Enable usage of experimental incremental compiler for web (#43576)

dev/devicelab/bin/tasks/linux_chrome_dev_mode.dart

@@ -6,5 +6,5 @@ import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/web_dev_mode_tests.dart';
 
 Future<void> main() async {
-  await task(createWebDevModeTest());
+  await task(createWebDevModeTest(WebDevice.webServer, false));
 }

dev/devicelab/bin/tasks/macos_chrome_dev_mode.dart

@@ -6,5 +6,5 @@ import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/web_dev_mode_tests.dart';
 
 Future<void> main() async {
-  await task(createWebDevModeTest());
+  await task(createWebDevModeTest(WebDevice.webServer, false));
 }

dev/devicelab/bin/tasks/web_incremental_test.dart

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/tasks/web_dev_mode_tests.dart';
+
+Future<void> main() async {
+  await task(createWebDevModeTest(WebDevice.chrome, true));
+}

dev/devicelab/bin/tasks/windows_chrome_dev_mode.dart

@@ -6,5 +6,5 @@ import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/tasks/web_dev_mode_tests.dart';
 
 Future<void> main() async {
-  await task(createWebDevModeTest());
+  await task(createWebDevModeTest(WebDevice.webServer, false));
 }

dev/devicelab/lib/tasks/web_dev_mode_tests.dart

@@ -20,12 +20,21 @@ const String kFirstRecompileTime  = 'FirstRecompileTime';
 const String kSecondStartupTime = 'SecondStartupTime';
 const String kSecondRestartTime = 'SecondRestartTime';
 
-TaskFunction createWebDevModeTest() {
+
+abstract class WebDevice {
+  static const String chrome = 'chrome';
+  static const String webServer = 'web-server';
+}
+
+TaskFunction createWebDevModeTest(String webDevice, bool enableIncrementalCompiler) {
   return () async {
     final List<String> options = <String>[
-      '--hot', '-d', 'web-server', '--verbose', '--resident', '--target=lib/main.dart',
+      '--hot', '-d', webDevice, '--verbose', '--resident', '--target=lib/main.dart',
     ];
     int hotRestartCount = 0;
+    final String expectedMessage = webDevice == WebDevice.webServer
+      ? 'Recompile complete'
+      : 'Reloaded application';
     final Map<String, int> measurements = <String, int>{};
     await inDirectory<void>(flutterDirectory, () async {
       rmTree(_editedFlutterGalleryDir);
@@ -38,6 +47,8 @@ TaskFunction createWebDevModeTest() {
               <String>['packages', 'get'],
               environment: <String, String>{
                 'FLUTTER_WEB': 'true',
+                if (enableIncrementalCompiler)
+                  'WEB_INCREMENTAL_COMPILER': 'true',
               },
           );
           await packagesGet.exitCode;
@@ -46,16 +57,26 @@ TaskFunction createWebDevModeTest() {
               flutterCommandArgs('run', options),
               environment: <String, String>{
                 'FLUTTER_WEB': 'true',
+                if (enableIncrementalCompiler)
+                  'WEB_INCREMENTAL_COMPILER': 'true',
               },
           );
 
