Add `--frontend-server-starter-path` option to `flutter run` and `flutter test` (#135038)

packages/flutter_tools/bin/macos_assemble.sh

@@ -123,6 +123,7 @@ BuildApp() {
     "-dSplitDebugInfo=${SPLIT_DEBUG_INFO}"
     "-dTrackWidgetCreation=${TRACK_WIDGET_CREATION}"
     "-dAction=${ACTION}"
+    "-dFrontendServerStarterPath=${FRONTEND_SERVER_STARTER_PATH}"
     "--DartDefines=${DART_DEFINES}"
     "--ExtraGenSnapshotOptions=${EXTRA_GEN_SNAPSHOT_OPTIONS}"
     "--ExtraFrontEndOptions=${EXTRA_FRONT_END_OPTIONS}"

packages/flutter_tools/bin/tool_backend.dart

@@ -13,6 +13,7 @@ Future<void> main(List<String> arguments) async {
 
   final String? dartDefines = Platform.environment['DART_DEFINES'];
   final bool dartObfuscation = Platform.environment['DART_OBFUSCATION'] == 'true';
+  final String? frontendServerStarterPath = Platform.environment['FRONTEND_SERVER_STARTER_PATH'];
   final String? extraFrontEndOptions = Platform.environment['EXTRA_FRONT_END_OPTIONS'];
   final String? extraGenSnapshotOptions = Platform.environment['EXTRA_GEN_SNAPSHOT_OPTIONS'];
   final String? flutterEngine = Platform.environment['FLUTTER_ENGINE'];
@@ -106,6 +107,8 @@ or
         '--DartDefines=$dartDefines',
       if (extraGenSnapshotOptions != null)
         '--ExtraGenSnapshotOptions=$extraGenSnapshotOptions',
+      if (frontendServerStarterPath != null)
+        '-dFrontendServerStarterPath=$frontendServerStarterPath',
       if (extraFrontEndOptions != null)
         '--ExtraFrontEndOptions=$extraFrontEndOptions',
       target,

packages/flutter_tools/bin/xcode_backend.dart

@@ -402,6 +402,7 @@ class Context {
       '-dTrackWidgetCreation=${environment['TRACK_WIDGET_CREATION'] ?? ''}',
       '-dDartObfuscation=${environment['DART_OBFUSCATION'] ?? ''}',
       '-dAction=${environment['ACTION'] ?? ''}',
+      '-dFrontendServerStarterPath=${environment['FRONTEND_SERVER_STARTER_PATH'] ?? ''}',
       '--ExtraGenSnapshotOptions=${environment['EXTRA_GEN_SNAPSHOT_OPTIONS'] ?? ''}',
       '--DartDefines=${environment['DART_DEFINES'] ?? ''}',
       '--ExtraFrontEndOptions=${environment['EXTRA_FRONT_END_OPTIONS'] ?? ''}',

packages/flutter_tools/gradle/src/main/groovy/flutter.groovy

@@ -964,6 +964,10 @@ class FlutterPlugin implements Plugin<Project> {
         if (project.hasProperty('track-widget-creation')) {
             trackWidgetCreationValue = project.property('track-widget-creation').toBoolean()
         }
+        String frontendServerStarterPathValue = null
+        if (project.hasProperty('frontend-server-starter-path')) {
+            frontendServerStarterPathValue = project.property('frontend-server-starter-path')
+        }
         String extraFrontEndOptionsValue = null
         if (project.hasProperty('extra-front-end-options')) {
             extraFrontEndOptionsValue = project.property('extra-front-end-options')
@@ -1052,6 +1056,7 @@ class FlutterPlugin implements Plugin<Project> {
                 targetPlatformValues = targetPlatforms
                 sourceDir getFlutterSourceDirectory()
                 intermediateDir project.file("${project.buildDir}/$INTERMEDIATES_DIR/flutter/${variant.name}/")
+                frontendServerStarterPath frontendServerStarterPathValue
                 extraFrontEndOptions extraFrontEndOptionsValue
                 extraGenSnapshotOptions extraGenSnapshotOptionsValue
                 splitDebugInfo splitDebugInfoValue
@@ -1290,6 +1295,8 @@ abstract class BaseFlutterTask extends DefaultTask {
     @Internal
     File intermediateDir
     @Optional @Input
+    String frontendServerStarterPath
+    @Optional @Input
     String extraFrontEndOptions
     @Optional @Input
     String extraGenSnapshotOptions
@@ -1394,6 +1401,9 @@ abstract class BaseFlutterTask extends DefaultTask {
             if (extraGenSnapshotOptions != null) {
                 args "--ExtraGenSnapshotOptions=${extraGenSnapshotOptions}"
             }
+            if (frontendServerStarterPath != null) {
+                args "-dFrontendServerStarterPath=${frontendServerStarterPath}"
+            }
             if (extraFrontEndOptions != null) {
                 args "--ExtraFrontEndOptions=${extraFrontEndOptions}"
             }

