[web] fix hot restart in entrypoint generated by `flutter create` (#110229)

dev/bots/service_worker_test.dart

@@ -30,10 +30,16 @@ enum ServiceWorkerTestType {
   withFlutterJs,
   withFlutterJsShort,
   withFlutterJsEntrypointLoadedEvent,
+
+  // Entrypoint generated by `flutter create`.
+  generatedEntrypoint,
 }
 
 // Run a web service worker test as a standalone Dart program.
 Future<void> main() async {
+  // When updating this list, also update `dev/bots/test.dart`. This `main()`
+  // function is only here for convenience. Adding tests here will not add them
+  // to LUCI.
   await runWebServiceWorkerTest(headless: false, testType: ServiceWorkerTestType.withoutFlutterJs);
   await runWebServiceWorkerTest(headless: false, testType: ServiceWorkerTestType.withFlutterJs);
   await runWebServiceWorkerTest(headless: false, testType: ServiceWorkerTestType.withFlutterJsShort);
@@ -42,13 +48,42 @@ Future<void> main() async {
   await runWebServiceWorkerTestWithCachingResources(headless: false, testType: ServiceWorkerTestType.withFlutterJs);
   await runWebServiceWorkerTestWithCachingResources(headless: false, testType: ServiceWorkerTestType.withFlutterJsShort);
   await runWebServiceWorkerTestWithCachingResources(headless: false, testType: ServiceWorkerTestType.withFlutterJsEntrypointLoadedEvent);
+  await runWebServiceWorkerTestWithGeneratedEntrypoint(headless: false);
   await runWebServiceWorkerTestWithBlockedServiceWorkers(headless: false);
+
   if (hasError) {
     print('One or more tests failed.');
     reportErrorsAndExit();
   }
 }
 
+// Regression test for https://github.com/flutter/flutter/issues/109093.
+//
+// Tests the entrypoint that's generated by `flutter create`.
+Future<void> runWebServiceWorkerTestWithGeneratedEntrypoint({
+  required bool headless,
+}) async {
+  await _generateEntrypoint();
+  await runWebServiceWorkerTestWithCachingResources(headless: headless, testType: ServiceWorkerTestType.generatedEntrypoint);
+}
+
+Future<void> _generateEntrypoint() async {
+  final Directory tempDirectory = Directory.systemTemp.createTempSync('flutter_web_generated_entrypoint.');
+  await runCommand(
+    _flutter,
+    <String>[ 'create', 'generated_entrypoint_test' ],
+    workingDirectory: tempDirectory.path,
+  );
+  final File generatedEntrypoint = File(path.join(tempDirectory.path, 'generated_entrypoint_test', 'web', 'index.html'));
+  final String generatedEntrypointCode = generatedEntrypoint.readAsStringSync();
+  final File testEntrypoint = File(path.join(
+    _testAppWebDirectory,
+    _testTypeToIndexFile(ServiceWorkerTestType.generatedEntrypoint),
+  ));
+  testEntrypoint.writeAsStringSync(generatedEntrypointCode);
+  tempDirectory.deleteSync(recursive: true);
+}
+
 Future<void> _setAppVersion(int version) async {
   final File targetFile = File(_targetPath);
   await targetFile.writeAsString(
@@ -77,6 +112,9 @@ String _testTypeToIndexFile(ServiceWorkerTestType type) {
     case ServiceWorkerTestType.withFlutterJsEntrypointLoadedEvent:
       indexFile = 'index_with_flutterjs_entrypoint_loaded.html';
       break;
+    case ServiceWorkerTestType.generatedEntrypoint:
+      indexFile = 'generated_entrypoint.html';
+      break;
   }
   return indexFile;
 }

dev/bots/test.dart

@@ -1179,6 +1179,7 @@ Future<void> _runWebLongRunningTests() async {
     () => runWebServiceWorkerTestWithCachingResources(headless: true, testType: ServiceWorkerTestType.withFlutterJs),
     () => runWebServiceWorkerTestWithCachingResources(headless: true, testType: ServiceWorkerTestType.withFlutterJsShort),
     () => runWebServiceWorkerTestWithCachingResources(headless: true, testType: ServiceWorkerTestType.withFlutterJsEntrypointLoadedEvent),
+    () => runWebServiceWorkerTestWithGeneratedEntrypoint(headless: true),
     () => runWebServiceWorkerTestWithBlockedServiceWorkers(headless: true),
     () => _runWebStackTraceTest('profile', 'lib/stack_trace.dart'),
     () => _runWebStackTraceTest('release', 'lib/stack_trace.dart'),

dev/integration_tests/web/web/.gitignore

+# This file is generated by a test. It should not be committed to source control.
+generated_entrypoint.html

packages/flutter_tools/templates/app_shared/web/index.html.tmpl

@@ -46,11 +46,12 @@
       _flutter.loader.loadEntrypoint({
         serviceWorker: {
           serviceWorkerVersion: serviceWorkerVersion,
+        },
+        onEntrypointLoaded: function(engineInitializer) {
+          engineInitializer.initializeEngine().then(function(appRunner) {
+            appRunner.runApp();
+          });
         }
-      }).then(function(engineInitializer) {
-        return engineInitializer.initializeEngine();
-      }).then(function(appRunner) {
-        return appRunner.runApp();
       });
     });
   </script>