diff --git a/packages/integration_test/CHANGELOG.md b/packages/integration_test/CHANGELOG.md
index 07ee671d77f9..9b711877332a 100644
--- a/packages/integration_test/CHANGELOG.md
+++ b/packages/integration_test/CHANGELOG.md
@@ -1,3 +1,9 @@
+# CHANGELOG
+
+## 0.10.0-nullsafety
+
+* (Prelease) Migration for sound null safety in Dart.
+
 ## 0.9.2+1
 
 * Update android compileSdkVersion to 29.
diff --git a/packages/integration_test/analysis_options.yaml b/packages/integration_test/analysis_options.yaml
new file mode 100644
index 000000000000..f4819cd5c313
--- /dev/null
+++ b/packages/integration_test/analysis_options.yaml
@@ -0,0 +1,4 @@
+include: ../../analysis_options.yaml
+analyzer:
+  enable-experiment:
+    - non-nullable
diff --git a/packages/integration_test/example/integration_test/_example_test_io.dart b/packages/integration_test/example/integration_test/_example_test_io.dart
index 7ed28963c32b..bd8923558e1a 100644
--- a/packages/integration_test/example/integration_test/_example_test_io.dart
+++ b/packages/integration_test/example/integration_test/_example_test_io.dart
@@ -32,7 +32,8 @@ void main() {
         find.byWidgetPredicate(
           (Widget widget) =>
               widget is Text &&
-              widget.data.startsWith('Platform: ${Platform.operatingSystem}'),
+              widget.data != null &&
+              widget.data!.startsWith('Platform: ${Platform.operatingSystem}'),
         ),
         findsOneWidget,
       );
diff --git a/packages/integration_test/example/integration_test/_example_test_web.dart b/packages/integration_test/example/integration_test/_example_test_web.dart
index e1141cc010c8..f656653d6912 100644
--- a/packages/integration_test/example/integration_test/_example_test_web.dart
+++ b/packages/integration_test/example/integration_test/_example_test_web.dart
@@ -26,7 +26,8 @@ void main() {
       find.byWidgetPredicate(
         (Widget widget) =>
             widget is Text &&
-            widget.data
+            widget.data != null &&
+            widget.data!
                 .startsWith('Platform: ${html.window.navigator.platform}\n'),
       ),
       findsOneWidget,
diff --git a/packages/integration_test/example/integration_test/_extended_test_io.dart b/packages/integration_test/example/integration_test/_extended_test_io.dart
index 56fee6f7179c..1de7c1a68b20 100644
--- a/packages/integration_test/example/integration_test/_extended_test_io.dart
+++ b/packages/integration_test/example/integration_test/_extended_test_io.dart
@@ -30,7 +30,8 @@ void main() {
       find.byWidgetPredicate(
         (Widget widget) =>
             widget is Text &&
-            widget.data.startsWith('Platform: ${Platform.operatingSystem}'),
+            widget.data != null &&
+            widget.data!.startsWith('Platform: ${Platform.operatingSystem}'),
       ),
       findsOneWidget,
     );
diff --git a/packages/integration_test/example/integration_test/_extended_test_web.dart b/packages/integration_test/example/integration_test/_extended_test_web.dart
index 210c2dac75ba..e49d632e270d 100644
--- a/packages/integration_test/example/integration_test/_extended_test_web.dart
+++ b/packages/integration_test/example/integration_test/_extended_test_web.dart
@@ -14,7 +14,8 @@ import 'package:integration_test_example/main.dart' as app;
 
 void main() {
   final IntegrationTestWidgetsFlutterBinding binding =
-      IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+      IntegrationTestWidgetsFlutterBinding.ensureInitialized()
+          as IntegrationTestWidgetsFlutterBinding;
 
