Workaround for Dart VM timeout (#127875)

Workaround solution for: https://github.com/flutter/flutter/issues/121231
See https://github.com/flutter/flutter/issues/120808#issuecomment-1551826299 Error Case 2 for more information.

Sometimes the `ios-deploy` process does not return the logs from the application. We've been unable to figure out why. This is a solution to workaround that by using `idevicesyslog` alongside `ios-deploy` as a backup in getting the log for the Dart VM url. As explained in https://github.com/flutter/flutter/issues/120808#issuecomment-1551826299, when error case 2 happens, the `idevicesyslog` does successfully find the Dart VM.

Also, in the comments of the code it mentions `syslog` is not written on iOS 13+, this was added in response to this issue: https://github.com/flutter/flutter/issues/41133.

However, `idevicesyslog` does in fact work (at least for iOS 16), we use it to collect device logs for our CI tests already: https://github.com/flutter/flutter/blob/1dc26f80f04c1c1091a83c5fead9b3aa83483292/dev/devicelab/lib/framework/devices.dart#L998-L1006

dev/devicelab/lib/framework/utils.dart

@@ -471,6 +471,10 @@ List<String> _flutterCommandArgs(String command, List<String> options) {
     if (localEngineSrcPath != null) ...<String>['--local-engine-src-path', localEngineSrcPath],
     if (localWebSdk != null) ...<String>['--local-web-sdk', localWebSdk],
     ...options,
+    // Use CI flag when running devicelab tests, except for `packages`/`pub` commands.
+    // `packages`/`pub` commands effectively runs the `pub` tool, which does not have
+    // the same allowed args.
+    if (!command.startsWith('packages') && !command.startsWith('pub')) '--ci',
   ];
 }
 

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

@@ -33,6 +33,7 @@ import '../resident_runner.dart';
 import '../run_cold.dart';
 import '../run_hot.dart';
 import '../runner/flutter_command.dart';
+import '../runner/flutter_command_runner.dart';
 import '../vmservice.dart';
 
 /// A Flutter-command that attaches to applications that have been launched
@@ -528,6 +529,7 @@ known, it can be explicitly provided to attach via the command-line, e.g.
       ddsPort: ddsPort,
       devToolsServerAddress: devToolsServerAddress,
       serveObservatory: serveObservatory,
+      usingCISystem: usingCISystem,
     );
 
     return buildInfo.isDebug
@@ -535,7 +537,7 @@ known, it can be explicitly provided to attach via the command-line, e.g.
           flutterDevices,
           target: targetFile,
           debuggingOptions: debuggingOptions,
-          packagesFilePath: globalResults!['packages'] as String?,
+          packagesFilePath: globalResults![FlutterGlobalOptions.kPackagesOption] as String?,
           projectRootPath: stringArg('project-root'),
           dillOutputPath: stringArg('output-dill'),
           ipv6: usesIpv6,

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

@@ -6,6 +6,7 @@ import '../base/common.dart';
 import '../cache.dart';
 import '../globals.dart' as globals;
 import '../runner/flutter_command.dart';
+import '../runner/flutter_command_runner.dart';
 import '../version.dart';
 
 class ChannelCommand extends FlutterCommand {
@@ -40,7 +41,7 @@ class ChannelCommand extends FlutterCommand {
       case 0:
         await _listChannels(
           showAll: boolArg('all'),
-          verbose: globalResults?['verbose'] == true,
+          verbose: globalResults?[FlutterGlobalOptions.kVerboseFlag] == true,
         );
         return FlutterCommandResult.success();
       case 1:

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

@@ -25,6 +25,7 @@ import '../custom_devices/custom_devices_config.dart';
 import '../device_port_forwarder.dart';
 import '../features.dart';
 import '../runner/flutter_command.dart';
+import '../runner/flutter_command_runner.dart';
 
 /// just the function signature of the [print] function.
 /// The Object arg may be null.
@@ -811,7 +812,7 @@ Delete a device from the config file.
   Future<FlutterCommandResult> runCommand() async {
     checkFeatureEnabled();
 
-    final String? id = globalResults!['device-id'] as String?;
+    final String? id = globalResults![FlutterGlobalOptions.kDeviceIdOption] as String?;
     if (id == null || !customDevicesConfig.contains(id)) {
       throwToolExit('Couldn\'t find device with id "$id" in config at "${customDevicesConfig.configPath}"');
     }