           final Completer<void> stdoutDone = Completer<void>();
           final Completer<void> stderrDone = Completer<void>();
           final Stopwatch sw = Stopwatch()..start();
+          bool restarted = false;
           process.stdout
               .transform<String>(utf8.decoder)
               .transform<String>(const LineSplitter())
               .listen((String line) {
+            // TODO(jonahwilliams): non-dwds builds do not know when the browser is loaded.
+            if (line.contains('Ignoring terminal input')) {
+              Future<void>.delayed(const Duration(seconds: 1)).then((void _) {
+                process.stdin.write(restarted ? 'q' : 'r');
+              });
+              return;
+            }
             if (line.contains('To hot restart')) {
               // measure clean start-up time.
               sw.stop();
@@ -63,9 +84,10 @@ TaskFunction createWebDevModeTest() {
               sw
                 ..reset()
                 ..start();
-              process.stdin.write('R');
+              process.stdin.write('r');
+              return;
             }
-            if (line.contains('Recompile complete')) {
+            if (line.contains(expectedMessage)) {
               if (hotRestartCount == 0) {
                 measurements[kFirstRestartTime] = sw.elapsedMilliseconds;
                 // Update the file and reload again.
@@ -80,9 +102,10 @@ TaskFunction createWebDevModeTest() {
                 sw
                   ..reset()
                   ..start();
-                process.stdin.writeln('R');
+                process.stdin.writeln('r');
                 ++hotRestartCount;
               } else {
+                restarted = true;
                 measurements[kFirstRecompileTime] = sw.elapsedMilliseconds;
                 // Quit after second hot restart.
                 process.stdin.writeln('q');
@@ -119,24 +142,35 @@ TaskFunction createWebDevModeTest() {
               flutterCommandArgs('run', options),
               environment: <String, String>{
                 'FLUTTER_WEB': 'true',
+                if (enableIncrementalCompiler)
+                  'WEB_INCREMENTAL_COMPILER': 'true',
               },
           );
           final Completer<void> stdoutDone = Completer<void>();
           final Completer<void> stderrDone = Completer<void>();
+          bool restarted = false;
           process.stdout
               .transform<String>(utf8.decoder)
               .transform<String>(const LineSplitter())
               .listen((String line) {
-
+            // TODO(jonahwilliams): non-dwds builds do not know when the browser is loaded.
+            if (line.contains('Ignoring terminal input')) {
+              Future<void>.delayed(const Duration(seconds: 1)).then((void _) {
+                process.stdin.write(restarted ? 'q' : 'r');
+              });
+              return;
+            }
             if (line.contains('To hot restart')) {
               measurements[kSecondStartupTime] = sw.elapsedMilliseconds;
               sw
                 ..reset()
                 ..start();
-              process.stdin.write('R');
+              process.stdin.write('r');
+              return;
             }
-            if (line.contains('Recompile complete')) {
-               measurements[kSecondRestartTime] = sw.elapsedMilliseconds;
+            if (line.contains(expectedMessage)) {
+              restarted = true;
+              measurements[kSecondRestartTime] = sw.elapsedMilliseconds;
               process.stdin.writeln('q');
             }
             print('stdout: $line');

dev/devicelab/manifest.yaml

@@ -112,6 +112,13 @@ tasks:
     stage: devicelab
     required_agent_capabilities: ["linux/android"]
 
+  web_incremental_test:
+    description: >
+      Verify that the experimental frontend server support is functional.
+    stage: devicelab
+    required_agent_capabilities: ["linux/android"]
+    flaky: true
+
   flutter_gallery_ios__compile:
     description: >
       Collects various performance metrics of compiling the Flutter

packages/flutter_tools/lib/src/artifacts.dart

@@ -28,7 +28,7 @@ enum Artifact {
   platformLibrariesJson,
   flutterPatchedSdkPath,
   frontendServerSnapshotForEngineDartSdk,
-  /// The root directory of the dartk SDK.
+  /// The root directory of the dart SDK.
   engineDartSdkPath,
   /// The dart binary used to execute any of the required snapshots.
   engineDartBinary,

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -430,7 +430,7 @@ class AppDomain extends Domain {
 
     if (await device.targetPlatform == TargetPlatform.web_javascript) {
       runner = webRunnerFactory.createWebRunner(
-        device,
+        flutterDevice,
         flutterProject: flutterProject,
         target: target,
         debuggingOptions: options,

packages/flutter_tools/lib/src/commands/run.dart

@@ -453,7 +453,7 @@ class RunCommand extends RunCommandBase {
       );
     } else if (webMode) {
       runner = webRunnerFactory.createWebRunner(
-        devices.single,
+        flutterDevices.single,
         target: targetFile,
         flutterProject: flutterProject,
         ipv6: ipv6,

packages/flutter_tools/lib/src/compile.dart

@@ -201,7 +201,6 @@ class PackageUriMapper {
   PackageUriMapper(String scriptPath, String packagesPath, String fileSystemScheme, List<String> fileSystemRoots) {
     final Map<String, Uri> packageMap = PackageMap(fs.path.absolute(packagesPath)).map;
     final String scriptUri = Uri.file(scriptPath, windows: platform.isWindows).toString();
-
     for (String packageName in packageMap.keys) {
       final String prefix = packageMap[packageName].toString();
       // Only perform a multi-root mapping if there are multiple roots.

