Null safety migration of packages/flutter_tools/test/commands.shard/hermetic, part 2/3 (#110708)

* Migrate packages/flutter_tools/test/commands.shard/hermetic, part 2/3 * Fix tests * Fix analysis * Chris's comments

Null safety migration of packages/flutter_tools/test/commands.shard/hermetic, part 2/3 (#110708)
* Migrate packages/flutter_tools/test/commands.shard/hermetic, part 2/3 * Fix tests * Fix analysis * Chris's comments
22cef489 · Liam Appelbe · GitHub · 9dbc09de · 22cef489 · 22cef489
Unverified Commit 22cef489 authored Sep 06, 2022 by Liam Appelbe Committed by GitHub Sep 06, 2022
12 changed files
--- a/packages/flutter_tools/lib/src/commands/custom_devices.dart
+++ b/packages/flutter_tools/lib/src/commands/custom_devices.dart
@@ -598,39 +598,39 @@ class CustomDevicesAddCommand extends CustomDevicesCommandBase {
    inputs = StreamQueue<String>(nonClosingKeystrokes.stream);
-    final String id = await (askForString(
+    final String id = (await askForString(
      'id',
      description:
        'Please enter the id you want to device to have. Must contain only '
        'alphanumeric or underscore characters.',
      example: 'pi',
      validator: (String s) async => RegExp(r'^\w+$').hasMatch(s),
-    ) as FutureOr<String>);
+    ))!;
-    final String label = await (askForString(
+    final String label = (await askForString(
      'label',
      description:
        'Please enter the label of the device, which is a slightly more verbose '
        'name for the device.',
      example: 'Raspberry Pi',
-    ) as FutureOr<String>);
+    ))!;
-    final String sdkNameAndVersion = await (askForString(
+    final String sdkNameAndVersion = (await askForString(
      'SDK name and version',
      example: 'Raspberry Pi 4 Model B+',
-    ) as FutureOr<String>);
+    ))!;
    final bool enabled = await askForBool(
      'enabled',
      description: 'Should the device be enabled?',
    );
-    final String targetStr = await (askForString(
+    final String targetStr = (await askForString(
      'target',
      description: 'Please enter the hostname or IPv4/v6 address of the device.',
      example: 'raspberrypi',
      validator: (String s) async => _isValidHostname(s) || _isValidIpAddr(s)
-    ) as FutureOr<String>);
+    ))!;
    final InternetAddress? targetIp = InternetAddress.tryParse(targetStr);
    final bool useIp = targetIp != null;
@@ -639,20 +639,20 @@ class CustomDevicesAddCommand extends CustomDevicesCommandBase {
      ? InternetAddress.loopbackIPv6
      : InternetAddress.loopbackIPv4;
-    final String username = await (askForString(
+    final String username = (await askForString(
      'username',
      description: 'Please enter the username used for ssh-ing into the remote device.',
      example: 'pi',
      defaultsTo: 'no username',
-    ) as FutureOr<String>);
+    ))!;
-    final String remoteRunDebugCommand = await (askForString(
+    final String remoteRunDebugCommand = (await askForString(
      'run command',
      description:
        'Please enter the command executed on the remote device for starting '
        r'the app. "/tmp/${appName}" is the path to the asset bundle.',
      example: r'flutter-pi /tmp/${appName}'
-    ) as FutureOr<String>);
+    ))!;
    final bool usePortForwarding = await askForBool(
      'use port forwarding',
@@ -663,12 +663,12 @@ class CustomDevicesAddCommand extends CustomDevicesCommandBase {
        'not using port forwarding.',
    );
-    final String screenshotCommand = await (askForString(
+    final String screenshotCommand = (await askForString(
      'screenshot command',
      description: 'Enter the command executed on the remote device for taking a screenshot.',
      example: r"fbgrab /tmp/screenshot.png && cat /tmp/screenshot.png | base64 | tr -d ' \n\t'",
      defaultsTo: 'no screenshotting support',
-    ) as FutureOr<String>);
+    ))!;
    // SSH expects IPv6 addresses to use the bracket syntax like URIs do too,
    // but the IPv6 the user enters is a raw IPv6 address, so we need to wrap it.
@@ -820,8 +820,8 @@ Delete a device from the config file.
  Future<FlutterCommandResult> runCommand() async {
    checkFeatureEnabled();
-    final String id = globalResults!['device-id'] as String;
+    final String? id = globalResults!['device-id'] as String?;
-    if (!customDevicesConfig.contains(id)) {
+    if (id == null || !customDevicesConfig.contains(id)) {
      throwToolExit('Couldn\'t find device with id "$id" in config at "${customDevicesConfig.configPath}"');
    }

--- a/packages/flutter_tools/lib/src/commands/daemon.dart
+++ b/packages/flutter_tools/lib/src/commands/daemon.dart
@@ -1590,7 +1590,7 @@ class DebounceOperationQueue<T, K> {
  final Map<K, Future<T>> _operationQueue = <K, Future<T>>{};
  Future<void>? _inProgressAction;
-  Future<T>? queueAndDebounce(
+  Future<T> queueAndDebounce(
    K operationType,
    Duration debounceDuration,
    Future<T> Function() action,
@@ -1599,7 +1599,7 @@ class DebounceOperationQueue<T, K> {
    // debounce timer and return its future.
    if (_operationQueue[operationType] != null) {
      _debounceTimers[operationType]?.reset();
-      return _operationQueue[operationType];
+      return _operationQueue[operationType]!;
    }
    // Otherwise, put one in the queue with a timer.

