Migrate integration test shard test data to null safety (#92147)

packages/flutter_tools/test/integration.shard/test_data/deferred_components_config.dart

@@ -2,15 +2,13 @@
 // 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 '../test_utils.dart';
 
 abstract class DeferredComponentsConfig {
   String get deferredLibrary;
-  String get deferredComponentsGolden;
+  String? get deferredComponentsGolden;
   String get androidSettings;
   String get androidBuild;
   String get androidLocalProperties;
@@ -30,8 +28,9 @@ abstract class DeferredComponentsConfig {
     if (deferredLibrary != null) {
       writeFile(fileSystem.path.join(dir.path, 'lib', 'deferred_library.dart'), deferredLibrary);
     }
-    if (deferredComponentsGolden != null) {
-      writeFile(fileSystem.path.join(dir.path, 'deferred_components_loading_units.yaml'), deferredComponentsGolden);
+    final String? golden = deferredComponentsGolden;
+    if (golden != null) {
+      writeFile(fileSystem.path.join(dir.path, 'deferred_components_loading_units.yaml'), golden);
     }
     if (androidSettings != null) {
       writeFile(fileSystem.path.join(dir.path, 'android', 'settings.gradle'), androidSettings);

packages/flutter_tools/test/integration.shard/test_driver.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io' as io; // flutter_ignore: dart_io_import
@@ -13,7 +11,6 @@ import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/utils.dart';
-import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 import 'package:vm_service/vm_service.dart';
 import 'package:vm_service/vm_service_io.dart';
@@ -42,28 +39,28 @@ const Duration quitTimeout = Duration(seconds: 10);
 abstract class FlutterTestDriver {
   FlutterTestDriver(
     this._projectFolder, {
-    String logPrefix,
+    String? logPrefix,
   }) : _logPrefix = logPrefix != null ? '$logPrefix: ' : '';
 
   final Directory _projectFolder;
   final String _logPrefix;
-  Process _process;
-  int _processPid;
+  Process? _process;
+  int? _processPid;
   final StreamController<String> _stdout = StreamController<String>.broadcast();
   final StreamController<String> _stderr = StreamController<String>.broadcast();
   final StreamController<String> _allMessages = StreamController<String>.broadcast();
   final StringBuffer _errorBuffer = StringBuffer();
-  String _lastResponse;
-  Uri _vmServiceWsUri;
-  int _attachPort;
+  String? _lastResponse;
+  Uri? _vmServiceWsUri;
+  int? _attachPort;
   bool _hasExited = false;
 
-  VmService _vmService;
+  VmService? _vmService;
   String get lastErrorInfo => _errorBuffer.toString();
   Stream<String> get stdout => _stdout.stream;
-  int get vmServicePort => _vmServiceWsUri.port;
+  int? get vmServicePort => _vmServiceWsUri?.port;
   bool get hasExited => _hasExited;
-  Uri get vmServiceWsUri => _vmServiceWsUri;
+  Uri? get vmServiceWsUri => _vmServiceWsUri;
 
   String lastTime = '';
   void _debugPrint(String message, { String topic = '' }) {
@@ -89,7 +86,7 @@ abstract class FlutterTestDriver {
 
   Future<void> _setupProcess(
     List<String> arguments, {
-    String script,
+    String? script,
     bool withDebugger = false,
     bool singleWidgetReloads = false,
   }) async {
@@ -122,12 +119,12 @@ abstract class FlutterTestDriver {
 
     // This class doesn't use the result of the future. It's made available
     // via a getter for external uses.
-    unawaited(_process.exitCode.then((int code) {
+    unawaited(_process!.exitCode.then((int code) {
       _debugPrint('Process exited ($code)');
       _hasExited = true;
     }));
-    transformToLines(_process.stdout).listen(_stdout.add);
-    transformToLines(_process.stderr).listen(_stderr.add);
+    transformToLines(_process!.stdout).listen(_stdout.add);
+    transformToLines(_process!.stderr).listen(_stderr.add);
 
     // Capture stderr to a buffer so we can show it all if any requests fail.
     _stderr.stream.listen(_errorBuffer.writeln);
@@ -137,18 +134,18 @@ abstract class FlutterTestDriver {
     _stderr.stream.listen((String message) => _debugPrint(message, topic: '<=stderr='));
   }
 
-  Future<void> get done => _process.exitCode;
+  Future<void> get done async => _process?.exitCode;
 
