corporate: Invoice self-hosted fixed-price plans with stale data.

Because license counts do not change the amount due for plans with
a fixed-price, we invoice them for self-hosted customers even when
the audit log data from the server is stale.

corporate/lib/stripe.py

@@ -5531,6 +5531,15 @@ def check_remote_server_audit_log_data(
     next_invoice_date = plan.next_invoice_date
     last_audit_log_update = remote_server.last_audit_log_update
     if last_audit_log_update is None or next_invoice_date > last_audit_log_update:
+        # We still process fixed-price plans because the current license count
+        # won't change the amount due or the fact that we should downgrade the
+        # plan when it is scheduled to end.
+        if plan.fixed_price is not None:
+            # TODO: Possibly send an internal billing notice so that billing admin
+            # have a record that the customer's license ledger entries do not
+            # reflect actual audit log data from the remote server.
+            return True
+
         if not plan.stale_audit_log_data_email_sent:
             maybe_send_stale_audit_log_data_email(
                 plan, billing_session, next_invoice_date, last_audit_log_update

corporate/tests/test_stripe.py

@@ -10017,16 +10017,26 @@ class TestRemoteServerBillingFlow(StripeTestCase, RemoteServerTestCase):
         ]:
             self.assert_in_response(substring, response)
 
-        # The last audit log update was 25 days before the plan's next
-        # invoice date, so invoicing the fixed-price plan fails, and an
-        # internal billing notice is sent.
+        # Since fixed-price plans do not depend on license counts for the
+        # amount due, we invoice them even if the audit log data is stale
+        # from the server.
         last_audit_log_update = self.now + timedelta(days=5)
         with time_machine.travel(last_audit_log_update, tick=False):
             send_server_data_to_push_bouncer(consider_usage_statistics=False)
         invoice_plans_as_needed(self.next_month)
         current_plan.refresh_from_db()
-        self.assertEqual(current_plan.next_invoice_date, self.next_month)
-        self.assertTrue(current_plan.stale_audit_log_data_email_sent)
+        updated_invoice_date = self.next_month + timedelta(days=29)
+        self.assertEqual(current_plan.next_invoice_date, updated_invoice_date)
+        self.assertFalse(current_plan.stale_audit_log_data_email_sent)
+
+        # Audit log data is up-to-date when the plan is next invoiced.
+        with time_machine.travel(updated_invoice_date, tick=False):
+            send_server_data_to_push_bouncer(consider_usage_statistics=False)
+        invoice_plans_as_needed(updated_invoice_date)
+        current_plan.refresh_from_db()
+        final_invoice_date = updated_invoice_date + timedelta(days=31)
+        self.assertEqual(current_plan.next_invoice_date, final_invoice_date)
+        self.assertFalse(current_plan.stale_audit_log_data_email_sent)
 
     @responses.activate
     @mock_stripe()