Migrate rest of the services and dwds_vm_client.dart to null safety (#1688)

* Migrate debugging/inspector.dart to null safety

* Migrate expression evaluator to null safety

* format

* Fix failing tests

* Migrate services/chrome_proxu_service.dart to null safety

* Migrate rest of the services and dwds_vm_client to null safety

* Made Inspector.getObject return non-null value

* Allow null _ddsUri in debug_service.dart

* Address CR comments

Author: Anna Gringauze

dwds/lib/src/connections/debug_connection.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:vm_service/vm_service.dart';
@@ -22,7 +20,7 @@ class DebugConnection {
   /// Null until [close] is called.
   ///
   /// All subsequent calls to [close] will return this future.
-  Future<void> _closed;
+  Future<void>? _closed;
 
   DebugConnection(this._appDebugServices) {
     _appDebugServices.chromeProxyService.remoteDebugger.onClose.first.then((_) {

dwds/lib/src/debugging/inspector.dart

@@ -403,8 +403,7 @@ class AppInspector implements AppInspectorInterface {
     }
     final libraryId = _scriptIdToLibraryId[scriptId];
     if (libraryId == null) {
-      throwInvalidParam('getObject',
-          'No library for script $scriptRef with libraryId: $libraryId');
+      throwInvalidParam('getObject', 'No library for script $scriptRef');
     }
     return Script(
         uri: scriptRef.uri,

dwds/lib/src/dwds_vm_client.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 import 'dart:convert';
 
@@ -32,7 +30,7 @@ class DwdsVmClient {
   /// Null until [close] is called.
   ///
   /// All subsequent calls to [close] will return this future.
-  Future<void> _closed;
+  Future<void>? _closed;
 
   DwdsVmClient(this.client, this._requestController, this._responseController);
 
@@ -57,7 +55,7 @@ class DwdsVmClient {
             '$request');
         return;
       }
-      requestController.sink.add(jsonDecode(request) as Map<String, dynamic>);
+      requestController.sink.add(jsonDecode(request) as Map<String, Object>);
     });
     final chromeProxyService =
         debugService.chromeProxyService as ChromeProxyService;
@@ -73,7 +71,7 @@ class DwdsVmClient {
       return <String, dynamic>{
         'result': <String, Object>{
           'views': <Object>[
-            for (var isolate in isolates)
+            for (var isolate in isolates ?? [])
               <String, Object>{
                 'id': isolate.id,
                 'isolate': isolate.toJson(),
@@ -119,7 +117,7 @@ class DwdsVmClient {
     await client.registerService('ext.dwds.emitEvent', 'DWDS');
 
     client.registerServiceCallback('_yieldControlToDDS', (request) async {
-      final ddsUri = request['uri'] as String;
+      final ddsUri = request['uri'] as String?;
       if (ddsUri == null) {
         return RPCError(
           request['method'] as String,
@@ -146,30 +144,26 @@ class DwdsVmClient {
 
