Migrated more dwds directories to null safety (#1660)

* Removed dependecies on dwds.dart inside dwds code

* Migrate loaders and debugging/metadata directories to null safety

* Add format errors

* Removed unnecessary 'late' from metadata fields

* Format

* Migrated more dwds directories to null safety:

connection (some files)
handlers (some files)
readers
servers
services (some files)
utilities

* Fix test failures

* Fix injector test failure

Author: Anna Gringauze

dwds/lib/src/connections/app_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 'dart:convert';
 

dwds/lib/src/handlers/injector.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';
@@ -32,7 +30,7 @@ const _clientScript = 'dwds/src/injected/client';
 /// information.
 class DwdsInjector {
   final LoadStrategy _loadStrategy;
-  final Future<String> _extensionUri;
+  final Future<String>? _extensionUri;
   final _devHandlerPaths = StreamController<String>();
   final _logger = Logger('DwdsInjector');
   final bool _enableDevtoolsLaunch;
@@ -41,14 +39,14 @@ class DwdsInjector {
 
   DwdsInjector(
     this._loadStrategy, {
-    Future<String> extensionUri,
-    bool enableDevtoolsLaunch,
-    bool useSseForInjectedClient,
-    bool emitDebugEvents,
+    Future<String>? extensionUri,
+    bool enableDevtoolsLaunch = false,
+    bool useSseForInjectedClient = true,
+    bool emitDebugEvents = true,
   })  : _extensionUri = extensionUri,
         _enableDevtoolsLaunch = enableDevtoolsLaunch,
-        _useSseForInjectedClient = useSseForInjectedClient ?? true,
-        _emitDebugEvents = emitDebugEvents ?? true;
+        _useSseForInjectedClient = useSseForInjectedClient,
+        _emitDebugEvents = emitDebugEvents;
 
   /// Returns the embedded dev handler paths.
   ///
@@ -60,6 +58,9 @@ class DwdsInjector {
           if (request.url.path.endsWith('$_clientScript.js')) {
             final uri = await Isolate.resolvePackageUri(
                 Uri.parse('package:$_clientScript.js'));
+            if (uri == null) {
+              throw StateError('Cannot resolve "package:$_clientScript.js"');
+            }
             final result = await File(uri.toFilePath()).readAsString();
             return Response.ok(result, headers: {
               HttpHeaders.contentTypeHeader: 'application/javascript'
@@ -123,8 +124,7 @@ class DwdsInjector {
             return response.change(body: body, headers: newHeaders);
           } else {
             final loadResponse = await _loadStrategy.handler(request);
-            if (loadResponse != null &&
-                loadResponse.statusCode != HttpStatus.notFound) {
+            if (loadResponse.statusCode != HttpStatus.notFound) {
               return loadResponse;
             }
             return innerHandler(request);
@@ -140,7 +140,7 @@ String _injectClientAndHoistMain(
   String appId,
   String devHandlerPath,
   String entrypointPath,
-  String extensionUri,
+  String? extensionUri,
   LoadStrategy loadStrategy,
   bool enableDevtoolsLaunch,
   bool emitDebugEvents,
@@ -194,7 +194,7 @@ String _injectedClientSnippet(
   String appId,
   String devHandlerPath,
   String entrypointPath,
-  String extensionUri,
+  String? extensionUri,
   LoadStrategy loadStrategy,
   bool enableDevtoolsLaunch,
   bool emitDebugEvents,

dwds/lib/src/readers/frontend_server_asset_reader.dart

@@ -2,11 +2,10 @@
 // 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:convert';
 import 'dart:io';
 
+import 'package:logging/logging.dart';
 import 'package:package_config/package_config.dart';
 import 'package:path/path.dart' as p;
 
@@ -15,6 +14,7 @@ import '../readers/asset_reader.dart';
 /// A reader for Dart sources and related source maps provided by the Frontend
 /// Server.
 class FrontendServerAssetReader implements AssetReader {
+  final _logger = Logger('FrontendServerAssetReader');
   final File _mapOriginal;
   final File _mapIncremental;
   final File _jsonOriginal;
@@ -49,29 +49,38 @@ class FrontendServerAssetReader implements AssetReader {
             .absolute(p.join(_packageRoot, '.dart_tool/package_config.json'))));
 
   @override
-  Future<String> dartSourceContents(String serverPath) async {
-    if (!serverPath.endsWith('.dart')) return null;
-    final packageConfig = await _packageConfig;
-
-    Uri fileUri;
-    if (serverPath.startsWith('packages/')) {
-      final packagePath = serverPath.replaceFirst('packages/', 'package:');
-      fileUri = packageConfig.resolve(Uri.parse(packagePath));
-    } else {
-      fileUri = p.toUri(p.join(_packageRoot, serverPath));
+  Future<String?> dartSourceContents(String serverPath) async {
+    if (serverPath.endsWith('.dart')) {
+      final packageConfig = await _packageConfig;
+
+      Uri? fileUri;
+      if (serverPath.startsWith('packages/')) {
+        final packagePath = serverPath.replaceFirst('packages/', 'package:');
+        fileUri = packageConfig.resolve(Uri.parse(packagePath));
+      } else {
+        fileUri = p.toUri(p.join(_packageRoot, serverPath));
+      }
+      if (fileUri != null) {
+        final source = File(fileUri.toFilePath());
+        if (source.existsSync()) return source.readAsString();
+      }
     }
-
-    final source = File(fileUri.toFilePath());
-    if (!await source.exists()) return null;
-    return await source.readAsString();
+    _logger.severe('Cannot find source contents for $serverPath');
+    return null;
   }
 