packages/flutter_tools/lib/src/build_info.dart

@@ -23,6 +23,7 @@ class BuildInfo {
     this.mode,
     this.flavor, {
     this.trackWidgetCreation = false,
+    this.frontendServerStarterPath,
     List<String>? extraFrontEndOptions,
     List<String>? extraGenSnapshotOptions,
     List<String>? fileSystemRoots,
@@ -82,6 +83,10 @@ class BuildInfo {
   /// Whether the build should track widget creation locations.
   final bool trackWidgetCreation;
 
+  /// If provided, the frontend server will be started in JIT mode from this
+  /// file.
+  final String? frontendServerStarterPath;
+
   /// Extra command-line options for front-end.
   final List<String> extraFrontEndOptions;
 
@@ -237,6 +242,8 @@ class BuildInfo {
       if (dartDefines.isNotEmpty)
         kDartDefines: encodeDartDefines(dartDefines),
       kDartObfuscation: dartObfuscation.toString(),
+      if (frontendServerStarterPath != null)
+        kFrontendServerStarterPath: frontendServerStarterPath!,
       if (extraFrontEndOptions.isNotEmpty)
         kExtraFrontEndOptions: extraFrontEndOptions.join(','),
       if (extraGenSnapshotOptions.isNotEmpty)
@@ -274,6 +281,8 @@ class BuildInfo {
       if (dartDefines.isNotEmpty)
         'DART_DEFINES': encodeDartDefines(dartDefines),
       'DART_OBFUSCATION': dartObfuscation.toString(),
+      if (frontendServerStarterPath != null)
+        'FRONTEND_SERVER_STARTER_PATH': frontendServerStarterPath!,
       if (extraFrontEndOptions.isNotEmpty)
         'EXTRA_FRONT_END_OPTIONS': extraFrontEndOptions.join(','),
       if (extraGenSnapshotOptions.isNotEmpty)
@@ -310,6 +319,8 @@ class BuildInfo {
       if (dartDefines.isNotEmpty)
         '-Pdart-defines=${encodeDartDefines(dartDefines)}',
       '-Pdart-obfuscation=$dartObfuscation',
+      if (frontendServerStarterPath != null)
+        '-Pfrontend-server-starter-path=$frontendServerStarterPath',
       if (extraFrontEndOptions.isNotEmpty)
         '-Pextra-front-end-options=${extraFrontEndOptions.join(',')}',
       if (extraGenSnapshotOptions.isNotEmpty)
@@ -901,6 +912,9 @@ const String kTargetFile = 'TargetFile';
 /// Whether to enable or disable track widget creation.
 const String kTrackWidgetCreation = 'TrackWidgetCreation';
 
+/// If provided, the frontend server will be started in JIT mode from this file.
+const String kFrontendServerStarterPath = 'FrontendServerStarterPath';
+
 /// Additional configuration passed to the dart front end.
 ///
 /// This is expected to be a comma separated list of strings.

packages/flutter_tools/lib/src/build_system/targets/common.dart

@@ -178,6 +178,7 @@ class KernelSnapshot extends Target {
     final TargetPlatform targetPlatform = getTargetPlatformForName(targetPlatformEnvironment);
 