 void _processSendEvent(Map<String, dynamic> event,
     ChromeProxyService chromeProxyService, DwdsStats dwdsStats) {
-  final type = event['type'] as String;
-  final payload = event['payload'] as Map<String, dynamic>;
+  final type = event['type'] as String?;
+  final payload = event['payload'] as Map<String, dynamic>?;
   switch (type) {
     case 'DevtoolsEvent':
       {
         _logger.finest('Received DevTools event: $event');
-        final action = payload == null ? null : payload['action'] as String;
-        final screen = payload == null ? null : payload['screen'] as String;
-        if (action == 'pageReady') {
+        final action = payload?['action'] as String?;
+        final screen = payload?['screen'] as String?;
+        if (screen != null && action == 'pageReady') {
           if (dwdsStats.isFirstDebuggerReady) {
-            if (dwdsStats.devToolsStart != null) {
-              final time = DateTime.now()
-                  .difference(dwdsStats.devToolsStart)
-                  .inMilliseconds;
-              emitEvent(DwdsEvent.devToolsLoad(time, screen));
-              _logger.fine('DevTools load time: $time ms');
-            }
-            if (dwdsStats.debuggerStart != null) {
-              final time = DateTime.now()
-                  .difference(dwdsStats.debuggerStart)
-                  .inMilliseconds;
-              emitEvent(DwdsEvent.debuggerReady(time, screen));
-              _logger.fine('Debugger ready time: $time ms');
-            }
+            final debuggerReadyTime = DateTime.now()
+                .difference(dwdsStats.devToolsStart)
+                .inMilliseconds;
+            emitEvent(DwdsEvent.devToolsLoad(debuggerReadyTime, screen));
+            _logger.fine('DevTools load time: $debuggerReadyTime ms');
+            final debuggerStartTime = DateTime.now()
+                .difference(dwdsStats.debuggerStart)
+                .inMilliseconds;
+            emitEvent(DwdsEvent.debuggerReady(debuggerStartTime, screen));
+            _logger.fine('Debugger ready time: $debuggerStartTime ms');
           } else {
             _logger
                 .finest('Debugger and DevTools startup times alredy recorded.'
@@ -213,14 +207,15 @@ Future<Map<String, dynamic>> _hotRestart(
         .jsEvaluate('\$dartHotRestartDwds(\'$runId\');', awaitPromise: true);
     _logger.info('\$dartHotRestartDwds request complete.');
   } on WipError catch (exception) {
-    final code = exception.error['code'];
+    final code = exception.error?['code'];
+    final message = exception.error?['message'];
     // This corresponds to `Execution context was destroyed` which can
     // occur during a hot restart that must fall back to a full reload.
     if (code != RPCError.kServerError) {
       return {
         'error': {
-          'code': exception.error['code'],
-          'message': exception.error['message'],
+          'code': code,
+          'message': message,
           'data': exception,
         }
       };
@@ -255,9 +250,14 @@ Future<void> _disableBreakpointsAndResume(
     VmService client, ChromeProxyService chromeProxyService) async {
   _logger.info('Attempting to disable breakpoints and resume the isolate');
   final vm = await client.getVM();
-  if (vm.isolates.isEmpty) throw StateError('No active isolate to resume.');
-  final isolateRef = vm.isolates.first;
-
+  final isolates = vm.isolates;
+  if (isolates == null || isolates.isEmpty) {
+    throw StateError('No active isolate to resume.');
+  }
+  final isolateId = isolates.first.id;
+  if (isolateId == null) {
+    throw StateError('No active isolate to resume.');
+  }
   await chromeProxyService.disableBreakpoints();
   try {
     // Any checks for paused status result in race conditions or hangs
@@ -274,7 +274,7 @@ Future<void> _disableBreakpointsAndResume(
     // ignore failures indicating that the app is already running:
     //
     // WipError -32000 Can only perform operation while paused.
-    await client.resume(isolateRef.id);
+    await client.resume(isolateId);
   } on RPCError catch (e, s) {
     if (!e.message.contains('Can only perform operation while paused')) {
       _logger.severe('Hot restart failed to resume exiting isolate', e, s);

dwds/lib/src/services/app_debug_services.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import '../dwds_vm_client.dart';
@@ -23,12 +21,12 @@ class AppDebugServices {
   /// Null until [close] is called.
   ///
   /// All subsequent calls to [close] will return this future.
-  Future<void> _closed;
+  Future<void>? _closed;
 
   /// The instance ID for the currently connected application, if there is one.
   ///
   /// We only allow a given app to be debugged in a single tab at a time.
-  String connectedInstanceId;
+  String? connectedInstanceId;
 
   AppDebugServices(this.debugService, this.dwdsVmClient, this.dwdsStats);
 

dwds/lib/src/services/chrome_proxy_service.dart

@@ -128,7 +128,7 @@ class ChromeProxyService implements VmServiceInterface {
     LoadStrategy loadStrategy,
     AppConnection appConnection,
     ExecutionContext executionContext,
-    ExpressionCompiler expressionCompiler,
+    ExpressionCompiler? expressionCompiler,
     SdkConfigurationProvider sdkConfigurationProvider,
   ) async {
     final vm = VM(

