diff --git a/packages/flutter_tools/lib/src/commands/run.dart b/packages/flutter_tools/lib/src/commands/run.dart
index 714a8b9c32..9cb22e3b01 100644
--- a/packages/flutter_tools/lib/src/commands/run.dart
+++ b/packages/flutter_tools/lib/src/commands/run.dart
@@ -512,7 +512,7 @@ class RunCommand extends RunCommandBase {
   }
 
   @visibleForTesting
-  Future<ResidentRunner?> createRunner({
+  Future<ResidentRunner> createRunner({
     required bool hotMode,
     required List<FlutterDevice> flutterDevices,
     required String? applicationBinaryPath,
@@ -669,12 +669,12 @@ class RunCommand extends RunCommandBase {
         ),
     ];
 
-    final ResidentRunner runner = await (createRunner(
+    final ResidentRunner runner = await createRunner(
       applicationBinaryPath: applicationBinaryPath,
       flutterDevices: flutterDevices,
       flutterProject: flutterProject,
       hotMode: hotMode,
-    ) as FutureOr<ResidentRunner>);
+    );
 
     DateTime? appStartedTime;
     // Sync completer so the completing agent attaching to the resident doesn't
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/install_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/install_test.dart
index 4504abd8d1..54810d8711 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/install_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/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/file.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/android/android_device.dart';
@@ -27,7 +25,7 @@ void main() {
       Cache.disableLocking();
     });
 
-    FileSystem fileSystem;
+    late FileSystem fileSystem;
     setUp(() {
       fileSystem = MemoryFileSystem.test();
       fileSystem.file('pubspec.yaml').createSync(recursive: true);
@@ -114,7 +112,7 @@ class FakeApplicationPackageFactory extends Fake implements ApplicationPackageFa
   final ApplicationPackage app;
 
   @override
-  Future<ApplicationPackage> getPackageForPlatform(TargetPlatform platform, {BuildInfo buildInfo, File applicationBinary}) async {
+  Future<ApplicationPackage> getPackageForPlatform(TargetPlatform platform, {BuildInfo? buildInfo, File? applicationBinary}) async {
     return app;
   }
 }
@@ -131,13 +129,13 @@ class FakeIOSDevice extends Fake implements IOSDevice {
   @override
   Future<bool> isAppInstalled(
     IOSApp app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async => false;
 
   @override
   Future<bool> installApp(
     IOSApp app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async => true;
 }
 
@@ -151,12 +149,12 @@ class FakeAndroidDevice extends Fake implements AndroidDevice {
   @override
   Future<bool> isAppInstalled(
     AndroidApk app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async => false;
 
   @override
   Future<bool> installApp(
     AndroidApk app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async => true;
 }
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/logs_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/logs_test.dart
index c6550bdffa..2aaa015bbd 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/logs_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/logs_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/base/common.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/logs.dart';
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
index 6db68d011d..53ffc0d30c 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/precache_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/base/logger.dart';
 import 'package:flutter_tools/src/base/platform.dart';
 import 'package:flutter_tools/src/cache.dart';
@@ -16,7 +14,7 @@ import '../../src/fakes.dart';
 import '../../src/test_flutter_command_runner.dart';
 
 void main() {
-  FakeCache cache;
+  late FakeCache cache;
 
   setUp(() {
     cache = FakeCache();
@@ -429,7 +427,7 @@ class FakeCache extends Fake implements Cache {
   bool isUpToDateValue = false;
   bool clearedStampFiles = false;
   bool locked = false;
-  Set<DevelopmentArtifact> artifacts;
+  Set<DevelopmentArtifact>? artifacts;
 
   @override
   Future<void> lock() async {
@@ -455,7 +453,7 @@ class FakeCache extends Fake implements Cache {
   }
 
   @override
-  Set<String> platformOverrideArtifacts;
+  Set<String>? platformOverrideArtifacts;
 
   @override
   bool includeAllPlatforms = false;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/proxied_devices_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/proxied_devices_test.dart
index e70fcdc5af..1cfa8ff6c4 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/proxied_devices_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/proxied_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 'package:file/memory.dart';
@@ -24,18 +22,18 @@ import '../../src/context.dart';
 import '../../src/fake_devices.dart';
 
 void main() {
-  Daemon daemon;
-  NotifyingLogger notifyingLogger;
-  BufferLogger bufferLogger;
-  FakeAndroidDevice fakeDevice;
+  Daemon? daemon;
+  late NotifyingLogger notifyingLogger;
+  late BufferLogger bufferLogger;
+  late FakeAndroidDevice fakeDevice;
 