packages/flutter_tools/lib/src/devfs.dart

@@ -349,12 +349,19 @@ class UpdateFSReport {
   int get invalidatedSourcesCount => _invalidatedSourcesCount;
   int get syncedBytes => _syncedBytes;
 
+  /// JavaScript modules produced by the incremental compiler in `dartdevc`
+  /// mode.
+  ///
+  /// Only used for JavaScript compilation.
+  List<String> invalidatedModules;
+
   void incorporateResults(UpdateFSReport report) {
     if (!report._success) {
       _success = false;
     }
     _invalidatedSourcesCount += report._invalidatedSourcesCount;
     _syncedBytes += report._syncedBytes;
+    invalidatedModules ??= report.invalidatedModules;
   }
 
   bool _success;

packages/flutter_tools/lib/src/features.dart

@@ -151,10 +151,15 @@ const Feature flutterAndroidEmbeddingV2Feature = Feature(
 const Feature flutterWebIncrementalCompiler = Feature(
   name: 'Enable the incremental compiler for web builds',
   configSetting: 'enable-web-incremental-compiler',
+  environmentOverride: 'WEB_INCREMENTAL_COMPILER',
   master: FeatureChannelSetting(
     available: true,
     enabledByDefault: false,
   ),
+  dev: FeatureChannelSetting(
+    available: true,
+    enabledByDefault: false,
+  ),
 );
 
 /// A [Feature] is a process for conditionally enabling tool features.

packages/flutter_tools/lib/src/web/bootstrap.dart

@@ -75,21 +75,25 @@ define("main_module", ["$entrypoint", "dart_sdk"], function(app, dart_sdk) {
   dart_sdk.dart.setStartAsyncSynchronously(true);
   dart_sdk._isolate_helper.startRootIsolate(() => {}, []);
   dart_sdk._debugger.registerDevtoolsFormatter();
-  dart_sdk.ui.webOnlyInitializePlatform();
+  let voidToNull = () => (voidToNull = dart_sdk.dart.constFn(dart_sdk.dart.fnType(dart_sdk.core.Null, [dart_sdk.dart.void])))();
 
   // Attach the main entrypoint and hot reload functionality to the window.
   window.\$mainEntrypoint = app.main.main;
   if (window.\$hotReload == null) {
     window.\$hotReload = function(cb) {
-      dart_sdk.developer.invokeExtension("ext.flutter.disassemble", "{}");
-      dart_sdk.dart.hotRestart();
-      window.\$mainEntrypoint();
-      if (cb != null) {
-        cb();
-      }
+      dart_sdk.developer.invokeExtension("ext.flutter.disassemble", "{}").then((_) => {
+        dart_sdk.dart.hotRestart();
+        dart_sdk.ui.webOnlyInitializePlatform().then(dart_sdk.core.Null, dart_sdk.dart.fn(_ => {
+          window.\$mainEntrypoint();
+          window.requestAnimationFrame(cb);
+        }, voidToNull()));
+      });
     }
   }
-  app.main.main();
+
+  dart_sdk.ui.webOnlyInitializePlatform().then(dart_sdk.core.Null, dart_sdk.dart.fn(_ => {
+    app.main.main();
+  }, voidToNull()));
 });
 
 // Require JS configuration.

packages/flutter_tools/lib/src/web/chrome.dart

@@ -71,6 +71,11 @@ void resetChromeForTesting() {
   ChromeLauncher._currentCompleter = Completer<Chrome>();
 }
 