--- a/packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_web_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:args/command_runner.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
@@ -23,7 +21,7 @@ import '../../src/test_build_system.dart';
 import '../../src/test_flutter_command_runner.dart';
 void main() {
-  FileSystem fileSystem;
+  late FileSystem fileSystem;
  final Platform fakePlatform = FakePlatform(
    environment: <String, String>{
      'FLUTTER_ROOT': '/',
@@ -243,7 +241,7 @@ class TestWebBuildCommand extends FlutterCommand {
  final String description = 'Build a test executable app.';
  @override
-  Future<FlutterCommandResult> runCommand() async => null;
+  Future<FlutterCommandResult> runCommand() async => FlutterCommandResult.fail();
  @override
  bool get shouldRunPub => false;

--- a/packages/flutter_tools/test/commands.shard/hermetic/build_windows_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_windows_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:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
@@ -43,10 +41,9 @@ final Platform notWindowsPlatform = FakePlatform(
 );
 void main() {
-  FileSystem fileSystem;
+  late FileSystem fileSystem;
+  late ProcessManager processManager;
-  ProcessManager processManager;
+  late TestUsage usage;
-  TestUsage usage;
  setUpAll(() {
    Cache.disableLocking();
@@ -75,7 +72,7 @@ void main() {
  // Returns the command matching the build_windows call to generate CMake
  // files.
  FakeCommand cmakeGenerationCommand({
-    void Function() onRun,
+    void Function()? onRun,
    String generator = _defaultGenerator,
  }) {
    return FakeCommand(
@@ -95,7 +92,7 @@ void main() {
  // Returns the command matching the build_windows call to build.
  FakeCommand buildCommand(String buildMode, {
    bool verbose = false,
-    void Function() onRun,
+    void Function()? onRun,
    String stdout = '',
  }) {
    return FakeCommand(
@@ -974,7 +971,7 @@ class FakeVisualStudio extends Fake implements VisualStudio {
  });
  @override
-  final String cmakePath;
+  final String? cmakePath;
  @override
  final String cmakeGenerator;

--- a/packages/flutter_tools/test/commands.shard/hermetic/create_usage_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/create_usage_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:args/command_runner.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/cache.dart';
@@ -28,13 +26,13 @@ class FakePub extends Fake implements Pub {
  @override
  Future<void> get({
-    PubContext context,
+    PubContext? context,
-    String directory,
+    String? directory,
    bool skipIfAbsent = false,
    bool upgrade = false,
    bool offline = false,
    bool generateSyntheticPackage = false,
-    String flutterRootOverride,
+    String? flutterRootOverride,
    bool checkUpToDate = false,
    bool shouldSkipThirdPartyGenerator = true,
    bool printProgress = true,
@@ -50,8 +48,8 @@ class FakePub extends Fake implements Pub {
 void main() {
  group('usageValues', () {
-    Testbed testbed;
+    late Testbed testbed;
-    FakePub fakePub;
+    late FakePub fakePub;
    setUpAll(() {
      Cache.disableLocking();

--- a/packages/flutter_tools/test/commands.shard/hermetic/custom_devices_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/custom_devices_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:typed_data';
@@ -23,7 +21,6 @@ import 'package:flutter_tools/src/commands/custom_devices.dart';
 import 'package:flutter_tools/src/custom_devices/custom_device_config.dart';
 import 'package:flutter_tools/src/custom_devices/custom_devices_config.dart';
 import 'package:flutter_tools/src/runner/flutter_command_runner.dart';
-import 'package:meta/meta.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
@@ -171,7 +168,7 @@ final Platform windowsPlatform = FakePlatform(
 );
 class FakeTerminal implements Terminal {
-  factory FakeTerminal({Platform platform}) {
+  factory FakeTerminal({required Platform platform}) {
    return FakeTerminal._private(
        stdio: FakeStdio(),
        platform: platform
@@ -179,8 +176,8 @@ class FakeTerminal implements Terminal {
  }
  FakeTerminal._private({
-    this.stdio,
+    required this.stdio,
-    Platform platform
+    required Platform platform
  }) :
    terminal = AnsiTerminal(
      stdio: stdio,
@@ -215,9 +212,9 @@ class FakeTerminal implements Terminal {
  @override
  Future<String> promptForCharInput(
    List<String> acceptedCharacters, {
-    Logger logger,
+    required Logger logger,
-    String prompt,
+    String? prompt,
-    int defaultChoiceIndex,
+    int? defaultChoiceIndex,
    bool displayAcceptedCharacters = true
  }) => terminal.promptForCharInput(
      acceptedCharacters,
@@ -253,10 +250,10 @@ class FakeTerminal implements Terminal {
 class FakeCommandRunner extends FlutterCommandRunner {
  FakeCommandRunner({
-    @required Platform platform,
+    required Platform platform,
-    @required FileSystem fileSystem,
+    required FileSystem fileSystem,
-    @required Logger logger,
+    required Logger logger,
-    UserMessages userMessages
+    UserMessages? userMessages
  }) : _platform = platform,
       _fileSystem = fileSystem,
       _logger = logger,
@@ -285,7 +282,7 @@ class FakeCommandRunner extends FlutterCommandRunner {
          userMessages: _userMessages,
        );
        // For compatibility with tests that set this to a relative path.
-        Cache.flutterRoot = _fileSystem.path.normalize(_fileSystem.path.absolute(Cache.flutterRoot));
+        Cache.flutterRoot = _fileSystem.path.normalize(_fileSystem.path.absolute(Cache.flutterRoot!));
        return super.runCommand(topLevelResults);
      }
    );
@@ -295,13 +292,13 @@ class FakeCommandRunner extends FlutterCommandRunner {
 /// May take platform, logger, processManager and fileSystem from context if
 /// not explicitly specified.
 CustomDevicesCommand createCustomDevicesCommand({
-  CustomDevicesConfig Function(FileSystem, Logger) config,
+  CustomDevicesConfig Function(FileSystem, Logger)? config,
-  Terminal Function(Platform) terminal,
+  Terminal Function(Platform)? terminal,
-  Platform platform,
+  Platform? platform,
-  FileSystem fileSystem,
+  FileSystem? fileSystem,
-  ProcessManager processManager,
+  ProcessManager? processManager,
-  Logger logger,
+  Logger? logger,
-  PrintFn usagePrintFn,
+  PrintFn? usagePrintFn,
  bool featureEnabled = false
 }) {
  platform ??= FakePlatform();
@@ -340,13 +337,13 @@ CustomDevicesCommand createCustomDevicesCommand({
 /// May take platform, logger, processManager and fileSystem from context if
 /// not explicitly specified.
