Fixed members import-with-tier alpha creating unexpected invoices (#20695)

ref https://linear.app/tryghost/issue/ONC-199

The `updateSubscriptionItemPrice()` method in our Stripe library used by the importer when moving a subscription over to a Ghost product/price was setting `proration_behavior: 'always_invoice'`. This resulted in invoices being created when changing the subscription (even though no prices were changing as far as the customer is concerned) and in some cases where a customer previously had a one-off discount the customer was incorrectly charged the proration difference because the discount was no longer applied to the new invoice.

- updated `updateSubscriptionItemPrice()` to accept an `options` param allowing the `proration_behavior` property passed to the Stripe API to be overridden on a per-call basis
- updated the `forceStripeSubscriptionToProduct()` method used by the importer to pass an options object with `prorationBehavior: 'none'` when updating the subscription item price so that no invoice and no unexpected charges occur when importing

ghost/members-importer/lib/MembersCSVImporterStripeUtils.js

@@ -153,7 +153,8 @@ module.exports = class MembersCSVImporterStripeUtils {
             await this._stripeAPIService.updateSubscriptionItemPrice(
                 stripeSubscription.id,
                 stripeSubscriptionItem.id,
-                newStripePrice.id
+                newStripePrice.id,
+                {prorationBehavior: 'none'}
             );
 
             stripePriceId = newStripePrice.id;
@@ -167,7 +168,8 @@ module.exports = class MembersCSVImporterStripeUtils {
                 await this._stripeAPIService.updateSubscriptionItemPrice(
                     stripeSubscription.id,
                     stripeSubscriptionItem.id,
-                    stripePriceId
+                    stripePriceId,
+                    {prorationBehavior: 'none'}
                 );
             }
         }

ghost/members-importer/test/MembersCSVImporterStripeUtils.test.js

@@ -304,7 +304,8 @@ describe('MembersCSVImporterStripeUtils', function () {
             stripeAPIServiceStub.updateSubscriptionItemPrice.calledWithExactly(
                 stripeCustomer.subscriptions.data[0].id,
                 stripeCustomerSubscriptionItem.id,
-                GHOST_PRODUCT_STRIPE_PRICE_ID
+                GHOST_PRODUCT_STRIPE_PRICE_ID,
+                {prorationBehavior: 'none'}
             ).should.be.true();
         });
 
@@ -346,7 +347,8 @@ describe('MembersCSVImporterStripeUtils', function () {
             stripeAPIServiceStub.updateSubscriptionItemPrice.calledWithExactly(
                 stripeCustomer.subscriptions.data[0].id,
                 stripeCustomerSubscriptionItem.id,
-                NEW_STRIPE_PRICE_ID
+                NEW_STRIPE_PRICE_ID,
+                {prorationBehavior: 'none'}
             ).should.be.true();
         });
 

ghost/stripe/lib/StripeAPI.js

@@ -698,20 +698,23 @@ module.exports = class StripeAPI {
      * @param {string} subscriptionId - The ID of the Subscription to modify
      * @param {string} id - The ID of the SubscriptionItem
      * @param {string} price - The ID of the new Price
+     * @param {object} [options={}] - Additional data to set on the subscription object
+     * @param {('always_invoice'|'create_prorations'|'none')} [options.prorationBehavior='always_invoice'] - The proration behavior to use. See [Stripe docs](https://docs.stripe.com/api/subscriptions/update#update_subscription-proration_behavior) for more info
+     * @param {string} [options.cancellationReason=null] - The user defined cancellation reason
      *
      * @returns {Promise<import('stripe').Stripe.Subscription>}
      */
-    async updateSubscriptionItemPrice(subscriptionId, id, price) {
+    async updateSubscriptionItemPrice(subscriptionId, id, price, options = {}) {
         await this._rateLimitBucket.throttle();
         const subscription = await this._stripe.subscriptions.update(subscriptionId, {
-            proration_behavior: 'always_invoice',
+            proration_behavior: options.prorationBehavior || 'always_invoice',
             items: [{
                 id,
                 price
             }],
             cancel_at_period_end: false,
             metadata: {
-                cancellation_reason: null
+                cancellation_reason: options.cancellationReason ?? null
             }
         });
         return subscription;