+@visibleForTesting
+void launchChromeInstance(Chrome chrome) {
+  ChromeLauncher._currentCompleter.complete(chrome);
+}
+
 /// Responsible for launching chrome with devtools configured.
 class ChromeLauncher {
   const ChromeLauncher();

packages/flutter_tools/lib/src/web/devfs_web.dart

@@ -7,12 +7,18 @@ import 'dart:typed_data';
 import 'package:meta/meta.dart';
 import 'package:mime/mime.dart' as mime;
 
+import '../artifacts.dart';
+import '../asset.dart';
 import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
 import '../build_info.dart';
+import '../bundle.dart';
+import '../compile.dart';
 import '../convert.dart';
+import '../devfs.dart';
 import '../globals.dart';
+import 'bootstrap.dart';
 
 /// A web server which handles serving JavaScript and assets.
 ///
@@ -49,7 +55,10 @@ class WebAssetServer {
   }
 
   final HttpServer _httpServer;
+  // If holding these in memory is too much overhead, this can be switched to a
+  // RandomAccessFile and read on demand.
   final Map<String, Uint8List> _files = <String, Uint8List>{};
+  final Map<String, Uint8List> _sourcemaps = <String, Uint8List>{};
 
   // handle requests for JavaScript source, dart sources maps, or asset files.
   Future<void> _handleRequest(HttpRequest request) async {
@@ -71,8 +80,7 @@ class WebAssetServer {
     }
 
     // If this is a JavaScript file, it must be in the in-memory cache.
-    // Attempt to look up the file by URI, returning a 404 if it is not
-    // found.
+    // Attempt to look up the file by URI.
     if (_files.containsKey(request.uri.path)) {
       final List<int> bytes = _files[request.uri.path];
       response.headers
@@ -82,6 +90,18 @@ class WebAssetServer {
       await response.close();
       return;
     }
+    // If this is a sourcemap file, then it might be in the in-memory cache.
+    // Attempt to lookup the file by URI.
+    if (_sourcemaps.containsKey(request.uri.path)) {
+      final List<int> bytes = _sourcemaps[request.uri.path];
+      response.headers
+        ..add('Content-Length', bytes.length)
+        ..add('Content-Type', 'application/json');
+      response.add(bytes);
+      await response.close();
+      return;
+    }
+
     // If this is a dart file, it must be on the local file system and is
     // likely coming from a source map request. Attempt to look in the
     // local filesystem for it, and return a 404 if it is not found. The tool
@@ -95,6 +115,18 @@ class WebAssetServer {
       file = fs.file(fs.path.join(getAssetBuildDirectory(), fs.path.relative(assetPath)));
     }
 
