Migrate android_device to null safety (#92128)

packages/flutter_tools/lib/src/android/android_device.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 
 import 'package:meta/meta.dart';
@@ -60,13 +58,13 @@ class AndroidDevice extends Device {
   AndroidDevice(
     String id, {
     this.productID,
-    this.modelID,
+    required this.modelID,
     this.deviceCodeName,
-    @required Logger logger,
-    @required ProcessManager processManager,
-    @required Platform platform,
-    @required AndroidSdk androidSdk,
-    @required FileSystem fileSystem,
+    required Logger logger,
+    required ProcessManager processManager,
+    required Platform platform,
+    required AndroidSdk androidSdk,
+    required FileSystem fileSystem,
     AndroidConsoleSocketFactory androidConsoleSocketFactory = kAndroidConsoleSocketFactory,
   }) : _logger = logger,
        _processManager = processManager,
@@ -90,17 +88,12 @@ class AndroidDevice extends Device {
   final ProcessUtils _processUtils;
   final AndroidConsoleSocketFactory _androidConsoleSocketFactory;
 
-  final String productID;
+  final String? productID;
   final String modelID;
-  final String deviceCodeName;
-
-  Map<String, String> _properties;
-  bool _isLocalEmulator;
-  TargetPlatform _applicationPlatform;
+  final String? deviceCodeName;
 
-  Future<String> _getProperty(String name) async {
-    if (_properties == null) {
-      _properties = <String, String>{};
+  late final Future<Map<String, String>> _properties = () async {
+    Map<String, String> properties = <String, String>{};
 
     final List<String> propCommand = adbCommandForDevice(<String>['shell', 'getprop']);
     _logger.printTrace(propCommand.join(' '));
@@ -114,7 +107,7 @@ class AndroidDevice extends Device {
         stderrEncoding: latin1,
       );
       if (result.exitCode == 0 || _allowHeapCorruptionOnWindows(result.exitCode, _platform)) {
-          _properties = parseAdbDeviceProperties(result.stdout as String);
+        properties = parseAdbDeviceProperties(result.stdout as String);
       } else {
         _logger.printError('Error ${result.exitCode} retrieving device properties for $name:');
         _logger.printError(result.stderr as String);
@@ -122,28 +115,26 @@ class AndroidDevice extends Device {
     } on ProcessException catch (error) {
       _logger.printError('Error retrieving device properties for $name: $error');
     }
-    }
+    return properties;
+  }();
 
-    return _properties[name];
+  Future<String?> _getProperty(String name) async {
+    return (await _properties)[name];
   }
 
   @override
-  Future<bool> get isLocalEmulator async {
-    if (_isLocalEmulator == null) {
-      final String hardware = await _getProperty('ro.hardware');
+  late final Future<bool> isLocalEmulator = () async {
+    final String? hardware = await _getProperty('ro.hardware');
     _logger.printTrace('ro.hardware = $hardware');
     if (kKnownHardware.containsKey(hardware)) {
       // Look for known hardware models.
-        _isLocalEmulator = kKnownHardware[hardware] == HardwareType.emulator;
-      } else {
+      return kKnownHardware[hardware] == HardwareType.emulator;
+    }
     // Fall back to a best-effort heuristic-based approach.
-        final String characteristics = await _getProperty('ro.build.characteristics');
+    final String? characteristics = await _getProperty('ro.build.characteristics');
     _logger.printTrace('ro.build.characteristics = $characteristics');
-        _isLocalEmulator = characteristics != null && characteristics.contains('emulator');
-      }
-    }
-    return _isLocalEmulator;
-  }
+    return characteristics != null && characteristics.contains('emulator');
+  }();
 
   /// The unique identifier for the emulator that corresponds to this device, or
   /// null if it is not an emulator.
@@ -152,7 +143,7 @@ class AndroidDevice extends Device {
   /// this name may require connecting to the device and if an error occurs null
   /// will be returned.
   @override
-  Future<String> get emulatorId async {
+  Future<String?> get emulatorId async {
     if (!(await isLocalEmulator)) {
       return null;
     }
@@ -161,13 +152,13 @@ class AndroidDevice extends Device {
     // Android Console port number.
     final RegExp emulatorPortRegex = RegExp(r'emulator-(\d+)');
 
