Fix multivalue implementation.

This commit refs #6311

party.py

@@ -30,6 +30,14 @@ class Party:
             return pool.get('party.party.invoice_to')
         return super(Party, cls).multivalue_model(field)
 
+    def multivalue_record(self, field, **pattern):
+        Value = self.multivalue_model(field)
+        if Value.__name__ == 'party.party.invoice_to':
+            pattern = pattern.copy()
+            pattern['party'] = self
+            return Value(**pattern)
+        return super(Party, self).multivalue_record(field, **pattern)
+
 
 class PartyInvoiceTo(ModelSQL, CompanyValueMixin):
     "Party Invoice to"

tests/test_account_invoice.py

@@ -1,16 +1,35 @@
 # The COPYRIGHT file at the top level of this repository contains the full
 # copyright notices and license terms.
 import unittest
+from trytond.pool import Pool
 import trytond.tests.test_tryton
-from trytond.tests.test_tryton import ModuleTestCase
+from trytond.tests.test_tryton import ModuleTestCase, with_transaction
 
 
 class TestCase(ModuleTestCase):
     """Test module"""
     module = 'account_invoice_party_invoice_to'
 
-    def setUp(self):
-        super(TestCase, self).setUp()
+    @with_transaction()
+    def test_party(self):
+        'Test configuration accounts are used as fallback on party'
+        pool = Pool()
+        Party = pool.get('party.party')
+
+        party1 = Party(name='Party to pay')
+        party1.save()
+        self.assertIsNone(party1.customer_to_invoice)
+        self.assertIsNone(party1.supplier_to_invoice)
+
+        party2 = Party(name='Party to receive')
+        party2.save()
+
+        party = Party(name='Party')
+        party.customer_to_invoice = party1
+        party.supplier_to_invoice = party2
+        party.save()
+        self.assertEqual(party.customer_to_invoice, party1)
+        self.assertEqual(party.supplier_to_invoice, party2)
 
 
 def suite():