 CommandRunner<void> createCustomDevicesCommandRunner({
-  CustomDevicesConfig Function(FileSystem, Logger) config,
+  CustomDevicesConfig Function(FileSystem, Logger)? config,
-  Terminal Function(Platform) terminal,
+  Terminal Function(Platform)? terminal,
-  Platform platform,
+  Platform? platform,
-  FileSystem fileSystem,
+  FileSystem? fileSystem,
-  ProcessManager processManager,
+  ProcessManager? processManager,
-  Logger logger,
+  Logger? logger,
-  PrintFn usagePrintFn,
+  PrintFn? usagePrintFn,
  bool featureEnabled = false,
 }) {
  platform ??= FakePlatform();
@@ -372,17 +369,17 @@ CommandRunner<void> createCustomDevicesCommandRunner({
 }
 FakeTerminal createFakeTerminalForAddingSshDevice({
-  @required Platform platform,
+  required Platform platform,
-  @required String id,
+  required String id,
-  @required String label,
+  required String label,
-  @required String sdkNameAndVersion,
+  required String sdkNameAndVersion,
-  @required String enabled,
+  required String enabled,
-  @required String hostname,
+  required String hostname,
-  @required String username,
+  required String username,
-  @required String runDebug,
+  required String runDebug,
-  @required String usePortForwarding,
+  required String usePortForwarding,
-  @required String screenshot,
+  required String screenshot,
-  @required String apply
+  required String apply
 }) {
  return FakeTerminal(platform: platform)
    ..simulateStdin(id)

--- a/packages/flutter_tools/test/commands.shard/hermetic/daemon_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/daemon_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:io' as io;
 import 'dart:typed_data';
@@ -57,7 +55,7 @@ class FakeDaemonStreams implements DaemonStreams {
  }
  @override
-  void send(Map<String, dynamic> message, [ List<int> binary ]) {
+  void send(Map<String, Object?> message, [ List<int>? binary ]) {
    outputs.add(DaemonMessage(message, binary != null ? Stream<List<int>>.value(binary) : null));
  }
@@ -70,12 +68,12 @@ class FakeDaemonStreams implements DaemonStreams {
 }
 void main() {
-  Daemon daemon;
+  late Daemon daemon;
-  NotifyingLogger notifyingLogger;
+  late NotifyingLogger notifyingLogger;
  group('daemon', () {
-    FakeDaemonStreams daemonStreams;
+    late FakeDaemonStreams daemonStreams;
-    DaemonConnection daemonConnection;
+    late DaemonConnection daemonConnection;
    setUp(() {
      BufferLogger bufferLogger;
      bufferLogger = BufferLogger.test();
@@ -100,7 +98,7 @@ void main() {
        daemonConnection,
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'daemon.version'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'daemon.version'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['result'], isNotEmpty);
@@ -115,7 +113,7 @@ void main() {
      // Use the flutter_gallery project which has a known set of supported platforms.
      final String projectPath = globals.fs.path.join(getFlutterRoot(), 'dev', 'integration_tests', 'flutter_gallery');
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
        'id': 0,
        'method': 'daemon.getSupportedPlatforms',
        'params': <String, Object>{'projectRoot': projectPath},
@@ -124,7 +122,7 @@ void main() {
      expect(response.data['id'], 0);
      expect(response.data['result'], isNotEmpty);
-      expect((response.data['result'] as Map<String, dynamic>)['platforms'], <String>{'macos'});
+      expect((response.data['result']! as Map<String, Object?>)['platforms'], <String>{'macos'});
    }, overrides: <Type, Generator>{
      // Disable Android/iOS and enable macOS to make sure result is consistent and defaults are tested off.
      FeatureFlags: () => TestFeatureFlags(isAndroidEnabled: false, isIOSEnabled: false, isMacOSEnabled: true),
@@ -137,11 +135,11 @@ void main() {
      );
      globals.printError('daemon.logMessage test');
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere((DaemonMessage message) {
-        return message.data['event'] == 'daemon.logMessage' && (message.data['params'] as Map<String, dynamic>)['level'] == 'error';
+        return message.data['event'] == 'daemon.logMessage' && (message.data['params']! as Map<String, Object?>)['level'] == 'error';
      });
      expect(response.data['id'], isNull);
      expect(response.data['event'], 'daemon.logMessage');
-      final Map<String, String> logMessage = castStringKeyedMap(response.data['params']).cast<String, String>();
+      final Map<String, String> logMessage = castStringKeyedMap(response.data['params'])!.cast<String, String>();
      expect(logMessage['level'], 'error');
      expect(logMessage['message'], 'daemon.logMessage test');
    }, overrides: <Type, Generator>{
@@ -155,11 +153,11 @@ void main() {
      );
      globals.printWarning('daemon.logMessage test');
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere((DaemonMessage message) {
-        return message.data['event'] == 'daemon.logMessage' && (message.data['params'] as Map<String, dynamic>)['level'] == 'warning';
+        return message.data['event'] == 'daemon.logMessage' && (message.data['params']! as Map<String, Object?>)['level'] == 'warning';
      });
      expect(response.data['id'], isNull);
      expect(response.data['event'], 'daemon.logMessage');
-      final Map<String, String> logMessage = castStringKeyedMap(response.data['params']).cast<String, String>();
+      final Map<String, String> logMessage = castStringKeyedMap(response.data['params'])!.cast<String, String>();
      expect(logMessage['level'], 'warning');
      expect(logMessage['message'], 'daemon.logMessage test');
    }, overrides: <Type, Generator>{
@@ -203,7 +201,7 @@ void main() {
        daemonConnection,
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'daemon.shutdown'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'daemon.shutdown'}));
      return daemon.onExit.then<void>((int code) async {
        await daemonStreams.inputs.close();
        expect(code, 0);
@@ -216,7 +214,7 @@ void main() {
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'app.restart'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'app.restart'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['error'], contains('appId is required'));
@@ -228,7 +226,7 @@ void main() {
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
        'id': 0,
        'method': 'app.callServiceExtension',
        'params': <String, String>{
@@ -246,7 +244,7 @@ void main() {
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'app.stop'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'app.stop'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['error'], contains('appId is required'));
@@ -257,7 +255,7 @@ void main() {
        daemonConnection,
