Null safety migration of packages/flutter_tools/test/general.shard, part 2/2 (#110712)

* Migrate packages/flutter_tools/test/general.shard, part 2/2

* Fix analysis

* Fix tests

* Fix analysis

* Apply suggestions from code review
Co-authored-by: Christopher Fujino <fujino@google.com>
Co-authored-by: Christopher Fujino <fujino@google.com>

packages/flutter_tools/lib/src/resident_runner.dart

@@ -707,7 +707,7 @@ abstract class ResidentHandlers {
       }
       final List<FlutterView> views = await device!.vmService!.getFlutterViews();
       for (final FlutterView view in views) {
-        final Map<String, Object>? rasterData =
+        final Map<String, Object?>? rasterData =
           await device.vmService!.renderFrameWithRasterStats(
             viewId: view.id,
             uiIsolateId: view.uiIsolate!.id,

packages/flutter_tools/lib/src/vmservice.dart

@@ -557,7 +557,7 @@ class FlutterVmService {
   /// for rasterization which is not reflective of how long the frame takes in
   /// production. This is primarily intended to be used to identify the layers
   /// that result in the most raster perf degradation.
-  Future<Map<String, Object>?> renderFrameWithRasterStats({
+  Future<Map<String, Object?>?> renderFrameWithRasterStats({
     required String? viewId,
     required String? uiIsolateId,
   }) async {
@@ -568,7 +568,7 @@ class FlutterVmService {
         'viewId': viewId,
       },
     );
-    return response?.json as Map<String, Object>?;
+    return response?.json;
   }
 
   Future<String> flutterDebugDumpApp({

packages/flutter_tools/test/general.shard/args_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/args.dart';
 import 'package:args/command_runner.dart';
 import 'package:flutter_tools/executable.dart' as executable;
@@ -111,7 +109,7 @@ void main() {
   });
 }
 
-void verifyCommandRunner(CommandRunner<Object> runner) {
+void verifyCommandRunner(CommandRunner<Object?> runner) {
   expect(runner.argParser, isNotNull, reason: '${runner.runtimeType} has no argParser');
   expect(runner.argParser.allowsAnything, isFalse, reason: '${runner.runtimeType} allows anything');
   expect(runner.argParser.allowTrailingOptions, isFalse, reason: '${runner.runtimeType} allows trailing options');
@@ -119,7 +117,7 @@ void verifyCommandRunner(CommandRunner<Object> runner) {
   runner.commands.values.forEach(verifyCommand);
 }
 
-void verifyCommand(Command<Object> runner) {
+void verifyCommand(Command<Object?> runner) {
   expect(runner.argParser, isNotNull, reason: 'command ${runner.name} has no argParser');
   verifyOptions(runner.name, runner.argParser.options.values);
 
@@ -161,7 +159,7 @@ const String _needHelp = "Every option must have help explaining what it does, e
 
 const String _header = ' Comment: ';
 
-void verifyOptions(String command, Iterable<Option> options) {
+void verifyOptions(String? command, Iterable<Option> options) {
   String target;
   if (command == null) {
     target = 'the global argument "';
@@ -191,10 +189,11 @@ void verifyOptions(String command, Iterable<Option> options) {
     if (option.defaultsTo != null) {
       expect(option.help, isNot(contains('Default')), reason: '${_header}Help for $target--${option.name}" mentions the default value but that is redundant with the defaultsTo option which is also specified (and preferred).');
 
