Switching proration not working as the documentation is understood

[WillBrubaker]

Describe the bug

Maybe this can be thought of as a double switch. After an initial purchase of a subscription and a subsequent downgrade, and then an upgrade, the pro-rated switch price seems incorrect.

To Reproduce

1. Prorate for upgrades and downgrades of all subscription products
2. Subscription length is never prorated
3. Never prorate the sign up fee.
4. A subscription has weekly, monthly, and yearly variations. Each are $1 for their period.
5. Purchase the monthly variation.
6. Switch to the yearly variation ($0 due at checkout)
7. Switch to the weekly variation. $1 due at checkout.

Expected behavior

Upgrades indicates to me that there should not be a gap payment collected.

Actual behavior

There's a charge for something I feel I've already paid for but not received.

Product impact

• [yes ] Does this issue affect WooCommerce Subscriptions? yes/no/tbc, add issue ref
• [ no] Does this issue affect WooCommerce Payments? yes/no/tbc, add issue ref

Additional context

7149492-zen

[james-allan]

Issue transferred to the subscriptions plugin repo. subscriptions-core doesn't contain subscription switching feature code.

See https://github.com/woocommerce/woocommerce-subscriptions/issues/4568