   testWidgets('verify text', (WidgetTester tester) async {
     // Build our app and trigger a frame.
@@ -31,7 +32,8 @@ void main() {
       find.byWidgetPredicate(
         (Widget widget) =>
             widget is Text &&
-            widget.data
+            widget.data != null &&
+            widget.data!
                 .startsWith('Platform: ${html.window.navigator.platform}\n'),
       ),
       findsOneWidget,
diff --git a/packages/integration_test/example/pubspec.yaml b/packages/integration_test/example/pubspec.yaml
index 9384e9763935..eae87b9ee485 100644
--- a/packages/integration_test/example/pubspec.yaml
+++ b/packages/integration_test/example/pubspec.yaml
@@ -3,7 +3,7 @@ description: Demonstrates how to use the integration_test plugin.
 publish_to: 'none'
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: '>=2.10.0-56.0.dev <3.0.0'
   flutter: ">=1.6.7 <2.0.0"
 
 dependencies:
diff --git a/packages/integration_test/example/test_driver/failure.dart b/packages/integration_test/example/test_driver/failure.dart
index 02fc55e94a53..eea86dd388e8 100644
--- a/packages/integration_test/example/test_driver/failure.dart
+++ b/packages/integration_test/example/test_driver/failure.dart
@@ -33,7 +33,9 @@ void main() {
     await expectLater(
       find.byWidgetPredicate(
         (Widget widget) =>
-            widget is Text && widget.data.startsWith('This should fail'),
+            widget is Text &&
+            widget.data != null &&
+            widget.data!.startsWith('This should fail'),
       ),
       findsOneWidget,
     );
diff --git a/packages/integration_test/lib/_callback_io.dart b/packages/integration_test/lib/_callback_io.dart
index c1a447e27cab..cdca850db3e3 100644
--- a/packages/integration_test/lib/_callback_io.dart
+++ b/packages/integration_test/lib/_callback_io.dart
@@ -21,7 +21,7 @@ class IOCallbackManager implements CallbackManager {
   @override
   Future<Map<String, dynamic>> callback(
       Map<String, String> params, IntegrationTestResults testRunner) async {
-    final String command = params['command'];
+    final String command = params['command'] as String;
     Map<String, String> response;
     switch (command) {
       case 'request_data':
diff --git a/packages/integration_test/lib/_callback_web.dart b/packages/integration_test/lib/_callback_web.dart
index 036098148d99..978558884058 100644
--- a/packages/integration_test/lib/_callback_web.dart
+++ b/packages/integration_test/lib/_callback_web.dart
@@ -75,14 +75,13 @@ class WebCallbackManager implements CallbackManager {
   @override
   Future<Map<String, dynamic>> callback(
       Map<String, String> params, IntegrationTestResults testRunner) async {
-    final String command = params['command'];
+    final String command = params['command'] as String;
     Map<String, String> response;
     switch (command) {
       case 'request_data':
         return params['message'] == null
             ? _requestData(testRunner)
-            : _requestDataWithMessage(params['message'], testRunner);
-        break;
+            : _requestDataWithMessage(params['message'] as String, testRunner);
       case 'get_health':
         response = <String, String>{'status': 'ok'};
         break;
diff --git a/packages/integration_test/lib/common.dart b/packages/integration_test/lib/common.dart
index 53714a8e97ee..c328da6158a8 100644
--- a/packages/integration_test/lib/common.dart
+++ b/packages/integration_test/lib/common.dart
@@ -16,26 +16,26 @@ class Response {
   final bool _allTestsPassed;
 
   /// The extra information to be added along side the test result.
-  Map<String, dynamic> data;
+  Map<String, dynamic>? data;
 
   /// Constructor to use for positive response.
   Response.allTestsPassed({this.data})
-      : this._allTestsPassed = true,
-        this._failureDetails = null;
+      : _allTestsPassed = true,
+        _failureDetails = <Failure>[];
 
   /// Constructor for failure response.
   Response.someTestsFailed(this._failureDetails, {this.data})
-      : this._allTestsPassed = false;
+      : _allTestsPassed = false;
 
   /// Constructor for failure response.
-  Response.toolException({String ex})
-      : this._allTestsPassed = false,
-        this._failureDetails = [Failure('ToolException', ex)];
+  Response.toolException({String? ex})
+      : _allTestsPassed = false,
+        _failureDetails = <Failure>[Failure('ToolException', ex)];
 
   /// Constructor for web driver commands response.
   Response.webDriverCommand({this.data})
-      : this._allTestsPassed = false,
-        this._failureDetails = null;
+      : _allTestsPassed = false,
+        _failureDetails = <Failure>[];
 