-    final Match portMatch = emulatorPortRegex.firstMatch(id);
+    final Match? portMatch = emulatorPortRegex.firstMatch(id);
     if (portMatch == null || portMatch.groupCount < 1) {
       return null;
     }
 
     const String host = 'localhost';
-    final int port = int.parse(portMatch.group(1));
+    final int port = int.parse(portMatch.group(1)!);
     _logger.printTrace('Fetching avd name for $name via Android console on $host:$port');
 
     try {
@@ -196,8 +187,7 @@ class AndroidDevice extends Device {
   }
 
   @override
-  Future<TargetPlatform> get targetPlatform async {
-    if (_applicationPlatform == null) {
+  late final Future<TargetPlatform> targetPlatform = () async {
     // http://developer.android.com/ndk/guides/abis.html (x86, armeabi-v7a, ...)
     switch (await _getProperty('ro.product.cpu.abi')) {
       case 'arm64-v8a':
@@ -205,27 +195,20 @@ class AndroidDevice extends Device {
         // like the Kindle Fire 8, misreport the abilist. We might not
         // be able to retrieve this property, in which case we fall back
         // to assuming 64 bit.
-          final String abilist = await _getProperty('ro.product.cpu.abilist');
+        final String? abilist = await _getProperty('ro.product.cpu.abilist');
         if (abilist == null || abilist.contains('arm64-v8a')) {
-            _applicationPlatform = TargetPlatform.android_arm64;
+          return TargetPlatform.android_arm64;
         } else {
-            _applicationPlatform = TargetPlatform.android_arm;
+          return TargetPlatform.android_arm;
         }
-          break;
       case 'x86_64':
-          _applicationPlatform = TargetPlatform.android_x64;
-          break;
+        return TargetPlatform.android_x64;
       case 'x86':
-          _applicationPlatform = TargetPlatform.android_x86;
-          break;
+        return TargetPlatform.android_x86;
       default:
-          _applicationPlatform = TargetPlatform.android_arm;
-          break;
-      }
-    }
-
-    return _applicationPlatform;
+        return TargetPlatform.android_arm;
     }
+  }();
 
   @override
   Future<bool> supportsRuntimeMode(BuildMode buildMode) async {
@@ -249,28 +232,27 @@ class AndroidDevice extends Device {
       case TargetPlatform.windows_x64:
         throw UnsupportedError('Invalid target platform for Android');
     }
-    throw null; // dead code, remove after null migration
   }
 
   @override
   Future<String> get sdkNameAndVersion async => 'Android ${await _sdkVersion} (API ${await apiVersion})';
 
-  Future<String> get _sdkVersion => _getProperty('ro.build.version.release');
+  Future<String?> get _sdkVersion => _getProperty('ro.build.version.release');
 
   @visibleForTesting
-  Future<String> get apiVersion => _getProperty('ro.build.version.sdk');
+  Future<String?> get apiVersion => _getProperty('ro.build.version.sdk');
 
-  AdbLogReader _logReader;
-  AdbLogReader _pastLogReader;
-  AndroidDevicePortForwarder _portForwarder;
+  AdbLogReader? _logReader;
+  AdbLogReader? _pastLogReader;
+  AndroidDevicePortForwarder? _portForwarder;
 
   List<String> adbCommandForDevice(List<String> args) {
-    return <String>[_androidSdk.adbPath, '-s', id, ...args];
+    return <String>[_androidSdk.adbPath!, '-s', id, ...args];
   }
 
   Future<RunResult> runAdbCheckedAsync(
     List<String> params, {
-    String workingDirectory,
+    String? workingDirectory,
     bool allowReentrantFlutter = false,
   }) async {
     return _processUtils.run(
@@ -284,11 +266,11 @@ class AndroidDevice extends Device {
 
   bool _isValidAdbVersion(String adbVersion) {
     // Sample output: 'Android Debug Bridge version 1.0.31'
-    final Match versionFields = RegExp(r'(\d+)\.(\d+)\.(\d+)').firstMatch(adbVersion);
+    final Match? versionFields = RegExp(r'(\d+)\.(\d+)\.(\d+)').firstMatch(adbVersion);
     if (versionFields != null) {
-      final int majorVersion = int.parse(versionFields[1]);
-      final int minorVersion = int.parse(versionFields[2]);
-      final int patchVersion = int.parse(versionFields[3]);
+      final int majorVersion = int.parse(versionFields[1]!);
+      final int minorVersion = int.parse(versionFields[2]!);
+      final int patchVersion = int.parse(versionFields[3]!);
       if (majorVersion > 1) {
         return true;
       }
@@ -306,19 +288,20 @@ class AndroidDevice extends Device {
   }
 