-  FakeApplicationPackageFactory applicationPackageFactory;
-  MemoryFileSystem memoryFileSystem;
-  FakeProcessManager fakeProcessManager;
+  late FakeApplicationPackageFactory applicationPackageFactory;
+  late MemoryFileSystem memoryFileSystem;
+  late FakeProcessManager fakeProcessManager;
 
   group('ProxiedDevices', () {
-    DaemonConnection serverDaemonConnection;
-    DaemonConnection clientDaemonConnection;
+    late DaemonConnection serverDaemonConnection;
+    late DaemonConnection clientDaemonConnection;
     setUp(() {
       bufferLogger = BufferLogger.test();
       notifyingLogger = NotifyingLogger(verbose: false, parent: bufferLogger);
@@ -60,7 +58,7 @@ void main() {
 
     tearDown(() async {
       if (daemon != null) {
-        return daemon.shutdown();
+        return daemon!.shutdown();
       }
       notifyingLogger.dispose();
       await serverDaemonConnection.dispose();
@@ -74,7 +72,7 @@ void main() {
       );
       fakeDevice = FakeAndroidDevice();
       final FakePollingDeviceDiscovery discoverer = FakePollingDeviceDiscovery();
-      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
+      daemon!.deviceDomain.addDeviceDiscoverer(discoverer);
       discoverer.addDevice(fakeDevice);
 
       final ProxiedDevices proxiedDevices = ProxiedDevices(clientDaemonConnection, logger: bufferLogger);
@@ -95,7 +93,7 @@ void main() {
       );
       fakeDevice = FakeAndroidDevice();
       final FakePollingDeviceDiscovery discoverer = FakePollingDeviceDiscovery();
-      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
+      daemon!.deviceDomain.addDeviceDiscoverer(discoverer);
       discoverer.addDevice(fakeDevice);
 
       final ProxiedDevices proxiedDevices = ProxiedDevices(clientDaemonConnection, logger: bufferLogger);
@@ -115,7 +113,7 @@ void main() {
       );
       fakeDevice = FakeAndroidDevice();
       final FakePollingDeviceDiscovery discoverer = FakePollingDeviceDiscovery();
-      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
+      daemon!.deviceDomain.addDeviceDiscoverer(discoverer);
       discoverer.addDevice(fakeDevice);
 
       final ProxiedDevices proxiedDevices = ProxiedDevices(clientDaemonConnection, logger: bufferLogger);
@@ -145,7 +143,7 @@ void main() {
       );
       fakeDevice = FakeAndroidDevice();
       final FakePollingDeviceDiscovery discoverer = FakePollingDeviceDiscovery();
-      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
+      daemon!.deviceDomain.addDeviceDiscoverer(discoverer);
       discoverer.addDevice(fakeDevice);
 
       final ProxiedDevices proxiedDevices = ProxiedDevices(clientDaemonConnection, logger: bufferLogger);
@@ -173,9 +171,9 @@ void main() {
 
       expect(launchResult.started, true);
       // The returned observatoryUri was a forwarded port, so we cannot compare them directly.
-      expect(launchResult.observatoryUri.path, observatoryUri.path);
+      expect(launchResult.observatoryUri!.path, observatoryUri.path);
 
-      expect(applicationPackageFactory.applicationBinaryRequested.readAsStringSync(), 'dummy content');
+      expect(applicationPackageFactory.applicationBinaryRequested!.readAsStringSync(), 'dummy content');
       expect(applicationPackageFactory.platformRequested, TargetPlatform.android_arm);
 
       expect(fakeDevice.startAppPackage, applicationPackage);
@@ -197,7 +195,7 @@ void main() {
       );
       fakeDevice = FakeAndroidDevice();
       final FakePollingDeviceDiscovery discoverer = FakePollingDeviceDiscovery();
-      daemon.deviceDomain.addDeviceDiscoverer(discoverer);
+      daemon!.deviceDomain.addDeviceDiscoverer(discoverer);
       discoverer.addDevice(fakeDevice);
 
       final ProxiedDevices proxiedDevices = ProxiedDevices(clientDaemonConnection, logger: bufferLogger);
@@ -230,7 +228,7 @@ class FakeDaemonStreams implements DaemonStreams {
   }
 
