Allow Developers to enable Accessibility testing on WebFlutterDriver and get...

Allow Developers to enable Accessibility testing on WebFlutterDriver and get the underlying webDriver (#65051)

examples/hello_world/test_driver/smoke_web_engine_test.dart

@@ -2,10 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:flutter_driver/flutter_driver.dart';
 import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;
+import 'package:webdriver/async_io.dart';
 
-/// The following test is used as a simple smoke test for verfying Flutter
+/// The following test is used as a simple smoke test for verifying Flutter
 /// Framework and Flutter Web Engine integration.
 void main() {
   group('Hello World App', () {
@@ -28,5 +31,20 @@ void main() {
     test('title is correct', () async {
       expect(await driver.getText(titleFinder), 'Hello, world!');
     });
+
+    test('enable accessibility', () async {
+      await driver.enableAccessibility();
+
+      await Future<void>.delayed(const Duration(seconds: 2));
+
+      // Elements with tag "flt-semantics" would show up after enabling
+      // accessibility.
+      //
+      // The tag used here is based on
+      // https://github.com/flutter/engine/blob/master/lib/web_ui/lib/src/engine/semantics/semantics.dart#L534
+      final WebElement element = await driver.webDriver.findElement(const By.tagName('flt-semantics'));
+
+      expect(element, isNotNull);
+    });
   });
 }

packages/flutter_driver/lib/src/driver/driver.dart

@@ -8,6 +8,7 @@ import 'dart:io';
 import 'package:json_rpc_2/json_rpc_2.dart' as rpc;
 import 'package:meta/meta.dart';
 import 'package:vm_service_client/vm_service_client.dart';
+import 'package:webdriver/async_io.dart' as async_io;
 
 import '../common/diagnostics_tree.dart';
 import '../common/error.dart';
@@ -169,6 +170,14 @@ abstract class FlutterDriver {
   /// Getter of serviceClient.
   VMServiceClient get serviceClient => throw UnimplementedError();
 
+  /// Getter of webDriver.
+  async_io.WebDriver get webDriver => throw UnimplementedError();
+
+  /// Enables accessibility feature.
+  Future<void> enableAccessibility() async {
+    throw UnimplementedError();
+  }
+
   /// Sends [command] to the Flutter Driver extensions.
   /// This must be implemented by subclass.
   ///

packages/flutter_driver/lib/src/driver/vmservice_driver.dart

@@ -12,6 +12,7 @@ import 'package:json_rpc_2/json_rpc_2.dart' as rpc;
 import 'package:meta/meta.dart';
 import 'package:path/path.dart' as p;
 import 'package:vm_service_client/vm_service_client.dart';
+import 'package:webdriver/async_io.dart' as async_io;
 import 'package:web_socket_channel/io.dart';
 
 import '../../flutter_driver.dart';
@@ -303,6 +304,9 @@ class VMServiceFlutterDriver extends FlutterDriver {
   @override
   VMServiceClient get serviceClient => _serviceClient;
 
+  @override
+  async_io.WebDriver get webDriver => throw UnsupportedError('VMServiceFlutterDriver does not support webDriver');
+
   /// The main isolate hosting the Flutter application.
   ///
   /// If you used the [registerExtension] API to instrument your application,
@@ -316,6 +320,11 @@ class VMServiceFlutterDriver extends FlutterDriver {
   /// Whether to log communication between host and app to `flutter_driver_commands.log`.
   final bool _logCommunicationToFile;
 
+  @override
+  Future<void> enableAccessibility() async {
+    throw UnsupportedError('VMServiceFlutterDriver does not support enableAccessibility');
+  }
+
   @override
   Future<Map<String, dynamic>> sendCommand(Command command) async {
     Map<String, dynamic> response;

packages/flutter_driver/lib/src/driver/web_driver.dart

@@ -30,6 +30,7 @@ class WebFlutterDriver extends FlutterDriver {
 
   final FlutterWebConnection _connection;
   DateTime _startTime;
+  bool _accessibilityEnabled = false;
 
   /// Start time for tracing.
   @visibleForTesting
@@ -41,11 +42,15 @@ class WebFlutterDriver extends FlutterDriver {
   @override
   VMServiceClient get serviceClient => throw UnsupportedError('WebFlutterDriver does not support serviceClient');
 