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'device.getDevices'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'device.getDevices'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['result'], isList);
@@ -271,10 +269,10 @@ void main() {
      final FakePollingDeviceDiscovery discoverer = FakePollingDeviceDiscovery();
      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
      discoverer.addDevice(FakeAndroidDevice());
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'device.getDevices'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'device.getDevices'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
-      final dynamic result = response.data['result'];
+      final Object? result = response.data['result'];
      expect(result, isList);
      expect(result, isNotEmpty);
    });
@@ -293,7 +291,7 @@ void main() {
        expect(response.data['event'], 'device.added');
        expect(response.data['params'], isMap);
-        final Map<String, dynamic> params = castStringKeyedMap(response.data['params']);
+        final Map<String, Object?> params = castStringKeyedMap(response.data['params'])!;
        expect(params['platform'], isNotEmpty); // the fake device has a platform of 'android-arm'
      });
    }, overrides: <Type, Generator>{
@@ -307,7 +305,7 @@ void main() {
        daemonConnection,
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'device.discoverDevices'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'device.discoverDevices'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['result'], isList);
@@ -321,10 +319,10 @@ void main() {
      final FakePollingDeviceDiscovery discoverer = FakePollingDeviceDiscovery();
      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
      discoverer.addDevice(FakeAndroidDevice());
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'device.discoverDevices'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'device.discoverDevices'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
-      final dynamic result = response.data['result'];
+      final Object? result = response.data['result'];
      expect(result, isList);
      expect(result, isNotEmpty);
      expect(discoverer.discoverDevicesCalled, true);
@@ -339,17 +337,17 @@ void main() {
      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
      final FakeAndroidDevice device = FakeAndroidDevice();
      discoverer.addDevice(device);
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
        'id': 0,
        'method': 'device.supportsRuntimeMode',
-        'params': <String, dynamic>{
+        'params': <String, Object?>{
          'deviceId': 'device',
          'buildMode': 'profile',
        },
      }));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
-      final dynamic result = response.data['result'];
+      final Object? result = response.data['result'];
      expect(result, true);
      expect(device.supportsRuntimeModeCalledBuildMode, BuildMode.profile);
    });
@@ -365,17 +363,17 @@ void main() {
      discoverer.addDevice(device);
      final FakeDeviceLogReader logReader = FakeDeviceLogReader();
      device.logReader = logReader;
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
        'id': 0,
        'method': 'device.logReader.start',
-        'params': <String, dynamic>{
+        'params': <String, Object?>{
          'deviceId': 'device',
        },
      }));
      final Stream<DaemonMessage> broadcastOutput = daemonStreams.outputs.stream.asBroadcastStream();
      final DaemonMessage firstResponse = await broadcastOutput.firstWhere(_notEvent);
      expect(firstResponse.data['id'], 0);
-      final String logReaderId = firstResponse.data['result'] as String;
+      final String? logReaderId = firstResponse.data['result'] as String?;
      expect(logReaderId, isNotNull);
      // Try sending logs.
@@ -387,10 +385,10 @@ void main() {
      // Now try to stop the log reader.
      expect(logReader.disposeCalled, false);
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
        'id': 1,
        'method': 'device.logReader.stop',
-        'params': <String, dynamic>{
+        'params': <String, Object?>{
          'id': logReaderId,
        },
      }));
@@ -400,7 +398,7 @@ void main() {
    });
    group('device.startApp and .stopApp', () {
-      FakeApplicationPackageFactory applicationPackageFactory;
+      late FakeApplicationPackageFactory applicationPackageFactory;
      setUp(() {
        applicationPackageFactory = FakeApplicationPackageFactory();
      });
@@ -419,27 +417,27 @@ void main() {
        // First upload the application package.
        final FakeApplicationPackage applicationPackage = FakeApplicationPackage();
        applicationPackageFactory.applicationPackage = applicationPackage;
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
          'id': 0,
          'method': 'device.uploadApplicationPackage',
-          'params': <String, dynamic>{
+          'params': <String, Object?>{
            'targetPlatform': 'android',
            'applicationBinary': 'test_file',
          },
        }));
        final DaemonMessage applicationPackageIdResponse = await broadcastOutput.firstWhere(_notEvent);
        expect(applicationPackageIdResponse.data['id'], 0);
-        expect(applicationPackageFactory.applicationBinaryRequested.basename, 'test_file');
+        expect(applicationPackageFactory.applicationBinaryRequested!.basename, 'test_file');
        expect(applicationPackageFactory.platformRequested, TargetPlatform.android);
-        final String applicationPackageId = applicationPackageIdResponse.data['result'] as String;
+        final String? applicationPackageId = applicationPackageIdResponse.data['result'] as String?;
        // Try starting the app.
        final Uri observatoryUri = Uri.parse('http://127.0.0.1:12345/observatory');
        device.launchResult = LaunchResult.succeeded(observatoryUri: observatoryUri);
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
          'id': 1,
          'method': 'device.startApp',
-          'params': <String, dynamic>{
+          'params': <String, Object?>{
            'deviceId': 'device',
            'applicationPackageId': applicationPackageId,
            'debuggingOptions': DebuggingOptions.enabled(BuildInfo.debug).toJson(),
@@ -448,15 +446,15 @@ void main() {
        final DaemonMessage startAppResponse = await broadcastOutput.firstWhere(_notEvent);
        expect(startAppResponse.data['id'], 1);
        expect(device.startAppPackage, applicationPackage);
-        final Map<String, dynamic> startAppResult = startAppResponse.data['result'] as Map<String, dynamic>;
+        final Map<String, Object?> startAppResult = startAppResponse.data['result']! as Map<String, Object?>;
        expect(startAppResult['started'], true);
        expect(startAppResult['observatoryUri'], observatoryUri.toString());
        // Try stopping the app.
