Users can change the quantity of items in My Cart screen
Users can add promotion:
Use "SAVE10" or "SAVE20" as a valid promo code (save 10% and save 20% relatively)
Upon invalid code, an error message will be prop to users
Users can remove current used code in My Cart screen.
Total = subtotal + tax(13%) + promotion (if applied)
App Deploy
For every push on developer an master branch, a unit test will be run to check the functionality of the code (refer Mobile/test and workflow/testScreens.yml)
For every pull request on master, the app will be built again and automately published on Expo (refer to workflows/publish_mobile_app.yml)