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

@@ -26,6 +26,7 @@ import '../resident_runner.dart';
 import '../run_cold.dart';
 import '../run_hot.dart';
 import '../runner/flutter_command.dart';
+import '../runner/flutter_command_runner.dart';
 import '../tracing.dart';
 import '../vmservice.dart';
 import '../web/web_runner.dart';
@@ -247,6 +248,7 @@ abstract class RunCommandBase extends FlutterCommand with DeviceBasedDevelopment
         uninstallFirst: uninstallFirst,
         enableDartProfiling: enableDartProfiling,
         enableEmbedderApi: enableEmbedderApi,
+        usingCISystem: usingCISystem,
       );
     } else {
       return DebuggingOptions.enabled(
@@ -298,6 +300,7 @@ abstract class RunCommandBase extends FlutterCommand with DeviceBasedDevelopment
         serveObservatory: boolArg('serve-observatory'),
         enableDartProfiling: enableDartProfiling,
         enableEmbedderApi: enableEmbedderApi,
+        usingCISystem: usingCISystem,
       );
     }
   }
@@ -643,7 +646,7 @@ class RunCommand extends RunCommandBase {
               : globals.fs.file(applicationBinaryPath),
           trackWidgetCreation: trackWidgetCreation,
           projectRootPath: stringArg('project-root'),
-          packagesFilePath: globalResults!['packages'] as String?,
+          packagesFilePath: globalResults![FlutterGlobalOptions.kPackagesOption] as String?,
           dillOutputPath: stringArg('output-dill'),
           ipv6: ipv6 ?? false,
           multidexEnabled: boolArg('multidex'),

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

@@ -422,6 +422,7 @@ class TestCommand extends FlutterCommand with DeviceBasedDevelopmentArtifacts {
       disablePortPublication: true,
       enableDds: enableDds,
       nullAssertions: boolArg(FlutterOptions.kNullAssertions),
+      usingCISystem: usingCISystem,
     );
 
     Device? integrationTestDevice;

packages/flutter_tools/lib/src/device.dart

@@ -971,6 +971,7 @@ class DebuggingOptions {
     this.serveObservatory = false,
     this.enableDartProfiling = true,
     this.enableEmbedderApi = false,
+    this.usingCISystem = false,
    }) : debuggingEnabled = true;
 
   DebuggingOptions.disabled(this.buildInfo, {
@@ -993,6 +994,7 @@ class DebuggingOptions {
       this.uninstallFirst = false,
       this.enableDartProfiling = true,
       this.enableEmbedderApi = false,
+      this.usingCISystem = false,
     }) : debuggingEnabled = false,
       useTestFonts = false,
       startPaused = false,
@@ -1069,6 +1071,7 @@ class DebuggingOptions {
     required this.serveObservatory,
     required this.enableDartProfiling,
     required this.enableEmbedderApi,
+    required this.usingCISystem,
   });
 
   final bool debuggingEnabled;
@@ -1109,6 +1112,7 @@ class DebuggingOptions {
   final bool serveObservatory;
   final bool enableDartProfiling;
   final bool enableEmbedderApi;
+  final bool usingCISystem;
 
   /// Whether the tool should try to uninstall a previously installed version of the app.
   ///
@@ -1243,6 +1247,7 @@ class DebuggingOptions {
     'serveObservatory': serveObservatory,
     'enableDartProfiling': enableDartProfiling,
     'enableEmbedderApi': enableEmbedderApi,
+    'usingCISystem': usingCISystem,
   };
 
   static DebuggingOptions fromJson(Map<String, Object?> json, BuildInfo buildInfo) =>
@@ -1294,6 +1299,7 @@ class DebuggingOptions {
       serveObservatory: (json['serveObservatory'] as bool?) ?? false,
       enableDartProfiling: (json['enableDartProfiling'] as bool?) ?? true,
       enableEmbedderApi: (json['enableEmbedderApi'] as bool?) ?? false,
+      usingCISystem: (json['usingCISystem'] as bool?) ?? false,
     );
 }
 

packages/flutter_tools/lib/src/ios/devices.dart

@@ -482,7 +482,10 @@ class IOSDevice extends Device {
       int installationResult = 1;
       if (debuggingOptions.debuggingEnabled) {
         _logger.printTrace('Debugging is enabled, connecting to vmService');
-        final DeviceLogReader deviceLogReader = getLogReader(app: package);
+        final DeviceLogReader deviceLogReader = getLogReader(
+          app: package,
+          usingCISystem: debuggingOptions.usingCISystem,
+        );
 