   Future<bool> _checkForSupportedAdbVersion() async {
-    if (_androidSdk == null) {
+    final String? adbPath = _androidSdk.adbPath;
+    if (adbPath == null) {
       return false;
     }
 
     try {
       final RunResult adbVersion = await _processUtils.run(
-        <String>[_androidSdk.adbPath, 'version'],
+        <String>[adbPath, 'version'],
         throwOnError: true,
       );
       if (_isValidAdbVersion(adbVersion.stdout)) {
         return true;
       }
-      _logger.printError('The ADB at "${_androidSdk.adbPath}" is too old; please install version 1.0.39 or later.');
+      _logger.printError('The ADB at "$adbPath" is too old; please install version 1.0.39 or later.');
     } on Exception catch (error, trace) {
       _logger.printError('Error running ADB: $error', stackTrace: trace);
     }
@@ -327,13 +310,17 @@ class AndroidDevice extends Device {
   }
 
   Future<bool> _checkForSupportedAndroidVersion() async {
+    final String? adbPath = _androidSdk.adbPath;
+    if (adbPath == null) {
+      return false;
+    }
     try {
       // If the server is automatically restarted, then we get irrelevant
       // output lines like this, which we want to ignore:
       //   adb server is out of date.  killing..
       //   * daemon started successfully *
       await _processUtils.run(
-        <String>[_androidSdk.adbPath, 'start-server'],
+        <String>[adbPath, 'start-server'],
         throwOnError: true,
       );
 
@@ -343,7 +330,7 @@ class AndroidDevice extends Device {
       final String sdkVersion = await _getProperty('ro.build.version.sdk')
         ?? minApiLevel.toString();
 
-      final int sdkVersionParsed = int.tryParse(sdkVersion);
+      final int? sdkVersionParsed = int.tryParse(sdkVersion);
       if (sdkVersionParsed == null) {
         _logger.printError('Unexpected response from getprop: "$sdkVersion"');
         return false;
@@ -385,7 +372,7 @@ class AndroidDevice extends Device {
   @override
   Future<bool> isAppInstalled(
     AndroidApk app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     // This call takes 400ms - 600ms.
     try {
@@ -414,9 +401,9 @@ class AndroidDevice extends Device {
   @override
   Future<bool> installApp(
     AndroidApk app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
-    if (!await _isAdbValid()) {
+    if (!await _adbIsValid) {
       return false;
     }
     final bool wasInstalled = await isAppInstalled(app, userIdentifier: userIdentifier);
@@ -446,7 +433,7 @@ class AndroidDevice extends Device {
 
   Future<bool> _installApp(
     AndroidApk app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     if (!app.file.existsSync()) {
       _logger.printError('"${_fileSystem.path.relative(app.file.path)}" does not exist.');
@@ -469,7 +456,7 @@ class AndroidDevice extends Device {
     // Some versions of adb exit with exit code 0 even on failure :(
     // Parsing the output to check for failures.
     final RegExp failureExp = RegExp(r'^Failure.*$', multiLine: true);
-    final String failure = failureExp.stringMatch(installResult.stdout);
+    final String? failure = failureExp.stringMatch(installResult.stdout);
     if (failure != null) {
       _logger.printError('Package install error: $failure');
       return false;
@@ -497,9 +484,9 @@ class AndroidDevice extends Device {
   @override
   Future<bool> uninstallApp(
     AndroidApk app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
-    if (!await _isAdbValid()) {
+    if (!await _adbIsValid) {
       return false;
     }
 
@@ -519,7 +506,7 @@ class AndroidDevice extends Device {
       return false;
     }
     final RegExp failureExp = RegExp(r'^Failure.*$', multiLine: true);
-    final String failure = failureExp.stringMatch(uninstallOut);
+    final String? failure = failureExp.stringMatch(uninstallOut);
     if (failure != null) {
       _logger.printError('Package uninstall error: $failure');
       return false;
@@ -528,25 +515,24 @@ class AndroidDevice extends Device {
   }
 
   // Whether the adb and Android versions are aligned.
-  bool _adbIsValid;
-  Future<bool> _isAdbValid() async {
-    return _adbIsValid ??= await _checkForSupportedAdbVersion() && await _checkForSupportedAndroidVersion();
-  }
+  late final Future<bool> _adbIsValid = () async {
+    return await _checkForSupportedAdbVersion() && await _checkForSupportedAndroidVersion();
+  }();
 
-  AndroidApk _package;
+  AndroidApk? _package;
 
   @override
   Future<LaunchResult> startApp(
     AndroidApk package, {
-    String mainPath,
-    String route,
-    DebuggingOptions debuggingOptions,
-    Map<String, dynamic> platformArgs = const <String, Object>{},
+    String? mainPath,
+    String? route,
+    required DebuggingOptions debuggingOptions,
+    Map<String, Object?> platformArgs = const <String, Object>{},
     bool prebuiltApplication = false,
     bool ipv6 = false,
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
-    if (!await _isAdbValid()) {
+    if (!await _adbIsValid) {
       return LaunchResult.failed();
     }
 
