[flutter_tools][web] serve dummy service_worker and manifest file in run mode (#50115)

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

@@ -49,7 +49,7 @@ class WebAssetServer {
       final InternetAddress address = (await InternetAddress.lookup(hostname)).first;
       final HttpServer httpServer = await HttpServer.bind(address, port);
       final Packages packages =
-          await loadPackagesFile(Uri.base.resolve('.packages'));
+          await loadPackagesFile(Uri.base.resolve('.packages'), loader: (Uri uri) => globals.fs.file(uri).readAsBytes());
       return WebAssetServer(httpServer, packages, address,
           onError: (dynamic error, StackTrace stackTrace) {
         httpServer.close(force: true);
@@ -73,6 +73,12 @@ class WebAssetServer {
   final Packages _packages;
   final InternetAddress internetAddress;
 
+  @visibleForTesting
+  Uint8List getFile(String path) => _files[path];
+
+  @visibleForTesting
+  Uint8List getSourceMap(String path) => _sourcemaps[path];
+
   // handle requests for JavaScript source, dart sources maps, or asset files.
   Future<void> _handleRequest(HttpRequest request) async {
     final HttpResponse response = request.response;
@@ -102,7 +108,7 @@ class WebAssetServer {
     // If this is a JavaScript file, it must be in the in-memory cache.
     // Attempt to look up the file by URI.
     if (_files.containsKey(requestPath)) {
-      final List<int> bytes = _files[requestPath];
+      final List<int> bytes = getFile(requestPath);
       response.headers
         ..add('Content-Length', bytes.length)
         ..add('Content-Type', 'application/javascript');
@@ -113,7 +119,7 @@ class WebAssetServer {
     // 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(requestPath)) {
-      final List<int> bytes = _sourcemaps[requestPath];
+      final List<int> bytes = getSourceMap(requestPath);
       response.headers
         ..add('Content-Length', bytes.length)
         ..add('Content-Type', 'application/json');
@@ -258,7 +264,9 @@ class WebDevFS implements DevFS {
   final String hostname;
   final int port;
   final String _packagesFilePath;
-  WebAssetServer _webAssetServer;
+
+  @visibleForTesting
+  WebAssetServer webAssetServer;
 
   @override
   List<Uri> sources = <Uri>[];
@@ -275,13 +283,13 @@ class WebDevFS implements DevFS {
 
   @override
   Future<Uri> create() async {
-    _webAssetServer = await WebAssetServer.start(hostname, port);
+    webAssetServer = await WebAssetServer.start(hostname, port);
     return Uri.parse('http://$hostname:$port');
   }
 
   @override
   Future<void> destroy() async {
-    await _webAssetServer.dispose();
+    await webAssetServer.dispose();
   }
 