         // If the device supports syslog reading, prefer launching the app without
         // attaching the debugger to avoid the overhead of the unnecessary extra running process.
@@ -629,12 +632,14 @@ class IOSDevice extends Device {
   DeviceLogReader getLogReader({
     covariant IOSApp? app,
     bool includePastLogs = false,
+    bool usingCISystem = false,
   }) {
     assert(!includePastLogs, 'Past log reading not supported on iOS devices.');
     return _logReaders.putIfAbsent(app, () => IOSDeviceLogReader.create(
       device: this,
       app: app,
       iMobileDevice: _iMobileDevice,
+      usingCISystem: usingCISystem,
     ));
   }
 
@@ -749,17 +754,20 @@ class IOSDeviceLogReader extends DeviceLogReader {
     this._deviceId,
     this.name,
     String appName,
+    bool usingCISystem,
   ) : // Match for lines for the runner in syslog.
       //
       // iOS 9 format:  Runner[297] <Notice>:
       // iOS 10 format: Runner(Flutter)[297] <Notice>:
-      _runnerLineRegex = RegExp(appName + r'(\(Flutter\))?\[[\d]+\] <[A-Za-z]+>: ');
+      _runnerLineRegex = RegExp(appName + r'(\(Flutter\))?\[[\d]+\] <[A-Za-z]+>: '),
+      _usingCISystem = usingCISystem;
 
   /// Create a new [IOSDeviceLogReader].
   factory IOSDeviceLogReader.create({
     required IOSDevice device,
     IOSApp? app,
     required IMobileDevice iMobileDevice,
+    bool usingCISystem = false,
   }) {
     final String appName = app?.name?.replaceAll('.app', '') ?? '';
     return IOSDeviceLogReader._(
@@ -768,6 +776,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
       device.id,
       device.name,
       appName,
+      usingCISystem,
     );
   }
 
@@ -775,9 +784,17 @@ class IOSDeviceLogReader extends DeviceLogReader {
   factory IOSDeviceLogReader.test({
     required IMobileDevice iMobileDevice,
     bool useSyslog = true,
+    bool usingCISystem = false,
+    int? majorSdkVersion,
   }) {
+    final int sdkVersion;
+    if (majorSdkVersion != null) {
+      sdkVersion = majorSdkVersion;
+    } else {
+      sdkVersion = useSyslog ? 12 : 13;
+    }
     return IOSDeviceLogReader._(
-      iMobileDevice, useSyslog ? 12 : 13, '1234', 'test', 'Runner');
+      iMobileDevice, sdkVersion, '1234', 'test', 'Runner', usingCISystem);
   }
 
   @override
@@ -785,6 +802,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
   final int _majorSdkVersion;
   final String _deviceId;
   final IMobileDevice _iMobileDevice;
+  final bool _usingCISystem;
 
   // Matches a syslog line from the runner.
   RegExp _runnerLineRegex;
@@ -810,12 +828,42 @@ class IOSDeviceLogReader extends DeviceLogReader {
   // Sometimes (race condition?) we try to send a log after the controller has
   // been closed. See https://github.com/flutter/flutter/issues/99021 for more
   // context.
-  void _addToLinesController(String message) {
+  void _addToLinesController(String message, IOSDeviceLogSource source) {
     if (!linesController.isClosed) {
+      if (_excludeLog(message, source)) {
+        return;
+      }
       linesController.add(message);
     }
   }
 
+  /// Used to track messages prefixed with "flutter:" when [useBothLogDeviceReaders]
+  /// is true.
+  final List<String> _streamFlutterMessages = <String>[];
+
+  /// When using both `idevicesyslog` and `ios-deploy`, exclude logs with the
+  /// "flutter:" prefix if they have already been added to the stream. This is
+  /// to prevent duplicates from being printed.
+  ///
+  /// If a message does not have the prefix, exclude it if the message's
+  /// source is `idevicesyslog`. This is done because `ios-deploy` and
+  /// `idevicesyslog` often have different prefixes on non-flutter messages
+  /// and are often not critical for CI tests.
+  bool _excludeLog(String message, IOSDeviceLogSource source) {
+    if (!useBothLogDeviceReaders) {
+      return false;
+    }
+    if (message.startsWith('flutter:')) {
+      if (_streamFlutterMessages.contains(message)) {
+        return true;
+      }
+      _streamFlutterMessages.add(message);
+    } else if (source == IOSDeviceLogSource.idevicesyslog) {
+      return true;
+    }
+    return false;
+  }
+
   final List<StreamSubscription<void>> _loggingSubscriptions = <StreamSubscription<void>>[];
 