-      if (option.allowedHelp != null) {
-        for (final String allowedValue in option.allowedHelp.keys) {
+      final Map<String, String>? allowedHelp = option.allowedHelp;
+      if (allowedHelp != null) {
+        for (final String allowedValue in allowedHelp.keys) {
           expect(
-            option.allowedHelp[allowedValue],
+            allowedHelp[allowedValue],
             isNot(anyOf(contains('default'), contains('Default'))),
             reason: '${_header}Help for $target--${option.name} $allowedValue" mentions the default value but that is redundant with the defaultsTo option which is also specified (and preferred).',
           );
@@ -202,7 +201,7 @@ void verifyOptions(String command, Iterable<Option> options) {
       }
     }
     expect(option.help, isNot(matches(_bannedArgumentReferencePatterns)), reason: '${_header}Help for $target--${option.name}" contains the string "--" in an unexpected way. If it\'s trying to mention another argument, it should be quoted, as in "--foo".');
-    for (final String line in option.help.split('\n')) {
+    for (final String line in option.help!.split('\n')) {
       if (!line.startsWith('    ')) {
         expect(line, isNot(contains('  ')), reason: '${_header}Help for $target--${option.name}" has excessive whitespace (check e.g. for double spaces after periods or round line breaks in the source).');
         expect(line, matches(_allowedTrailingPatterns), reason: '${_header}A line in the help for $target--${option.name}" does not end with the expected period that a full sentence should end with. (If the help ends with a URL, place it after a colon, don\'t leave a trailing period; if it\'s sample code, prefix the line with four spaces.)');

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

@@ -2,7 +2,7 @@
 // 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';
@@ -45,10 +45,10 @@ const FakeCommand kListEmulatorsCommand = FakeCommand(
 );
 
 void main() {
-  FakeProcessManager fakeProcessManager;
-  FakeAndroidSdk sdk;
-  FileSystem fileSystem;
-  Xcode xcode;
+  late FakeProcessManager fakeProcessManager;
+  late FakeAndroidSdk sdk;
+  late FileSystem fileSystem;
+  late Xcode xcode;
 
   setUp(() {
     fileSystem = MemoryFileSystem.test();
@@ -110,7 +110,16 @@ void main() {
     });
 
     testWithoutContext('getEmulatorsById', () async {
-      final TestEmulatorManager testEmulatorManager = TestEmulatorManager(emulators);
+      final TestEmulatorManager testEmulatorManager = TestEmulatorManager(emulators,
+        logger: BufferLogger.test(),
+        processManager: fakeProcessManager,
+        androidWorkflow: AndroidWorkflow(
+          androidSdk: sdk,
+          featureFlags: TestFeatureFlags(),
+          operatingSystemUtils: FakeOperatingSystemUtils(),
+        ),
+        fileSystem: fileSystem,
+      );
 
       expect(await testEmulatorManager.getEmulatorsMatching('Nexus_5'), <Emulator>[emulator1]);
       expect(await testEmulatorManager.getEmulatorsMatching('Nexus_5X'), <Emulator>[emulator2]);
@@ -340,7 +349,12 @@ void main() {
 }
 
 class TestEmulatorManager extends EmulatorManager {
-  TestEmulatorManager(this.allEmulators);
+  TestEmulatorManager(this.allEmulators, {
+    required super.logger,
+    required super.processManager,
+    required super.androidWorkflow,
+    required super.fileSystem,
+  });
 
   final List<Emulator> allEmulators;
 
@@ -374,16 +388,16 @@ class FakeEmulator extends Emulator {
 
 class FakeAndroidSdk extends Fake implements AndroidSdk {
   @override
-  String avdManagerPath;
+  String? avdManagerPath;
 
   @override
-  String emulatorPath;
+  String? emulatorPath;
 
   @override
-  String adbPath;
+  String? adbPath;
 
   @override
-  String getAvdManagerPath() => avdManagerPath;
+  String? getAvdManagerPath() => avdManagerPath;
 
   @override
   String getAvdPath() => 'avd';

packages/flutter_tools/test/general.shard/resident_web_runner_cold_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';
@@ -28,9 +26,9 @@ import '../src/context.dart';
 import '../src/test_build_system.dart';
 
 void main() {
-  FakeFlutterDevice mockFlutterDevice;
-  FakeWebDevFS mockWebDevFS;
-  FileSystem fileSystem;
+  late FakeFlutterDevice mockFlutterDevice;
+  late FakeWebDevFS mockWebDevFS;
+  late FileSystem fileSystem;
 
   setUp(() {
     fileSystem = MemoryFileSystem.test();
@@ -191,22 +189,22 @@ class FakeWebDevice extends Fake implements Device {
 
   @override
   Future<bool> stopApp(
-    covariant ApplicationPackage app, {
-    String userIdentifier,
+    covariant ApplicationPackage? app, {
+    String? userIdentifier,
   }) async {
     return true;
   }
 