   @override
-  void send(Map<String, dynamic> message, [ List<int> binary ]) {
+  void send(Map<String, dynamic> message, [ List<int>? binary ]) {
     outputs.add(DaemonMessage(message, binary != null ? Stream<List<int>>.value(binary) : null));
   }
 
@@ -294,48 +292,48 @@ 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;
-  LaunchResult launchResult;
+  ApplicationPackage? startAppPackage;
+  late LaunchResult launchResult;
   @override
   Future<LaunchResult> startApp(
     ApplicationPackage package, {
-    String mainPath,
-    String route,
-    DebuggingOptions debuggingOptions,
-    Map<String, Object> platformArgs = const <String, Object>{},
+    String? mainPath,
+    String? route,
+    DebuggingOptions? debuggingOptions,
+    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;
   }
 
-  List<int> screenshot;
+  late List<int> screenshot;
   @override
   Future<void> takeScreenshot(File outputFile) {
     return outputFile.writeAsBytes(screenshot);
@@ -347,10 +345,10 @@ class FakeDeviceLogReader implements DeviceLogReader {
   bool disposeCalled = false;
 
   @override
-  int appPid;
+  int? appPid;
 
   @override
-  FlutterVmService connectedVMService;
+  FlutterVmService? connectedVMService;
 
   @override
   void dispose() {
@@ -366,12 +364,12 @@ class FakeDeviceLogReader implements DeviceLogReader {
 }
 
 class FakeApplicationPackageFactory implements ApplicationPackageFactory {
-  TargetPlatform platformRequested;
-  File applicationBinaryRequested;
-  ApplicationPackage applicationPackage;
+  TargetPlatform? platformRequested;
+  File? applicationBinaryRequested;
+  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;
@@ -382,5 +380,5 @@ class FakeApplicationPackage extends Fake implements ApplicationPackage {}
 
 class FakePrebuiltApplicationPackage extends Fake implements PrebuiltApplicationPackage {
   @override
-  File applicationPackage;
+  late File applicationPackage;
 }
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart
index 4ebcb4ff40..8ad2c8787d 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/run_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:file/file.dart';
@@ -31,7 +29,6 @@ import 'package:flutter_tools/src/reporting/reporting.dart';
 import 'package:flutter_tools/src/resident_runner.dart';
 import 'package:flutter_tools/src/runner/flutter_command.dart';
 import 'package:flutter_tools/src/vmservice.dart';
-import 'package:meta/meta.dart';
 import 'package:test/fake.dart';
 import 'package:vm_service/vm_service.dart';
 
@@ -47,8 +44,8 @@ void main() {
   });
 
   group('run', () {
-    FakeDeviceManager mockDeviceManager;
-    FileSystem fileSystem;
+    late FakeDeviceManager mockDeviceManager;
+    late FileSystem fileSystem;
 
     setUp(() {
       mockDeviceManager = FakeDeviceManager();
@@ -142,10 +139,10 @@ void main() {
     });
 
     group('run app', () {
-      MemoryFileSystem fs;
-      Artifacts artifacts;
-      TestUsage usage;
-      FakeAnsiTerminal fakeTerminal;
+      late MemoryFileSystem fs;
+      late Artifacts artifacts;
+      late TestUsage usage;
+      late FakeAnsiTerminal fakeTerminal;
 
       setUpAll(() {
         Cache.disableLocking();
@@ -555,8 +552,8 @@ void main() {
     });
 
     group('Fatal Logs', () {
-      TestRunCommandWithFakeResidentRunner command;
-      MemoryFileSystem fs;
+      late TestRunCommandWithFakeResidentRunner command;
+      late MemoryFileSystem fs;
 
       setUp(() {
         command = TestRunCommandWithFakeResidentRunner()
@@ -666,7 +663,7 @@ void main() {
   });
 
   group('dart-defines and web-renderer options', () {
-    List<String> dartDefines;
+    late List<String> dartDefines;
 
     setUp(() {
       dartDefines = <String>[];
@@ -707,7 +704,7 @@ void main() {
   });
 
   group('terminal', () {
-    FakeAnsiTerminal fakeTerminal;
+    late FakeAnsiTerminal fakeTerminal;
 
     setUp(() {
       fakeTerminal = FakeAnsiTerminal();
@@ -877,7 +874,7 @@ void main() {
     expect(options.webLaunchUrl, 'http://flutter.dev');
 
     final RegExp pattern = RegExp(r'^((http)?:\/\/)[^\s]+');
-    expect(pattern.hasMatch(options.webLaunchUrl), true);
+    expect(pattern.hasMatch(options.webLaunchUrl!), true);
   }, overrides: <Type, Generator>{
     ProcessManager: () => FakeProcessManager.any(),
     Logger: () => BufferLogger.test(),
@@ -889,7 +886,7 @@ class FakeDeviceManager extends Fake implements DeviceManager {
   List<Device> targetDevices = <Device>[];
 