@@ -589,19 +575,19 @@ class AndroidDevice extends Device {
     if (!prebuiltApplication || _androidSdk.licensesAvailable && _androidSdk.latestVersion == null) {
       _logger.printTrace('Building APK');
       final FlutterProject project = FlutterProject.current();
-      await androidBuilder.buildApk(
+      await androidBuilder!.buildApk(
           project: project,
-          target: mainPath,
+          target: mainPath ?? 'lib/main.dart',
           androidBuildInfo: AndroidBuildInfo(
             debuggingOptions.buildInfo,
             targetArchs: <AndroidArch>[androidArch],
             fastStart: debuggingOptions.fastStart,
-            multidexEnabled: (platformArgs['multidex'] as bool) ?? false,
+            multidexEnabled: (platformArgs['multidex'] as bool?) ?? false,
           ),
       );
       // Package has been built, so we can get the updated application ID and
       // activity name from the .apk.
-      package = await ApplicationPackageFactory.instance
+      package = await ApplicationPackageFactory.instance!
         .getPackageForPlatform(devicePlatform, buildInfo: debuggingOptions.buildInfo) as AndroidApk;
     }
     // There was a failure parsing the android project information.
@@ -616,8 +602,8 @@ class AndroidDevice extends Device {
       return LaunchResult.failed();
     }
 
-    final bool traceStartup = platformArgs['trace-startup'] as bool ?? false;
-    ProtocolDiscovery observatoryDiscovery;
+    final bool traceStartup = platformArgs['trace-startup'] as bool? ?? false;
+    ProtocolDiscovery? observatoryDiscovery;
 
     if (debuggingOptions.debuggingEnabled) {
       observatoryDiscovery = ProtocolDiscovery.observatory(
@@ -637,6 +623,8 @@ class AndroidDevice extends Device {
     }
 
     final String dartVmFlags = computeDartVmFlags(debuggingOptions);
+    final String? traceAllowlist = debuggingOptions.traceAllowlist;
+    final String? traceSkiaAllowlist = debuggingOptions.traceSkiaAllowlist;
     final List<String> cmd = <String>[
       'shell', 'am', 'start',
       '-a', 'android.intent.action.RUN',
@@ -653,10 +641,10 @@ class AndroidDevice extends Device {
         ...<String>['--ez', 'skia-deterministic-rendering', 'true'],
       if (debuggingOptions.traceSkia)
         ...<String>['--ez', 'trace-skia', 'true'],
-      if (debuggingOptions.traceAllowlist != null)
-        ...<String>['--es', 'trace-allowlist', debuggingOptions.traceAllowlist],
-      if (debuggingOptions.traceSkiaAllowlist != null)
-        ...<String>['--es', 'trace-skia-allowlist', debuggingOptions.traceSkiaAllowlist],
+      if (traceAllowlist != null)
+        ...<String>['--es', 'trace-allowlist', traceAllowlist],
+      if (traceSkiaAllowlist != null)
+        ...<String>['--es', 'trace-skia-allowlist', traceSkiaAllowlist],
       if (debuggingOptions.traceSystrace)
         ...<String>['--ez', 'trace-systrace', 'true'],
       if (debuggingOptions.endlessTraceBuffer)
@@ -703,9 +691,9 @@ class AndroidDevice extends Device {
     // device has printed "Observatory is listening on...".
     _logger.printTrace('Waiting for observatory port to be available...');
     try {
-      Uri observatoryUri;
+      Uri? observatoryUri;
       if (debuggingOptions.buildInfo.isDebug || debuggingOptions.buildInfo.isProfile) {
-        observatoryUri = await observatoryDiscovery.uri;
+        observatoryUri = await observatoryDiscovery?.uri;
         if (observatoryUri == null) {
           _logger.printError(
             'Error waiting for a debug connection: '
@@ -719,7 +707,7 @@ class AndroidDevice extends Device {
       _logger.printError('Error waiting for a debug connection: $error');
       return LaunchResult.failed();
     } finally {
-      await observatoryDiscovery.cancel();
+      await observatoryDiscovery?.cancel();
     }
   }
 
@@ -735,7 +723,7 @@ class AndroidDevice extends Device {
   @override
   Future<bool> stopApp(
     AndroidApk app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) {
     if (app == null) {
       return Future<bool>.value(false);
@@ -754,11 +742,16 @@ class AndroidDevice extends Device {
 