   Future<void> connectToVmService({ bool pauseOnExceptions = false }) async {
     _vmService = await vmServiceConnectUri('$_vmServiceWsUri');
-    _vmService.onSend.listen((String s) => _debugPrint(s, topic: '=vm=>'));
-    _vmService.onReceive.listen((String s) => _debugPrint(s, topic: '<=vm='));
+    _vmService!.onSend.listen((String s) => _debugPrint(s, topic: '=vm=>'));
+    _vmService!.onReceive.listen((String s) => _debugPrint(s, topic: '<=vm='));
 
     final Completer<void> isolateStarted = Completer<void>();
-    _vmService.onIsolateEvent.listen((Event event) {
+    _vmService!.onIsolateEvent.listen((Event event) {
       if (event.kind == EventKind.kIsolateStart) {
         isolateStarted.complete();
-      } else if (event.kind == EventKind.kIsolateExit && event.isolate.id == _flutterIsolateId) {
+      } else if (event.kind == EventKind.kIsolateExit && event.isolate?.id == _flutterIsolateId) {
         // Hot restarts cause all the isolates to exit, so we need to refresh
         // our idea of what the Flutter isolate ID is.
         _flutterIsolateId = null;
@@ -156,17 +153,17 @@ abstract class FlutterTestDriver {
     });
 
     await Future.wait(<Future<Success>>[
-      _vmService.streamListen('Isolate'),
-      _vmService.streamListen('Debug'),
+      _vmService!.streamListen('Isolate'),
+      _vmService!.streamListen('Debug'),
     ]);
 
-    if ((await _vmService.getVM()).isolates.isEmpty) {
+    if ((await _vmService!.getVM()).isolates?.isEmpty != false) {
       await isolateStarted.future;
     }
 
     await waitForPause();
     if (pauseOnExceptions) {
-      await _vmService.setExceptionPauseMode(
+      await _vmService!.setExceptionPauseMode(
         await _getFlutterIsolateId(),
         ExceptionPauseMode.kUnhandled,
       );
@@ -175,9 +172,9 @@ abstract class FlutterTestDriver {
 
   Future<Response> callServiceExtension(
     String extension, {
-    Map<String, dynamic> args = const <String, dynamic>{},
+    Map<String, Object?> args = const <String, Object>{},
   }) async {
-    final int port = _vmServiceWsUri != null ? vmServicePort : _attachPort;
+    final int? port = _vmServiceWsUri != null ? vmServicePort : _attachPort;
     final VmService vmService = await vmServiceConnectUri('ws://localhost:$port/ws');
     final Isolate isolate = await waitForExtension(vmService, extension);
     return vmService.callServiceExtension(
@@ -203,29 +200,29 @@ abstract class FlutterTestDriver {
         });
 
     _debugPrint('Sending SIGTERM to $_processPid..');
-    io.Process.killPid(_processPid, io.ProcessSignal.sigterm);
-    return _process.exitCode.timeout(quitTimeout, onTimeout: _killForcefully);
+    io.Process.killPid(_processPid!);
+    return _process!.exitCode.timeout(quitTimeout, onTimeout: _killForcefully);
   }
 
   Future<int> _killForcefully() {
     _debugPrint('Sending SIGKILL to $_processPid..');
-    ProcessSignal.sigkill.send(_processPid);
-    return _process.exitCode;
+    ProcessSignal.sigkill.send(_processPid!);
+    return _process!.exitCode;
   }
 
-  String _flutterIsolateId;
+  String? _flutterIsolateId;
   Future<String> _getFlutterIsolateId() async {
     // Currently these tests only have a single isolate. If this
     // ceases to be the case, this code will need changing.
     if (_flutterIsolateId == null) {
-      final VM vm = await _vmService.getVM();
-      _flutterIsolateId = vm.isolates.single.id;
+      final VM vm = await _vmService!.getVM();
+      _flutterIsolateId = vm.isolates!.single.id;
     }
-    return _flutterIsolateId;
+    return _flutterIsolateId!;
   }
 
   Future<Isolate> getFlutterIsolate() async {
-    final Isolate isolate = await _vmService.getIsolate(await _getFlutterIsolateId());
+    final Isolate isolate = await _vmService!.getIsolate(await _getFlutterIsolateId());
     return isolate;
   }
 
@@ -247,7 +244,7 @@ abstract class FlutterTestDriver {
 
   Future<void> addBreakpoint(Uri uri, int line) async {
     _debugPrint('Sending breakpoint for: $uri:$line');
-    await _vmService.addBreakpointWithScriptUri(
+    await _vmService!.addBreakpointWithScriptUri(
       await _getFlutterIsolateId(),
       uri.toString(),
       line,
@@ -286,10 +283,10 @@ abstract class FlutterTestDriver {
   Future<Event> subscribeToDebugEvent(String kind, String isolateId) {
     _debugPrint('Start listening for $kind events');
 