   @override
@@ -835,6 +883,10 @@ class IOSDeviceLogReader extends DeviceLogReader {
 
   static const int minimumUniversalLoggingSdkVersion = 13;
 
+  /// Listen to Dart VM for logs on iOS 13 or greater.
+  ///
+  /// Only send logs to stream if [_iosDeployDebugger] is null or
+  /// the [_iosDeployDebugger] debugger is not attached.
   Future<void> _listenToUnifiedLoggingEvents(FlutterVmService connectedVmService) async {
     if (_majorSdkVersion < minimumUniversalLoggingSdkVersion) {
       return;
@@ -859,7 +911,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
       }
       final String message = processVmServiceMessage(event);
       if (message.isNotEmpty) {
-        _addToLinesController(message);
+        _addToLinesController(message, IOSDeviceLogSource.unifiedLogging);
       }
     }
 
@@ -871,8 +923,10 @@ class IOSDeviceLogReader extends DeviceLogReader {
 
   /// Log reader will listen to [debugger.logLines] and will detach debugger on dispose.
   IOSDeployDebugger? get debuggerStream => _iosDeployDebugger;
+
+  /// Send messages from ios-deploy debugger stream to device log reader stream.
   set debuggerStream(IOSDeployDebugger? debugger) {
-    // Logging is gathered from syslog on iOS 13 and earlier.
+    // Logging is gathered from syslog on iOS earlier than 13.
     if (_majorSdkVersion < minimumUniversalLoggingSdkVersion) {
       return;
     }
@@ -882,7 +936,10 @@ class IOSDeviceLogReader extends DeviceLogReader {
     }
     // Add the debugger logs to the controller created on initialization.
     _loggingSubscriptions.add(debugger.logLines.listen(
-      (String line) => _addToLinesController(_debuggerLineHandler(line)),
+      (String line) => _addToLinesController(
+        _debuggerLineHandler(line),
+        IOSDeviceLogSource.iosDeploy,
+      ),
       onError: linesController.addError,
       onDone: linesController.close,
       cancelOnError: true,
@@ -893,18 +950,38 @@ class IOSDeviceLogReader extends DeviceLogReader {
   // Strip off the logging metadata (leave the category), or just echo the line.
   String _debuggerLineHandler(String line) => _debuggerLoggingRegex.firstMatch(line)?.group(1) ?? line;
 
+  /// Use both logs from `idevicesyslog` and `ios-deploy` when debugging from CI system
+  /// since sometimes `ios-deploy` does not return the device logs:
+  /// https://github.com/flutter/flutter/issues/121231
+  @visibleForTesting
+  bool get useBothLogDeviceReaders {
+    return _usingCISystem && _majorSdkVersion >= 16;
+  }
+
+  /// Start and listen to idevicesyslog to get device logs for iOS versions
+  /// prior to 13 or if [useBothLogDeviceReaders] is true.
   void _listenToSysLog() {
-    // syslog is not written on iOS 13+.
-    if (_majorSdkVersion >= minimumUniversalLoggingSdkVersion) {
+    // Syslog stopped working on iOS 13 (https://github.com/flutter/flutter/issues/41133).
+    // However, from at least iOS 16, it has began working again. It's unclear
+    // why it started working again so only use syslogs for iOS versions prior
+    // to 13 unless [useBothLogDeviceReaders] is true.
+    if (!useBothLogDeviceReaders && _majorSdkVersion >= minimumUniversalLoggingSdkVersion) {
       return;
     }
     _iMobileDevice.startLogger(_deviceId).then<void>((Process process) {
       process.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_newSyslogLineHandler());
       process.stderr.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_newSyslogLineHandler());
       process.exitCode.whenComplete(() {
-        if (linesController.hasListener) {
-          linesController.close();
+        if (!linesController.hasListener) {
+          return;
+        }
+        // When using both log readers, do not close the stream on exit.
+        // This is to allow ios-deploy to be the source of authority to close
+        // the stream.
+        if (useBothLogDeviceReaders && debuggerStream != null) {
+          return;
         }
+        linesController.close();
       });
       assert(idevicesyslogProcess == null);
       idevicesyslogProcess = process;
@@ -926,7 +1003,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
     return (String line) {
       if (printing) {
         if (!_anyLineRegex.hasMatch(line)) {
-          _addToLinesController(decodeSyslog(line));
+          _addToLinesController(decodeSyslog(line), IOSDeviceLogSource.idevicesyslog);
           return;
         }
 