   @override
   Future<MemoryInfo> queryMemoryInfo() async {
+    final AndroidApk? package = _package;
+    if (package == null) {
+      _logger.printError('Android package unknown, skipping dumpsys meminfo.');
+      return const MemoryInfo.empty();
+    }
     final RunResult runResult = await _processUtils.run(adbCommandForDevice(<String>[
       'shell',
       'dumpsys',
       'meminfo',
-      _package.id,
+      package.id,
       '-d',
     ]));
 
@@ -775,7 +768,7 @@ class AndroidDevice extends Device {
 
   @override
   FutureOr<DeviceLogReader> getLogReader({
-    AndroidApk app,
+    AndroidApk? app,
     bool includePastLogs = false,
   }) async {
     // The Android log reader isn't app-specific. The `app` parameter isn't used.
@@ -794,19 +787,25 @@ class AndroidDevice extends Device {
   }
 
   @override
-  DevicePortForwarder get portForwarder => _portForwarder ??= AndroidDevicePortForwarder(
+  late final DevicePortForwarder? portForwarder = () {
+    final String? adbPath = _androidSdk.adbPath;
+    if (adbPath == null) {
+      return null;
+    }
+    return AndroidDevicePortForwarder(
       processManager: _processManager,
       logger: _logger,
       deviceId: id,
-    adbPath: _androidSdk.adbPath,
+      adbPath: adbPath,
     );
+  }();
 
   static final RegExp _timeRegExp = RegExp(r'^\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{3}', multiLine: true);
 
   /// Return the most recent timestamp in the Android log or [null] if there is
   /// no available timestamp. The format can be passed to logcat's -T option.
   @visibleForTesting
-  Future<String> lastLogcatTimestamp() async {
+  Future<String?> lastLogcatTimestamp() async {
     RunResult output;
     try {
       output = await runAdbCheckedAsync(<String>[
@@ -816,7 +815,7 @@ class AndroidDevice extends Device {
       _logger.printError('Failed to extract the most recent timestamp from the Android log: $error.');
       return null;
     }
-    final Match timeMatch = _timeRegExp.firstMatch(output.stdout);
+    final Match? timeMatch = _timeRegExp.firstMatch(output.stdout);
     return timeMatch?.group(0);
   }
 
@@ -854,7 +853,7 @@ Map<String, String> parseAdbDeviceProperties(String str) {
   final Map<String, String> properties = <String, String>{};
   final RegExp propertyExp = RegExp(r'\[(.*?)\]: \[(.*?)\]');
   for (final Match match in propertyExp.allMatches(str)) {
-    properties[match.group(1)] = match.group(2);
+    properties[match.group(1)!] = match.group(2)!;
   }
   return properties;
 }
@@ -1011,12 +1010,7 @@ class AndroidMemoryInfo extends MemoryInfo {
 
 /// A log reader that logs from `adb logcat`.
 class AdbLogReader extends DeviceLogReader {
-  AdbLogReader._(this._adbProcess, this.name)  {
-    _linesController = StreamController<String>.broadcast(
-      onListen: _start,
-      onCancel: _stop,
-    );
-  }
+  AdbLogReader._(this._adbProcess, this.name);
 
   @visibleForTesting
   factory AdbLogReader.test(Process adbProcess, String name) = AdbLogReader._;
@@ -1029,7 +1023,7 @@ class AdbLogReader extends DeviceLogReader {
   }) async {
     // logcat -T is not supported on Android releases before Lollipop.
     const int kLollipopVersionCode = 21;
-    final int apiVersion = (String v) {
+    final int? apiVersion = (String? v) {
       // If the API version string isn't found, conservatively assume that the
       // version is less recent than the one we're looking for.
       return v == null ? kLollipopVersionCode - 1 : int.tryParse(v);
@@ -1052,7 +1046,7 @@ class AdbLogReader extends DeviceLogReader {
     } else if (apiVersion != null && apiVersion >= kLollipopVersionCode) {
       // Otherwise, filter for logs appearing past the present.
       // '-T 0` means the timestamp of the logcat command invocation.
-      final String lastLogcatTimestamp = await device.lastLogcatTimestamp();
+      final String? lastLogcatTimestamp = await device.lastLogcatTimestamp();
       args.addAll(<String>[
         '-T',
         if (lastLogcatTimestamp != null) "'$lastLogcatTimestamp'" else '0',
@@ -1067,7 +1061,10 @@ class AdbLogReader extends DeviceLogReader {
   @override
   final String name;
 
-  StreamController<String> _linesController;
+  late final StreamController<String> _linesController = StreamController<String>.broadcast(
+    onListen: _start,
+    onCancel: _stop,
+  );
 