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{
          'id': 2,
          'method': 'device.stopApp',
-          'params': <String, dynamic>{
+          'params': <String, Object?>{
            'deviceId': 'device',
            'applicationPackageId': applicationPackageId,
          },
@@ -464,7 +462,7 @@ void main() {
        final DaemonMessage stopAppResponse = await broadcastOutput.firstWhere(_notEvent);
        expect(stopAppResponse.data['id'], 2);
        expect(device.stopAppPackage, applicationPackage);
-        final bool stopAppResult = stopAppResponse.data['result'] as bool;
+        final bool? stopAppResult = stopAppResponse.data['result'] as bool?;
        expect(stopAppResult, true);
      }, overrides: <Type, Generator>{
        ApplicationPackageFactory: () => applicationPackageFactory,
@@ -477,7 +475,7 @@ void main() {
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'emulator.launch'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'emulator.launch'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['error'], contains('emulatorId is required'));
@@ -488,8 +486,8 @@ void main() {
        daemonConnection,
        notifyingLogger: notifyingLogger,
      );
-      final Map<String, dynamic> params = <String, dynamic>{'emulatorId': 'device', 'coldBoot': 1};
+      final Map<String, Object?> params = <String, Object?>{'emulatorId': 'device', 'coldBoot': 1};
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'emulator.launch', 'params': params}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'emulator.launch', 'params': params}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['error'], contains('coldBoot is not a bool'));
@@ -500,7 +498,7 @@ void main() {
        daemonConnection,
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'emulator.getEmulators'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'emulator.getEmulators'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere(_notEvent);
      expect(response.data['id'], 0);
      expect(response.data['result'], isList);
@@ -519,8 +517,8 @@ void main() {
      unawaited(daemonStreams.outputs.stream
        .firstWhere((DaemonMessage request) => request.data['method'] == 'app.exposeUrl')
        .then((DaemonMessage request) {
-          expect((request.data['params'] as Map<String, dynamic>)['url'], equals(originalUrl));
+          expect((request.data['params']! as Map<String, Object?>)['url'], equals(originalUrl));
-          daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': request.data['id'], 'result': <String, dynamic>{'url': mappedUrl}}));
+          daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': request.data['id'], 'result': <String, Object?>{'url': mappedUrl}}));
        })
      );
@@ -534,9 +532,9 @@ void main() {
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'devtools.serve'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'devtools.serve'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere((DaemonMessage response) => response.data['id'] == 0);
-      final Map<String, dynamic> result = response.data['result'] as Map<String, dynamic>;
+      final Map<String, Object?> result = response.data['result']! as Map<String, Object?>;
      expect(result, isNotEmpty);
      expect(result['host'], '127.0.0.1');
      expect(result['port'], 1234);
@@ -550,9 +548,9 @@ void main() {
        notifyingLogger: notifyingLogger,
      );
-      daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'devtools.serve'}));
+      daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'devtools.serve'}));
      final DaemonMessage response = await daemonStreams.outputs.stream.firstWhere((DaemonMessage response) => response.data['id'] == 0);
-      final Map<String, dynamic> result = response.data['result'] as Map<String, dynamic>;
+      final Map<String, Object?> result = response.data['result']! as Map<String, Object?>;
      expect(result, isNotEmpty);
      expect(result['host'], null);
      expect(result['port'], null);
@@ -565,8 +563,8 @@ void main() {
      await io.IOOverrides.runWithIOOverrides(() async {
        final FakeSocket socket = FakeSocket();
        bool connectCalled = false;
-        int connectPort;
+        int? connectPort;
-        ioOverrides.connectCallback = (dynamic host, int port) async {
+        ioOverrides.connectCallback = (Object? host, int port) async {
          connectCalled = true;
          connectPort = port;
          if (host == io.InternetAddress.loopbackIPv4) {
@@ -579,7 +577,7 @@ void main() {
          daemonConnection,
          notifyingLogger: notifyingLogger,
        );
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'proxy.connect', 'params': <String, dynamic>{'port': 123}}));
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'proxy.connect', 'params': <String, Object?>{'port': 123}}));
        final Stream<DaemonMessage> broadcastOutput = daemonStreams.outputs.stream.asBroadcastStream();
        final DaemonMessage firstResponse = await broadcastOutput.firstWhere(_notEvent);
@@ -588,7 +586,7 @@ void main() {
        expect(connectCalled, true);
        expect(connectPort, 123);
-        final Object id = firstResponse.data['result'];
+        final Object? id = firstResponse.data['result'];
        // Can send received data as event.
        socket.controller.add(Uint8List.fromList(<int>[10, 11, 12]));
@@ -596,22 +594,22 @@ void main() {
          (DaemonMessage message) => message.data['event'] != null && message.data['event'] == 'proxy.data.$id',
        );
        expect(dataEvent.binary, isNotNull);
-        final List<List<int>> data = await dataEvent.binary.toList();
+        final List<List<int>> data = await dataEvent.binary!.toList();
        expect(data[0], <int>[10, 11, 12]);
        // Can proxy data to the socket.
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'proxy.write', 'params': <String, dynamic>{'id': id}}, Stream<List<int>>.value(<int>[21, 22, 23])));
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'proxy.write', 'params': <String, Object?>{'id': id}}, Stream<List<int>>.value(<int>[21, 22, 23])));
        await pumpEventQueue();
        expect(socket.addedData[0], <int>[21, 22, 23]);
        // Closes the connection when disconnect request received.
        expect(socket.closeCalled, false);
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'proxy.disconnect', 'params': <String, dynamic>{'id': id}}));
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'proxy.disconnect', 'params': <String, Object?>{'id': id}}));
        await pumpEventQueue();
        expect(socket.closeCalled, true);
        // Sends disconnected event when socket.done completer finishes.