   @override
-  String specifiedDeviceId;
+  String? specifiedDeviceId;
 
   @override
   bool hasSpecifiedAllDevices = false;
@@ -903,7 +900,7 @@ class FakeDeviceManager extends Fake implements DeviceManager {
   }
 
   @override
-  Future<List<Device>> findTargetDevices(FlutterProject flutterProject, {Duration timeout}) async {
+  Future<List<Device>> findTargetDevices(FlutterProject? flutterProject, {Duration? timeout}) async {
     return targetDevices;
   }
 
@@ -950,7 +947,7 @@ class FakeDevice extends Fake implements Device {
   @override
   String get id => 'fake_device';
 
-  void _throwToolExit(int code) => throwToolExit('FakeDevice tool exit', exitCode: code);
+  Never _throwToolExit(int code) => throwToolExit('FakeDevice tool exit', exitCode: code);
 
   @override
   Future<bool> get isLocalEmulator => Future<bool>.value(_isLocalEmulator);
@@ -987,7 +984,7 @@ class FakeDevice extends Fake implements Device {
 
   @override
   DeviceLogReader getLogReader({
-    ApplicationPackage app,
+    ApplicationPackage? app,
     bool includePastLogs = false,
   }) {
     return FakeDeviceLogReader();
@@ -1002,27 +999,27 @@ class FakeDevice extends Fake implements Device {
   @override
   PlatformType get platformType => _platformType;
 
-  bool startAppSuccess;
+  late bool startAppSuccess;
 
   @override
-  DevFSWriter createDevFSWriter(
-    covariant ApplicationPackage app,
-    String userIdentifier,
+  DevFSWriter? createDevFSWriter(
+    covariant ApplicationPackage? app,
+    String? userIdentifier,
   ) {
     return null;
   }
 
   @override
   Future<LaunchResult> startApp(
-    ApplicationPackage package, {
-    String mainPath,
-    String route,
-    DebuggingOptions debuggingOptions,
-    Map<String, dynamic> platformArgs,
+    ApplicationPackage? package, {
+    String? mainPath,
+    String? route,
+    required DebuggingOptions debuggingOptions,
+    Map<String, Object?> platformArgs = const <String, Object?>{},
     bool prebuiltApplication = false,
     bool usesTerminalUi = true,
     bool ipv6 = false,
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     if (startAppSuccess == false) {
       return LaunchResult.failed();
@@ -1045,19 +1042,18 @@ class FakeDevice extends Fake implements Device {
       }
       _throwToolExit(kSuccess);
     }
-    return null;
   }
 }
 
 class TestRunCommandWithFakeResidentRunner extends RunCommand {
-  FakeResidentRunner fakeResidentRunner;
+  late FakeResidentRunner fakeResidentRunner;
 
   @override
   Future<ResidentRunner> createRunner({
-    @required bool hotMode,
-    @required List<FlutterDevice> flutterDevices,
-    @required String applicationBinaryPath,
-    @required FlutterProject flutterProject,
+    required bool hotMode,
+    required List<FlutterDevice> flutterDevices,
+    required String? applicationBinaryPath,
+    required FlutterProject flutterProject,
   }) async {
     return fakeResidentRunner;
   }
@@ -1077,26 +1073,26 @@ class TestRunCommandThatOnlyValidates extends RunCommand {
 }
 
 class FakeResidentRunner extends Fake implements ResidentRunner {
-  RPCError rpcError;
+  RPCError? rpcError;
 
   @override
   Future<int> run({
-    Completer<DebugConnectionInfo> connectionInfoCompleter,
-    Completer<void> appStartedCompleter,
+    Completer<DebugConnectionInfo>? connectionInfoCompleter,
+    Completer<void>? appStartedCompleter,
     bool enableDevTools = false,
-    String route,
+    String? route,
   }) async {
     await null;
     if (rpcError != null) {
-      throw rpcError;
+      throw rpcError!;
     }
     return 0;
   }
 }
 
 class DaemonCapturingRunCommand extends RunCommand {
-  /*late*/ Daemon daemon;
-  /*late*/ CapturingAppDomain appDomain;
+  late Daemon daemon;
+  late CapturingAppDomain appDomain;
 
