fix requestNotificationPermission()

requestNotificationPermission() was returning undefined due to
incorrectly converting a string to an enum.

__test__/unit/notifications/subscriptionmanager.test.ts

@@ -0,0 +1,32 @@
+import MockNotification from '../../support/mocks/MockNotification';
+import { SubscriptionManager } from '../../../src/shared/managers/SubscriptionManager';
+import { NotificationPermission } from '../../../src/shared/models/NotificationPermission';
+
+describe('SubscriptionManager', () => {
+  describe('requestNotificationPermission', () => {
+    beforeEach(() => {
+      window.Notification = MockNotification;
+    });
+
+    test('default', async () => {
+      MockNotification.permission = 'default';
+      expect(await SubscriptionManager.requestNotificationPermission()).toBe(
+        NotificationPermission.Default,
+      );
+    });
+
+    test('denied', async () => {
+      MockNotification.permission = 'denied';
+      expect(await SubscriptionManager.requestNotificationPermission()).toBe(
+        NotificationPermission.Denied,
+      );
+    });
+
+    test('granted', async () => {
+      MockNotification.permission = 'granted';
+      expect(await SubscriptionManager.requestNotificationPermission()).toBe(
+        NotificationPermission.Granted,
+      );
+    });
+  });
+});

src/shared/managers/SubscriptionManager.ts

@@ -333,7 +333,7 @@ export class SubscriptionManager {
     const results = await window.Notification.requestPermission();
     // TODO: Clean up our custom NotificationPermission enum
     //         in favor of TS union type NotificationPermission instead of converting
-    return NotificationPermission[results];
+    return results as NotificationPermission;
   }
 
   public async isAlreadyRegisteredWithOneSignal(): Promise<boolean> {