   /// Whether the test ran successfully or not.
   bool get allTestsPassed => _allTestsPassed;
@@ -86,8 +86,8 @@ class Response {
 
   /// Create a list of Strings from [_failureDetails].
   List<String> _failureDetailsAsString() {
-    final List<String> list = List<String>();
-    if (_failureDetails == null || _failureDetails.isEmpty) {
+    final List<String> list = <String>[];
+    if (_failureDetails.isEmpty) {
       return list;
     }
 
@@ -100,7 +100,7 @@ class Response {
 
   /// Creates a [Failure] list using a json response.
   static List<Failure> _failureDetailsFromJson(List<dynamic> list) {
-    final List<Failure> failureList = List<Failure>();
+    final List<Failure> failureList = <Failure>[];
     list.forEach((s) {
       final String failure = s as String;
       failureList.add(Failure.fromJsonString(failure));
@@ -115,14 +115,14 @@ class Failure {
   final String methodName;
 
   /// The details of the failure such as stack trace.
-  final String details;
+  final String? details;
 
   /// Constructor requiring all fields during initialization.
   Failure(this.methodName, this.details);
 
   /// Serializes the object to JSON.
   String toJson() {
-    return json.encode(<String, String>{
+    return json.encode(<String, String?>{
       'methodName': methodName,
       'details': details,
     });
@@ -244,13 +244,13 @@ class WebDriverCommand {
 
   /// Constructor for [WebDriverCommandType.noop] command.
   WebDriverCommand.noop()
-      : this.type = WebDriverCommandType.noop,
-        this.values = Map();
+      : type = WebDriverCommandType.noop,
+        values = Map();
 
   /// Constructor for [WebDriverCommandType.noop] screenshot.
   WebDriverCommand.screenshot(String screenshot_name)
-      : this.type = WebDriverCommandType.screenshot,
-        this.values = {'screenshot_name': screenshot_name};
+      : type = WebDriverCommandType.screenshot,
+        values = {'screenshot_name': screenshot_name};
 
   /// Util method for converting [WebDriverCommandType] to a map entry.
   ///
@@ -294,7 +294,7 @@ abstract class IntegrationTestResults {
   List<Failure> get failureMethodsDetails;
 
   /// The extra data for the reported result.
-  Map<String, dynamic> get reportData;
+  Map<String, dynamic>? get reportData;
 
   /// Whether all the test methods completed succesfully.
   Completer<bool> get allTestsPassed;
diff --git a/packages/integration_test/lib/integration_test.dart b/packages/integration_test/lib/integration_test.dart
index 5a37e88a3c6e..c31ae0071519 100644
--- a/packages/integration_test/lib/integration_test.dart
+++ b/packages/integration_test/lib/integration_test.dart
@@ -80,7 +80,7 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
   @override
   bool get registerTestTextInput => false;
 
-  Size _surfaceSize;
+  Size? _surfaceSize;
 
   // This flag is used to print warning messages when tracking performance
   // under debug mode.
@@ -91,7 +91,7 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
   ///
   /// Set to null to use the default surface size.
   @override
-  Future<void> setSurfaceSize(Size size) {
+  Future<void> setSurfaceSize(Size? size) {
     return TestAsyncUtils.guard<void>(() async {
       assert(inTest);
       if (_surfaceSize == size) {
@@ -123,12 +123,17 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
   ///
   /// Returns an instance of the [IntegrationTestWidgetsFlutterBinding], creating and
   /// initializing it if necessary.
-  static WidgetsBinding ensureInitialized() {
+  static WidgetsBinding ensureInitialized(
+      {@visibleForTesting vm.VmService? vmService}) {
     if (WidgetsBinding.instance == null) {
       IntegrationTestWidgetsFlutterBinding();
     }
     assert(WidgetsBinding.instance is IntegrationTestWidgetsFlutterBinding);
-    return WidgetsBinding.instance;
+    if (vmService != null) {
+      (WidgetsBinding.instance as IntegrationTestWidgetsFlutterBinding)
+          ._cachedVmService = vmService;
+    }
+    return WidgetsBinding.instance!;
   }
 
   static const MethodChannel _channel =
@@ -150,9 +155,9 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
   ///
   /// The default value is `null`.
   @override
-  Map<String, dynamic> get reportData => _reportData;
-  Map<String, dynamic> _reportData;
-  set reportData(Map<String, dynamic> data) => this._reportData = data;
+  Map<String, dynamic>? get reportData => _reportData;
+  Map<String, dynamic>? _reportData;
+  set reportData(Map<String, dynamic>? data) => this._reportData = data;
 