-        socket.doneCompleter.complete();
+        socket.doneCompleter.complete(true);
        final DaemonMessage disconnectEvent = await broadcastOutput.firstWhere(
          (DaemonMessage message) => message.data['event'] != null && message.data['event'] == 'proxy.disconnected.$id',
        );
@@ -624,8 +622,8 @@ void main() {
      await io.IOOverrides.runWithIOOverrides(() async {
        final FakeSocket socket = FakeSocket();
        bool connectIpv4Called = false;
-        int connectPort;
+        int? connectPort;
-        ioOverrides.connectCallback = (dynamic host, int port) async {
+        ioOverrides.connectCallback = (Object? host, int port) async {
          connectPort = port;
          if (host == io.InternetAddress.loopbackIPv4) {
            connectIpv4Called = true;
@@ -639,7 +637,7 @@ void main() {
          daemonConnection,
          notifyingLogger: notifyingLogger,
        );
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'proxy.connect', 'params': <String, dynamic>{'port': 123}}));
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'proxy.connect', 'params': <String, Object?>{'port': 123}}));
        final Stream<DaemonMessage> broadcastOutput = daemonStreams.outputs.stream.asBroadcastStream();
        final DaemonMessage firstResponse = await broadcastOutput.firstWhere(_notEvent);
@@ -653,13 +651,13 @@ void main() {
    testUsingContext('proxy.connect fails if both ipv6 and ipv4 failed', () async {
      final TestIOOverrides ioOverrides = TestIOOverrides();
      await io.IOOverrides.runWithIOOverrides(() async {
-        ioOverrides.connectCallback = (dynamic host, int port) => throw const io.SocketException('fail');
+        ioOverrides.connectCallback = (Object? host, int port) => throw const io.SocketException('fail');
        daemon = Daemon(
          daemonConnection,
          notifyingLogger: notifyingLogger,
        );
-        daemonStreams.inputs.add(DaemonMessage(<String, dynamic>{'id': 0, 'method': 'proxy.connect', 'params': <String, dynamic>{'port': 123}}));
+        daemonStreams.inputs.add(DaemonMessage(<String, Object?>{'id': 0, 'method': 'proxy.connect', 'params': <String, Object?>{'port': 123}}));
        final Stream<DaemonMessage> broadcastOutput = daemonStreams.outputs.stream.asBroadcastStream();
        final DaemonMessage firstResponse = await broadcastOutput.firstWhere(_notEvent);
@@ -671,7 +669,7 @@ void main() {
  });
  group('notifyingLogger', () {
-    BufferLogger bufferLogger;
+    late BufferLogger bufferLogger;
    setUp(() {
      bufferLogger = BufferLogger.test();
    });
@@ -713,7 +711,7 @@ void main() {
  });
  group('daemon queue', () {
-    DebounceOperationQueue<int, String> queue;
+    late DebounceOperationQueue<int, String> queue;
    const Duration debounceDuration = Duration(seconds: 1);
    setUp(() {
@@ -741,7 +739,7 @@ void main() {
      await _runFakeAsync((FakeAsync time) async {
        final List<Future<int>> operations = <Future<int>>[
          queue.queueAndDebounce('OP1', debounceDuration, () async => 1),
-          Future<int>.delayed(debounceDuration * 2).then((_) =>
+          Future<void>.delayed(debounceDuration * 2).then((_) =>
              queue.queueAndDebounce('OP1', debounceDuration, () async => 2)),
        ];
@@ -873,42 +871,42 @@ class FakeAndroidDevice extends Fake implements AndroidDevice {
  @override
  bool get supportsStartPaused => true;
-  BuildMode supportsRuntimeModeCalledBuildMode;
+  BuildMode? supportsRuntimeModeCalledBuildMode;
  @override
  Future<bool> supportsRuntimeMode(BuildMode buildMode) async {
    supportsRuntimeModeCalledBuildMode = buildMode;
    return true;
  }
-  DeviceLogReader logReader;
+  late DeviceLogReader logReader;
  @override
  FutureOr<DeviceLogReader> getLogReader({
-    covariant ApplicationPackage app,
+    covariant ApplicationPackage? app,
    bool includePastLogs = false,
  }) => logReader;
-  ApplicationPackage startAppPackage;
+  ApplicationPackage? startAppPackage;
-  LaunchResult launchResult;
+  late LaunchResult launchResult;
  @override
  Future<LaunchResult> startApp(
    ApplicationPackage package, {
-    String mainPath,
+    String? mainPath,
-    String route,
+    String? route,
-    DebuggingOptions debuggingOptions,
+    DebuggingOptions? debuggingOptions,
-    Map<String, Object> platformArgs = const <String, Object>{},
+    Map<String, Object?> platformArgs = const <String, Object>{},
    bool prebuiltApplication = false,
    bool ipv6 = false,
-    String userIdentifier,
+    String? userIdentifier,
  }) async {
    startAppPackage = package;
    return launchResult;
  }
-  ApplicationPackage stopAppPackage;
+  ApplicationPackage? stopAppPackage;
  @override
  Future<bool> stopApp(
    ApplicationPackage app, {
-    String userIdentifier,
+    String? userIdentifier,
  }) async {
    stopAppPackage = app;
    return true;
@@ -920,10 +918,10 @@ class FakeDeviceLogReader implements DeviceLogReader {
  bool disposeCalled = false;
  @override
-  int appPid;
+  int? appPid;
  @override
-  FlutterVmService connectedVMService;
+  FlutterVmService? connectedVMService;
  @override
  void dispose() {
@@ -941,22 +939,22 @@ class FakeDeviceLogReader implements DeviceLogReader {
 class FakeDevtoolsLauncher extends Fake implements DevtoolsLauncher {
  FakeDevtoolsLauncher(this._serverAddress);
-  final DevToolsServerAddress _serverAddress;
+  final DevToolsServerAddress? _serverAddress;
  @override
-  Future<DevToolsServerAddress> serve() async => _serverAddress;
+  Future<DevToolsServerAddress?> serve() async => _serverAddress;
  @override
  Future<void> close() async {}
 }
 class FakeApplicationPackageFactory implements ApplicationPackageFactory {
-  TargetPlatform platformRequested;