   @override
@@ -314,55 +322,32 @@ class WebDevFS implements DevFS {
     assert(trackWidgetCreation != null);
     assert(generator != null);
     if (bundleFirstUpload) {
-      final File requireJS = globals.fs.file(globals.fs.path.join(
-        globals.artifacts.getArtifactPath(Artifact.engineDartSdkPath),
-        'lib',
-        'dev_compiler',
-        'kernel',
-        'amd',
-        'require.js',
-      ));
-      final File dartSdk = globals.fs.file(globals.fs.path.join(
-        globals.artifacts.getArtifactPath(Artifact.flutterWebSdk),
-        'kernel',
-        'amd',
-        'dart_sdk.js',
-      ));
-      final File dartSdkSourcemap = globals.fs.file(globals.fs.path.join(
-        globals.artifacts.getArtifactPath(Artifact.flutterWebSdk),
-        'kernel',
-        'amd',
-        'dart_sdk.js.map',
-      ));
-      final File stackTraceMapper = globals.fs.file(globals.fs.path.join(
-        globals.artifacts.getArtifactPath(Artifact.engineDartSdkPath),
-        'lib',
-        'dev_compiler',
-        'web',
-        'dart_stack_trace_mapper.js',
-      ));
       final String entrypoint = PackageUriMapper(mainPath, '.packages', null, null)
         .map(mainPath)
         ?.pathSegments?.join('/');
-      _webAssetServer.writeFile(
+      webAssetServer.writeFile('/manifest.json', '{"info":"manifest not generated in run mode."}');
+      webAssetServer.writeFile('/flutter_service_worker.js', '// Service worker not loaded in run mode.');
+      webAssetServer.writeFile(
           '/main.dart.js',
           generateBootstrapScript(
             requireUrl: _filePathToUriFragment(requireJS.path),
             mapperUrl: _filePathToUriFragment(stackTraceMapper.path),
             entrypoint: entrypoint != null ? '/packages/$entrypoint.lib.js' : '$mainPath.lib.js',
           ));
-      _webAssetServer.writeFile(
+      webAssetServer.writeFile(
           '/main_module.js',
           generateMainModule(
             entrypoint: entrypoint != null ? '/packages/$entrypoint.lib.js' : '$mainPath.lib.js',
           ));
-      _webAssetServer.writeFile('/dart_sdk.js', dartSdk.readAsStringSync());
-      _webAssetServer.writeFile(
+      webAssetServer.writeFile('/dart_sdk.js', dartSdk.readAsStringSync());
+      webAssetServer.writeFile(
           '/dart_sdk.js.map', dartSdkSourcemap.readAsStringSync());
       // TODO(jonahwilliams): refactor the asset code in this and the regular devfs to
       // be shared.
-      await writeBundle(
-          globals.fs.directory(getAssetBuildDirectory()), bundle.entries);
+      if (bundle != null) {
+        await writeBundle(
+            globals.fs.directory(getAssetBuildDirectory()), bundle.entries);
+      }
     }
     final DateTime candidateCompileTime = DateTime.now();
     if (fullRestart) {
@@ -391,7 +376,7 @@ class WebDevFS implements DevFS {
       codeFile = globals.fs.file('${compilerOutput.outputFilename}.sources');
       manifestFile = globals.fs.file('${compilerOutput.outputFilename}.json');
       sourcemapFile = globals.fs.file('${compilerOutput.outputFilename}.map');
-      modules = _webAssetServer.write(codeFile, manifestFile, sourcemapFile);
+      modules = webAssetServer.write(codeFile, manifestFile, sourcemapFile);
     } on FileSystemException catch (err) {
       throwToolExit('Failed to load recompiled sources:\n$err');
     }
@@ -401,6 +386,41 @@ class WebDevFS implements DevFS {
         invalidatedSourcesCount: invalidatedFiles.length)
       ..invalidatedModules = modules.map(_filePathToUriFragment).toList();
   }
+
+  @visibleForTesting
+  final File requireJS = globals.fs.file(globals.fs.path.join(
+    globals.artifacts.getArtifactPath(Artifact.engineDartSdkPath),
+    'lib',
+    'dev_compiler',
+    'kernel',
+    'amd',
+    'require.js',
+  ));
+
+  @visibleForTesting
+  final File dartSdk = globals.fs.file(globals.fs.path.join(
+    globals.artifacts.getArtifactPath(Artifact.flutterWebSdk),
+    'kernel',
+    'amd',
+    'dart_sdk.js',
+  ));
+
+  @visibleForTesting
+  final File dartSdkSourcemap = globals.fs.file(globals.fs.path.join(
+    globals.artifacts.getArtifactPath(Artifact.flutterWebSdk),
+    'kernel',
+    'amd',
+    'dart_sdk.js.map',
+  ));
+
+  @visibleForTesting
+  final File stackTraceMapper = globals.fs.file(globals.fs.path.join(
+    globals.artifacts.getArtifactPath(Artifact.engineDartSdkPath),
+    'lib',
+    'dev_compiler',
+    'web',
+    'dart_stack_trace_mapper.js',
+  ));
 }
 
 String _filePathToUriFragment(String path) {

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

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
+import 'package:flutter_tools/src/compile.dart';
 import 'package:flutter_tools/src/convert.dart';
 import 'package:flutter_tools/src/web/devfs_web.dart';
 import 'package:mockito/mockito.dart';
@@ -321,6 +322,43 @@ void main() {
 
     verify(mockHttpServer.close()).called(1);
   }));
+
+  test('Can start web server with specified assets', () => testbed.run(() async {
+    globals.fs.file('a.sources').writeAsStringSync('');
+    globals.fs.file('a.json').writeAsStringSync('{}');
+    globals.fs.file('a.map').writeAsStringSync('{}');
+    globals.fs.file('.packages').writeAsStringSync('\n');
+
+    final ResidentCompiler residentCompiler = MockResidentCompiler();
+    when(residentCompiler.recompile(
+      any,
+      any,
+      outputPath: anyNamed('outputPath'),
+      packagesFilePath: anyNamed('packagesFilePath'),
+    )).thenAnswer((Invocation invocation) async {
+      return const CompilerOutput('a', 0, <Uri>[]);
+    });
+
+    final WebDevFS webDevFS = WebDevFS('localhost', 0, '.packages');
+    webDevFS.requireJS.createSync(recursive: true);
+    webDevFS.dartSdk.createSync(recursive: true);
+    webDevFS.dartSdkSourcemap.createSync(recursive: true);
+    webDevFS.stackTraceMapper.createSync(recursive: true);
+
+    await webDevFS.create();
+    await webDevFS.update(
+      mainPath: globals.fs.path.join('lib', 'main.dart'),
+      generator: residentCompiler,
+      trackWidgetCreation: true,
+      bundleFirstUpload: true,
+      invalidatedFiles: <Uri>[],
+    );
+
+    expect(webDevFS.webAssetServer.getFile('/manifest.json'), isNotNull);
+    expect(webDevFS.webAssetServer.getFile('/flutter_service_worker.js'), isNotNull);
+
+    await webDevFS.destroy();
+  }));
 }
 
 class MockHttpServer extends Mock implements HttpServer {}
@@ -328,3 +366,4 @@ class MockHttpRequest extends Mock implements HttpRequest {}
 class MockHttpResponse extends Mock implements HttpResponse {}
 class MockHttpHeaders extends Mock implements HttpHeaders {}
 class MockPlatform extends Mock implements Platform {}
+class MockResidentCompiler extends Mock implements ResidentCompiler {}