-    return _vmService.onDebugEvent
+    return _vmService!.onDebugEvent
       .where((Event event) {
-        return event.isolate.id == isolateId
-            && event.kind.startsWith(kind);
+        return event.isolate?.id == isolateId
+            && event.kind?.startsWith(kind) == true;
       }).first;
   }
 
@@ -302,85 +299,87 @@ abstract class FlutterTestDriver {
         // But also check if the isolate was already at the state we need (only after we've
         // set up the subscription) to avoid races. If it already in the desired state, we
         // don't need to wait for the event.
-        final Isolate isolate = await _vmService.getIsolate(isolateId);
-        if (isolate.pauseEvent.kind.startsWith(kind)) {
-          _debugPrint('Isolate was already at "$kind" (${isolate.pauseEvent.kind}).');
+        final VmService vmService = _vmService!;
+        final Isolate isolate = await vmService.getIsolate(isolateId);
+        if (isolate.pauseEvent?.kind?.startsWith(kind) == true) {
+          _debugPrint('Isolate was already at "$kind" (${isolate.pauseEvent!.kind}).');
           event.ignore();
         } else {
           _debugPrint('Waiting for "$kind" event to arrive...');
           await event;
         }
 
-        return _vmService.getIsolate(isolateId);
+        return vmService.getIsolate(isolateId);
       },
       task: 'Waiting for isolate to $kind',
     );
   }
 
-  Future<Isolate> resume({ bool waitForNextPause = false }) => _resume(null, waitForNextPause);
-  Future<Isolate> stepOver({ bool waitForNextPause = true }) => _resume(StepOption.kOver, waitForNextPause);
-  Future<Isolate> stepOverAsync({ bool waitForNextPause = true }) => _resume(StepOption.kOverAsyncSuspension, waitForNextPause);
-  Future<Isolate> stepInto({ bool waitForNextPause = true }) => _resume(StepOption.kInto, waitForNextPause);
-  Future<Isolate> stepOut({ bool waitForNextPause = true }) => _resume(StepOption.kOut, waitForNextPause);
+  Future<Isolate?> resume({ bool waitForNextPause = false }) => _resume(null, waitForNextPause);
+  Future<Isolate?> stepOver({ bool waitForNextPause = true }) => _resume(StepOption.kOver, waitForNextPause);
+  Future<Isolate?> stepOverAsync({ bool waitForNextPause = true }) => _resume(StepOption.kOverAsyncSuspension, waitForNextPause);
+  Future<Isolate?> stepInto({ bool waitForNextPause = true }) => _resume(StepOption.kInto, waitForNextPause);
+  Future<Isolate?> stepOut({ bool waitForNextPause = true }) => _resume(StepOption.kOut, waitForNextPause);
 
   Future<bool> isAtAsyncSuspension() async {
     final Isolate isolate = await getFlutterIsolate();
-    return isolate.pauseEvent.atAsyncSuspension == true;
+    return isolate.pauseEvent?.atAsyncSuspension == true;
   }
 
-  Future<Isolate> stepOverOrOverAsyncSuspension({ bool waitForNextPause = true }) async {
+  Future<Isolate?> stepOverOrOverAsyncSuspension({ bool waitForNextPause = true }) async {
     if (await isAtAsyncSuspension()) {
       return stepOverAsync(waitForNextPause: waitForNextPause);
     }
     return stepOver(waitForNextPause: waitForNextPause);
   }
 
-  Future<Isolate> _resume(String step, bool waitForNextPause) async {
+  Future<Isolate?> _resume(String? step, bool waitForNextPause) async {
     assert(waitForNextPause != null);
     final String isolateId = await _getFlutterIsolateId();
 
     final Future<Event> resume = subscribeToResumeEvent(isolateId);
     final Future<Event> pause = subscribeToPauseEvent(isolateId);
 
-    await _timeoutWithMessages<dynamic>(
-      () async => _vmService.resume(isolateId, step: step),
+    await _timeoutWithMessages<Object?>(
+      () async => _vmService!.resume(isolateId, step: step),
       task: 'Resuming isolate (step=$step)',
     );
     await waitForResumeEvent(isolateId, resume);
-    return waitForNextPause? waitForPauseEvent(isolateId, pause): null;
+    return waitForNextPause ? waitForPauseEvent(isolateId, pause) : null;
   }
 
   Future<ObjRef> evaluateInFrame(String expression) async {
     return _timeoutWithMessages<ObjRef>(
-      () async => await _vmService.evaluateInFrame(await _getFlutterIsolateId(), 0, expression) as ObjRef,
+      () async => await _vmService!.evaluateInFrame(await _getFlutterIsolateId(), 0, expression) as ObjRef,
       task: 'Evaluating expression ($expression)',
     );
   }
 