dwds/lib/src/services/debug_service.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
@@ -38,8 +36,8 @@ Logger _logger = Logger('DebugService');
 void Function(WebSocketChannel, String) _createNewConnectionHandler(
   ChromeProxyService chromeProxyService,
   ServiceExtensionRegistry serviceExtensionRegistry, {
-  void Function(Map<String, dynamic>) onRequest,
-  void Function(Map<String, dynamic>) onResponse,
+  void Function(Map<String, dynamic>)? onRequest,
+  void Function(Map<String, dynamic>)? onResponse,
 }) {
   return (webSocket, protocol) {
     final responseController = StreamController<Map<String, Object>>();
@@ -49,7 +47,7 @@ void Function(WebSocketChannel, String) _createNewConnectionHandler(
     }));
     final inputStream = webSocket.stream.map((value) {
       if (value is List<int>) {
-        value = utf8.decode(value as List<int>);
+        value = utf8.decode(value);
       } else if (value is! String) {
         throw StateError(
             'Got value with unexpected type ${value.runtimeType} from web '
@@ -78,8 +76,8 @@ Future<void> _handleSseConnections(
   SseHandler handler,
   ChromeProxyService chromeProxyService,
   ServiceExtensionRegistry serviceExtensionRegistry, {
-  void Function(Map<String, dynamic>) onRequest,
-  void Function(Map<String, dynamic>) onResponse,
+  void Function(Map<String, dynamic>)? onRequest,
+  void Function(Map<String, dynamic>)? onResponse,
 }) async {
   while (await handler.connections.hasNext) {
     final connection = await handler.connections.next;
@@ -116,7 +114,7 @@ Future<void> _handleSseConnections(
 ///
 /// Creates a [ChromeProxyService] from an existing Chrome instance.
 class DebugService {
-  static String _ddsUri;
+  static String? _ddsUri;
 
   final VmServiceInterface chromeProxyService;
   final String hostname;
@@ -126,13 +124,13 @@ class DebugService {
   final HttpServer _server;
   final bool _useSse;
   final bool _spawnDds;
-  final UrlEncoder _urlEncoder;
-  DartDevelopmentService _dds;
+  final UrlEncoder? _urlEncoder;
+  DartDevelopmentService? _dds;
 
   /// Null until [close] is called.
   ///
   /// All subsequent calls to [close] will return this future.
-  Future<void> _closed;
+  Future<void>? _closed;
 
   DebugService._(
       this.chromeProxyService,
@@ -147,7 +145,7 @@ class DebugService {
 
   Future<void> close() => _closed ??= Future.wait([
         _server.close(),
-        if (_dds != null) _dds.shutdown(),
+        if (_dds != null) _dds!.shutdown(),
       ]);
 
   Future<void> startDartDevelopmentService() async {
@@ -170,8 +168,9 @@ class DebugService {
   }
 
   String get uri {
-    if (_spawnDds && _dds != null) {
-      return (_useSse ? _dds.sseUri : _dds.wsUri).toString();
+    final dds = _dds;
+    if (_spawnDds && dds != null) {
+      return (_useSse ? dds.sseUri : dds.wsUri).toString();
     }
     return (_useSse
             ? Uri(
@@ -189,12 +188,12 @@ class DebugService {
         .toString();
   }
 
-  String _encodedUri;
+  String? _encodedUri;
   Future<String> get encodedUri async {
-    if (_encodedUri != null) return _encodedUri;
-    var encodedUri = uri;
-    if (_urlEncoder != null) encodedUri = await _urlEncoder(encodedUri);
-    return _encodedUri = encodedUri;
+    if (_encodedUri != null) return _encodedUri!;
+    var encoded = uri;
+    if (_urlEncoder != null) encoded = await _urlEncoder!(encoded);
+    return _encodedUri = encoded;
   }
 
   static bool yieldControlToDDS(String uri) {
@@ -214,15 +213,14 @@ class DebugService {
     AssetReader assetReader,
     LoadStrategy loadStrategy,
     AppConnection appConnection,
-    UrlEncoder urlEncoder, {
-    void Function(Map<String, dynamic>) onRequest,
-    void Function(Map<String, dynamic>) onResponse,
+    UrlEncoder? urlEncoder, {
+    void Function(Map<String, dynamic>)? onRequest,
+    void Function(Map<String, dynamic>)? onResponse,
     bool spawnDds = true,
-    bool useSse,
-    ExpressionCompiler expressionCompiler,
-    SdkConfigurationProvider sdkConfigurationProvider,
+    bool useSse = false,
+    ExpressionCompiler? expressionCompiler,
+    required SdkConfigurationProvider sdkConfigurationProvider,
   }) async {
-    useSse ??= false;
     final chromeProxyService = await ChromeProxyService.create(
       remoteDebugger,
       root,