and exposes RemoteTester in the Python SDK.

Author: FeodorFitsner

client/integration_test/app_test.dart

@@ -1,12 +1,11 @@
 import 'dart:io';
 
 import 'package:flet_client/main.dart' as app;
+import 'package:flet_integration_test/flet_integration_test.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:integration_test/integration_test.dart';
 
-import 'flutter_tester.dart';
-
 void main() {
   var binding = IntegrationTestWidgetsFlutterBinding.ensureInitialized();
 
@@ -15,7 +14,20 @@ void main() {
       var dir = Directory.current.path;
       debugPrint("Current dir: $dir");
 
-      app.tester = FlutterWidgetTester(tester, binding);
+      const testerServerUrl = String.fromEnvironment("FLET_TEST_SERVER_URL");
+      FlutterWidgetTester? widgetTester;
+
+      if (testerServerUrl.isNotEmpty) {
+        debugPrint("Connecting to remote tester at $testerServerUrl");
+        widgetTester = await RemoteWidgetTester.connect(
+          tester: tester,
+          binding: binding,
+          serverUri: Uri.parse(testerServerUrl),
+        );
+      } else {
+        widgetTester = FlutterWidgetTester(tester, binding);
+        app.tester = widgetTester;
+      }
 
       List<String> args = [];
       const fletTestAppUrl = String.fromEnvironment("FLET_TEST_APP_URL");
@@ -36,10 +48,10 @@ void main() {
       app.main(args);
 
       await Future.delayed(const Duration(milliseconds: 500));
-      await app.tester?.pump(duration: const Duration(seconds: 1));
-      await app.tester
-          ?.pumpAndSettle(duration: const Duration(milliseconds: 100));
-      await app.tester?.waitForTeardown();
+      await widgetTester?.pump(duration: const Duration(seconds: 1));
+      await widgetTester?.pumpAndSettle(
+          duration: const Duration(milliseconds: 100));
+      await widgetTester?.waitForTeardown();
     });
   });
 }

client/pubspec.lock

@@ -313,6 +313,13 @@ packages:
       relative: true
     source: path
     version: "0.1.0"
+  flet_integration_test:
+    dependency: "direct dev"
+    description:
+      path: "../packages/flet_integration_test"
+      relative: true
+    source: path
+    version: "0.1.0"
   flet_lottie:
     dependency: "direct main"
     description:

client/pubspec.yaml

@@ -86,6 +86,8 @@ dependency_overrides:
 dev_dependencies:
   flutter_test:
     sdk: flutter
+  flet_integration_test:
+    path: ../packages/flet_integration_test
 
   # The "flutter_lints" package below contains a set of recommended lints to
   # encourage good coding practices. The lint set provided by the package is

packages/flet_integration_test/.gitignore

@@ -0,0 +1,32 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+# Libraries should not include pubspec.lock, per https://dart.dev/guides/libraries/private-files#pubspeclock.
+/pubspec.lock
+**/doc/api/
+.dart_tool/
+.packages
+build/
+.flutter-plugins
+.flutter-plugins-dependencies

packages/flet_integration_test/lib/flet_integration_test.dart

@@ -0,0 +1,3 @@
+export 'src/flutter_test_finder.dart';
+export 'src/flutter_tester.dart';
+export 'src/remote_widget_tester.dart';

…ntegration_test/flutter_test_finder.dart …on_test/lib/src/flutter_test_finder.dartclient/integration_test/flutter_test_finder.dart renamed to packages/flet_integration_test/lib/src/flutter_test_finder.dart client/integration_test/flutter_test_finder.dart renamed to packages/flet_integration_test/lib/src/flutter_test_finder.dart

@@ -4,7 +4,7 @@ import 'package:flutter_test/flutter_test.dart';
 class FlutterTestFinder extends TestFinder {
   final Finder finder;
 
-  FlutterTestFinder(this.finder) : super();
+  FlutterTestFinder(this.finder);
 
   @override
   int get count => finder.evaluate().length;

…ent/integration_test/flutter_tester.dart …gration_test/lib/src/flutter_tester.dartclient/integration_test/flutter_tester.dart renamed to packages/flet_integration_test/lib/src/flutter_tester.dart client/integration_test/flutter_tester.dart renamed to packages/flet_integration_test/lib/src/flutter_tester.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:typed_data';
 import 'dart:ui';
 
 import 'package:flet/flet.dart';
@@ -13,16 +14,20 @@ class FlutterWidgetTester implements Tester {
   final WidgetTester _tester;
   final IntegrationTestWidgetsFlutterBinding _binding;
   final lock = Lock();
-  final Completer _teardown = Completer();
+  final Completer _teardown = Completer<void>();
 
   FlutterWidgetTester(this._tester, this._binding);
 
+  @protected
+  IntegrationTestWidgetsFlutterBinding get binding => _binding;
+
   @override
   Future<void> pumpAndSettle({Duration? duration}) async {
     await lock.acquire();
     try {
-      await _tester
-          .pumpAndSettle(duration ?? const Duration(milliseconds: 100));
+      await _tester.pumpAndSettle(
+        duration ?? const Duration(milliseconds: 100),
+      );
     } finally {
       lock.release();
     }
@@ -60,7 +65,8 @@ class FlutterWidgetTester implements Tester {
     if (defaultTargetPlatform != TargetPlatform.android &&
         defaultTargetPlatform != TargetPlatform.iOS) {
       throw Exception(
-          "Full app screenshots are only available on Android and iOS.");
+        "Full app screenshots are only available on Android and iOS.",
+      );
     }
     if (defaultTargetPlatform == TargetPlatform.android) {
       await _binding.convertFlutterSurfaceToImage();