[FIX] account: register payment multi invoices

In the invoice list view, select one or more invoices
click on the action > register payment

In the wizard, put an amount inferior to the sum of invoices amount
Do a write off

Before this commit, the write off was ignored and the invoices not marked as paid

After this commit, the write is written, and the invoices marked as paid

OPW 1920839

closes odoo/odoo#30465

addons/account/models/account_payment.py

@@ -324,7 +324,7 @@ class account_register_payments(models.TransientModel):
         pmt_communication = self.show_communication_field and self.communication \
                             or self.group_invoices and ' '.join([inv.reference or inv.number for inv in invoices]) \
                             or invoices[0].reference # in this case, invoices contains only one element, since group_invoices is False
-        return {
+        values = {
             'journal_id': self.journal_id.id,
             'payment_method_id': self.payment_method_id.id,
             'payment_date': self.payment_date,
@@ -337,8 +337,13 @@ class account_register_payments(models.TransientModel):
             'partner_type': MAP_INVOICE_TYPE_PARTNER_TYPE[invoices[0].type],
             'partner_bank_account_id': bank_account.id,
             'multi': False,
+            'payment_difference_handling': self.payment_difference_handling,
+            'writeoff_account_id': self.writeoff_account_id.id,
+            'writeoff_label': self.writeoff_label,
         }
 
+        return values
+
     @api.multi
     def get_payments_vals(self):
         '''Compute the values for payments.

addons/account/tests/test_payment.py

@@ -595,3 +595,37 @@ class TestPayment(AccountingTestCase):
 
         # The invoice should now be paid
         self.assertEqual(invoice.state, 'paid', "Invoice should be in 'paid' state after having reconciled the two payments with a bank statement")
+
+    def test_register_payments_multi_invoices(self):
+        inv1 = self.create_invoice(amount=40)
+        inv2 = inv1.copy()
+        inv2.action_invoice_open()
+
+        batch_payment = self.env['account.register.payments'].with_context(active_ids=(inv1 + inv2).ids).create({
+            'amount': 70,
+            'partner_id': inv1.partner_id.id,
+            'journal_id': self.bank_journal_usd.id,
+            'invoice_ids': [(6, False, (inv1 + inv2).ids)],
+            'partner_type': 'customer',
+            'payment_difference_handling': 'reconcile',
+            'payment_type': 'inbound',
+            'payment_method_id': self.payment_method_manual_in.id,
+            'writeoff_account_id': self.account_revenue.id,
+            'writeoff_label': "why can't we live together"})
+
+        payment_id = batch_payment.create_payments()['res_id']
+        payment_id = self.env['account.payment'].browse(payment_id)
+
+        self.assertEqual(inv1.state, 'paid')
+        self.assertEqual(inv2.state, 'paid')
+
+        receivable_inv1 = inv1.move_id.line_ids.filtered(lambda l: l.account_id.internal_type == 'receivable')
+        receivable_inv2 = inv2.move_id.line_ids.filtered(lambda l: l.account_id.internal_type == 'receivable')
+        receivable_payment = payment_id.move_line_ids.filtered(lambda l: l.account_id.internal_type == 'receivable')
+
+        self.assertEqual(
+            receivable_inv1.full_reconcile_id.reconciled_line_ids,
+            receivable_inv1 + receivable_inv2 + receivable_payment
+        )
+        write_off_line = payment_id.move_line_ids.filtered(lambda l: l.account_id == payment_id.writeoff_account_id)
+        self.assertEqual(write_off_line.debit, 10)