[FIX] sale: fix amount to invoice for credit notes

Issue:
The `_compute_amount_to_invoice` computation wasn't taking
into account the fact that invoices have a direction (i.e. either
going outbound(+) or coming inbound(-) (cf. `_compute_direction_sign`)).
This, in turn, makes the value of `amount_to_invoice` incorrect
for sales order with a credit note.

Solution:
In  `_compute_amount_to_invoice`, multiply the value of
`invoice_amount_currency` with the opposite of  the
`direction_sign` of the invoice, to account for the invoice direction.

opw-3360439

X-original-commit: 06ef17f2eefe89abfca64721185ac053fa8de820

[FIX] sale: fix amount to invoice for credit notes

Issue:
The `_compute_amount_to_invoice` computation wasn't taking
into account the fact that invoices have a direction (i.e. either
going outbound(+) or coming inbound(-) (cf. `_compute_direction_sign`)).
This, in turn, makes the value of `amount_to_invoice` incorrect
for sales order with a credit note.

Solution:
In  `_compute_amount_to_invoice`, multiply the value of
`invoice_amount_currency` with the opposite of  the
`direction_sign` of the invoice, to account for the invoice direction.

opw-3360439

closes odoo/odoo#127914

X-original-commit: d258774f120fb470d969e68c05cf0d8da0c4557a
Signed-off-by: John Laterre (jol) <jol@odoo.com>

addons/sale/models/sale_order.py

@@ -612,7 +612,7 @@ class SaleOrder(models.Model):
             order.amount_to_invoice = order.amount_total
             for invoice in order.invoice_ids.filtered(lambda x: x.state == 'posted'):
                 invoice_amount_currency = invoice.currency_id._convert(
-                    invoice.tax_totals['amount_total'],
+                    invoice.tax_totals['amount_total'] * -invoice.direction_sign,
                     order.currency_id,
                     invoice.company_id,
                     invoice.date,

addons/sale/tests/test_sale_order_down_payment.py

@@ -452,16 +452,36 @@ class TestSaleOrderDownPayment(TestSaleCommon):
             'deposit_account_id': self.revenue_account.id,
         }).create_invoices()
 
+        invoice = sale_order.invoice_ids
+
         # Check that the warning does not appear even though we are creating an invoice
         # that should bring partner_a's credit above its limit.
-        self.assertEqual(sale_order.invoice_ids.partner_credit_warning, '')
+        self.assertEqual(invoice.partner_credit_warning, '')
+
 
         # Make the down payment invoice amount larger than the Amount to Invoice
         # and check that the warning appears with the correct amounts,
         # i.e. 1.500 instead of 2.500 (1.000 SO + 1.500 down payment invoice).
-        sale_order.invoice_ids.invoice_line_ids.quantity = 3
+        invoice.invoice_line_ids.quantity = 3
         self.assertEqual(
-            sale_order.invoice_ids.partner_credit_warning,
+            invoice.partner_credit_warning,
             "partner_a has reached its Credit Limit of: $\xa01,000.00\n"
             "Total amount due (including this document): $\xa01,500.00"
         )
+
+        invoice.invoice_line_ids.quantity = 1
+        invoice.action_post()
+
+        # Create a credit note reversing the invoice
+        self.env['account.move.reversal'].with_company(self.env.company).create(
+            {
+                'move_ids': [Command.set((invoice.id,))],
+                'journal_id': invoice.journal_id.id
+            }
+        ).reverse_moves()
+
+        credit_note = sale_order.invoice_ids[1]
+        credit_note.action_post()
+
+        # Check that the credit note is accounted for correctly for the amount_to_invoice
+        self.assertEqual(sale_order.amount_to_invoice, sale_order.amount_total)