+  TargetPlatform? platformRequested;
-  File applicationBinaryRequested;
+  File? applicationBinaryRequested;
-  ApplicationPackage applicationPackage;
+  ApplicationPackage? applicationPackage;
  @override
-  Future<ApplicationPackage> getPackageForPlatform(TargetPlatform platform, {BuildInfo buildInfo, File applicationBinary}) async {
+  Future<ApplicationPackage?> getPackageForPlatform(TargetPlatform platform, {BuildInfo? buildInfo, File? applicationBinary}) async {
    platformRequested = platform;
    applicationBinaryRequested = applicationBinary;
    return applicationPackage;
@@ -966,11 +964,11 @@ class FakeApplicationPackageFactory implements ApplicationPackageFactory {
 class FakeApplicationPackage extends Fake implements ApplicationPackage {}
 class TestIOOverrides extends io.IOOverrides {
-  Future<io.Socket> Function(dynamic host, int port) connectCallback;
+  late Future<io.Socket> Function(Object? host, int port) connectCallback;
  @override
-  Future<io.Socket> socketConnect(dynamic host, int port,
+  Future<io.Socket> socketConnect(Object? host, int port,
-      {dynamic sourceAddress, int sourcePort = 0, Duration timeout}) {
+      {Object? sourceAddress, int sourcePort = 0, Duration? timeout}) {
    return connectCallback(host, port);
  }
 }
@@ -983,10 +981,10 @@ class FakeSocket extends Fake implements io.Socket {
  @override
  StreamSubscription<Uint8List> listen(
-    void Function(Uint8List event) onData, {
+    void Function(Uint8List event)? onData, {
-    Function onError,
+    Function? onError,
-    void Function() onDone,
+    void Function()? onDone,
-    bool cancelOnError,
+    bool? cancelOnError,
  }) {
    return controller.stream.listen(onData, onError: onError, onDone: onDone, cancelOnError: cancelOnError);
  }

--- a/packages/flutter_tools/test/commands.shard/hermetic/devices_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/devices_test.dart
@@ -2,12 +2,12 @@
 // 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:convert';
 import 'package:flutter_tools/src/android/android_sdk.dart';
 import 'package:flutter_tools/src/artifacts.dart';
+import 'package:flutter_tools/src/base/terminal.dart';
+import 'package:flutter_tools/src/base/user_messages.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/devices.dart';
 import 'package:flutter_tools/src/device.dart';
@@ -24,7 +24,7 @@ void main() {
      Cache.disableLocking();
    });
-    Cache cache;
+    late Cache cache;
    setUp(() {
      cache = Cache.test(processManager: FakeProcessManager.any());
@@ -52,7 +52,7 @@ void main() {
    testUsingContext("get devices' platform types", () async {
      final List<String> platformTypes = Device.devicesPlatformTypes(
-        await globals.deviceManager.getAllConnectedDevices(),
+        await globals.deviceManager!.getAllConnectedDevices(),
      );
      expect(platformTypes, <String>['android', 'web']);
    }, overrides: <Type, Generator>{
@@ -133,14 +133,14 @@ webby (mobile)     • webby     • web-javascript • Web SDK (1.2.4) (emulato
 }
 class _FakeDeviceManager extends DeviceManager {
-  _FakeDeviceManager();
+  _FakeDeviceManager() : super(logger: testLogger, terminal: Terminal.test(), userMessages: userMessages);
  @override
  Future<List<Device>> getAllConnectedDevices() =>
    Future<List<Device>>.value(fakeDevices.map((FakeDeviceJsonData d) => d.dev).toList());
  @override
-  Future<List<Device>> refreshAllConnectedDevices({Duration timeout}) =>
+  Future<List<Device>> refreshAllConnectedDevices({Duration? timeout}) =>
    getAllConnectedDevices();
  @override
@@ -153,11 +153,13 @@ class _FakeDeviceManager extends DeviceManager {
 }
 class NoDevicesManager extends DeviceManager {
+  NoDevicesManager() : super(logger: testLogger, terminal: Terminal.test(), userMessages: userMessages);
  @override
  Future<List<Device>> getAllConnectedDevices() async => <Device>[];
  @override
-  Future<List<Device>> refreshAllConnectedDevices({Duration timeout}) =>
+  Future<List<Device>> refreshAllConnectedDevices({Duration? timeout}) =>
    getAllConnectedDevices();
  @override

--- a/packages/flutter_tools/test/commands.shard/hermetic/downgrade_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/downgrade_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/file.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/io.dart';
@@ -20,11 +18,11 @@ import '../../src/fakes.dart';
 import '../../src/test_flutter_command_runner.dart';
 void main() {
-  FileSystem fileSystem;
+  late FileSystem fileSystem;
-  BufferLogger bufferLogger;
+  late BufferLogger bufferLogger;
-  FakeTerminal terminal;
+  late FakeTerminal terminal;
-  ProcessManager processManager;
+  late ProcessManager processManager;
-  FakeStdio stdio;
+  late FakeStdio stdio;
  setUpAll(() {
    Cache.disableLocking();
@@ -224,11 +222,11 @@ class FakeTerminal extends Fake implements Terminal {
    _selected = selected;
  }
-  List<String> _characters;
+  List<String>? _characters;
-  String _selected;
+  late String _selected;
  @override
-  Future<String> promptForCharInput(List<String> acceptedCharacters, {Logger logger, String prompt, int defaultChoiceIndex, bool displayAcceptedCharacters = true}) async {
+  Future<String> promptForCharInput(List<String> acceptedCharacters, {Logger? logger, String? prompt, int? defaultChoiceIndex, bool displayAcceptedCharacters = true}) async {
    expect(acceptedCharacters, _characters);
    return _selected;
  }

--- a/packages/flutter_tools/test/commands.shard/hermetic/drive_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/drive_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/application_package.dart';
 import 'package:flutter_tools/src/base/common.dart';
@@ -25,10 +23,10 @@ import '../../src/context.dart';
