Microsoft Store API : Cannot create promo code for addon type 'Subscription'

I want to simulate purchase for a subscription addon. Its a free addon but still purchase process flow force asks me to enter Creditcard or paypal details. (was not expecting this)

I read here that one can create promo code to test the purchase process without feeding money. The promocode generation page displays all addons except of type 'Subscription'.

Q1. So question is how to i generate promocodes for a subscription type of addon ?

There is next question in pipeline related to same. I created promocode for a consumable addon now how do i use it ? There is only option gift card and when i paste promocode it show error as attached in screenshot.

So Q2. Even if i successfully create promocode, how and where i can use it during purchase flow. ?

It is not possible to generate promotional codes for subscription add-ons. This is mentioned on the document - Generate promotional codes : You can generate promotional codes for any app or add-on (with the exception of subscription add-ons) that you published to the Microsoft Store.

So you can't use such a way to test the purchase subscription.

A possible way for testing purposes is that you could create a test subscription add-on that is free to purchase. Then you could purchase it to check the purchase process. After you go through the whole purchase process and make sure everything is correct, you could do the same to the real subscription add-on.