@@ -938,8 +1015,7 @@ class IOSDeviceLogReader extends DeviceLogReader {
       if (match != null) {
         final String logLine = line.substring(match.end);
         // Only display the log line after the initial device and executable information.
-        _addToLinesController(decodeSyslog(logLine));
-
+        _addToLinesController(decodeSyslog(logLine), IOSDeviceLogSource.idevicesyslog);
         printing = true;
       }
     };
@@ -955,6 +1031,15 @@ class IOSDeviceLogReader extends DeviceLogReader {
   }
 }
 
+enum IOSDeviceLogSource {
+  /// Gets logs from ios-deploy debugger.
+  iosDeploy,
+  /// Gets logs from idevicesyslog.
+  idevicesyslog,
+  /// Gets logs from the Dart VM Service.
+  unifiedLogging,
+}
+
 /// A [DevicePortForwarder] specialized for iOS usage with iproxy.
 class IOSDevicePortForwarder extends DevicePortForwarder {
 

packages/flutter_tools/lib/src/resident_runner.dart

@@ -36,6 +36,8 @@ import 'devfs.dart';
 import 'device.dart';
 import 'features.dart';
 import 'globals.dart' as globals;
+import 'ios/application_package.dart';
+import 'ios/devices.dart';
 import 'project.dart';
 import 'resident_devtools_handler.dart';
 import 'run_cold.dart';
@@ -391,11 +393,19 @@ class FlutterDevice {
     return devFS!.create();
   }
 
-  Future<void> startEchoingDeviceLog() async {
+  Future<void> startEchoingDeviceLog(DebuggingOptions debuggingOptions) async {
     if (_loggingSubscription != null) {
       return;
     }
-    final Stream<String> logStream = (await device!.getLogReader(app: package)).logLines;
+    final Stream<String> logStream;
+    if (device is IOSDevice) {
+      logStream = (device! as IOSDevice).getLogReader(
+        app: package as IOSApp?,
+        usingCISystem: debuggingOptions.usingCISystem,
+      ).logLines;
+    } else {
+      logStream = (await device!.getLogReader(app: package)).logLines;
+    }
     _loggingSubscription = logStream.listen((String line) {
       if (!line.contains(globals.kVMServiceMessageRegExp)) {
         globals.printStatus(line, wrap: false);
@@ -451,7 +461,7 @@ class FlutterDevice {
       'multidex': hotRunner.multidexEnabled,
     };
 
-    await startEchoingDeviceLog();
+    await startEchoingDeviceLog(hotRunner.debuggingOptions);
 
     // Start the application.
     final Future<LaunchResult> futureResult = device!.startApp(
@@ -519,7 +529,7 @@ class FlutterDevice {
     platformArgs['trace-startup'] = coldRunner.traceStartup;
     platformArgs['multidex'] = coldRunner.multidexEnabled;
 
-    await startEchoingDeviceLog();
+    await startEchoingDeviceLog(coldRunner.debuggingOptions);
 
     final LaunchResult result = await device!.startApp(
       applicationPackage,

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -304,7 +304,10 @@ abstract class FlutterCommand extends Command<void> {
   /// Path to the Dart's package config file.
   ///
   /// This can be overridden by some of its subclasses.
-  String? get packagesPath => globalResults?['packages'] as String?;
+  String? get packagesPath => stringArg(FlutterGlobalOptions.kPackagesOption, global: true);
+
+  /// Whether flutter is being run from our CI.
+  bool get usingCISystem => boolArg(FlutterGlobalOptions.kContinuousIntegrationFlag, global: true);
 
   /// The value of the `--filesystem-scheme` argument.
   ///
@@ -1634,17 +1637,30 @@ Run 'flutter -h' (or 'flutter <command> -h') for available flutter commands and
   ///
   /// If no flag named [name] was added to the [ArgParser], an [ArgumentError]
   /// will be thrown.
-  bool boolArg(String name) => argResults![name] as bool;
+  bool boolArg(String name, {bool global = false}) {
+    if (global) {
+      return globalResults![name] as bool;
+    }
+    return argResults![name] as bool;
+  }
 