     // This configuration is all optional.
+    final String? frontendServerStarterPath = environment.defines[kFrontendServerStarterPath];
     final List<String> extraFrontEndOptions = decodeCommaSeparated(environment.defines, kExtraFrontEndOptions);
     final List<String>? fileSystemRoots = environment.defines[kFileSystemRoots]?.split(',');
     final String? fileSystemScheme = environment.defines[kFileSystemScheme];
@@ -254,6 +255,7 @@ class KernelSnapshot extends Target {
       linkPlatformKernelIn: forceLinkPlatform || buildMode.isPrecompiled,
       mainPath: targetFileAbsolute,
       depFilePath: environment.buildDir.childFile('kernel_snapshot.d').path,
+      frontendServerStarterPath: frontendServerStarterPath,
       extraFrontEndOptions: extraFrontEndOptions,
       fileSystemRoots: fileSystemRoots,
       fileSystemScheme: fileSystemScheme,

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

@@ -315,6 +315,7 @@ class RunCommand extends RunCommandBase {
     requiresPubspecYaml();
     usesFilesystemOptions(hide: !verboseHelp);
     usesExtraDartFlagOptions(verboseHelp: verboseHelp);
+    usesFrontendServerStarterPathOption(verboseHelp: verboseHelp);
     addEnableExperimentation(hide: !verboseHelp);
     usesInitializeFromDillOption(hide: !verboseHelp);
 

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

@@ -67,6 +67,7 @@ class TestCommand extends FlutterCommand with DeviceBasedDevelopmentArtifacts {
     requiresPubspecYaml();
     usesPubOption();
     addNullSafetyModeOptions(hide: !verboseHelp);
+    usesFrontendServerStarterPathOption(verboseHelp: verboseHelp);
     usesTrackWidgetCreation(verboseHelp: verboseHelp);
     addEnableExperimentation(hide: !verboseHelp);
     usesDartDefineOption();

packages/flutter_tools/lib/src/compile.dart

@@ -227,6 +227,7 @@ class KernelCompiler {
     TargetModel targetModel = TargetModel.flutter,
     bool linkPlatformKernelIn = false,
     bool aot = false,
+    String? frontendServerStarterPath,
     List<String>? extraFrontEndOptions,
     List<String>? fileSystemRoots,
     String? fileSystemScheme,
@@ -243,10 +244,12 @@ class KernelCompiler {
     String? nativeAssets,
   }) async {
     final TargetPlatform? platform = targetModel == TargetModel.dartdevc ? TargetPlatform.web_javascript : null;
-    final String frontendServer = _artifacts.getArtifactPath(
-      Artifact.frontendServerSnapshotForEngineDartSdk,
-      platform: platform,
-    );
+    final String frontendServer = (frontendServerStarterPath == null || frontendServerStarterPath.isEmpty)
+        ? _artifacts.getArtifactPath(
+            Artifact.frontendServerSnapshotForEngineDartSdk,
+            platform: platform,
+          )
+        : frontendServerStarterPath;
     // This is a URI, not a file path, so the forward slash is correct even on Windows.
     if (!sdkRoot.endsWith('/')) {
       sdkRoot = '$sdkRoot/';
@@ -490,6 +493,7 @@ abstract class ResidentCompiler {
     bool assumeInitializeFromDillUpToDate,
     TargetModel targetModel,
     bool unsafePackageSerialization,
+    String? frontendServerStarterPath,
     List<String> extraFrontEndOptions,
     String platformDill,
     List<String>? dartDefines,
@@ -605,6 +609,7 @@ class DefaultResidentCompiler implements ResidentCompiler {
     this.assumeInitializeFromDillUpToDate = false,
     this.targetModel = TargetModel.flutter,
     this.unsafePackageSerialization = false,
+    this.frontendServerStarterPath,
     this.extraFrontEndOptions,
     this.platformDill,
     List<String>? dartDefines,
@@ -635,6 +640,7 @@ class DefaultResidentCompiler implements ResidentCompiler {
   final String? initializeFromDill;
   final bool assumeInitializeFromDillUpToDate;
   final bool unsafePackageSerialization;
+  final String? frontendServerStarterPath;
   final List<String>? extraFrontEndOptions;
   final List<String> dartDefines;
   final String? librariesSpec;
@@ -771,10 +777,12 @@ class DefaultResidentCompiler implements ResidentCompiler {
     String? nativeAssetsUri,
   }) async {
     final TargetPlatform? platform = (targetModel == TargetModel.dartdevc) ? TargetPlatform.web_javascript : null;
-    final String frontendServer = artifacts.getArtifactPath(
-      Artifact.frontendServerSnapshotForEngineDartSdk,
-      platform: platform,
-    );
+    final String frontendServer = (frontendServerStarterPath == null || frontendServerStarterPath!.isEmpty)
+        ? artifacts.getArtifactPath(
+            Artifact.frontendServerSnapshotForEngineDartSdk,
+            platform: platform,
+          )
+        : frontendServerStarterPath!;
     final List<String> command = <String>[
       artifacts.getArtifactPath(Artifact.engineDartBinary, platform: platform),
       '--disable-dart-dev',