   @override
   Stream<String> get logLines => _linesController.stream;
@@ -1128,14 +1125,14 @@ class AdbLogReader extends DeviceLogReader {
     if (_linesController.isClosed) {
       return;
     }
-    final Match timeMatch = AndroidDevice._timeRegExp.firstMatch(line);
+    final Match? timeMatch = AndroidDevice._timeRegExp.firstMatch(line);
     if (timeMatch == null || line.length == timeMatch.end) {
       _acceptedLastLine = false;
       return;
     }
     // Chop off the time.
     line = line.substring(timeMatch.end + 1);
-    final Match logMatch = _logFormat.firstMatch(line);
+    final Match? logMatch = _logFormat.firstMatch(line);
     if (logMatch != null) {
       bool acceptLine = false;
 
@@ -1143,19 +1140,19 @@ class AdbLogReader extends DeviceLogReader {
         // While a fatal crash is going on, only accept lines from the crash
         // Otherwise the crash log in the console may get interrupted
 
-        final Match fatalMatch = _tombstoneLine.firstMatch(line);
+        final Match? fatalMatch = _tombstoneLine.firstMatch(line);
 
         if (fatalMatch != null) {
           acceptLine = true;
 
-          line = fatalMatch[1];
+          line = fatalMatch[1]!;
 
-          if (_tombstoneTerminator.hasMatch(fatalMatch[1])) {
+          if (_tombstoneTerminator.hasMatch(line)) {
             // Hit crash terminator, stop logging the crash info
             _fatalCrash = false;
           }
         }
-      } else if (appPid != null && int.parse(logMatch.group(1)) == appPid) {
+      } else if (appPid != null && int.parse(logMatch.group(1)!) == appPid) {
         acceptLine = true;
 
         if (_fatalLog.hasMatch(line)) {
@@ -1189,7 +1186,7 @@ class AdbLogReader extends DeviceLogReader {
 
   void _stop() {
     _linesController.close();
-    _adbProcess?.kill();
+    _adbProcess.kill();
   }
 
   @override
@@ -1201,10 +1198,10 @@ class AdbLogReader extends DeviceLogReader {
 /// A [DevicePortForwarder] implemented for Android devices that uses adb.
 class AndroidDevicePortForwarder extends DevicePortForwarder {
   AndroidDevicePortForwarder({
-    @required ProcessManager processManager,
-    @required Logger logger,
-    @required String deviceId,
-    @required String adbPath,
+    required ProcessManager processManager,
+    required Logger logger,
+    required String deviceId,
+    required String adbPath,
   }) : _deviceId = deviceId,
        _adbPath = adbPath,
        _logger = logger,
@@ -1215,7 +1212,7 @@ class AndroidDevicePortForwarder extends DevicePortForwarder {
   final Logger _logger;
   final ProcessUtils _processUtils;
 
-  static int _extractPort(String portString) {
+  static int? _extractPort(String portString) {
     return int.tryParse(portString.trim());
   }
 
@@ -1253,8 +1250,8 @@ class AndroidDevicePortForwarder extends DevicePortForwarder {
       }
 
       // Attempt to extract ports.
-      final int hostPort = _extractPort(splitLine[1]);
-      final int devicePort = _extractPort(splitLine[2]);
+      final int? hostPort = _extractPort(splitLine[1]);
+      final int? devicePort = _extractPort(splitLine[2]);
 
       // Failed, skip.
       if (hostPort == null || devicePort == null) {
@@ -1268,7 +1265,7 @@ class AndroidDevicePortForwarder extends DevicePortForwarder {
   }
 
   @override
-  Future<int> forward(int devicePort, { int hostPort }) async {
+  Future<int> forward(int devicePort, { int? hostPort }) async {
     hostPort ??= 0;
     final RunResult process = await _processUtils.run(
       <String>[
@@ -1320,7 +1317,7 @@ class AndroidDevicePortForwarder extends DevicePortForwarder {
       }
     }
 
-    return hostPort;
+    return hostPort!;
   }
 
   @override
@@ -1335,7 +1332,6 @@ class AndroidDevicePortForwarder extends DevicePortForwarder {
         '--remove',
         tcpLine,
       ],
-      throwOnError: false,
     );
     if (runResult.exitCode == 0) {
       return;

packages/flutter_tools/lib/src/android/android_device_discovery.dart

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
-import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 
 import '../base/common.dart';
@@ -29,13 +26,13 @@ import 'android_workflow.dart';
 ///   * [AndroidDevice], the type of discovered device.
 class AndroidDevices extends PollingDeviceDiscovery {
   AndroidDevices({
-    @required AndroidWorkflow androidWorkflow,
-    @required ProcessManager processManager,
-    @required Logger logger,
-    @required AndroidSdk androidSdk,
-    @required FileSystem fileSystem,
-    @required Platform platform,
-    @required UserMessages userMessages,
+    required AndroidWorkflow androidWorkflow,
+    required ProcessManager processManager,
+    required Logger logger,
+    AndroidSdk? androidSdk,
+    required FileSystem fileSystem,
+    required Platform platform,
+    required UserMessages userMessages,
   }) : _androidWorkflow = androidWorkflow,
        _androidSdk = androidSdk,
        _processUtils = ProcessUtils(
@@ -51,7 +48,7 @@ class AndroidDevices extends PollingDeviceDiscovery {
 