   /// Gets the parsed command-line option named [name] as a `String`.
   ///
   /// If no option named [name] was added to the [ArgParser], an [ArgumentError]
   /// will be thrown.
-  String? stringArg(String name) => argResults![name] as String?;
+  String? stringArg(String name, {bool global = false}) {
+    if (global) {
+      return globalResults![name] as String?;
+    }
+    return argResults![name] as String?;
+  }
 
   /// Gets the parsed command-line option named [name] as `List<String>`.
-  List<String> stringsArg(String name) {
-    return argResults![name]! as List<String>? ?? <String>[];
+  List<String> stringsArg(String name, {bool global = false}) {
+    if (global) {
+      return globalResults![name] as List<String>;
+    }
+    return argResults![name] as List<String>;
   }
 }
 

packages/flutter_tools/test/commands.shard/hermetic/attach_test.dart

@@ -1381,6 +1381,7 @@ class FakeIOSDevice extends Fake implements IOSDevice {
   DeviceLogReader getLogReader({
     IOSApp? app,
     bool includePastLogs = false,
+    bool usingCISystem = false,
   }) {
     if (onGetLogReader == null) {
       throw UnimplementedError(

packages/flutter_tools/test/commands.shard/hermetic/drive_test.dart

@@ -425,6 +425,7 @@ void main() {
       '--enable-software-rendering',
       '--skia-deterministic-rendering',
       '--enable-embedder-api',
+      '--ci',
     ]), throwsToolExit());
 
     final DebuggingOptions options = await command.createDebuggingOptions(false);
@@ -440,6 +441,7 @@ void main() {
     expect(options.traceSystrace, true);
     expect(options.enableSoftwareRendering, true);
     expect(options.skiaDeterministicRendering, true);
+    expect(options.usingCISystem, true);
   }, overrides: <Type, Generator>{
     Cache: () => Cache.test(processManager: FakeProcessManager.any()),
     FileSystem: () => MemoryFileSystem.test(),

packages/flutter_tools/test/commands.shard/hermetic/run_test.dart

@@ -1096,6 +1096,7 @@ void main() {
       '--enable-software-rendering',
       '--skia-deterministic-rendering',
       '--enable-embedder-api',
+      '--ci',
     ]), throwsToolExit());
 
     final DebuggingOptions options = await command.createDebuggingOptions(false);
@@ -1114,6 +1115,7 @@ void main() {
     expect(options.impellerForceGL, true);
     expect(options.enableSoftwareRendering, true);
     expect(options.skiaDeterministicRendering, true);
+    expect(options.usingCISystem, true);
   }, overrides: <Type, Generator>{
     Cache: () => Cache.test(processManager: FakeProcessManager.any()),
     FileSystem: () => MemoryFileSystem.test(),

packages/flutter_tools/test/general.shard/args_test.dart

@@ -30,11 +30,53 @@ void main() {
     }
   }));
 
+  testUsingContext('Global arg results are available in FlutterCommands', () async {
+    final DummyFlutterCommand command = DummyFlutterCommand(
+      commandFunction: () async {
+        return const FlutterCommandResult(ExitStatus.success);
+      },
+    );
+
+    final FlutterCommandRunner runner = FlutterCommandRunner(verboseHelp: true);
+
+    runner.addCommand(command);
+    await runner.run(<String>['dummy', '--${FlutterGlobalOptions.kContinuousIntegrationFlag}']);
+
+    expect(command.globalResults, isNotNull);
+    expect(command.boolArg(FlutterGlobalOptions.kContinuousIntegrationFlag, global: true), true);
+  });
+
+  testUsingContext('Global arg results are available in FlutterCommands sub commands', () async {
+    final DummyFlutterCommand command = DummyFlutterCommand(
+      commandFunction: () async {
+        return const FlutterCommandResult(ExitStatus.success);
+      },
+    );
+
+    final DummyFlutterCommand subcommand = DummyFlutterCommand(
+      name: 'sub',
+      commandFunction: () async {
+        return const FlutterCommandResult(ExitStatus.success);
+      },
+    );
+
+    command.addSubcommand(subcommand);
+
+    final FlutterCommandRunner runner = FlutterCommandRunner(verboseHelp: true);
+
+    runner.addCommand(command);
+    runner.addCommand(subcommand);
+    await runner.run(<String>['dummy', 'sub', '--${FlutterGlobalOptions.kContinuousIntegrationFlag}']);
+
+    expect(subcommand.globalResults, isNotNull);
+    expect(subcommand.boolArg(FlutterGlobalOptions.kContinuousIntegrationFlag, global: true), true);
+  });
+
   testUsingContext('bool? safe argResults', () async {
     final DummyFlutterCommand command = DummyFlutterCommand(
-        commandFunction: () async {
-          return const FlutterCommandResult(ExitStatus.success);
-        }
+      commandFunction: () async {
+        return const FlutterCommandResult(ExitStatus.success);
+      },
     );
     final FlutterCommandRunner runner = FlutterCommandRunner(verboseHelp: true);
     command.argParser.addFlag('key');
@@ -58,9 +100,9 @@ void main() {
 
