feat(messaging, web): add support for custom service worker script path in getToken method

packages/firebase_messaging/firebase_messaging/lib/src/messaging.dart

@@ -114,11 +114,17 @@ class FirebaseMessaging extends FirebasePluginPlatform {
   /// Returns the default FCM token for this device.
   ///
   /// On web, a [vapidKey] is required.
+  ///
+  /// On web, a custom messaging service worker can be registered with
+  /// [serviceWorkerScriptPath]. This must point to a JavaScript file in the
+  /// root of the app's `web` directory.
   Future<String?> getToken({
     String? vapidKey,
+    String? serviceWorkerScriptPath,
   }) {
     return _delegate.getToken(
       vapidKey: vapidKey,
+      serviceWorkerScriptPath: serviceWorkerScriptPath,
     );
   }
 

packages/firebase_messaging/firebase_messaging/test/firebase_messaging_test.dart

@@ -99,12 +99,35 @@ void main() {
     group('getToken', () {
       test('verify delegate method is called with correct args', () async {
         const vapidKey = 'test-vapid-key';
-        when(kMockMessagingPlatform.getToken(vapidKey: anyNamed('vapidKey')))
-            .thenAnswer((_) => Future.value(''));
+        when(kMockMessagingPlatform.getToken(
+          vapidKey: anyNamed('vapidKey'),
+          serviceWorkerScriptPath: anyNamed('serviceWorkerScriptPath'),
+        )).thenAnswer((_) => Future.value(''));
 
         await messaging!.getToken(vapidKey: vapidKey);
 
-        verify(kMockMessagingPlatform.getToken(vapidKey: vapidKey));
+        verify(kMockMessagingPlatform.getToken(
+          vapidKey: vapidKey,
+          serviceWorkerScriptPath: null,
+        ));
+      });
+
+      test('verify delegate method is called with service worker path',
+          () async {
+        const serviceWorkerScriptPath = 'custom-messaging-sw.js';
+        when(kMockMessagingPlatform.getToken(
+          vapidKey: anyNamed('vapidKey'),
+          serviceWorkerScriptPath: anyNamed('serviceWorkerScriptPath'),
+        )).thenAnswer((_) => Future.value(''));
+
+        await messaging!.getToken(
+          serviceWorkerScriptPath: serviceWorkerScriptPath,
+        );
+
+        verify(kMockMessagingPlatform.getToken(
+          vapidKey: null,
+          serviceWorkerScriptPath: serviceWorkerScriptPath,
+        ));
       });
     });
 

packages/firebase_messaging/firebase_messaging/test/mock.dart

@@ -96,9 +96,12 @@ class MockFirebaseMessaging extends Mock
   }
 
   @override
-  Future<String> getToken({String? vapidKey}) {
+  Future<String> getToken({String? vapidKey, String? serviceWorkerScriptPath}) {
     return super.noSuchMethod(
-        Invocation.method(#getToken, [], {#vapidKey: vapidKey}),
+        Invocation.method(#getToken, [], {
+          #vapidKey: vapidKey,
+          #serviceWorkerScriptPath: serviceWorkerScriptPath
+        }),
         returnValue: Future<String>.value(''),
         returnValueForMissingStub: Future<String>.value(''));
   }

packages/firebase_messaging/firebase_messaging_platform_interface/lib/src/method_channel/method_channel_messaging.dart

@@ -240,6 +240,7 @@ class MethodChannelFirebaseMessaging extends FirebaseMessagingPlatform {
   @override
   Future<String?> getToken({
     String? vapidKey, // not used yet; web only property
+    String? serviceWorkerScriptPath, // web only property
   }) async {
     await _APNSTokenCheck();
 

packages/firebase_messaging/firebase_messaging_platform_interface/lib/src/platform_interface/platform_interface_messaging.dart

