Cancel payments if the pending price of the order changes

src/pretix/base/services/orders.py

@@ -931,6 +931,21 @@ class OrderChangeManager:
             if self.order.pending_sum <= Decimal('0.00'):
                 self.order.status = Order.STATUS_PAID
                 self.order.save()
+            elif self.open_payment:
+                self.open_payment.state = OrderPayment.PAYMENT_STATE_CANCELED
+                self.open_payment.save()
+                self.order.log_action('pretix.event.order.payment.canceled', {
+                    'local_id': self.open_payment.local_id,
+                    'provider': self.open_payment.provider,
+                }, user=self.user, auth=self.auth)
+        elif self.order.status in (Order.STATUS_PENDING, Order.STATUS_EXPIRED) and self._totaldiff > 0:
+            if self.open_payment:
+                self.open_payment.state = OrderPayment.PAYMENT_STATE_CANCELED
+                self.open_payment.save()
+                self.order.log_action('pretix.event.order.payment.canceled', {
+                    'local_id': self.open_payment.local_id,
+                    'provider': self.open_payment.provider,
+                }, user=self.user, auth=self.auth)
 
     def _check_paid_to_free(self):
         if self.order.total == 0 and (self._totaldiff < 0 or (self.split_order and self.split_order.total > 0)):

src/tests/base/test_orders.py

@@ -1103,6 +1103,18 @@ class OrderChangeManagerTests(TestCase):
         assert o2.invoice_address != ia
         assert o2.invoice_address.company == 'Sample'
 
+    def test_change_price_of_pending_order_with_payment(self):
+        self.order.status = Order.STATUS_PENDING
+        self.order.save()
+        assert self.order.payments.last().state == OrderPayment.PAYMENT_STATE_CREATED
+        assert self.order.payments.last().amount == Decimal('46.00')
+
+        self.ocm.change_price(self.op1, Decimal('27.00'))
+        self.ocm.commit()
+
+        assert self.order.payments.last().state == OrderPayment.PAYMENT_STATE_CANCELED
+        assert self.order.payments.last().amount == Decimal('46.00')
+
     def test_split_reverse_charge(self):
         ia = self._enable_reverse_charge()