   testUsingContext('String? safe argResults', () async {
     final DummyFlutterCommand command = DummyFlutterCommand(
-        commandFunction: () async {
-          return const FlutterCommandResult(ExitStatus.success);
-        }
+      commandFunction: () async {
+        return const FlutterCommandResult(ExitStatus.success);
+      },
     );
     final FlutterCommandRunner runner = FlutterCommandRunner(verboseHelp: true);
     command.argParser.addOption('key');
@@ -80,9 +122,9 @@ void main() {
 
   testUsingContext('List<String> safe argResults', () async {
     final DummyFlutterCommand command = DummyFlutterCommand(
-        commandFunction: () async {
-          return const FlutterCommandResult(ExitStatus.success);
-        }
+      commandFunction: () async {
+        return const FlutterCommandResult(ExitStatus.success);
+      },
     );
     final FlutterCommandRunner runner = FlutterCommandRunner(verboseHelp: true);
     command.argParser.addMultiOption(

packages/flutter_tools/test/general.shard/ios/ios_device_logger_test.dart

@@ -348,6 +348,165 @@ Runner(libsystem_asl.dylib)[297] <Notice>: libMobileGestalt
       );
     });
   });
+
+  group('both syslog and debugger stream', () {
+
+    testWithoutContext('useBothLogDeviceReaders is true when CI option is true and sdk is at least 16', () {
+      final IOSDeviceLogReader logReader = IOSDeviceLogReader.test(
+        iMobileDevice: IMobileDevice(
+          artifacts: artifacts,
+          processManager: processManager,
+          cache: fakeCache,
+          logger: logger,
+        ),
+        usingCISystem: true,
+        majorSdkVersion: 16,
+      );
+
+      expect(logReader.useBothLogDeviceReaders, isTrue);
+    });
+
+    testWithoutContext('useBothLogDeviceReaders is false when sdk is less than 16', () {
+      final IOSDeviceLogReader logReader = IOSDeviceLogReader.test(
+        iMobileDevice: IMobileDevice(
+          artifacts: artifacts,
+          processManager: processManager,
+          cache: fakeCache,
+          logger: logger,
+        ),
+        usingCISystem: true,
+        majorSdkVersion: 15,
+      );
+
+      expect(logReader.useBothLogDeviceReaders, isFalse);
+    });
+
+    testWithoutContext('useBothLogDeviceReaders is false when CI option is false', () {
+      final IOSDeviceLogReader logReader = IOSDeviceLogReader.test(
+        iMobileDevice: IMobileDevice(
+          artifacts: artifacts,
+          processManager: processManager,
+          cache: fakeCache,
+          logger: logger,
+        ),
+        majorSdkVersion: 16,
+      );
+
+      expect(logReader.useBothLogDeviceReaders, isFalse);
+    });
+
+    testWithoutContext('syslog only sends flutter messages to stream when useBothLogDeviceReaders is true', () async {
+      processManager.addCommand(
+        FakeCommand(
+            command: <String>[
+              ideviceSyslogPath, '-u', '1234',
+            ],
+            stdout: '''
+Runner(Flutter)[297] <Notice>: A is for ari
+Runner(Flutter)[297] <Notice>: I is for ichigo
+May 30 13:56:28 Runner(Flutter)[2037] <Notice>: flutter: The Dart VM service is listening on http://127.0.0.1:63098/35ZezGIQLnw=/
+May 30 13:56:28 Runner(Flutter)[2037] <Notice>: flutter: This is a test
+May 30 13:56:28 Runner(Flutter)[2037] <Notice>: [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(39)] Using the Impeller rendering backend.
+'''
+        ),
+      );
+      final IOSDeviceLogReader logReader = IOSDeviceLogReader.test(
+        iMobileDevice: IMobileDevice(
+          artifacts: artifacts,
+          processManager: processManager,
+          cache: fakeCache,
+          logger: logger,
+        ),
+        usingCISystem: true,
+        majorSdkVersion: 16,
+      );
+      final List<String> lines = await logReader.logLines.toList();
+
+      expect(logReader.useBothLogDeviceReaders, isTrue);