@@ -173,6 +173,7 @@ abstract class FirebaseMessagingPlatform extends PlatformInterface {
   /// Returns the default FCM token for this device and optionally [senderId].
   Future<String?> getToken({
     String? vapidKey,
+    String? serviceWorkerScriptPath,
   }) {
     throw UnimplementedError('getToken() is not implemented');
   }

packages/firebase_messaging/firebase_messaging_web/lib/firebase_messaging_web.dart

@@ -112,7 +112,8 @@ class FirebaseMessagingWeb extends FirebaseMessagingPlatform {
   }
 
   @override
-  Future<String?> getToken({String? vapidKey}) async {
+  Future<String?> getToken(
+      {String? vapidKey, String? serviceWorkerScriptPath}) async {
     _delegate;
 
     if (!_initialized) {
@@ -121,7 +122,8 @@ class FirebaseMessagingWeb extends FirebaseMessagingPlatform {
     }
 
     return convertWebExceptions(
-      () => _delegate.getToken(vapidKey: vapidKey),
+      () => _delegate.getToken(
+          vapidKey: vapidKey, serviceWorkerScriptPath: serviceWorkerScriptPath),
     );
   }
 

packages/firebase_messaging/firebase_messaging_web/lib/src/interop/messaging.dart

@@ -9,7 +9,7 @@ import 'dart:async';
 import 'dart:js_interop';
 
 import 'package:firebase_core_web/firebase_core_web_interop.dart';
-
+import 'package:web/web.dart' as web;
 import 'messaging_interop.dart' as messaging_interop;
 
 export 'messaging_interop.dart';
@@ -43,15 +43,24 @@ class Messaging extends JsObjectWrapper<messaging_interop.MessagingJsImpl> {
 
   /// After calling [requestPermission] you can call this method to get an FCM registration token
   /// that can be used to send push messages to this user.
-  Future<String> getToken({String? vapidKey}) async {
+  Future<String> getToken(
+      {String? vapidKey, String? serviceWorkerScriptPath}) async {
     try {
+      web.ServiceWorkerRegistration? serviceWorkerRegistration;
+      if (serviceWorkerScriptPath != null) {
+        serviceWorkerRegistration = await web.window.navigator.serviceWorker
+            .register(serviceWorkerScriptPath.toJS)
+            .toDart;
+      }
       final token = (await messaging_interop
               .getToken(
                   jsObject,
-                  vapidKey == null
+                  vapidKey == null && serviceWorkerRegistration == null
                       ? null
                       : messaging_interop.GetTokenOptions(
-                          vapidKey: vapidKey.toJS))
+                          vapidKey: vapidKey?.toJS,
+                          serviceWorkerRegistration: serviceWorkerRegistration,
+                        ))
               .toDart)
           .toDart;
       return token;
@@ -62,7 +71,10 @@ class Messaging extends JsObjectWrapper<messaging_interop.MessagingJsImpl> {
       if (err.toString().toLowerCase().contains('no active service worker') &&
           firstGetTokenCall) {
         firstGetTokenCall = false;
-        return getToken(vapidKey: vapidKey);
+        return getToken(
+          vapidKey: vapidKey,
+          serviceWorkerScriptPath: serviceWorkerScriptPath,
+        );
       }
       rethrow;
     }

packages/firebase_messaging/firebase_messaging_web/lib/src/interop/messaging_interop.dart

@@ -9,6 +9,7 @@
 library;
 
 import 'dart:js_interop';
+import 'package:web/web.dart' as web;
 
 import 'package:firebase_core_web/firebase_core_web_interop.dart';
 
@@ -50,8 +51,10 @@ extension type GetTokenOptions._(JSObject _) implements JSObject {
   external factory GetTokenOptions({
     JSString? vapidKey,
     /*dynamic serviceWorkerRegistration */
+    web.ServiceWorkerRegistration? serviceWorkerRegistration,
   });
   external JSString get vapidKey;
+  external web.ServiceWorkerRegistration get serviceWorkerRegistration;
 }
 
 extension type NotificationPayloadJsImpl._(JSObject _) implements JSObject {