   Future<InstanceRef> evaluate(String targetId, String expression) async {
     return _timeoutWithMessages<InstanceRef>(
-      () async => await _vmService.evaluate(await _getFlutterIsolateId(), targetId, expression) as InstanceRef,
+      () async => await _vmService!.evaluate(await _getFlutterIsolateId(), targetId, expression) as InstanceRef,
       task: 'Evaluating expression ($expression for $targetId)',
     );
   }
 
   Future<Frame> getTopStackFrame() async {
     final String flutterIsolateId = await _getFlutterIsolateId();
-    final Stack stack = await _vmService.getStack(flutterIsolateId);
-    if (stack.frames.isEmpty) {
+    final Stack stack = await _vmService!.getStack(flutterIsolateId);
+    final List<Frame>? frames = stack.frames;
+    if (frames == null || frames.isEmpty) {
       throw Exception('Stack is empty');
     }
-    return stack.frames.first;
+    return frames.first;
   }
 
-  Future<SourcePosition> getSourceLocation() async {
+  Future<SourcePosition?> getSourceLocation() async {
     final String flutterIsolateId = await _getFlutterIsolateId();
     final Frame frame = await getTopStackFrame();
-    final Script script = await _vmService.getObject(flutterIsolateId, frame.location.script.id) as Script;
-    return _lookupTokenPos(script.tokenPosTable, frame.location.tokenPos);
+    final Script script = await _vmService!.getObject(flutterIsolateId, frame.location!.script!.id!) as Script;
+    return _lookupTokenPos(script.tokenPosTable!, frame.location!.tokenPos!);
   }
 
-  SourcePosition _lookupTokenPos(List<List<int>> table, int tokenPos) {
+  SourcePosition? _lookupTokenPos(List<List<int>> table, int tokenPos) {
     for (final List<int> row in table) {
       final int lineNumber = row[0];
       int index = 1;
@@ -395,9 +394,9 @@ abstract class FlutterTestDriver {
     return null;
   }
 
-  Future<Map<String, dynamic>> _waitFor({
-    String event,
-    int id,
+  Future<Map<String, Object?>> _waitFor({
+    String? event,
+    int? id,
     Duration timeout = defaultTimeout,
     bool ignoreAppStopEvent = false,
   }) async {
@@ -405,30 +404,31 @@ abstract class FlutterTestDriver {
     assert(event != null || id != null);
     assert(event == null || id == null);
     final String interestingOccurrence = event != null ? '$event event' : 'response to request $id';
-    final Completer<Map<String, dynamic>> response = Completer<Map<String, dynamic>>();
-    StreamSubscription<String> subscription;
+    final Completer<Map<String, Object?>> response = Completer<Map<String, Object?>>();
+    StreamSubscription<String>? subscription;
     subscription = _stdout.stream.listen((String line) async {
-      final Map<String, dynamic> json = parseFlutterResponse(line);
+      final Map<String, Object?>? json = parseFlutterResponse(line);
       _lastResponse = line;
       if (json == null) {
         return;
       }
       if ((event != null && json['event'] == event) ||
           (id != null && json['id'] == id)) {
-        await subscription.cancel();
+        await subscription?.cancel();
         _debugPrint('OK ($interestingOccurrence)');
         response.complete(json);
       } else if (!ignoreAppStopEvent && json['event'] == 'app.stop') {
-        await subscription.cancel();
+        await subscription?.cancel();
         final StringBuffer error = StringBuffer();
         error.write('Received app.stop event while waiting for $interestingOccurrence\n\n$_errorBuffer');
-        if (json['params'] != null) {
-          final Map<String, dynamic> params = json['params'] as Map<String, dynamic>;
-          if (params['error'] != null) {
-            error.write('${params['error']}\n\n');
+        final Object? jsonParams = json['params'];
+        if (jsonParams is Map<String, Object?>) {
+          if (jsonParams['error'] != null) {
+            error.write('${jsonParams['error']}\n\n');
           }
-          if (json['params'] != null && params['trace'] != null) {
-            error.write('${params['trace']}\n\n');
+          final Object? trace = jsonParams['trace'];
+          if (trace != null) {
+            error.write('$trace\n\n');
           }
         }
         response.completeError(Exception(error.toString()));
@@ -444,7 +444,7 @@ abstract class FlutterTestDriver {
 
   Future<T> _timeoutWithMessages<T>(
     Future<T> Function() callback, {
-    @required String task,
+    required String task,
     Duration timeout = defaultTimeout,
   }) {
     assert(task != null);
@@ -476,7 +476,7 @@ abstract class FlutterTestDriver {
     });
     final Future<T> future = callback().whenComplete(longWarning.cancel);
 