+      expect(processManager, hasNoRemainingExpectations);
+      expect(lines, <String>[
+        'flutter: The Dart VM service is listening on http://127.0.0.1:63098/35ZezGIQLnw=/',
+        'flutter: This is a test'
+      ]);
+    });
+
+    testWithoutContext('IOSDeviceLogReader uses both syslog and ios-deploy debugger', () async {
+      processManager.addCommand(
+        FakeCommand(
+            command: <String>[
+              ideviceSyslogPath, '-u', '1234',
+            ],
+            stdout: '''
+May 30 13:56:28 Runner(Flutter)[2037] <Notice>: flutter: The Dart VM service is listening on http://127.0.0.1:63098/35ZezGIQLnw=/
+May 30 13:56:28 Runner(Flutter)[2037] <Notice>: flutter: Check for duplicate
+May 30 13:56:28 Runner(Flutter)[2037] <Notice>: [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(39)] Using the Impeller rendering backend.
+'''
+        ),
+      );
+
+      final Stream<String> debuggingLogs = Stream<String>.fromIterable(<String>[
+        '2023-06-01 12:49:01.445093-0500 Runner[2225:533240] flutter: Check for duplicate',
+        '(lldb) 2023-05-30 13:48:52.461894-0500 Runner[2019:1101495] [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(39)] Using the Impeller rendering backend.',
+      ]);
+
+      final IOSDeviceLogReader logReader = IOSDeviceLogReader.test(
+        iMobileDevice: IMobileDevice(
+          artifacts: artifacts,
+          processManager: processManager,
+          cache: fakeCache,
+          logger: logger,
+        ),
+        usingCISystem: true,
+        majorSdkVersion: 16,
+      );
+      final FakeIOSDeployDebugger iosDeployDebugger = FakeIOSDeployDebugger();
+      iosDeployDebugger.logLines = debuggingLogs;
+      logReader.debuggerStream = iosDeployDebugger;
+      final Future<List<String>> logLines = logReader.logLines.toList();
+      final List<String> lines = await logLines;
+
+      expect(logReader.useBothLogDeviceReaders, isTrue);
+      expect(processManager, hasNoRemainingExpectations);
+      expect(lines.length, 3);
+      expect(lines, containsAll(<String>[
+        '(lldb) 2023-05-30 13:48:52.461894-0500 Runner[2019:1101495] [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(39)] Using the Impeller rendering backend.',
+        'flutter: The Dart VM service is listening on http://127.0.0.1:63098/35ZezGIQLnw=/',
+        'flutter: Check for duplicate',
+      ]));
+
+    });
+
+    testWithoutContext('IOSDeviceLogReader only uses ios-deploy debugger when useBothLogDeviceReaders is false', () async {
+      final Stream<String> debuggingLogs = Stream<String>.fromIterable(<String>[
+        '(lldb) 2023-05-30 13:48:52.461894-0500 Runner[2019:1101495] [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(39)] Using the Impeller rendering backend.',
+        '',
+      ]);
+
+      final IOSDeviceLogReader logReader = IOSDeviceLogReader.test(
+        iMobileDevice: IMobileDevice(
+          artifacts: artifacts,
+          processManager: processManager,
+          cache: fakeCache,
+          logger: logger,
+        ),
+        majorSdkVersion: 16,
+      );
+      final FakeIOSDeployDebugger iosDeployDebugger = FakeIOSDeployDebugger();
+      iosDeployDebugger.logLines = debuggingLogs;
+      logReader.debuggerStream = iosDeployDebugger;
+      final Future<List<String>> logLines = logReader.logLines.toList();
+      final List<String> lines = await logLines;
+
+      expect(logReader.useBothLogDeviceReaders, isFalse);
+      expect(processManager, hasNoRemainingExpectations);
+      expect(
+        lines.contains(
+          '(lldb) 2023-05-30 13:48:52.461894-0500 Runner[2019:1101495] [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(39)] Using the Impeller rendering backend.',
+        ),
+        isTrue,
+      );
+    });
+  });
 }
 
 class FakeIOSDeployDebugger extends Fake implements IOSDeployDebugger {