   @override
   Future<LaunchResult> startApp(
-    covariant ApplicationPackage package, {
-    String mainPath,
-    String route,
-    DebuggingOptions debuggingOptions,
-    Map<String, dynamic> platformArgs,
+    covariant ApplicationPackage? package, {
+    String? mainPath,
+    String? route,
+    DebuggingOptions? debuggingOptions,
+    Map<String, dynamic>? platformArgs,
     bool prebuiltApplication = false,
     bool ipv6 = false,
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     return LaunchResult.succeeded();
   }
@@ -219,14 +217,14 @@ class FakeFlutterDevice extends Fake implements FlutterDevice {
   final FakeWebDevice device;
 
 
-  DevFS _devFS;
+  DevFS? _devFS;
 
   @override
-  DevFS get devFS => _devFS;
+  DevFS? get devFS => _devFS;
 
   @override
-  set devFS(DevFS value) { }
+  set devFS(DevFS? value) { }
 
   @override
-  FlutterVmService vmService;
+  FlutterVmService? vmService;
 }

packages/flutter_tools/test/general.shard/vmservice_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:fake_async/fake_async.dart';
@@ -62,7 +60,7 @@ final FakeVmServiceRequest listViewsRequest = FakeVmServiceRequest(
 
 void main() {
   testWithoutContext('VmService registers reloadSources', () async {
-    Future<void> reloadSources(String isolateId, { bool pause, bool force}) async {}
+    Future<void> reloadSources(String isolateId, { bool? pause, bool? force}) async {}
 
     final MockVMService mockVMService = MockVMService();
     await setUpVmService(
@@ -217,7 +215,7 @@ void main() {
       windows: false,
     ));
 
-    final Map<String, Object> rawRequest = json.decode(await completer.future) as Map<String, Object>;
+    final Map<String, Object?>? rawRequest = json.decode(await completer.future) as Map<String, Object?>?;
 
     expect(rawRequest, allOf(<Matcher>[
       containsPair('method', kSetAssetBundlePathMethod),
@@ -245,7 +243,7 @@ void main() {
       windows: true,
     ));
 
-    final Map<String, Object> rawRequest = json.decode(await completer.future) as Map<String, Object>;
+    final Map<String, Object?>? rawRequest = json.decode(await completer.future) as Map<String, Object?>?;
 
     expect(rawRequest, allOf(<Matcher>[
       containsPair('method', kSetAssetBundlePathMethod),
@@ -269,7 +267,7 @@ void main() {
       viewId: 'abc',
     ));
 
-    final Map<String, Object> rawRequest = json.decode(await completer.future) as Map<String, Object>;
+    final Map<String, Object?>? rawRequest = json.decode(await completer.future) as Map<String, Object?>?;
 
     expect(rawRequest, allOf(<Matcher>[
       containsPair('method', kGetSkSLsMethod),
@@ -291,7 +289,7 @@ void main() {
       uiIsolateId: 'def',
     ));
 
-    final Map<String, Object> rawRequest = json.decode(await completer.future) as Map<String, Object>;
+    final Map<String, Object?>? rawRequest = json.decode(await completer.future) as Map<String, Object?>?;
 
     expect(rawRequest, allOf(<Matcher>[
       containsPair('method', kFlushUIThreadTasksMethod),
@@ -469,7 +467,7 @@ void main() {
       ]
     );
 
-    final Map<String, Object> skSLs = await fakeVmServiceHost.vmService.getSkSLs(
+    final Map<String, Object?>? skSLs = await fakeVmServiceHost.vmService.getSkSLs(
       viewId: '1234',
     );
     expect(skSLs, isNull);
@@ -477,19 +475,19 @@ void main() {
     final List<FlutterView> views = await fakeVmServiceHost.vmService.getFlutterViews();
     expect(views, isEmpty);
 
-    final vm_service.Response screenshot = await fakeVmServiceHost.vmService.screenshot();
+    final vm_service.Response? screenshot = await fakeVmServiceHost.vmService.screenshot();
     expect(screenshot, isNull);
 
-    final vm_service.Response screenshotSkp = await fakeVmServiceHost.vmService.screenshotSkp();
+    final vm_service.Response? screenshotSkp = await fakeVmServiceHost.vmService.screenshotSkp();
     expect(screenshotSkp, isNull);
 