   /// Manages callbacks received from driver side and commands send to driver
   /// side.
@@ -189,7 +194,7 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
     Future<void> testBody(),
     VoidCallback invariantTester, {
     String description = '',
-    Duration timeout,
+    Duration? timeout,
   }) async {
     await super.runTest(
       testBody,
@@ -200,28 +205,28 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
     results[description] ??= _success;
   }
 
-  vm.VmService _vmService;
+  vm.VmService? _cachedVmService;
+  Future<vm.VmService> get _vmService async {
+    if (_cachedVmService == null) {
+      final developer.ServiceProtocolInfo info =
+          await developer.Service.getInfo();
+      assert(info.serverUri != null);
+      _cachedVmService = await vm_io.vmServiceConnectUri(
+        'ws://localhost:${info.serverUri!.port}${info.serverUri!.path}ws',
+      );
+    }
+    return _cachedVmService!;
+  }
 
   /// Initialize the [vm.VmService] settings for the timeline.
   @visibleForTesting
   Future<void> enableTimeline({
     List<String> streams = const <String>['all'],
-    @visibleForTesting vm.VmService vmService,
   }) async {
-    assert(streams != null);
+    assert(streams != null); // ignore: unnecessary_null_comparison
     assert(streams.isNotEmpty);
-    if (vmService != null) {
-      _vmService = vmService;
-    }
-    if (_vmService == null) {
-      final developer.ServiceProtocolInfo info =
-          await developer.Service.getInfo();
-      assert(info.serverUri != null);
-      _vmService = await vm_io.vmServiceConnectUri(
-        'ws://localhost:${info.serverUri.port}${info.serverUri.path}ws',
-      );
-    }
-    await _vmService.setVMTimelineFlags(streams);
+    final vm.VmService vmService = await _vmService;
+    await vmService.setVMTimelineFlags(streams);
   }
 
   /// Runs [action] and returns a [vm.Timeline] trace for it.
@@ -243,16 +248,17 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
     bool retainPriorEvents = false,
   }) async {
     await enableTimeline(streams: streams);
+    final vm.VmService vmService = await _vmService;
     if (retainPriorEvents) {
       await action();
-      return await _vmService.getVMTimeline();
+      return await vmService.getVMTimeline();
     }
 
-    await _vmService.clearVMTimeline();
-    final vm.Timestamp startTime = await _vmService.getVMTimelineMicros();
+    await vmService.clearVMTimeline();
+    final vm.Timestamp startTime = await vmService.getVMTimelineMicros();
     await action();
-    final vm.Timestamp endTime = await _vmService.getVMTimelineMicros();
-    return await _vmService.getVMTimeline(
+    final vm.Timestamp endTime = await vmService.getVMTimelineMicros();
+    return await vmService.getVMTimeline(
       timeOriginMicros: startTime.timestamp,
       timeExtentMicros: endTime.timestamp,
     );
@@ -285,7 +291,7 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
       retainPriorEvents: retainPriorEvents,
     );
     reportData ??= <String, dynamic>{};
-    reportData[reportKey] = timeline.toJson();
+    reportData![reportKey] = timeline.toJson();
   }
 