   final AndroidWorkflow _androidWorkflow;
   final ProcessUtils _processUtils;
-  final AndroidSdk _androidSdk;
+  final AndroidSdk? _androidSdk;
   final ProcessManager _processManager;
   final Logger _logger;
   final FileSystem _fileSystem;
@@ -65,13 +62,13 @@ class AndroidDevices extends PollingDeviceDiscovery {
   bool get canListAnything => _androidWorkflow.canListDevices;
 
   @override
-  Future<List<Device>> pollingGetDevices({ Duration timeout }) async {
+  Future<List<Device>> pollingGetDevices({ Duration? timeout }) async {
     if (_doesNotHaveAdb()) {
       return <AndroidDevice>[];
     }
     String text;
     try {
-      text = (await _processUtils.run(<String>[_androidSdk.adbPath, 'devices', '-l'],
+      text = (await _processUtils.run(<String>[_androidSdk!.adbPath!, 'devices', '-l'],
         throwOnError: true,
       )).stdout.trim();
     } on ProcessException catch (exception) {
@@ -94,7 +91,7 @@ class AndroidDevices extends PollingDeviceDiscovery {
       return <String>[];
     }
 
-    final RunResult result = await _processUtils.run(<String>[_androidSdk.adbPath, 'devices', '-l']);
+    final RunResult result = await _processUtils.run(<String>[_androidSdk!.adbPath!, 'devices', '-l']);
     if (result.exitCode != 0) {
       return <String>[];
     }
@@ -108,8 +105,8 @@ class AndroidDevices extends PollingDeviceDiscovery {
 
   bool _doesNotHaveAdb() {
     return _androidSdk == null ||
-      _androidSdk.adbPath == null ||
-      !_processManager.canRun(_androidSdk.adbPath);
+      _androidSdk?.adbPath == null ||
+      !_processManager.canRun(_androidSdk!.adbPath);
   }
 
   // 015d172c98400a03       device usb:340787200X product:nakasi model:Nexus_7 device:grouper
@@ -120,8 +117,8 @@ class AndroidDevices extends PollingDeviceDiscovery {
   /// in which case information for that parameter won't be populated.
   void _parseADBDeviceOutput(
     String text, {
-    List<AndroidDevice> devices,
-    List<String> diagnostics,
+    List<AndroidDevice>? devices,
+    List<String>? diagnostics,
   }) {
     // Check for error messages from adb
     if (!text.contains('List of devices')) {
@@ -146,11 +143,11 @@ class AndroidDevices extends PollingDeviceDiscovery {
       }
 
       if (_kDeviceRegex.hasMatch(line)) {
-        final Match match = _kDeviceRegex.firstMatch(line);
+        final Match match = _kDeviceRegex.firstMatch(line)!;
 
-        final String deviceID = match[1];
-        final String deviceState = match[2];
-        String rest = match[3];
+        final String deviceID = match[1]!;
+        final String deviceState = match[2]!;
+        String rest = match[3]!;
 
         final Map<String, String> info = <String, String>{};
         if (rest != null && rest.isNotEmpty) {
@@ -163,8 +160,9 @@ class AndroidDevices extends PollingDeviceDiscovery {
           }
         }
 
-        if (info['model'] != null) {
-          info['model'] = cleanAdbDeviceName(info['model']);
+        final String? model = info['model'];
+        if (model != null) {
+          info['model'] = cleanAdbDeviceName(model);
         }
 
         if (deviceState == 'unauthorized') {
@@ -180,7 +178,7 @@ class AndroidDevices extends PollingDeviceDiscovery {
             productID: info['product'],
             modelID: info['model'] ?? deviceID,
             deviceCodeName: info['device'],
-            androidSdk: _androidSdk,
+            androidSdk: _androidSdk!,
             fileSystem: _fileSystem,
             logger: _logger,
             platform: _platform,

packages/flutter_tools/test/general.shard/android/adb_log_reader_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 
 import 'package:flutter_tools/src/android/android_device.dart';
@@ -183,7 +181,7 @@ void main() {
   });
 }
 