+    // If it isn't a project source or an asset, it must be a dart SDK source.
+    // or a flutter web SDK source.
+    if (!file.existsSync()) {
+      final Directory dartSdkParent = fs.directory(artifacts.getArtifactPath(Artifact.engineDartSdkPath)).parent;
+      file = fs.file(fs.path.joinAll(<String>[dartSdkParent.path, ...request.uri.pathSegments]));
+    }
+
+    if (!file.existsSync()) {
+      final String flutterWebSdk = artifacts.getArtifactPath(Artifact.flutterWebSdk);
+      file = fs.file(fs.path.joinAll(<String>[flutterWebSdk, ...request.uri.pathSegments]));
+    }
+
     if (!file.existsSync()) {
       response.statusCode = HttpStatus.notFound;
       await response.close();
@@ -131,30 +163,186 @@ class WebAssetServer {
   /// Update the in-memory asset server with the provided source and manifest files.
   ///
   /// Returns a list of updated modules.
-  List<String> write(File sourceFile, File manifestFile) {
+  List<String> write(File codeFile, File manifestFile, File sourcemapFile) {
     final List<String> modules = <String>[];
-    final Uint8List bytes = sourceFile.readAsBytesSync();
+    final Uint8List codeBytes = codeFile.readAsBytesSync();
+    final Uint8List sourcemapBytes = sourcemapFile.readAsBytesSync();
     final Map<String, Object> manifest = json.decode(manifestFile.readAsStringSync());
     for (String filePath in manifest.keys) {
       if (filePath == null) {
         printTrace('Invalid manfiest file: $filePath');
         continue;
       }
-      final List<Object> offsets = manifest[filePath];
-      if (offsets.length != 2) {
+      final Map<String, Object> offsets = manifest[filePath];
+      final List<Object> codeOffsets = offsets['code'];
+      final List<Object> sourcemapOffsets = offsets['sourcemap'];
+      if (codeOffsets.length != 2 || sourcemapOffsets.length != 2) {
         printTrace('Invalid manifest byte offsets: $offsets');
         continue;
       }
-      final int start = offsets[0];
-      final int end = offsets[1];
-      if (start < 0 || end > bytes.lengthInBytes) {
-        printTrace('Invalid byte index: [$start, $end]');
+
+      final int codeStart = codeOffsets[0];
+      final int codeEnd = codeOffsets[1];
+      if (codeStart < 0 || codeEnd > codeBytes.lengthInBytes) {
+        printTrace('Invalid byte index: [$codeStart, $codeEnd]');
         continue;
       }
-      final Uint8List byteView = Uint8List.view(bytes.buffer, start, end - start);
+      final Uint8List byteView = Uint8List.view(
+        codeBytes.buffer,
+        codeStart,
+        codeEnd - codeStart,
+      );
       _files[filePath] = byteView;
+
+      final int sourcemapStart = sourcemapOffsets[0];
+      final int sourcemapEnd = sourcemapOffsets[1];
+      if (sourcemapStart < 0 || sourcemapEnd > sourcemapBytes.lengthInBytes) {
+        printTrace('Invalid byte index: [$sourcemapStart, $sourcemapEnd]');
+        continue;
+      }
+      final Uint8List sourcemapView = Uint8List.view(
+        sourcemapBytes.buffer,
+        sourcemapStart,
+        sourcemapEnd - sourcemapStart ,
+      );
+      _sourcemaps['$filePath.map'] = sourcemapView;
+
       modules.add(filePath);
     }
     return modules;
   }
 }
+
+class WebDevFS implements DevFS {
+  WebDevFS(this.hostname, this.port, this._packagesFilePath);
+
+  final String hostname;
+  final int port;
+  final String _packagesFilePath;
+  WebAssetServer _webAssetServer;
+
+  @override
+  List<Uri> sources = <Uri>[];
+
+  @override
+  DateTime lastCompiled;
+
+  // We do not evict assets on the web.
+  @override
+  Set<String> get assetPathsToEvict => const <String>{};
+
+  @override
+  Uri get baseUri => null;
+
+  @override
