Steps to test it:
1. Go to Control Panel > Consumer Manager.
2. Add 3 new Consumers (named APP1, APP2, APP3)
3. Edit APP2, drag 2 Mobile App extensions to the extensions panel and fill in the required fields. Use PlaceholderAPP2-1 and PlaceholderAPP2-2 for the names.
4. Edit APP3, drag 2 Mobile App extensions to the extensions panel and fill in the required fields. Use PlaceholderAPP3-1 and PlaceholderAPP3-2 for the names.
5. Go to a Site > Site Admin > Configuration > Audience Targeting
6. Add a Campaign, click Save and Continue, go to the Promotions tab and add a new promotion.
7. Drag the Mobile App channel to the channel panel.
8. Assert that:
- The applicationId list contains APP2 and APP3, but not APP1. This is because APP1 contains no extension for Mobile App.
- When you select APP2 or APP3, their respective placeholders are available in the placeholder Id list.