     // Checking that this doesn't throw.
     await fakeVmServiceHost.vmService.setTimelineFlags(<String>['test']);
 
-    final vm_service.Response timeline = await fakeVmServiceHost.vmService.getTimeline();
+    final vm_service.Response? timeline = await fakeVmServiceHost.vmService.getTimeline();
     expect(timeline, isNull);
 
-    final Map<String, Object> rasterStats =
+    final Map<String, Object?>? rasterStats =
       await fakeVmServiceHost.vmService.renderFrameWithRasterStats(viewId: '1', uiIsolateId: '12');
     expect(rasterStats, isNull);
 
@@ -505,7 +503,7 @@ void main() {
       ]
     );
 
-    final vm_service.Isolate isolate = await fakeVmServiceHost.vmService.getIsolateOrNull(
+    final vm_service.Isolate? isolate = await fakeVmServiceHost.vmService.getIsolateOrNull(
       'isolate/123',
     );
     expect(isolate, null);
@@ -535,7 +533,7 @@ void main() {
       ]
     );
 
-    final Map<String, Object> rasterStats =
+    final Map<String, Object?>? rasterStats =
       await fakeVmServiceHost.vmService.renderFrameWithRasterStats(viewId: 'view/1', uiIsolateId: 'isolate/123');
     expect(rasterStats, equals(response));
 
@@ -629,7 +627,7 @@ void main() {
         isolate.toJson()
           ..['id'] = '2'
           ..['extensionRPCs'] = <String>[otherExtensionName],
-      );
+      )!;
 
       final FlutterView fakeFlutterView2 = FlutterView(
         id: '2',
@@ -680,7 +678,7 @@ void main() {
 
     testWithoutContext('does not rethrow a sentinel exception if the initially queried flutter view disappears', () async {
       const String otherExtensionName = 'ext.flutter.test.otherExtension';
-      final vm_service.Isolate isolate2 = vm_service.Isolate.parse(
+      final vm_service.Isolate? isolate2 = vm_service.Isolate.parse(
         isolate.toJson()
           ..['id'] = '2'
           ..['extensionRPCs'] = <String>[otherExtensionName],
@@ -836,7 +834,7 @@ void main() {
 
   testUsingContext('WebSocket URL construction uses correct URI join primitives', () async {
     final Completer<String> completer = Completer<String>();
-    openChannelForTesting = (String url, {io.CompressionOptions compression, Logger logger}) async {
+    openChannelForTesting = (String url, {io.CompressionOptions compression = io.CompressionOptions.compressionDefault, required Logger logger}) async {
       completer.complete(url);
       throw Exception('');
     };
@@ -883,8 +881,8 @@ class FakeDevice extends Fake implements Device { }
 /// A [WebSocketConnector] that always throws an [io.SocketException].
 Future<io.WebSocket> failingWebSocketConnector(
   String url, {
-  io.CompressionOptions compression,
-  Logger logger,
+  io.CompressionOptions? compression,
+  Logger? logger,
 }) {
   throw const io.SocketException('Failed WebSocket connection');
 }

packages/flutter_tools/test/general.shard/web/devfs_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 'dart:async';
 import 'dart:io' hide Directory, File;
 
@@ -23,7 +21,6 @@ import 'package:flutter_tools/src/globals.dart' as globals;
 import 'package:flutter_tools/src/isolated/devfs_web.dart';
 import 'package:flutter_tools/src/web/compile.dart';
 import 'package:logging/logging.dart' as logging;
-import 'package:meta/meta.dart';
 import 'package:package_config/package_config.dart';
 import 'package:shelf/shelf.dart';
 import 'package:test/fake.dart';
@@ -41,14 +38,14 @@ const List<int> kTransparentImage = <int>[
 ];
 
 void main() {
-  Testbed testbed;
-  WebAssetServer webAssetServer;
-  ReleaseAssetServer releaseAssetServer;
-  Platform linux;
-  PackageConfig packages;
-  Platform windows;
-  FakeHttpServer httpServer;
-  BufferLogger logger;
+  late Testbed testbed;
+  late WebAssetServer webAssetServer;
+  late ReleaseAssetServer releaseAssetServer;
+  late Platform linux;
+  late PackageConfig packages;
+  late Platform windows;
+  late FakeHttpServer httpServer;
+  late BufferLogger logger;
 