   @override
   Daemon createMachineDaemon() {
@@ -1108,29 +1104,29 @@ class DaemonCapturingRunCommand extends RunCommand {
 }
 
 class CapturingAppDomain extends AppDomain {
-  CapturingAppDomain(Daemon daemon) : super(daemon);
+  CapturingAppDomain(super.daemon);
 
-  bool /*?*/ multidexEnabled;
-  String /*?*/ userIdentifier;
+  bool? multidexEnabled;
+  String? userIdentifier;
 
   @override
   Future<AppInstance> startApp(
     Device device,
     String projectDirectory,
     String target,
-    String route,
+    String? route,
     DebuggingOptions options,
     bool enableHotReload, {
-    File applicationBinary,
-    @required bool trackWidgetCreation,
-    String projectRootPath,
-    String packagesFilePath,
-    String dillOutputPath,
+    File? applicationBinary,
+    required bool trackWidgetCreation,
+    String? projectRootPath,
+    String? packagesFilePath,
+    String? dillOutputPath,
     bool ipv6 = false,
     bool multidexEnabled = false,
-    String isolateFilter,
+    String? isolateFilter,
     bool machine = true,
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     this.multidexEnabled = multidexEnabled;
     this.userIdentifier = userIdentifier;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/screenshot_command_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/screenshot_command_test.dart
index 2e075d4c97..8c005b69de 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/screenshot_command_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/screenshot_command_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/base/io.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/cache.dart';
@@ -23,7 +21,7 @@ void main() {
     testUsingContext('rasterizer and skia screenshots do not require a device', () async {
       // Throw a specific exception when attempting to make a VM Service connection to
       // verify that we've made it past the initial validation.
-      openChannelForTesting = (String url, {CompressionOptions compression, Logger logger}) async {
+      openChannelForTesting = (String url, {CompressionOptions? compression, Logger? logger}) async {
         expect(url, 'ws://localhost:8181/ws');
         throw Exception('dummy');
       };
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_test.dart
index 97bfd1c32a..5e632024bf 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_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/base/common.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
@@ -18,7 +16,7 @@ import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('shell_completion', () {
-    FakeStdio fakeStdio;
+    late FakeStdio fakeStdio;
 
     setUp(() {
       Cache.disableLocking();
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/symbolize_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/symbolize_test.dart
index bd601705c2..fb5d1810db 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/symbolize_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/symbolize_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';
 
@@ -15,7 +13,6 @@ import 'package:flutter_tools/src/base/terminal.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/symbolize.dart';
 import 'package:flutter_tools/src/convert.dart';
-import 'package:meta/meta.dart';
 import 'package:test/fake.dart';
 
 import '../../src/common.dart';
@@ -24,8 +21,8 @@ import '../../src/fakes.dart';
 import '../../src/test_flutter_command_runner.dart';
 
 void main() {
-  MemoryFileSystem fileSystem;
-  FakeStdio stdio;
+  late MemoryFileSystem fileSystem;
+  late FakeStdio stdio;
 
   setUpAll(() {
     Cache.disableLocking();
@@ -154,9 +151,9 @@ void main() {
 class ThrowingDwarfSymbolizationService extends Fake implements DwarfSymbolizationService {
   @override
   Future<void> decode({
-    @required Stream<List<int>> input,
-    @required IOSink output,
-    @required Uint8List symbols,
+    required Stream<List<int>> input,
+    required IOSink output,
+    required Uint8List symbols,
   }) async {
     throwToolExit('test');
   }
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart
index ecf81933ee..8fa700837a 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/test_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';
 