+  Future<Uri> create() async {
+    _webAssetServer = await WebAssetServer.start(hostname, port);
+   return Uri.base;
+  }
+
+  @override
+  Future<void> destroy() async {
+    await _webAssetServer.dispose();
+  }
+
+  @override
+  Uri deviceUriToHostUri(Uri deviceUri) {
+    return deviceUri;
+  }
+
+  @override
+  String get fsName => 'web_asset';
+
+  @override
+  Directory get rootDirectory => null;
+
+  @override
+  Future<UpdateFSReport> update({
+    String mainPath,
+    String target,
+    AssetBundle bundle,
+    DateTime firstBuildTime,
+    bool bundleFirstUpload = false,
+    @required ResidentCompiler generator,
+    String dillOutputPath,
+    @required bool trackWidgetCreation,
+    bool fullRestart = false,
+    String projectRootPath,
+    String pathToReload,
+    List<Uri> invalidatedFiles,
+  }) async {
+    assert(trackWidgetCreation != null);
+    assert(generator != null);
+    if (bundleFirstUpload) {
+      final File requireJS = fs.file(fs.path.join(
+        artifacts.getArtifactPath(Artifact.engineDartSdkPath),
+        'lib',
+        'dev_compiler',
+        'kernel',
+        'amd',
+        'require.js',
+      ));
+      final File dartSdk = fs.file(fs.path.join(
+        artifacts.getArtifactPath(Artifact.flutterWebSdk),
+        'kernel',
+        'amd',
+        'dart_sdk.js',
+      ));
+      final File dartSdkSourcemap = fs.file(fs.path.join(
+        artifacts.getArtifactPath(Artifact.flutterWebSdk),
+        'kernel',
+        'amd',
+        'dart_sdk.js.map',
+      ));
+      final File stackTraceMapper = fs.file(fs.path.join(
+        artifacts.getArtifactPath(Artifact.engineDartSdkPath),
+        'lib',
+        'dev_compiler',
+        'web',
+        'dart_stack_trace_mapper.js',
+      ));
+      _webAssetServer.writeFile('/main.dart.js', generateBootstrapScript(
+        requireUrl: requireJS.path,
+        mapperUrl: stackTraceMapper.path,
+        entrypoint: '$mainPath.js',
+      ));
+      _webAssetServer.writeFile('/main_module.js', generateMainModule(
+        entrypoint: '$mainPath.js',
+      ));
+      _webAssetServer.writeFile('/dart_sdk.js', dartSdk.readAsStringSync());
+      _webAssetServer.writeFile('/dart_sdk.js.map', dartSdkSourcemap.readAsStringSync());
+    }
+    final DateTime candidateCompileTime = DateTime.now();
+    if (fullRestart) {
+      generator.reset();
+    }
+     final CompilerOutput compilerOutput = await generator.recompile(
+      mainPath,
+      invalidatedFiles,
+      outputPath:  dillOutputPath ?? getDefaultApplicationKernelPath(trackWidgetCreation: trackWidgetCreation),
+      packagesFilePath : _packagesFilePath,
+    );
+    if (compilerOutput == null || compilerOutput.errorCount > 0) {
+      return UpdateFSReport(success: false);
+    }
+    // Only update the last compiled time if we successfully compiled.
+    lastCompiled = candidateCompileTime;
+    // list of sources that needs to be monitored are in [compilerOutput.sources]
+    sources = compilerOutput.sources;
+    File codeFile;
+    File manifestFile;
+    File sourcemapFile;
+    List<String> modules;
+    try {
+      codeFile = fs.file('${compilerOutput.outputFilename}.sources');
+      manifestFile = fs.file('${compilerOutput.outputFilename}.json');
+      sourcemapFile = fs.file('${compilerOutput.outputFilename}.map');
+      modules = _webAssetServer.write(codeFile, manifestFile, sourcemapFile);
+    } on FileSystemException catch (err) {
+      throwToolExit('Failed to load recompiled sources:\n$err');
+    }
+    return UpdateFSReport(success: true, syncedBytes: codeFile.lengthSync(),
+      invalidatedSourcesCount: invalidatedFiles.length)
+        ..invalidatedModules = modules;
+  }
+}