packages/flutter_tools/lib/src/resident_runner.dart

@@ -67,6 +67,7 @@ class FlutterDevice {
          targetModel: targetModel,
          dartDefines: buildInfo.dartDefines,
          packagesPath: buildInfo.packagesPath,
+         frontendServerStarterPath: buildInfo.frontendServerStarterPath,
          extraFrontEndOptions: buildInfo.extraFrontEndOptions,
          artifacts: globals.artifacts!,
          processManager: globals.processManager,
@@ -155,6 +156,7 @@ class FlutterDevice {
         ),
         assumeInitializeFromDillUpToDate: buildInfo.assumeInitializeFromDillUpToDate,
         targetModel: TargetModel.dartdevc,
+        frontendServerStarterPath: buildInfo.frontendServerStarterPath,
         extraFrontEndOptions: extraFrontEndOptions,
         platformDill: globals.fs.file(platformDillPath).absolute.uri.toString(),
         dartDefines: buildInfo.dartDefines,
@@ -185,6 +187,7 @@ class FlutterDevice {
         fileSystemScheme: buildInfo.fileSystemScheme,
         targetModel: targetModel,
         dartDefines: buildInfo.dartDefines,
+        frontendServerStarterPath: buildInfo.frontendServerStarterPath,
         extraFrontEndOptions: extraFrontEndOptions,
         initializeFromDill: buildInfo.initializeFromDill ?? getDefaultCachedKernelPath(
           trackWidgetCreation: buildInfo.trackWidgetCreation,

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -112,6 +112,7 @@ class FlutterCommandResult {
 
 /// Common flutter command line options.
 abstract final class FlutterOptions {
+  static const String kFrontendServerStarterPath = 'frontend-server-starter-path';
   static const String kExtraFrontEndOptions = 'extra-front-end-options';
   static const String kExtraGenSnapshotOptions = 'extra-gen-snapshot-options';
   static const String kEnableExperiment = 'enable-experiment';
@@ -849,6 +850,18 @@ abstract class FlutterCommand extends Command<void> {
     );
   }
 
+  void usesFrontendServerStarterPathOption({required bool verboseHelp}) {
+    argParser.addOption(
+      FlutterOptions.kFrontendServerStarterPath,
+      help: 'When this value is provided, the frontend server will be started '
+            'in JIT mode from the specified file, instead of from the AOT '
+            'snapshot shipped with the Dart SDK. The specified file can either '
+            'be a Dart source file, or an AppJIT snapshot. This option does '
+            'not affect web builds.',
+      hide: !verboseHelp,
+    );
+  }
+
   /// Enables support for the hidden options --extra-front-end-options and
   /// --extra-gen-snapshot-options.
   void usesExtraDartFlagOptions({ required bool verboseHelp }) {
@@ -1239,6 +1252,10 @@ abstract class FlutterCommand extends Command<void> {
         ? stringArg('flavor')
         : null,
       trackWidgetCreation: trackWidgetCreation,
+      frontendServerStarterPath: argParser.options
+              .containsKey(FlutterOptions.kFrontendServerStarterPath)
+          ? stringArg(FlutterOptions.kFrontendServerStarterPath)
+          : null,
       extraFrontEndOptions: extraFrontEndOptions.isNotEmpty
         ? extraFrontEndOptions
         : null,