@@ -12,7 +10,8 @@ import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/logger.dart';
-import 'package:flutter_tools/src/build_info.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/test.dart';
 import 'package:flutter_tools/src/device.dart';
@@ -22,7 +21,6 @@ import 'package:flutter_tools/src/test/runner.dart';
 import 'package:flutter_tools/src/test/test_time_recorder.dart';
 import 'package:flutter_tools/src/test/test_wrapper.dart';
 import 'package:flutter_tools/src/test/watcher.dart';
-import 'package:meta/meta.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
@@ -59,8 +57,8 @@ final String _packageConfigContents = json.encode(<String, Object>{
 
 void main() {
   Cache.disableLocking();
-  MemoryFileSystem fs;
-  LoggingLogger logger;
+  late MemoryFileSystem fs;
+  late LoggingLogger logger;
 
   setUp(() {
     fs = MemoryFileSystem.test();
@@ -790,51 +788,47 @@ class FakeFlutterTestRunner implements FlutterTestRunner {
   FakeFlutterTestRunner(this.exitCode, [this.leastRunTime]);
 
   int exitCode;
-  Duration leastRunTime;
-  bool lastEnableObservatoryValue;
-  DebuggingOptions lastDebuggingOptionsValue;
+  Duration? leastRunTime;
+  bool? lastEnableObservatoryValue;
+  late DebuggingOptions lastDebuggingOptionsValue;
 
   @override
   Future<int> runTests(
     TestWrapper testWrapper,
     List<String> testFiles, {
-    @required DebuggingOptions debuggingOptions,
-    Directory workDir,
+    required DebuggingOptions debuggingOptions,
     List<String> names = const <String>[],
     List<String> plainNames = const <String>[],
-    String tags,
-    String excludeTags,
+    String? tags,
+    String? excludeTags,
     bool enableObservatory = false,
     bool ipv6 = false,
     bool machine = false,
-    String precompiledDillPath,
-    Map<String, String> precompiledDillFiles,
-    BuildMode buildMode,
-    bool trackWidgetCreation = false,
+    String? precompiledDillPath,
+    Map<String, String>? precompiledDillFiles,
     bool updateGoldens = false,
-    TestWatcher watcher,
-    int concurrency,
-    String testAssetDirectory,
-    FlutterProject flutterProject,
-    String icudtlPath,
-    Directory coverageDirectory,
+    TestWatcher? watcher,
+    required int? concurrency,
+    String? testAssetDirectory,
+    FlutterProject? flutterProject,
+    String? icudtlPath,
+    Directory? coverageDirectory,
     bool web = false,
-    String randomSeed,
-    @override List<String> extraFrontEndOptions,
-    String reporter,
-    String timeout,
+    String? randomSeed,
+    String? reporter,
+    String? timeout,
     bool runSkipped = false,
-    int shardIndex,
-    int totalShards,
-    Device integrationTestDevice,
-    String integrationTestUserIdentifier,
-    TestTimeRecorder testTimeRecorder,
+    int? shardIndex,
+    int? totalShards,
+    Device? integrationTestDevice,
+    String? integrationTestUserIdentifier,
+    TestTimeRecorder? testTimeRecorder,
   }) async {
     lastEnableObservatoryValue = enableObservatory;
     lastDebuggingOptionsValue = debuggingOptions;
 
     if (leastRunTime != null) {
-      await Future<void>.delayed(leastRunTime);
+      await Future<void>.delayed(leastRunTime!);
     }
 
     return exitCode;
@@ -842,7 +836,7 @@ class FakeFlutterTestRunner implements FlutterTestRunner {
 }
 
 class FakePackageTest implements TestWrapper {
-  List<String> lastArgs;
+  List<String>? lastArgs;
 
   @override
   Future<void> main(List<String> args) async {
@@ -857,7 +851,7 @@ class FakePackageTest implements TestWrapper {
 }
 
 class _FakeDeviceManager extends DeviceManager {
-  _FakeDeviceManager(this._connectedDevices);
+  _FakeDeviceManager(this._connectedDevices) : super(logger: testLogger, terminal: Terminal.test(), userMessages: userMessages);
 
   final List<Device> _connectedDevices;
 
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/upgrade_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/upgrade_test.dart
index 5e31c7ec3d..1bfdb01ea8 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/upgrade_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/upgrade_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:args/command_runner.dart';
@@ -20,12 +18,12 @@ import '../../src/fakes.dart' show FakeFlutterVersion;
 import '../../src/test_flutter_command_runner.dart';
 
 void main() {
-  FileSystem fileSystem;
-  BufferLogger logger;
-  FakeProcessManager processManager;
+  late FileSystem fileSystem;
+  late BufferLogger logger;
+  late FakeProcessManager processManager;
   UpgradeCommand command;
-  CommandRunner<void> runner;
-  FlutterVersion flutterVersion;
+  late CommandRunner<void> runner;
+  late FlutterVersion flutterVersion;
 
   setUpAll(() {
     Cache.disableLocking();