migrate vm service to null safety (#88320)

packages/flutter_tools/lib/src/compile.dart

@@ -471,8 +471,8 @@ abstract class ResidentCompiler {
     List<Uri>? invalidatedFiles, {
     required String outputPath,
     required PackageConfig packageConfig,
-    required String projectRootPath,
     required FileSystem fs,
+    String? projectRootPath,
     bool suppressErrors = false,
     bool checkDartPluginRegistry = false,
   });

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

@@ -481,7 +481,7 @@ void main() {
   });
 
   testWithoutContext('computeDartVmFlags handles various combinations of Dart VM flags and null_assertions', () {
-    expect(computeDartVmFlags(DebuggingOptions.enabled(BuildInfo.debug, dartFlags: null)), '');
+    expect(computeDartVmFlags(DebuggingOptions.enabled(BuildInfo.debug)), '');
     expect(computeDartVmFlags(DebuggingOptions.enabled(BuildInfo.debug, dartFlags: '--foo')), '--foo');
     expect(computeDartVmFlags(DebuggingOptions.enabled(BuildInfo.debug, dartFlags: '', nullAssertions: true)), '--null_assertions');
     expect(computeDartVmFlags(DebuggingOptions.enabled(BuildInfo.debug, dartFlags: '--foo', nullAssertions: true)), '--foo,--null_assertions');

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

@@ -796,7 +796,7 @@ void main() {
         },
       ),
     ]);
-    final FakeDelegateFlutterDevice flutterDevice =  FakeDelegateFlutterDevice(
+    final FakeDelegateFlutterDevice flutterDevice = FakeDelegateFlutterDevice(
       device,
       BuildInfo.debug,
       FakeResidentCompiler(),

packages/flutter_tools/test/src/fake_vm_services.dart

@@ -2,14 +2,11 @@
 // 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:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/convert.dart';
 import 'package:flutter_tools/src/vmservice.dart';
-import 'package:meta/meta.dart';
 import 'package:test_api/test_api.dart' hide test; // ignore: deprecated_member_use
 import 'package:vm_service/vm_service.dart' as vm_service;
 
@@ -19,9 +16,9 @@ export 'package:test_api/test_api.dart' hide test, isInstanceOf; // ignore: depr
 /// and response structure.
 class FakeVmServiceHost {
   FakeVmServiceHost({
-    @required List<VmServiceExpectation> requests,
-    Uri httpAddress,
-    Uri wsAddress,
+    required List<VmServiceExpectation> requests,
+    Uri? httpAddress,
+    Uri? wsAddress,
   }) : _requests = requests {
     _vmService = FlutterVmService(vm_service.VmService(
       _input.stream,
@@ -44,16 +41,16 @@ class FakeVmServiceHost {
         return;
       }
       if (fakeRequest.errorCode == null) {
-        _input.add(json.encode(<String, Object>{
+        _input.add(json.encode(<String, Object?>{
           'jsonrpc': '2.0',
           'id': request['id'],
           'result': fakeRequest.jsonResponse ?? <String, Object>{'type': 'Success'},
         }));
       } else {
-        _input.add(json.encode(<String, Object>{
+        _input.add(json.encode(<String, Object?>{
           'jsonrpc': '2.0',
           'id': request['id'],
-          'error': <String, Object>{
+          'error': <String, Object?>{
             'code': fakeRequest.errorCode,
           }
         }));
@@ -67,7 +64,7 @@ class FakeVmServiceHost {
   final StreamController<String> _output = StreamController<String>();
 
   FlutterVmService get vmService => _vmService;
-  FlutterVmService _vmService;
+  late final FlutterVmService _vmService;
 
 
   bool get hasRemainingExpectations => _requests.isNotEmpty;
@@ -95,7 +92,7 @@ abstract class VmServiceExpectation {
 
 class FakeVmServiceRequest implements VmServiceExpectation {
   const FakeVmServiceRequest({
-    @required this.method,
+    required this.method,
     this.args = const <String, Object>{},
     this.jsonResponse,
     this.errorCode,
@@ -109,9 +106,9 @@ class FakeVmServiceRequest implements VmServiceExpectation {
 
   /// If non-null, the error code for a [vm_service.RPCError] in place of a
   /// standard response.
-  final int errorCode;
-  final Map<String, Object> args;
-  final Map<String, Object> jsonResponse;
+  final int? errorCode;
+  final Map<String, Object>? args;
+  final Map<String, Object>? jsonResponse;
 
   @override
   bool get isRequest => true;
@@ -119,8 +116,8 @@ class FakeVmServiceRequest implements VmServiceExpectation {
 
 class FakeVmServiceStreamResponse implements VmServiceExpectation {
   const FakeVmServiceStreamResponse({
-    @required this.event,
-    @required this.streamId,
+    required this.event,
+    required this.streamId,
   });
 
   final vm_service.Event event;