packages/flutter_tools/lib/src/test/test_compiler.dart

@@ -121,6 +121,7 @@ class TestCompiler {
       initializeFromDill: testFilePath,
       dartDefines: buildInfo.dartDefines,
       packagesPath: buildInfo.packagesPath,
+      frontendServerStarterPath: buildInfo.frontendServerStarterPath,
       extraFrontEndOptions: buildInfo.extraFrontEndOptions,
       platform: globals.platform,
       testCompilation: true,

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

@@ -175,6 +175,7 @@ void main() {
       dartDefines: <String>['foo=2', 'bar=2'],
       dartObfuscation: true,
       splitDebugInfoPath: 'foo/',
+      frontendServerStarterPath: 'foo/bar/frontend_server_starter.dart',
       extraFrontEndOptions: <String>['--enable-experiment=non-nullable', 'bar'],
       extraGenSnapshotOptions: <String>['--enable-experiment=non-nullable', 'fizz'],
       bundleSkSLPath: 'foo/bar/baz.sksl.json',
@@ -190,6 +191,7 @@ void main() {
       'BuildMode': 'debug',
       'DartDefines': 'Zm9vPTI=,YmFyPTI=',
       'DartObfuscation': 'true',
+      'FrontendServerStarterPath': 'foo/bar/frontend_server_starter.dart',
       'ExtraFrontEndOptions': '--enable-experiment=non-nullable,bar',
       'ExtraGenSnapshotOptions': '--enable-experiment=non-nullable,fizz',
       'SplitDebugInfo': 'foo/',
@@ -211,6 +213,7 @@ void main() {
       dartDefines: <String>['foo=2', 'bar=2'],
       dartObfuscation: true,
       splitDebugInfoPath: 'foo/',
+      frontendServerStarterPath: 'foo/bar/frontend_server_starter.dart',
       extraFrontEndOptions: <String>['--enable-experiment=non-nullable', 'bar'],
       extraGenSnapshotOptions: <String>['--enable-experiment=non-nullable', 'fizz'],
       bundleSkSLPath: 'foo/bar/baz.sksl.json',
@@ -226,6 +229,7 @@ void main() {
       'DART_DEFINES': 'Zm9vPTI=,YmFyPTI=',
       'DART_OBFUSCATION': 'true',
       'SPLIT_DEBUG_INFO': 'foo/',
+      'FRONTEND_SERVER_STARTER_PATH': 'foo/bar/frontend_server_starter.dart',
       'EXTRA_FRONT_END_OPTIONS': '--enable-experiment=non-nullable,bar',
       'EXTRA_GEN_SNAPSHOT_OPTIONS': '--enable-experiment=non-nullable,fizz',
       'BUNDLE_SKSL_PATH': 'foo/bar/baz.sksl.json',
@@ -242,6 +246,7 @@ void main() {
       dartDefineConfigJsonMap: <String, Object>{'baz': '2'},
       dartObfuscation: true,
       splitDebugInfoPath: 'foo/',
+      frontendServerStarterPath: 'foo/bar/frontend_server_starter.dart',
       extraFrontEndOptions: <String>['--enable-experiment=non-nullable', 'bar'],
       extraGenSnapshotOptions: <String>['--enable-experiment=non-nullable', 'fizz'],
       bundleSkSLPath: 'foo/bar/baz.sksl.json',
@@ -253,6 +258,7 @@ void main() {
     expect(buildInfo.toGradleConfig(), <String>[
       '-Pdart-defines=Zm9vPTI=,YmFyPTI=',
       '-Pdart-obfuscation=true',
+      '-Pfrontend-server-starter-path=foo/bar/frontend_server_starter.dart',
       '-Pextra-front-end-options=--enable-experiment=non-nullable,bar',
       '-Pextra-gen-snapshot-options=--enable-experiment=non-nullable,fizz',
       '-Psplit-debug-info=foo/',

packages/flutter_tools/test/general.shard/build_system/targets/common_test.dart

@@ -217,6 +217,53 @@ native-assets: {}
     expect(processManager, hasNoRemainingExpectations);
   });
 