packages/flutter_tools/lib/src/web/web_runner.dart

@@ -17,7 +17,7 @@ abstract class WebRunnerFactory {
 
   /// Create a [ResidentRunner] for the web.
   ResidentRunner createWebRunner(
-    Device device, {
+    FlutterDevice device, {
     String target,
     @required bool stayResident,
     @required FlutterProject flutterProject,

packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart

@@ -63,11 +63,12 @@ void main() {
   test('Refuses to build using runner when missing index.html', () => testbed.run(() async {
     fs.file(fs.path.join('web', 'index.html')).deleteSync();
 
-    final ResidentWebRunner runner = ResidentWebRunner(
+    final ResidentWebRunner runner = DwdsWebRunnerFactory().createWebRunner(
       null,
       flutterProject: FlutterProject.current(),
       ipv6: false,
       debuggingOptions: DebuggingOptions.enabled(BuildInfo.debug),
+      stayResident: true,
     );
     expect(await runner.run(), 1);
   }));

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

@@ -26,17 +26,21 @@ void main() {
   Testbed testbed;
   MockFlutterWebFs mockWebFs;
   ResidentWebRunner residentWebRunner;
+  MockFlutterDevice mockFlutterDevice;
 
   setUp(() {
     mockWebFs = MockFlutterWebFs();
     final MockWebDevice mockWebDevice = MockWebDevice();
+    mockFlutterDevice = MockFlutterDevice();
+    when(mockFlutterDevice.device).thenReturn(mockWebDevice);
     testbed = Testbed(
       setup: () {
-        residentWebRunner = ResidentWebRunner(
-          mockWebDevice,
+        residentWebRunner =  residentWebRunner = DwdsWebRunnerFactory().createWebRunner(
+          mockFlutterDevice,
           flutterProject: FlutterProject.current(),
           debuggingOptions: DebuggingOptions.disabled(BuildInfo.release),
           ipv6: true,
+          stayResident: true,
         );
       },
       overrides: <Type, Generator>{
@@ -118,4 +122,4 @@ class MockFlutterWebFs extends Mock implements WebFs {}
 class MockDebugConnection extends Mock implements DebugConnection {}
 class MockVmService extends Mock implements VmService {}
 class MockStatus extends Mock implements Status {}
-
+class MockFlutterDevice extends Mock implements FlutterDevice {}

packages/flutter_tools/test/general.shard/web/devfs_web_test.dart

@@ -89,28 +89,36 @@ void main() {
   test('Handles against malformed manifest', () => testbed.run(() async {
     final File source = fs.file('source')
       ..writeAsStringSync('main() {}');
+    final File sourcemap = fs.file('sourcemap')
+      ..writeAsStringSync('{}');
 
     // Missing ending offset.
     final File manifestMissingOffset = fs.file('manifestA')
-      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <int>[0]}));
-    // Non-file URI.
-    final File manifestNonFileScheme = fs.file('manifestA')
-      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <int>[0, 10]}));
-
+      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <String, Object>{
+        'code': <int>[0],
+        'sourcemap': <int>[0],
+      }}));
     final File manifestOutOfBounds = fs.file('manifest')
-      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <int>[0, 100]}));
+      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <String, Object>{
+        'code': <int>[0, 100],
+        'sourcemap': <int>[0],
+      }}));
 
-    expect(webAssetServer.write(source, manifestMissingOffset), isEmpty);
-    expect(webAssetServer.write(source, manifestNonFileScheme), isEmpty);
-    expect(webAssetServer.write(source, manifestOutOfBounds), isEmpty);
+    expect(webAssetServer.write(source, manifestMissingOffset, sourcemap), isEmpty);
+    expect(webAssetServer.write(source, manifestOutOfBounds, sourcemap), isEmpty);
   }));
 
   test('serves JavaScript files from in memory cache', () => testbed.run(() async {
     final File source = fs.file('source')
       ..writeAsStringSync('main() {}');
+    final File sourcemap = fs.file('sourcemap')
+      ..writeAsStringSync('{}');
     final File manifest = fs.file('manifest')
-      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <int>[0, source.lengthSync()]}));
-    webAssetServer.write(source, manifest);
+      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <String, Object>{
+        'code': <int>[0, source.lengthSync()],
+        'sourcemap': <int>[0, 2],
+      }}));
+    webAssetServer.write(source, manifest, sourcemap);
 
     when(request.uri).thenReturn(Uri.parse('http://foobar/foo.js'));
     requestController.add(request);
@@ -136,9 +144,14 @@ void main() {
   test('handles missing JavaScript files from in memory cache', () => testbed.run(() async {
     final File source = fs.file('source')
       ..writeAsStringSync('main() {}');
+    final File sourcemap = fs.file('sourcemap')
+      ..writeAsStringSync('{}');
     final File manifest = fs.file('manifest')
-      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <int>[0, source.lengthSync()]}));
-    webAssetServer.write(source, manifest);
+      ..writeAsStringSync(json.encode(<String, Object>{'/foo.js': <String, Object>{
+        'code': <int>[0, source.lengthSync()],
+        'sourcemap': <int>[0, 2],
+      }}));
+    webAssetServer.write(source, manifest, sourcemap);
 
     when(request.uri).thenReturn(Uri.parse('http://foobar/bar.js'));
     requestController.add(request);