-    return future.catchError((dynamic error) {
+    return future.catchError((Object error) {
       if (!timeoutExpired) {
         timeoutExpired = true;
         _debugPrint(messages.toString());
@@ -489,11 +489,11 @@ abstract class FlutterTestDriver {
 class FlutterRunTestDriver extends FlutterTestDriver {
   FlutterRunTestDriver(
     Directory projectFolder, {
-    String logPrefix,
+    String? logPrefix,
     this.spawnDdsInstance = true,
   }) : super(projectFolder, logPrefix: logPrefix);
 
-  String _currentRunningAppId;
+  String? _currentRunningAppId;
 
   Future<void> run({
     bool withDebugger = false,
@@ -503,8 +503,8 @@ class FlutterRunTestDriver extends FlutterTestDriver {
     bool expressionEvaluation = true,
     bool structuredErrors = false,
     bool singleWidgetReloads = false,
-    String script,
-    List<String> additionalCommandArgs,
+    String? script,
+    List<String>? additionalCommandArgs,
   }) async {
     await _setupProcess(
       <String>[
@@ -541,7 +541,7 @@ class FlutterRunTestDriver extends FlutterTestDriver {
     bool startPaused = false,
     bool pauseOnExceptions = false,
     bool singleWidgetReloads = false,
-    List<String> additionalCommandArgs,
+    List<String>? additionalCommandArgs,
   }) async {
     _attachPort = port;
     await _setupProcess(
@@ -568,12 +568,12 @@ class FlutterRunTestDriver extends FlutterTestDriver {
   @override
   Future<void> _setupProcess(
     List<String> args, {
-    String script,
+    String? script,
     bool withDebugger = false,
     bool startPaused = false,
     bool pauseOnExceptions = false,
     bool singleWidgetReloads = false,
-    int attachPort,
+    int? attachPort,
   }) async {
     assert(!startPaused || withDebugger);
     await super._setupProcess(
@@ -589,7 +589,7 @@ class FlutterRunTestDriver extends FlutterTestDriver {
     // exited prematurely. This causes the currently suspended `await` to
     // deadlock until the test times out. Instead, this causes the test to fail
     // fast.
-    unawaited(_process.exitCode.then((_) {
+    unawaited(_process?.exitCode.then((_) {
       if (!prematureExitGuard.isCompleted) {
         prematureExitGuard.completeError(Exception('Process exited prematurely: ${args.join(' ')}: $_errorBuffer'));
       }
@@ -600,16 +600,16 @@ class FlutterRunTestDriver extends FlutterTestDriver {
         // Stash the PID so that we can terminate the VM more reliably than using
         // _process.kill() (`flutter` is a shell script so _process itself is a
         // shell, not the flutter tool's Dart process).
-        final Map<String, dynamic> connected = await _waitFor(event: 'daemon.connected');
-        _processPid = (connected['params'] as Map<String, dynamic>)['pid'] as int;
+        final Map<String, Object?> connected = await _waitFor(event: 'daemon.connected');
+        _processPid = (connected['params'] as Map<String, Object?>?)?['pid'] as int?;
 
         // Set this up now, but we don't wait it yet. We want to make sure we don't
         // miss it while waiting for debugPort below.
-        final Future<Map<String, dynamic>> started = _waitFor(event: 'app.started', timeout: appStartTimeout);
+        final Future<Map<String, Object?>> started = _waitFor(event: 'app.started', timeout: appStartTimeout);
 
         if (withDebugger) {
-          final Map<String, dynamic> debugPort = await _waitFor(event: 'app.debugPort', timeout: appStartTimeout);
-          final String wsUriString = (debugPort['params'] as Map<String, dynamic>)['wsUri'] as String;
+          final Map<String, Object?> debugPort = await _waitFor(event: 'app.debugPort', timeout: appStartTimeout);
+          final String wsUriString = (debugPort['params']! as Map<String, Object?>)['wsUri']! as String;
           _vmServiceWsUri = Uri.parse(wsUriString);
           await connectToVmService(pauseOnExceptions: pauseOnExceptions);
           if (!startPaused) {
@@ -626,7 +626,7 @@ class FlutterRunTestDriver extends FlutterTestDriver {
 