+  @override
+  async_io.WebDriver get webDriver => _connection._driver;
+
   /// Creates a driver that uses a connection provided by the given
   /// [hostUrl] which would fallback to environment variable VM_SERVICE_URL.
   /// Driver also depends on environment variables DRIVER_SESSION_ID,
-  /// BROWSER_SUPPORTS_TIMELINE, DRIVER_SESSION_URI, DRIVER_SESSION_SPEC
-  /// and ANDROID_CHROME_ON_EMULATOR for configurations.
+  /// BROWSER_SUPPORTS_TIMELINE, DRIVER_SESSION_URI, DRIVER_SESSION_SPEC,
+  /// DRIVER_SESSION_CAPABILITIES and ANDROID_CHROME_ON_EMULATOR for
+  /// configurations.
   static Future<FlutterDriver> connectWeb(
       {String hostUrl, Duration timeout}) async {
     hostUrl ??= Platform.environment['VM_SERVICE_URL'];
@@ -55,12 +60,29 @@ class WebFlutterDriver extends FlutterDriver {
       'session-uri': Platform.environment['DRIVER_SESSION_URI'],
       'session-spec': Platform.environment['DRIVER_SESSION_SPEC'],
       'android-chrome-on-emulator': Platform.environment['ANDROID_CHROME_ON_EMULATOR'] == 'true',
+      'session-capabilities': Platform.environment['DRIVER_SESSION_CAPABILITIES'],
     };
     final FlutterWebConnection connection = await FlutterWebConnection.connect
       (hostUrl, settings, timeout: timeout);
     return WebFlutterDriver.connectedTo(connection);
   }
 
+  @override
+  Future<void> enableAccessibility() async {
+    if (!_accessibilityEnabled) {
+      // Clicks the button to enable accessibility via Javascript for Desktop Web.
+      //
+      // The tag used in the script is based on
+      // https://github.com/flutter/engine/blob/master/lib/web_ui/lib/src/engine/semantics/semantics_helper.dart#L193
+      //
+      // TODO(angjieli): Support Mobile Web. (https://github.com/flutter/flutter/issues/65192)
+      await webDriver.execute(
+          'document.querySelector(\'flt-semantics-placeholder\').click();',
+          <String>[]);
+      _accessibilityEnabled = true;
+    }
+  }
+
   @override
   Future<Map<String, dynamic>> sendCommand(Command command) async {
     Map<String, dynamic> response;
@@ -177,12 +199,14 @@ class FlutterWebConnection {
       String url,
       Map<String, dynamic> settings,
       {Duration timeout}) async {
-    // Use sync WebDriver because async version will create a 15 seconds
-    // overhead when quitting.
-    final async_io.WebDriver driver = await async_io.fromExistingSession(
-        settings['session-id'].toString(),
-        uri: Uri.parse(settings['session-uri'].toString()),
-        spec: _convertToSpec(settings['session-spec'].toString().toLowerCase()));
+    final String sessionId = settings['session-id'].toString();
+    final Uri sessionUri = Uri.parse(settings['session-uri'].toString());
+    final async_io.WebDriver driver = async_io.WebDriver(
+        sessionUri,
+        sessionId,
+        json.decode(settings['session-capabilities'] as String) as Map<String, dynamic>,
+        async_io.AsyncIoRequestClient(sessionUri.resolve('session/$sessionId/')),
+        _convertToSpec(settings['session-spec'].toString().toLowerCase()));
     if (settings['android-chrome-on-emulator'] == true) {
       final Uri localUri = Uri.parse(url);
       // Converts to Android Emulator Uri.

packages/flutter_driver/test/flutter_driver_test.dart

@@ -768,6 +768,16 @@ void main() {
         expect(driver.waitFor(find.byTooltip('foo')), throwsDriverError);
       });
     });
+
+    group('VMServiceFlutterDriver Unsupported error', () {
+      test('enableAccessibility', () async {
+        expect(driver.enableAccessibility(), throwsA(isA<UnsupportedError>()));
+      });
+
+      test('webDriver', () async {
+        expect(() => driver.webDriver, throwsA(isA<UnsupportedError>()));
+      });
+    });
   });
 
   group('VMServiceFlutterDriver with custom timeout', () {
@@ -1117,7 +1127,7 @@ void main() {
       await driver.checkHealth();
     });
 
-    group('WebFlutterDriver Unimplemented error', () {
+    group('WebFlutterDriver Unimplemented/Unsupported error', () {
       test('forceGC', () async {
         expect(driver.forceGC(),
             throwsA(isA<UnimplementedError>()));

packages/flutter_tools/lib/src/commands/drive.dart

@@ -18,6 +18,7 @@ import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/process.dart';
 import '../build_info.dart';
+import '../convert.dart';
 import '../dart/package_map.dart';
 import '../device.dart';
 import '../globals.dart' as globals;
@@ -306,6 +307,7 @@ $ex
         'DRIVER_SESSION_ID': driver.id,
         'DRIVER_SESSION_URI': driver.uri.toString(),
         'DRIVER_SESSION_SPEC': driver.spec.toString(),
+        'DRIVER_SESSION_CAPABILITIES': json.encode(driver.capabilities),
         'SUPPORT_TIMELINE_ACTION': (browser == Browser.chrome).toString(),
         'FLUTTER_WEB_TEST': 'true',
         'ANDROID_CHROME_ON_EMULATOR': (isAndroidChrome && useEmulator).toString(),