+  testWithoutContext('KernelSnapshot correctly forwards FrontendServerStarterPath', () async {
+    fileSystem.file('.dart_tool/package_config.json')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('{"configVersion": 2, "packages":[]}');
+    androidEnvironment.buildDir.childFile('native_assets.yaml')
+      ..createSync(recursive: true)
+      ..writeAsStringSync(emptyNativeAssets);
+    final String build = androidEnvironment.buildDir.path;
+    final String flutterPatchedSdkPath = artifacts.getArtifactPath(
+      Artifact.flutterPatchedSdkPath,
+      platform: TargetPlatform.android_arm,
+      mode: BuildMode.profile,
+    );
+    processManager.addCommands(<FakeCommand>[
+      FakeCommand(command: <String>[
+        artifacts.getArtifactPath(Artifact.engineDartBinary),
+        '--disable-dart-dev',
+        'path/to/frontend_server_starter.dart',
+        '--sdk-root',
+        '$flutterPatchedSdkPath/',
+        '--target=flutter',
+        '--no-print-incremental-dependencies',
+        ...buildModeOptions(BuildMode.profile, <String>[]),
+        '--track-widget-creation',
+        '--aot',
+        '--tfa',
+        '--target-os',
+        'android',
+        '--packages',
+        '/.dart_tool/package_config.json',
+        '--output-dill',
+        '$build/app.dill',
+        '--depfile',
+        '$build/kernel_snapshot.d',
+        '--native-assets',
+        '$build/native_assets.yaml',
+        '--verbosity=error',
+        'file:///lib/main.dart',
+      ], stdout: 'result $kBoundaryKey\n$kBoundaryKey\n$kBoundaryKey $build/app.dill 0\n'),
+    ]);
+
+    await const KernelSnapshot()
+      .build(androidEnvironment..defines[kFrontendServerStarterPath] = 'path/to/frontend_server_starter.dart');
+
+    expect(processManager, hasNoRemainingExpectations);
+  });
+
   testWithoutContext('KernelSnapshot correctly forwards ExtraFrontEndOptions', () async {
     fileSystem.file('.dart_tool/package_config.json')
       ..createSync(recursive: true)

packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart

@@ -391,6 +391,38 @@ void main() {
     ProcessManager: () => processManager,
   }));
 
+  test('Dart2JSTarget ignores frontend server starter path option when calling dart2js', () => testbed.run(() async {
+    environment.defines[kBuildMode] = 'profile';
+    environment.defines[kFrontendServerStarterPath] = 'path/to/frontend_server_starter.dart';
+    processManager.addCommand(FakeCommand(
+      command: <String>[
+        ..._kDart2jsLinuxArgs,
+        '-Ddart.vm.profile=true',
+        '--no-source-maps',
+        '-o',
+        environment.buildDir.childFile('app.dill').absolute.path,
+        '--packages=.dart_tool/package_config.json',
+        '--cfe-only',
+        environment.buildDir.childFile('main.dart').absolute.path,
+      ]
+    ));
+    processManager.addCommand(FakeCommand(
+      command: <String>[
+        ..._kDart2jsLinuxArgs,
+        '-Ddart.vm.profile=true',
+        '--no-minify',
+        '--no-source-maps',
+        '-O4',
+        '-o',
+        environment.buildDir.childFile('main.dart.js').absolute.path,
+        environment.buildDir.childFile('app.dill').absolute.path,
+      ]
+    ));
+
+    await Dart2JSTarget(WebRendererMode.auto).build(environment);
+  }, overrides: <Type, Generator>{
+    ProcessManager: () => processManager,
+  }));
 
   test('Dart2JSTarget calls dart2js with expected args with enabled experiment', () => testbed.run(() async {
     environment.defines[kBuildMode] = 'profile';

