Allow changing total amount and payment status simultaneously (#4723)

Closes #4719

---------

Co-authored-by: Thomas Koopman <koopmant@users.noreply.github.com>

Author: amickan

app/grandchallenge/invoices/models.py

@@ -360,7 +360,8 @@ def clean(self):
         if (
             not self._state.adding
             and self.payment_type != PaymentTypeChoices.COMPLIMENTARY
-            and self.payment_status != PaymentStatusChoices.INITIALIZED
+            and self.initial_value("payment_status")
+            != PaymentStatusChoices.INITIALIZED
         ):
             # Assert total amount unchanged
             if (

app/tests/invoices_tests/test_models.py

@@ -451,6 +451,26 @@ def test_total_amount_can_change_for_complimentary_invoices():
         invoice.clean()
 
 
+@pytest.mark.parametrize(
+    "payment_type", (PaymentTypeChoices.PREPAID, PaymentTypeChoices.POSTPAID)
+)
+@pytest.mark.django_db
+def test_updating_total_amount_and_status_simultaneously_is_possible(
+    payment_type,
+):
+    invoice = InvoiceFactory(
+        payment_type=payment_type,
+        payment_status=PaymentStatusChoices.INITIALIZED,
+        support_costs_euros=0,
+        compute_costs_euros=1,
+        storage_costs_euros=2,
+    )
+    invoice.support_costs_euros = 2
+    invoice.payment_status = PaymentStatusChoices.REQUESTED
+    with nullcontext():
+        invoice.clean()
+
+
 @pytest.mark.django_db
 def test_invoices_cannot_be_deleted():
     invoice = InvoiceFactory()