packageInfo: support fallback logic testing

enabled test files and other modules to simulate packageInfo being null or set custom values via ZulipBinding.instance.packageInfo

Author: Abhisheksainii

lib/notifications/receive.dart

@@ -149,7 +149,6 @@ class NotificationService {
         await addFcmToken(connection, token: token);
 
       case TargetPlatform.iOS:
-         // TODO(#407) find actual value live
         await addApnsToken(connection, token: token, appid: (await ZulipBinding.instance.packageInfo)?.packageName ?? "com.zulip.flutter");
 
       case TargetPlatform.linux:

test/model/binding.dart

@@ -228,7 +228,7 @@ class TestZulipBinding extends ZulipBinding {
   BaseDeviceInfo? get syncDeviceInfo => deviceInfoResult;
 
   /// The value that `ZulipBinding.instance.packageInfo` should return.
-  PackageInfo packageInfoResult = _defaultPackageInfo;
+  PackageInfo? packageInfoResult = _defaultPackageInfo;
   static const _defaultPackageInfo = PackageInfo(version: '0.0.1', buildNumber: '1', packageName: 'com.zulip.flutter.test');
 
   void _resetPackageInfo() {
@@ -241,6 +241,10 @@ class TestZulipBinding extends ZulipBinding {
   @override
   PackageInfo? get syncPackageInfo => packageInfoResult;
 
+  void setPackageInfo(PackageInfo? packageInfo){
+    packageInfoResult= packageInfo;
+  }
+
   void _resetFirebase() {
     _firebaseInitialized = false;
     _firebaseMessaging = null;
@@ -380,7 +384,6 @@ class TestZulipBinding extends ZulipBinding {
   Future<void> toggleWakelock({required bool enable}) async {
     _wakelockEnabled = enable;
   }
-
 }
 
 class FakeFirebaseMessaging extends Fake implements FirebaseMessaging {

test/model/store_test.dart

@@ -1032,7 +1032,7 @@ void main() {
       if (defaultTargetPlatform == TargetPlatform.android) {
         checkLastRequestFcm(token: '012abc');
       } else {
-        checkLastRequestApns(token: '012abc', appid:(await testBinding.packageInfo)?.packageName?? 'com.zulip.flutter.test');
+        checkLastRequestApns(token: '012abc', appid:'com.zulip.flutter.test');
       }
 
       if (defaultTargetPlatform == TargetPlatform.android) {
@@ -1071,7 +1071,7 @@ void main() {
       if (defaultTargetPlatform == TargetPlatform.android) {
         checkLastRequestFcm(token: '012abc');
       } else {
-        checkLastRequestApns(token: '012abc', appid:(await testBinding.packageInfo)?.packageName?? 'com.zulip.flutter.test');
+        checkLastRequestApns(token: '012abc', appid:'com.zulip.flutter.test');
       }
 
       if (defaultTargetPlatform == TargetPlatform.android) {

test/notifications/receive_test.dart

@@ -34,8 +34,19 @@ void main() {
   group('tokens', () {
     test('APNs token registration using correct app bundle ID', () async {
       await init();
-      check((await testBinding.packageInfo)?.packageName?? 'com.zulip.flutter.test')
+      check((await testBinding.packageInfo)?.packageName)
         .equals('com.zulip.flutter.test');
     }, );
+
+    test('Fallback to default appBundleId if packageInfo is null', () async {
+      await init();
+      // setting package Info to null
+      testBinding.setPackageInfo(null);
+
+      const defaultAppId = 'com.zulip.flutter.test';
+
+      check((await testBinding.packageInfo)?.packageName?? defaultAppId)
+        .equals(defaultAppId);
+    }, );
   });
 }