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

@@ -87,6 +87,7 @@ void main() {
         BuildMode.debug,
         null,
         trackWidgetCreation: true,
+        frontendServerStarterPath: 'path/to/frontend_server_starter.dart',
         extraFrontEndOptions: <String>['test1', 'test2'],
         extraGenSnapshotOptions: <String>['test3', 'test4'],
         fileSystemRoots: <String>['test5', 'test6'],
@@ -106,6 +107,7 @@ void main() {
     expect(env!.defines[kTargetPlatform], 'ios');
     expect(env!.defines[kTargetFile], mainPath);
     expect(env!.defines[kTrackWidgetCreation], 'true');
+    expect(env!.defines[kFrontendServerStarterPath], 'path/to/frontend_server_starter.dart');
     expect(env!.defines[kExtraFrontEndOptions], 'test1,test2');
     expect(env!.defines[kExtraGenSnapshotOptions], 'test3,test4');
     expect(env!.defines[kFileSystemRoots], 'test5,test6');

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

@@ -1963,6 +1963,28 @@ flutter:
     ProcessManager: () => FakeProcessManager.any(),
   });
 
+  testUsingContext('FlutterDevice passes frontendServerStarterPath parameter if specified', () async {
+    fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
+    final FakeDevice device = FakeDevice();
+
+    final DefaultResidentCompiler? residentCompiler = (await FlutterDevice.create(
+      device,
+      buildInfo: const BuildInfo(
+        BuildMode.debug,
+        '',
+        treeShakeIcons: false,
+        frontendServerStarterPath: '/foo/bar/frontend_server_starter.dart',
+      ),
+      target: null, platform: FakePlatform(),
+    )).generator as DefaultResidentCompiler?;
+
+    expect(residentCompiler!.frontendServerStarterPath, '/foo/bar/frontend_server_starter.dart');
+  }, overrides: <Type, Generator>{
+    Artifacts: () => Artifacts.test(),
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
   testUsingContext('Handle existing VM service clients DDS error', () => testbed.run(() async {
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
     final FakeDevice device = FakeDevice()

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

@@ -51,6 +51,7 @@ void main() {
               '-dTrackWidgetCreation=',
               '-dDartObfuscation=',
               '-dAction=build',
+              '-dFrontendServerStarterPath=',
               '--ExtraGenSnapshotOptions=',
               '--DartDefines=',
               '--ExtraFrontEndOptions=',
@@ -103,6 +104,7 @@ void main() {
               '-dTrackWidgetCreation=',
               '-dDartObfuscation=',
               '-dAction=',
+              '-dFrontendServerStarterPath=',
               '--ExtraGenSnapshotOptions=',
               '--DartDefines=',
               '--ExtraFrontEndOptions=',
@@ -136,6 +138,7 @@ void main() {
       const String expandedCodeSignIdentity = 'F1326572E0B71C3C8442805230CB4B33B708A2E2';
       const String extraFrontEndOptions = '--some-option';
       const String extraGenSnapshotOptions = '--obfuscate';
+      const String frontendServerStarterPath = '/path/to/frontend_server_starter.dart';
       const String sdkRoot = '/path/to/sdk';
       const String splitDebugInfo = '/path/to/split/debug/info';
       const String trackWidgetCreation = 'true';
@@ -154,6 +157,7 @@ void main() {
           'EXTRA_FRONT_END_OPTIONS': extraFrontEndOptions,
           'EXTRA_GEN_SNAPSHOT_OPTIONS': extraGenSnapshotOptions,
           'FLUTTER_ROOT': flutterRoot.path,
+          'FRONTEND_SERVER_STARTER_PATH': frontendServerStarterPath,
           'INFOPLIST_PATH': 'Info.plist',
           'SDKROOT': sdkRoot,
           'SPLIT_DEBUG_INFO': splitDebugInfo,
@@ -177,6 +181,7 @@ void main() {
               '-dTrackWidgetCreation=$trackWidgetCreation',
               '-dDartObfuscation=$dartObfuscation',
               '-dAction=install',
+              '-dFrontendServerStarterPath=$frontendServerStarterPath',
               '--ExtraGenSnapshotOptions=$extraGenSnapshotOptions',
               '--DartDefines=$dartDefines',
               '--ExtraFrontEndOptions=$extraFrontEndOptions',