         // Now await the started event; if it had already happened the future will
         // have already completed.
-        _currentRunningAppId = ((await started)['params'] as Map<String, dynamic>)['appId'] as String;
+        _currentRunningAppId = ((await started)['params'] as Map<String, Object?>?)?['appId'] as String?;
         prematureExitGuard.complete();
       } on Exception catch (error, stackTrace) {
         prematureExitGuard.completeError(Exception(error.toString()), stackTrace);
@@ -637,7 +637,7 @@ class FlutterRunTestDriver extends FlutterTestDriver {
   }
 
   Future<void> hotRestart({ bool pause = false, bool debounce = false}) => _restart(fullRestart: true, pause: pause);
-  Future<void> hotReload({ bool debounce = false, int debounceDurationOverrideMs }) =>
+  Future<void> hotReload({ bool debounce = false, int? debounceDurationOverrideMs }) =>
       _restart(debounce: debounce, debounceDurationOverrideMs: debounceDurationOverrideMs);
 
   Future<void> scheduleFrame() async {
@@ -646,20 +646,20 @@ class FlutterRunTestDriver extends FlutterTestDriver {
     }
     await _sendRequest(
       'app.callServiceExtension',
-      <String, dynamic>{'appId': _currentRunningAppId, 'methodName': 'ext.ui.window.scheduleFrame'},
+      <String, Object?>{'appId': _currentRunningAppId, 'methodName': 'ext.ui.window.scheduleFrame'},
     );
   }
 
-  Future<void> _restart({ bool fullRestart = false, bool pause = false, bool debounce = false, int debounceDurationOverrideMs }) async {
+  Future<void> _restart({ bool fullRestart = false, bool pause = false, bool debounce = false, int? debounceDurationOverrideMs }) async {
     if (_currentRunningAppId == null) {
       throw Exception('App has not started yet');
     }
 
     _debugPrint('Performing ${ pause ? "paused " : "" }${ fullRestart ? "hot restart" : "hot reload" }...');
-    final Map<String, dynamic> hotReloadResponse = await _sendRequest(
+    final Map<String, Object?>? hotReloadResponse = await _sendRequest(
       'app.restart',
-      <String, dynamic>{'appId': _currentRunningAppId, 'fullRestart': fullRestart, 'pause': pause, 'debounce': debounce, 'debounceDurationOverrideMs': debounceDurationOverrideMs},
-    ) as Map<String, dynamic>;
+      <String, Object?>{'appId': _currentRunningAppId, 'fullRestart': fullRestart, 'pause': pause, 'debounce': debounce, 'debounceDurationOverrideMs': debounceDurationOverrideMs},
+    ) as Map<String, Object?>?;
     _debugPrint('${fullRestart ? "Hot restart" : "Hot reload"} complete.');
 
     if (hotReloadResponse == null || hotReloadResponse['code'] != 0) {
@@ -668,20 +668,22 @@ class FlutterRunTestDriver extends FlutterTestDriver {
   }
 
   Future<int> detach() async {
-    if (_process == null) {
+    final Process? process = _process;
+    if (process == null) {
       return 0;
     }
-    if (_vmService != null) {
+    final VmService? vmService = _vmService;
+    if (vmService != null) {
       _debugPrint('Closing VM service...');
-      await _vmService.dispose();
+      await vmService.dispose();
     }
     if (_currentRunningAppId != null) {
       _debugPrint('Detaching from app...');
       await Future.any<void>(<Future<void>>[
-        _process.exitCode,
+        process.exitCode,
         _sendRequest(
           'app.detach',
-          <String, dynamic>{'appId': _currentRunningAppId},
+          <String, Object?>{'appId': _currentRunningAppId},
         ),
       ]).timeout(
         quitTimeout,
@@ -690,21 +692,23 @@ class FlutterRunTestDriver extends FlutterTestDriver {
       _currentRunningAppId = null;
     }
     _debugPrint('Waiting for process to end...');
-    return _process.exitCode.timeout(quitTimeout, onTimeout: _killGracefully);
+    return process.exitCode.timeout(quitTimeout, onTimeout: _killGracefully);
   }
 
   Future<int> stop() async {
-    if (_vmService != null) {
+    final VmService? vmService = _vmService;
+    if (vmService != null) {
       _debugPrint('Closing VM service...');
-      await _vmService.dispose();
+      await vmService.dispose();
     }
+    final Process? process = _process;
     if (_currentRunningAppId != null) {
       _debugPrint('Stopping application...');
       await Future.any<void>(<Future<void>>[
-        _process.exitCode,
+        process!.exitCode,
         _sendRequest(
           'app.stop',
-          <String, dynamic>{'appId': _currentRunningAppId},
+          <String, Object?>{'appId': _currentRunningAppId},
         ),
       ]).timeout(
         quitTimeout,
@@ -712,33 +716,33 @@ class FlutterRunTestDriver extends FlutterTestDriver {
       );
       _currentRunningAppId = null;
     }
-    if (_process != null) {
+    if (process != null) {
       _debugPrint('Waiting for process to end...');
-      return _process.exitCode.timeout(quitTimeout, onTimeout: _killGracefully);
+      return process.exitCode.timeout(quitTimeout, onTimeout: _killGracefully);
     }
     return 0;
   }
 
