Unable to use Billing API when developing a Shopify app

[Chad_Johnson]

"Custom" Shopify apps (as opposed to "public" ones), often used for development purposes when developing Shopify apps, are unable to utilize the Billing API. Therefore, it is impossible to implement, test, and verify any functionality that deals with the RecurringApplicationCharge API. I feel this is a short-sighted choice on Shopify's part.

I want to bring this to Shopify's attention.

I also want to ask: How are we to actually implement, test, and verify integrations with the Billing API when developing an app?

[ShopDoctors]

Bumping up. Would it be possible to enable this for custom app when the existing `test` parameter is set to `true`, so that it can be used for automated testing? This would be especially valuable since we cannot test this when updating to a new API version without actually deploying the code to production.