   setUpAll(() async {
     packages = PackageConfig(<Package>[
@@ -66,15 +63,15 @@ void main() {
         httpServer,
         packages,
         InternetAddress.loopbackIPv4,
-        null,
-        null,
-        null,
+        <String, String>{},
+        <String, String>{},
+        NullSafetyMode.unsound,
       );
       releaseAssetServer = ReleaseAssetServer(
         globals.fs.file('main.dart').uri,
-        fileSystem: null, // ignore: avoid_redundant_argument_values
+        fileSystem: globals.fs,
         flutterRoot: null, // ignore: avoid_redundant_argument_values
-        platform: null, // ignore: avoid_redundant_argument_values
+        platform: FakePlatform(),
         webBuildDirectory: null, // ignore: avoid_redundant_argument_values
         basePath: null,
       );
@@ -183,10 +180,10 @@ void main() {
       }));
     webAssetServer.write(source, manifest, sourcemap, metadata);
 
-    final String merged = await webAssetServer.metadataContents('main_module.ddc_merged_metadata');
+    final String? merged = await webAssetServer.metadataContents('main_module.ddc_merged_metadata');
     expect(merged, equals(metadataContents));
 
-    final String single = await webAssetServer.metadataContents('foo.js.metadata');
+    final String? single = await webAssetServer.metadataContents('foo.js.metadata');
     expect(single, equals(metadataContents));
   }, overrides: <Type, Generator>{
     Platform: () => linux,
@@ -292,9 +289,9 @@ void main() {
       httpServer,
       packages,
       InternetAddress.loopbackIPv4,
-      null,
-      null,
-      null,
+      <String, String>{},
+      <String, String>{},
+      NullSafetyMode.unsound,
     );
 
     expect(webAssetServer.basePath, 'foo/bar');
@@ -311,9 +308,9 @@ void main() {
       httpServer,
       packages,
       InternetAddress.loopbackIPv4,
-      null,
-      null,
-      null,
+      <String, String>{},
+      <String, String>{},
+      NullSafetyMode.unsound,
     );
 
     // Defaults to "/" when there's no base element.
@@ -332,9 +329,9 @@ void main() {
         httpServer,
         packages,
         InternetAddress.loopbackIPv4,
-        null,
-        null,
-        null,
+        <String, String>{},
+        <String, String>{},
+        NullSafetyMode.unsound,
       ),
       throwsToolExit(),
     );
@@ -352,9 +349,9 @@ void main() {
         httpServer,
         packages,
         InternetAddress.loopbackIPv4,
-        null,
-        null,
-        null,
+        <String, String>{},
+        <String, String>{},
+        NullSafetyMode.unsound,
       ),
       throwsToolExit(),
     );
@@ -380,7 +377,7 @@ void main() {
 
     final Response response = await webAssetServer
       .handleRequest(Request('GET', Uri.parse('http://foobar/foo.js')));
-    final String etag = response.headers[HttpHeaders.etagHeader];
+    final String etag = response.headers[HttpHeaders.etagHeader]!;
 
     final Response cachedResponse = await webAssetServer
       .handleRequest(Request('GET', Uri.parse('http://foobar/foo.js'), headers: <String, String>{
@@ -622,14 +619,14 @@ void main() {
 
     final Response response = await webAssetServer
       .handleRequest(Request('GET', Uri.parse('http://foobar/assets/fooπ')));
-    final String etag = response.headers[HttpHeaders.etagHeader];
+    final String etag = response.headers[HttpHeaders.etagHeader]!;
 
     expect(etag.runes, everyElement(predicate((int char) => char < 255)));
   }));
 
   test('serves /packages/<package>/<path> files as if they were '
        'package:<package>/<path> uris', () => testbed.run(() async {
-    final Uri expectedUri = packages.resolve(
+    final Uri? expectedUri = packages.resolve(
         Uri.parse('package:flutter_tools/foo.dart'));
     final File source = globals.fs.file(globals.fs.path.fromUri(expectedUri))
       ..createSync(recursive: true)
@@ -691,13 +688,13 @@ void main() {
 