   int id = 1;
-  Future<dynamic> _sendRequest(String method, dynamic params) async {
+  Future<Object?> _sendRequest(String method, Object? params) async {
     final int requestId = id++;
-    final Map<String, dynamic> request = <String, dynamic>{
+    final Map<String, Object?> request = <String, Object?>{
       'id': requestId,
       'method': method,
       'params': params,
     };
-    final String jsonEncoded = json.encode(<Map<String, dynamic>>[request]);
+    final String jsonEncoded = json.encode(<Map<String, Object?>>[request]);
     _debugPrint(jsonEncoded, topic: '=stdin=>');
 
     // Set up the response future before we send the request to avoid any
     // races. If the method we're calling is app.stop then we tell _waitFor not
     // to throw if it sees an app.stop event before the response to this request.
-    final Future<Map<String, dynamic>> responseFuture = _waitFor(
+    final Future<Map<String, Object?>> responseFuture = _waitFor(
       id: requestId,
       ignoreAppStopEvent: method == 'app.stop',
     );
-    _process.stdin.writeln(jsonEncoded);
-    final Map<String, dynamic> response = await responseFuture;
+    _process?.stdin.writeln(jsonEncoded);
+    final Map<String, Object?> response = await responseFuture;
 
     if (response['error'] != null || response['result'] == null) {
       _throwErrorResponse('Unexpected error response');
@@ -755,7 +759,7 @@ class FlutterRunTestDriver extends FlutterTestDriver {
 }
 
 class FlutterTestTestDriver extends FlutterTestDriver {
-  FlutterTestTestDriver(Directory _projectFolder, {String logPrefix})
+  FlutterTestTestDriver(Directory _projectFolder, {String? logPrefix})
     : super(_projectFolder, logPrefix: logPrefix);
 
   Future<void> test({
@@ -763,7 +767,7 @@ class FlutterTestTestDriver extends FlutterTestDriver {
     bool withDebugger = false,
     bool pauseOnExceptions = false,
     bool coverage = false,
-    Future<void> Function() beforeStart,
+    Future<void> Function()? beforeStart,
   }) async {
     await _setupProcess(<String>[
       'test',
@@ -778,10 +782,10 @@ class FlutterTestTestDriver extends FlutterTestDriver {
   @override
   Future<void> _setupProcess(
     List<String> args, {
-    String script,
+    String? script,
     bool withDebugger = false,
     bool pauseOnExceptions = false,
-    Future<void> Function() beforeStart,
+    Future<void> Function()? beforeStart,
     bool singleWidgetReloads = false,
   }) async {
     await super._setupProcess(
@@ -794,13 +798,13 @@ class FlutterTestTestDriver extends FlutterTestDriver {
     // Stash the PID so that we can terminate the VM more reliably than using
     // _proc.kill() (because _proc is a shell, because `flutter` is a shell
     // script).
-    final Map<String, dynamic> version = await _waitForJson();
-    _processPid = version['pid'] as int;
+    final Map<String, Object?>? version = await _waitForJson();
+    _processPid = version?['pid'] as int?;
 
     if (withDebugger) {
-      final Map<String, dynamic> startedProcessParams =
-          (await _waitFor(event: 'test.startedProcess', timeout: appStartTimeout))['params'] as Map<String, dynamic>;
-      final String vmServiceHttpString = startedProcessParams['observatoryUri'] as String;
+      final Map<String, Object?> startedProcessParams =
+          (await _waitFor(event: 'test.startedProcess', timeout: appStartTimeout))['params']! as Map<String, Object?>;
+      final String vmServiceHttpString = startedProcessParams['observatoryUri']! as String;
       _vmServiceWsUri = Uri.parse(vmServiceHttpString).replace(scheme: 'ws', path: '/ws');
       await connectToVmService(pauseOnExceptions: pauseOnExceptions);
       // Allow us to run code before we start, eg. to set up breakpoints.
@@ -811,19 +815,19 @@ class FlutterTestTestDriver extends FlutterTestDriver {
     }
   }
 