   /// Watches the [FrameTiming] during `action` and report it to the binding
@@ -324,6 +330,6 @@ class IntegrationTestWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding
     final FrameTimingSummarizer frameTimes =
         FrameTimingSummarizer(frameTimings);
     reportData ??= <String, dynamic>{};
-    reportData[reportKey] = frameTimes.summary;
+    reportData![reportKey] = frameTimes.summary;
   }
 }
diff --git a/packages/integration_test/lib/integration_test_driver.dart b/packages/integration_test/lib/integration_test_driver.dart
index 3b0e756000d0..32f1c502a37b 100644
--- a/packages/integration_test/lib/integration_test_driver.dart
+++ b/packages/integration_test/lib/integration_test_driver.dart
@@ -30,9 +30,9 @@ typedef ResponseDataCallback = FutureOr<void> Function(Map<String, dynamic>);
 Future<void> writeResponseData(
   Map<String, dynamic> data, {
   String testOutputFilename = 'integration_response_data',
-  String destinationDirectory,
+  String? destinationDirectory,
 }) async {
-  assert(testOutputFilename != null);
+  assert(testOutputFilename != null); // ignore: unnecessary_null_comparison
   destinationDirectory ??= testOutputsDirectory;
   await fs.directory(destinationDirectory).create(recursive: true);
   final File file = fs.file(path.join(
@@ -65,7 +65,7 @@ Future<void> writeResponseData(
 /// ```
 Future<void> integrationDriver({
   Duration timeout = const Duration(minutes: 1),
-  ResponseDataCallback responseDataCallback = writeResponseData,
+  ResponseDataCallback? responseDataCallback = writeResponseData,
 }) async {
   final FlutterDriver driver = await FlutterDriver.connect();
   final String jsonResult = await driver.requestData(null, timeout: timeout);
@@ -75,7 +75,7 @@ Future<void> integrationDriver({
   if (response.allTestsPassed) {
     print('All tests passed.');
     if (responseDataCallback != null) {
-      await responseDataCallback(response.data);
+      await responseDataCallback(response.data!);
     }
     exit(0);
   } else {
diff --git a/packages/integration_test/lib/integration_test_driver_extended.dart b/packages/integration_test/lib/integration_test_driver_extended.dart
index bc38bb71de50..c8892111f18c 100644
--- a/packages/integration_test/lib/integration_test_driver_extended.dart
+++ b/packages/integration_test/lib/integration_test_driver_extended.dart
@@ -8,7 +8,7 @@ import 'package:flutter_driver/flutter_driver.dart';
 /// Example Integration Test which can also run WebDriver command depending on
 /// the requests coming from the test methods.
 Future<void> integrationDriver(
-    {FlutterDriver driver, Function onScreenshot}) async {
+    {FlutterDriver? driver, required Function onScreenshot}) async {
   if (driver == null) {
     driver = await FlutterDriver.connect();
   }
@@ -23,13 +23,13 @@ Future<void> integrationDriver(
   // Until `integration_test` returns a [WebDriverCommandType.noop], keep
   // executing WebDriver commands.
   while (response.data != null &&
-      response.data['web_driver_command'] != null &&
-      response.data['web_driver_command'] != '${WebDriverCommandType.noop}') {
-    final String webDriverCommand = response.data['web_driver_command'];
+      response.data!['web_driver_command'] != null &&
+      response.data!['web_driver_command'] != '${WebDriverCommandType.noop}') {
+    final String webDriverCommand = response.data!['web_driver_command'];
     if (webDriverCommand == '${WebDriverCommandType.screenshot}') {
       // Use `driver.screenshot()` method to get a screenshot of the web page.
       final List<int> screenshotImage = await driver.screenshot();
-      final String screenshotName = response.data['screenshot_name'];
+      final String screenshotName = response.data!['screenshot_name'];
 
       final bool screenshotSuccess =
           await onScreenshot(screenshotName, screenshotImage);
@@ -55,8 +55,8 @@ Future<void> integrationDriver(
 
   // If No-op command is sent, ask for the result of all tests.
   if (response.data != null &&
-      response.data['web_driver_command'] != null &&
-      response.data['web_driver_command'] == '${WebDriverCommandType.noop}') {
+      response.data!['web_driver_command'] != null &&
+      response.data!['web_driver_command'] == '${WebDriverCommandType.noop}') {
     jsonResponse = await driver.requestData(null);
 