     final Uri uri = await webDevFS.create();
     webDevFS.webAssetServer.entrypointCacheDirectory = globals.fs.currentDirectory;
-    final String webPrecompiledSdk = globals.artifacts
+    final String webPrecompiledSdk = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledSdk).path;
-    final String webPrecompiledSdkSourcemaps = globals.artifacts
+    final String webPrecompiledSdkSourcemaps = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledSdkSourcemaps).path;
-    final String webPrecompiledCanvaskitSdk = globals.artifacts
+    final String webPrecompiledCanvaskitSdk = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledCanvaskitSdk).path;
-    final String webPrecompiledCanvaskitSdkSourcemaps = globals.artifacts
+    final String webPrecompiledCanvaskitSdkSourcemaps = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledCanvaskitSdkSourcemaps).path;
     globals.fs.currentDirectory
       .childDirectory('lib')
@@ -808,13 +805,13 @@ void main() {
       .childFile('web_entrypoint.dart')
       ..createSync(recursive: true)
       ..writeAsStringSync('GENERATED');
-    final String webPrecompiledSdk = globals.artifacts
+    final String webPrecompiledSdk = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledSoundSdk).path;
-    final String webPrecompiledSdkSourcemaps = globals.artifacts
+    final String webPrecompiledSdkSourcemaps = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledSoundSdkSourcemaps).path;
-    final String webPrecompiledCanvaskitSdk = globals.artifacts
+    final String webPrecompiledCanvaskitSdk = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledCanvaskitSoundSdk).path;
-    final String webPrecompiledCanvaskitSdkSourcemaps = globals.artifacts
+    final String webPrecompiledCanvaskitSdkSourcemaps = globals.artifacts!
       .getHostArtifact(HostArtifact.webPrecompiledCanvaskitSoundSdkSourcemaps).path;
     globals.fs.file(webPrecompiledSdk)
       ..createSync(recursive: true)
@@ -917,7 +914,7 @@ void main() {
         webDevFS.webAssetServer.dwds = FakeDwds(<AppConnection>[firstConnection, secondConnection]);
 
         int vmServiceFactoryInvocationCount = 0;
-        Future<vm_service.VmService> vmServiceFactory(Uri uri, {CompressionOptions compression, @required Logger logger}) {
+        Future<vm_service.VmService> vmServiceFactory(Uri uri, {CompressionOptions? compression, required Logger logger}) {
           if (vmServiceFactoryInvocationCount > 0) {
             fail('Called vmServiceFactory twice!');
           }
@@ -927,7 +924,7 @@ void main() {
             () => FakeVmService(),
           );
         }
-        return webDevFS.connect(false, vmServiceFactory: vmServiceFactory).then<void>((ConnectionResult firstConnectionResult) {
+        return webDevFS.connect(false, vmServiceFactory: vmServiceFactory).then<void>((ConnectionResult? firstConnectionResult) {
           return webDevFS.destroy();
         });
       });
@@ -1078,7 +1075,7 @@ void main() {
       false,
       Uri.base,
       null,
-      null,
+      NullSafetyMode.unsound,
       testMode: true);
 
     expect(webAssetServer.defaultResponseHeaders['x-frame-options'], null);
@@ -1179,20 +1176,20 @@ class FakeHttpServer extends Fake implements HttpServer {
 }
 
 class FakeResidentCompiler extends Fake implements ResidentCompiler {
-  CompilerOutput output;
+  CompilerOutput? output;
 
   @override
   void addFileSystemRoot(String root) { }
 
   @override
-  Future<CompilerOutput> recompile(Uri mainUri, List<Uri> invalidatedFiles, {
-    String outputPath,
-    PackageConfig packageConfig,
-    String projectRootPath,
-    FileSystem fs,
+  Future<CompilerOutput?> recompile(Uri mainUri, List<Uri>? invalidatedFiles, {
+    String? outputPath,
+    PackageConfig? packageConfig,
+    String? projectRootPath,
+    FileSystem? fs,
     bool suppressErrors = false,
     bool checkDartPluginRegistry = false,
-    File dartPluginRegistrant,
+    File? dartPluginRegistrant,
   }) async {
     return output;
   }
@@ -1202,7 +1199,7 @@ class FakeShaderCompiler implements DevelopmentShaderCompiler {
   const FakeShaderCompiler();
 