   @override
-  Future<String> sourceMapContents(String serverPath) async {
-    if (!serverPath.endsWith('lib.js.map')) return null;
-    if (!serverPath.startsWith('/')) serverPath = '/$serverPath';
-    // Strip the .map, sources are looked up by their js path.
-    return _mapContents[p.withoutExtension(serverPath)];
+  Future<String?> sourceMapContents(String serverPath) async {
+    if (serverPath.endsWith('lib.js.map')) {
+      if (!serverPath.startsWith('/')) serverPath = '/$serverPath';
+      // Strip the .map, sources are looked up by their js path.
+      serverPath = p.withoutExtension(serverPath);
+      if (_mapContents.containsKey(serverPath)) {
+        return _mapContents[serverPath];
+      }
+    }
+    _logger.severe('Cannot find source map contents for $serverPath');
+    return null;
   }
 
   /// Updates the internal caches by reading the Frontend Server output files.

dwds/lib/src/readers/proxy_server_asset_reader.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';
@@ -20,14 +18,11 @@ import 'asset_reader.dart';
 class ProxyServerAssetReader implements AssetReader {
   final _logger = Logger('ProxyServerAssetReader');
 
-  Handler _handler;
-  http.Client _client;
+  late final Handler _handler;
+  late final http.Client _client;
 
   ProxyServerAssetReader(int assetServerPort,
-      {String root, String host, bool isHttps}) {
-    host ??= 'localhost';
-    root ??= '';
-    isHttps ??= false;
+      {String root = '', String host = 'localhost', bool isHttps = false}) {
     final scheme = isHttps ? 'https://' : 'http://';
     final inner = HttpClient()
       ..maxConnectionsPerHost = 200
@@ -37,19 +32,19 @@ class ProxyServerAssetReader implements AssetReader {
         ? IOClient(inner..badCertificateCallback = (cert, host, port) => true)
         : IOClient(inner);
     var url = '$scheme$host:$assetServerPort/';
-    if (root?.isNotEmpty ?? false) url += '$root/';
+    if (root.isNotEmpty) url += '$root/';
     _handler = proxyHandler(url, client: _client);
   }
 
   @override
-  Future<String> dartSourceContents(String serverPath) =>
+  Future<String?> dartSourceContents(String serverPath) =>
       _readResource(serverPath);
 
   @override
-  Future<String> sourceMapContents(String serverPath) =>
+  Future<String?> sourceMapContents(String serverPath) =>
       _readResource(serverPath);
 
-  Future<String> _readResource(String path) async {
+  Future<String?> _readResource(String path) async {
     // Handlers expect a fully formed HTML URI. The actual hostname and port
     // does not matter.
     final response =
@@ -71,7 +66,7 @@ class ProxyServerAssetReader implements AssetReader {
   }
 
   @override
-  Future<String> metadataContents(String serverPath) =>
+  Future<String?> metadataContents(String serverPath) =>
       _readResource(serverPath);
 
   @override

dwds/lib/src/servers/devtools.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:io';
 
 typedef DevtoolsLauncher = Future<DevTools> Function(String hostname);
@@ -17,7 +15,7 @@ class DevTools {
   /// Null until [close] is called.
   ///
   /// All subsequent calls to [close] will return this future.
-  Future<void> _closed;
+  Future<void>? _closed;
 
   DevTools(this.hostname, this.port, this._server);
 

dwds/lib/src/servers/extension_backend.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:io';
 
@@ -20,21 +18,20 @@ import 'extension_debugger.dart';
 const authenticationResponse = 'Dart Debug Authentication Success!\n\n'
     'You can close this tab and launch the Dart Debug Extension again.';
 
-Logger _logger = Logger('ExtensionBackend');
-
 /// A backend for the Dart Debug Extension.
 ///
 /// Sets up an SSE handler to communicate with the extension background.
 /// Uses that SSE channel to create an [ExtensionDebugger].
 class ExtensionBackend {
+  static final _logger = Logger('ExtensionBackend');
   final String hostname;
   final int port;
   final HttpServer _server;
 
   /// Null until [close] is called.
   ///
   /// All subsequent calls to [close] will return this future.
-  Future<void> _closed;
+  Future<void>? _closed;
 
   ExtensionBackend._(
       SocketHandler socketHandler, this.hostname, this.port, this._server)
@@ -47,7 +44,8 @@ class ExtensionBackend {
     cascade = cascade.add((request) {
       if (request.url.path == authenticationPath) {
         return Response.ok(authenticationResponse, headers: {
-          'Access-Control-Allow-Origin': request.headers['origin'],
+          if (request.headers.containsKey('origin'))
+            'Access-Control-Allow-Origin': request.headers['origin']!,
           'Access-Control-Allow-Credentials': 'true'
         });
       }