     response = Response.fromJson(jsonResponse);
diff --git a/packages/integration_test/pubspec.yaml b/packages/integration_test/pubspec.yaml
index 44aa2c56790f..8d8ee13c83a7 100644
--- a/packages/integration_test/pubspec.yaml
+++ b/packages/integration_test/pubspec.yaml
@@ -1,10 +1,10 @@
 name: integration_test
 description: Runs tests that use the flutter_test API as integration tests.
-version: 0.9.2+1
+version: 0.10.0-nullsafety
 homepage: https://github.com/flutter/plugins/tree/master/packages/integration_test
 
 environment:
-  sdk: ">=2.2.2 <3.0.0"
+  sdk: '>=2.10.0-56.0.dev <3.0.0'
   flutter: ">=1.12.13+hotfix.5 <2.0.0"
 
 dependencies:
@@ -19,7 +19,6 @@ dependencies:
 
 dev_dependencies:
   pedantic: ^1.8.0
-  mockito: ^4.1.1
 
 flutter:
   plugin:
diff --git a/packages/integration_test/test/binding_test.dart b/packages/integration_test/test/binding_test.dart
index ef4efc59aac0..e7d3fd3f3f11 100644
--- a/packages/integration_test/test/binding_test.dart
+++ b/packages/integration_test/test/binding_test.dart
@@ -5,40 +5,25 @@ import 'package:flutter/material.dart';
 import 'package:integration_test/integration_test.dart';
 import 'package:integration_test/common.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
 import 'package:vm_service/vm_service.dart' as vm;
 
-vm.Timeline _ktimelines = vm.Timeline(
-  traceEvents: <vm.TimelineEvent>[],
-  timeOriginMicros: 100,
-  timeExtentMicros: 200,
-);
-
 void main() async {
-  Future<Map<String, dynamic>> request;
+  late Future<Map<String, dynamic>> request;
 
   group('Test Integration binding', () {
-    final WidgetsBinding binding =
-        IntegrationTestWidgetsFlutterBinding.ensureInitialized();
-    assert(binding is IntegrationTestWidgetsFlutterBinding);
-    final IntegrationTestWidgetsFlutterBinding integrationBinding =
-        binding as IntegrationTestWidgetsFlutterBinding;
-
-    MockVM mockVM;
-    List<int> clockTimes = [100, 200];
+    late FakeVmService fakeVmService;
+    late IntegrationTestWidgetsFlutterBinding integrationBinding;
 
     setUp(() {
+      fakeVmService = FakeVmService();
+      integrationBinding =
+          IntegrationTestWidgetsFlutterBinding.ensureInitialized(
+        vmService: fakeVmService,
+      ) as IntegrationTestWidgetsFlutterBinding;
+
       request = integrationBinding.callback(<String, String>{
         'command': 'request_data',
       });
-      mockVM = MockVM();
-      when(mockVM.getVMTimeline(
-        timeOriginMicros: anyNamed('timeOriginMicros'),
-        timeExtentMicros: anyNamed('timeExtentMicros'),
-      )).thenAnswer((_) => Future.value(_ktimelines));
-      when(mockVM.getVMTimelineMicros()).thenAnswer(
-        (_) => Future.value(vm.Timestamp(timestamp: clockTimes.removeAt(0))),
-      );
     });
 
     testWidgets('Run Integration app', (WidgetTester tester) async {
@@ -76,13 +61,13 @@ void main() async {
     });
 
     testWidgets('Test traceAction', (WidgetTester tester) async {
-      await integrationBinding.enableTimeline(vmService: mockVM);
+      await integrationBinding.enableTimeline();
       await integrationBinding.traceAction(() async {});
       expect(integrationBinding.reportData, isNotNull);
-      expect(integrationBinding.reportData.containsKey('timeline'), true);
+      expect(integrationBinding.reportData!.containsKey('timeline'), true);
       expect(
-        json.encode(integrationBinding.reportData['timeline']),
-        json.encode(_ktimelines),
+        json.encode(integrationBinding.reportData!['timeline']),
+        json.encode(fakeVmService.kTimelines),
       );
     });
   });
@@ -95,8 +80,27 @@ void main() async {
         (await request)['response'] as Map<String, dynamic>;
     final String message = response['message'] as String;
     Response result = Response.fromJson(message);
-    assert(result.data['answer'] == 42);
+    assert(result.data!['answer'] == 42);
   });
 }
 