-AndroidDevice createFakeDevice(int sdkLevel) {
+AndroidDevice createFakeDevice(int? sdkLevel) {
   return FakeAndroidDevice(
     sdkLevel.toString(),
     kLastLogcatTimestamp,

packages/flutter_tools/test/general.shard/android/android_device_discovery_test.dart

@@ -72,7 +72,6 @@ void main() {
 
   testWithoutContext('AndroidDevices returns empty device list and diagnostics on null Android SDK', () async {
     final AndroidDevices androidDevices = AndroidDevices(
-      androidSdk: null,
       logger: BufferLogger.test(),
       androidWorkflow: AndroidWorkflow(
         androidSdk: FakeAndroidSdk(null),

packages/flutter_tools/test/general.shard/android/android_device_port_forwarder_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_tools/src/android/android_device.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/device_port_forwarder.dart';

packages/flutter_tools/test/general.shard/android/android_device_start_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/android/android_device.dart';
 import 'package:flutter_tools/src/android/android_sdk.dart';
@@ -42,9 +40,9 @@ const FakeCommand kShaCommand = FakeCommand(
 );
 
 void main() {
-  FileSystem fileSystem;
-  FakeProcessManager processManager;
-  AndroidSdk androidSdk;
+  late FileSystem fileSystem;
+  late FakeProcessManager processManager;
+  late AndroidSdk androidSdk;
 
   setUp(() {
     processManager = FakeProcessManager.empty();

packages/flutter_tools/test/general.shard/android/android_device_stop_test.dart

-// Copyright 2014 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// @dart = 2.8
-
-import 'package:file/memory.dart';
-import 'package:flutter_tools/src/android/android_device.dart';
-import 'package:flutter_tools/src/android/android_sdk.dart';
-import 'package:flutter_tools/src/base/logger.dart';
-import 'package:flutter_tools/src/base/platform.dart';
-import 'package:test/fake.dart';
-
-import '../../src/common.dart';
-import '../../src/fake_process_manager.dart';
-
-void main() {
-  testWithoutContext('AndroidDevice.stopApp handles a null ApplicationPackage', () async {
-    final AndroidDevice androidDevice = AndroidDevice('1234',
-      androidSdk: FakeAndroidSdk(),
-      fileSystem: MemoryFileSystem.test(),
-      logger: BufferLogger.test(),
-      platform: FakePlatform(),
-      processManager: FakeProcessManager.any(),
-    );
-
-    expect(await androidDevice.stopApp(null), false);
-  });
-}
-
-class FakeAndroidSdk extends Fake implements AndroidSdk { }

packages/flutter_tools/test/general.shard/android/android_device_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 import 'dart:convert';
 import 'dart:typed_data';
@@ -459,15 +457,16 @@ Uptime: 441088659 Realtime: 521464097
 }
 
 AndroidDevice setUpAndroidDevice({
-  String id,
-  AndroidSdk androidSdk,
-  FileSystem fileSystem,
-  ProcessManager processManager,
-  Platform platform,
+  String? id,
+  AndroidSdk? androidSdk,
+  FileSystem? fileSystem,
+  ProcessManager? processManager,
+  Platform? platform,
   AndroidConsoleSocketFactory androidConsoleSocketFactory = kAndroidConsoleSocketFactory,
 }) {
   androidSdk ??= FakeAndroidSdk();
   return AndroidDevice(id ?? '1234',
+    modelID: 'TestModel',
     logger: BufferLogger.test(),
     platform: platform ?? FakePlatform(),
     androidSdk: androidSdk,

packages/flutter_tools/test/general.shard/android/android_install_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/android/android_device.dart';
 import 'package:flutter_tools/src/android/android_sdk.dart';
@@ -41,8 +39,8 @@ const FakeCommand kStoreShaCommand = FakeCommand(
 );
 
 void main() {
-  FileSystem fileSystem;
-  BufferLogger logger;
+  late FileSystem fileSystem;
+  late BufferLogger logger;
 
   setUp(() {
     fileSystem = MemoryFileSystem.test();
@@ -50,15 +48,16 @@ void main() {
   });
 
   AndroidDevice setUpAndroidDevice({
-    AndroidSdk androidSdk,
-    ProcessManager processManager,
+    AndroidSdk? androidSdk,
+    ProcessManager? processManager,
   }) {
     androidSdk ??= FakeAndroidSdk();
     return AndroidDevice('1234',
+      modelID: 'TestModel',
       logger: logger,
       platform: FakePlatform(),
       androidSdk: androidSdk,
-      fileSystem: fileSystem ?? MemoryFileSystem.test(),
+      fileSystem: fileSystem,
       processManager: processManager ?? FakeProcessManager.any(),
     );
   }