   @override
-  void configureCompiler(TargetPlatform platform, { @required bool enableImpeller }) { }
+  void configureCompiler(TargetPlatform? platform, { required bool enableImpeller }) { }
 
   @override
   Future<DevFSContent> recompileShader(DevFSContent inputShader) {

packages/flutter_tools/test/general.shard/web/golden_comparator_process_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:convert';
 
 import 'package:flutter_tools/src/base/file_system.dart';
@@ -16,11 +14,11 @@ import '../../src/fakes.dart';
 
 void main() {
   group('Test that TestGoldenComparatorProcess', () {
-    File imageFile;
-    Uri goldenKey;
-    File imageFile2;
-    Uri goldenKey2;
-    FakeProcess Function(String) createFakeProcess;
+    late File imageFile;
+    late Uri goldenKey;
+    late File imageFile2;
+    late Uri goldenKey2;
+    late FakeProcess Function(String) createFakeProcess;
 
     setUpAll(() {
       imageFile = globals.fs.file('test_image_file');

packages/flutter_tools/test/general.shard/web/migrations/scrub_generated_plugin_registrant_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/file_system.dart';
 import 'package:flutter_tools/src/build_system/build_system.dart';
@@ -22,13 +20,13 @@ void main() {
 
   group('ScrubGeneratedPluginRegistrant', () {
     // The files this migration deals with
-    File gitignore;
-    File registrant;
+    late File gitignore;
+    late File registrant;
 
     // Environment overrides
-    FileSystem fileSystem;
-    ProcessManager processManager;
-    BuildSystem buildSystem;
+    late FileSystem fileSystem;
+    late ProcessManager processManager;
+    late BuildSystem buildSystem;
 
     setUp(() {
       // Prepare environment overrides

packages/flutter_tools/test/general.shard/web/web_asset_server_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/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
@@ -28,7 +26,7 @@ final Platform platform = FakePlatform(
 );
 
 void main() {
-  FileSystem fileSystem;
+  late FileSystem fileSystem;
 
   setUp(() {
     fileSystem = MemoryFileSystem.test();

packages/flutter_tools/test/general.shard/web/web_expression_compiler_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:dwds/dwds.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
@@ -14,7 +12,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 
 void main() {
-  FileSystem fileSystem;
+  late FileSystem fileSystem;
 
   setUp(() {
     fileSystem = MemoryFileSystem.test();
@@ -27,7 +25,7 @@ void main() {
 
     final ExpressionCompilationResult result =
       await expressionCompiler.compileExpressionToJs(
-        null, null, 1, 1, null, null, null, null);
+        '', '', 1, 1, <String, String>{}, <String, String>{}, '', '');
 
     expectResult(result, false, 'a');
   });
@@ -39,7 +37,7 @@ void main() {
 
     final ExpressionCompilationResult result =
       await expressionCompiler.compileExpressionToJs(
-        null, null, 1, 1, null, null, null, null);
+        '', '', 1, 1, <String, String>{}, <String, String>{}, '', '');
 
     expectResult(result, true, 'Error: a');
   });
@@ -50,7 +48,7 @@ void main() {
 
     final ExpressionCompilationResult result =
       await expressionCompiler.compileExpressionToJs(
-        null, null, 1, 1, null, null, null, 'a');
+        '', '', 1, 1, <String, String>{}, <String, String>{}, '', 'a');
 
     expectResult(result, true, "InternalError: frontend server failed to compile 'a'");
   });
@@ -66,10 +64,10 @@ void expectResult(ExpressionCompilationResult result, bool isError, String value
 class FakeResidentCompiler extends Fake implements ResidentCompiler {
   FakeResidentCompiler(this.output);
 
-  final CompilerOutput output;
+  final CompilerOutput? output;
 
   @override
-  Future<CompilerOutput> compileExpressionToJs(
+  Future<CompilerOutput?> compileExpressionToJs(
     String libraryUri,
     int line,
     int column,