-class MockVM extends Mock implements vm.VmService {}
+class FakeVmService extends Fake implements vm.VmService {
+  final vm.Timeline kTimelines = vm.Timeline(
+    traceEvents: <vm.TimelineEvent>[],
+    timeOriginMicros: 100,
+    timeExtentMicros: 200,
+  );
+
+  final List<int> clockTimes = <int>[100, 200];
+
+  @override
+  Future<vm.Timeline> getVMTimeline(
+      {int? timeOriginMicros, int? timeExtentMicros}) async {
+    return kTimelines;
+  }
+
+  @override
+  Future<vm.Timestamp> getVMTimelineMicros() async {
+    return vm.Timestamp(timestamp: clockTimes.removeAt(0));
+  }
+}
diff --git a/packages/integration_test/test/data/fail_test_script.dart b/packages/integration_test/test/data/fail_test_script.dart
index 05a75d7d031e..4aa41bb15564 100644
--- a/packages/integration_test/test/data/fail_test_script.dart
+++ b/packages/integration_test/test/data/fail_test_script.dart
@@ -5,7 +5,8 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() async {
   final IntegrationTestWidgetsFlutterBinding binding =
-      IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+      IntegrationTestWidgetsFlutterBinding.ensureInitialized()
+          as IntegrationTestWidgetsFlutterBinding;
 
   testWidgets('failing test 1', (WidgetTester tester) async {
     expect(true, false);
diff --git a/packages/integration_test/test/data/pass_test_script.dart b/packages/integration_test/test/data/pass_test_script.dart
index 7e222c8e8961..cb0655323611 100644
--- a/packages/integration_test/test/data/pass_test_script.dart
+++ b/packages/integration_test/test/data/pass_test_script.dart
@@ -5,7 +5,8 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() async {
   final IntegrationTestWidgetsFlutterBinding binding =
-      IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+      IntegrationTestWidgetsFlutterBinding.ensureInitialized()
+          as IntegrationTestWidgetsFlutterBinding;
 
   testWidgets('passing test 1', (WidgetTester tester) async {
     expect(true, true);
diff --git a/packages/integration_test/test/data/pass_then_fail_test_script.dart b/packages/integration_test/test/data/pass_then_fail_test_script.dart
index 324c1c21cfa6..cfe0c720e4f0 100644
--- a/packages/integration_test/test/data/pass_then_fail_test_script.dart
+++ b/packages/integration_test/test/data/pass_then_fail_test_script.dart
@@ -5,7 +5,8 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() async {
   final IntegrationTestWidgetsFlutterBinding binding =
-      IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+      IntegrationTestWidgetsFlutterBinding.ensureInitialized()
+          as IntegrationTestWidgetsFlutterBinding;
 
   testWidgets('passing test', (WidgetTester tester) async {
     expect(true, true);
diff --git a/packages/integration_test/test/response_serialization_test.dart b/packages/integration_test/test/response_serialization_test.dart
index 8b969402035d..9476506ccff3 100644
--- a/packages/integration_test/test/response_serialization_test.dart
+++ b/packages/integration_test/test/response_serialization_test.dart
@@ -11,7 +11,8 @@ void main() {
   });
 
   test('Serialize and deserialize Response', () {
-    Response response, restored;
+    late Response response;
+    late Response restored;
     String jsonString;
 
     response = Response.allTestsPassed();
@@ -35,13 +36,13 @@ void main() {
     response = Response.allTestsPassed(data: data);
     jsonString = response.toJson();
     restored = Response.fromJson(jsonString);
-    expect(restored.data.keys, ['aaa']);
-    expect(restored.data.values, ['bbb']);
+    expect(restored.data!.keys, ['aaa']);
+    expect(restored.data!.values, ['bbb']);
 
     response = Response.someTestsFailed([fail, fail2], data: data);
     jsonString = response.toJson();
     restored = Response.fromJson(jsonString);
-    expect(restored.data.keys, ['aaa']);
-    expect(restored.data.values, ['bbb']);
+    expect(restored.data!.keys, ['aaa']);
+    expect(restored.data!.values, ['bbb']);
   });
 }