 import '../../src/test_flutter_command_runner.dart';
 void main() {
-  FileSystem fileSystem;
+  late FileSystem fileSystem;
-  BufferLogger logger;
+  late BufferLogger logger;
-  Platform platform;
+  late Platform platform;
-  FakeDeviceManager fakeDeviceManager;
+  late FakeDeviceManager fakeDeviceManager;
  setUp(() {
    fileSystem = MemoryFileSystem.test();
@@ -254,15 +252,15 @@ void main() {
 class ThrowingScreenshotDevice extends ScreenshotDevice {
  @override
  Future<LaunchResult> startApp(
-    ApplicationPackage package, {
+    ApplicationPackage? package, {
-      String mainPath,
+      String? mainPath,
-      String route,
+      String? route,
-      DebuggingOptions debuggingOptions,
+      DebuggingOptions? debuggingOptions,
-      Map<String, dynamic> platformArgs,
+      Map<String, dynamic>? platformArgs,
      bool prebuiltApplication = false,
      bool usesTerminalUi = true,
      bool ipv6 = false,
-      String userIdentifier,
+      String? userIdentifier,
    }) async {
    throwToolExit('cannot start app');
  }
@@ -289,15 +287,15 @@ class ScreenshotDevice extends Fake implements Device {
  @override
  Future<LaunchResult> startApp(
-    ApplicationPackage package, {
+    ApplicationPackage? package, {
-      String mainPath,
+      String? mainPath,
-      String route,
+      String? route,
-      DebuggingOptions debuggingOptions,
+      DebuggingOptions? debuggingOptions,
-      Map<String, dynamic> platformArgs,
+      Map<String, dynamic>? platformArgs,
      bool prebuiltApplication = false,
      bool usesTerminalUi = true,
      bool ipv6 = false,
-      String userIdentifier,
+      String? userIdentifier,
    }) async => LaunchResult.succeeded();
  @override
@@ -307,13 +305,13 @@ class ScreenshotDevice extends Fake implements Device {
 class FakePub extends Fake implements Pub {
  @override
  Future<void> get({
-    PubContext context,
+    PubContext? context,
-    String directory,
+    String? directory,
    bool skipIfAbsent = false,
    bool upgrade = false,
    bool offline = false,
    bool generateSyntheticPackage = false,
-    String flutterRootOverride,
+    String? flutterRootOverride,
    bool checkUpToDate = false,
    bool shouldSkipThirdPartyGenerator = true,
    bool printProgress = true,
@@ -324,13 +322,13 @@ class FakeDeviceManager extends Fake implements DeviceManager {
  List<Device> devices = <Device>[];
  @override
-  String specifiedDeviceId;
+  String? specifiedDeviceId;
  @override
  Future<List<Device>> getDevices() async => devices;
  @override
-  Future<List<Device>> findTargetDevices(FlutterProject flutterProject, {Duration timeout}) async => devices;
+  Future<List<Device>> findTargetDevices(FlutterProject? flutterProject, {Duration? timeout}) async => devices;
 }
 class FailingFakeFlutterDriverFactory extends Fake implements FlutterDriverFactory {
@@ -348,13 +346,13 @@ class FailingFakeDriverService extends Fake implements DriverService {
    List<String> arguments,
    Map<String, String> environment,
    PackageConfig packageConfig, {
-      bool headless,
+      bool? headless,
-      String chromeBinary,
+      String? chromeBinary,
-      String browserName,
+      String? browserName,
-      bool androidEmulator,
+      bool? androidEmulator,
-      int driverPort,
+      int? driverPort,
-      List<String> webBrowserFlags,
+      List<String>? webBrowserFlags,
-      List<String> browserDimension,
+      List<String>? browserDimension,
-      String profileMemory,
+      String? profileMemory,
    }) async => 1;
 }
--- a/packages/flutter_tools/test/commands.shard/hermetic/generate_localizations_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/generate_localizations_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/artifacts.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
@@ -18,10 +16,10 @@ import '../../src/fake_process_manager.dart';
 import '../../src/test_flutter_command_runner.dart';
 void main() {
-  FileSystem fileSystem;
+  late FileSystem fileSystem;
-  BufferLogger logger;
+  late BufferLogger logger;
-  Artifacts artifacts;
+  late Artifacts artifacts;
-  FakeProcessManager processManager;
+  late FakeProcessManager processManager;
  setUpAll(() {
    Cache.disableLocking();

--- a/packages/flutter_tools/test/commands.shard/hermetic/ide_config_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/ide_config_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:args/command_runner.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/cache.dart';
@@ -17,12 +15,12 @@ import '../../src/test_flutter_command_runner.dart';
 void main() {
  group('ide_config', () {
-    Directory tempDir;
+    late Directory tempDir;
-    Directory templateDir;
+    late Directory templateDir;
-    Directory intellijDir;
+    late Directory intellijDir;
-    Directory toolsDir;
+    late Directory toolsDir;
-    Map<String, String> getFilesystemContents([ Directory root ]) {
+    Map<String, String> getFilesystemContents([ Directory? root ]) {
      final String tempPath = tempDir.absolute.path;
      final List<String> paths =
        (root ?? tempDir).listSync(recursive: true).map((FileSystemEntity entity) {
@@ -67,7 +65,7 @@ void main() {
        if (manifest[key] != 'dir') {
          tempDir.childFile(key)
            ..createSync(recursive: true)
-            ..writeAsStringSync(manifest[key]);
+            ..writeAsStringSync(manifest[key]!);
        }
      }
    }
@@ -78,7 +76,7 @@ void main() {
    }
    Future<void> updateIdeConfig({
-      Directory dir,
+      Directory? dir,
      List<String> args = const <String>[],
      Map<String, String> expectedContents = const <String, String>{},
      List<String> unexpectedPaths = const <String>[],