-  Future<Map<String, dynamic>> _waitForJson({
+  Future<Map<String, Object?>?> _waitForJson({
     Duration timeout = defaultTimeout,
   }) async {
     assert(timeout != null);
-    return _timeoutWithMessages<Map<String, dynamic>>(
-      () => _stdout.stream.map<Map<String, dynamic>>(_parseJsonResponse)
-          .firstWhere((Map<String, dynamic> output) => output != null),
+    return _timeoutWithMessages<Map<String, Object?>?>(
+      () => _stdout.stream.map<Map<String, Object?>?>(_parseJsonResponse)
+          .firstWhere((Map<String, Object?>? output) => output != null),
       timeout: timeout,
       task: 'Waiting for JSON',
     );
   }
 
-  Map<String, dynamic> _parseJsonResponse(String line) {
+  Map<String, Object?>? _parseJsonResponse(String line) {
     try {
       return castStringKeyedMap(json.decode(line));
     } on Exception {
@@ -838,7 +842,7 @@ class FlutterTestTestDriver extends FlutterTestDriver {
     // end of test run.
     final StreamSubscription<String> subscription = _stdout.stream.listen(
         (String line) async {
-          final Map<String, dynamic> json = _parseJsonResponse(line);
+          final Map<String, Object?>? json = _parseJsonResponse(line);
           if (json != null && json['type'] != null && json['success'] != null) {
             done.complete(json['type'] == 'done' && json['success'] == true);
           }
@@ -846,9 +850,9 @@ class FlutterTestTestDriver extends FlutterTestDriver {
 
     await resume();
 
-    final Future<dynamic> timeoutFuture =
-        Future<dynamic>.delayed(defaultTimeout);
-    await Future.any<dynamic>(<Future<dynamic>>[done.future, timeoutFuture]);
+    final Future<Object> timeoutFuture =
+        Future<Object>.delayed(defaultTimeout);
+    await Future.any<Object>(<Future<Object>>[done.future, timeoutFuture]);
     await subscription.cancel();
     if (!done.isCompleted) {
       await quit();
@@ -860,10 +864,10 @@ Stream<String> transformToLines(Stream<List<int>> byteStream) {
   return byteStream.transform<String>(utf8.decoder).transform<String>(const LineSplitter());
 }
 
-Map<String, dynamic> parseFlutterResponse(String line) {
+Map<String, Object?>? parseFlutterResponse(String line) {
   if (line.startsWith('[') && line.endsWith(']') && line.length > 2) {
     try {
-      final Map<String, dynamic> response = castStringKeyedMap((json.decode(line) as List<dynamic>)[0]);
+      final Map<String, Object?>? response = castStringKeyedMap((json.decode(line) as List<Object?>)[0]);
       return response;
     } on FormatException {
       // Not valid JSON, so likely some other output that was surrounded by [brackets]
@@ -888,13 +892,13 @@ Future<Isolate> waitForExtension(VmService vmService, String extension) async {
     // Do nothing, already subscribed.
   }
   vmService.onExtensionEvent.listen((Event event) {
-    if (event.json['extensionKind'] == 'Flutter.FrameworkInitialization') {
+    if (event.json?['extensionKind'] == 'Flutter.FrameworkInitialization') {
       completer.complete();
     }
   });
-  final IsolateRef isolateRef = (await vmService.getVM()).isolates.first;
-  final Isolate isolate = await vmService.getIsolate(isolateRef.id);
-  if (isolate.extensionRPCs.contains(extension)) {
+  final IsolateRef isolateRef = (await vmService.getVM()).isolates!.first;
+  final Isolate isolate = await vmService.getIsolate(isolateRef.id!);
+  if (isolate.extensionRPCs!.contains(extension)) {
     return isolate;
   }
   await completer.future;

packages/flutter_tools/test/integration.shard/test_utils.dart

@@ -2,13 +2,10 @@
 // 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/local.dart';
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/platform.dart';
-import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 import 'package:vm_service/vm_service.dart';
 
@@ -91,18 +88,18 @@ List<String> getLocalEngineArguments() {
 }
 
 Future<void> pollForServiceExtensionValue<T>({
-  @required FlutterTestDriver testDriver,
-  @required String extension,
-  @required T continuePollingValue,
-  @required Matcher matches,
+  required FlutterTestDriver testDriver,
+  required String extension,
+  required T continuePollingValue,
+  required Matcher matches,
   String valueKey = 'value',
 }) async {
   for (int i = 0; i < 10; i++) {
     final Response response = await testDriver.callServiceExtension(extension);
-    if (response.json[valueKey] as T == continuePollingValue) {
+    if (response.json?[valueKey] as T == continuePollingValue) {
       await Future<void>.delayed(const Duration(seconds: 1));
     } else {
-      expect(response.json[valueKey] as T, matches);
+      expect(response.json?[valueKey] as T, matches);
       return;
     }
   }