Lot invoicing + Fee padding

modules/purchase_trade/lot.py

@@ -4767,7 +4767,7 @@ class LotInvoice(Wizard):
                         val['fee_quantity'] = f.quantity
                         val['fee_price'] = f.price
                         val['fee_unit'] = purchase_line.unit.id
-                        val['fee_amount'] = f.amount
+                        val['fee_amount'] = self._fee_display_amount(f, act)
                         val['fee_landed_cost'] = f.fee_landed_cost
                         fee_pur.append(val)
         if line:
@@ -4796,7 +4796,7 @@ class LotInvoice(Wizard):
                         val['fee_quantity'] = f.quantity
                         val['fee_price'] = f.price
                         val['fee_unit'] = current_sale_line.unit.id
-                        val['fee_amount'] = f.amount
+                        val['fee_amount'] = self._fee_display_amount(f, act)
                         val['fee_landed_cost'] = f.fee_landed_cost
                         fee_sale.append(val)
         if sale_line:
@@ -4818,9 +4818,20 @@ class LotInvoice(Wizard):
             'pp_pur': pp_pur,
             'fee_sale': fee_sale,
             'pp_sale': pp_sale,
-            'action': act
-            }
-
+            'action': act
+            }
+
+    @staticmethod
+    def _fee_display_amount(fee, action):
+        if (
+                action == 'final'
+                and getattr(fee, 'state', None) == 'invoiced'
+                and getattr(fee, 'add_padding', False)):
+            with Transaction().set_context(
+                    _purchase_trade_ignore_fee_padding=True):
+                return fee.amount
+        return fee.amount
+
     def transition_invoicing(self):
         Lot = Pool().get('lot.lot')
         Purchase = Pool().get('purchase.purchase')

modules/purchase_trade/tests/test_module.py

@@ -3402,6 +3402,25 @@ class PurchaseTradeTestCase(ModuleTestCase):
         self.assertEqual(fee_line.fee_quantity, Decimal('5'))
         self.assertEqual(fee_line.fee_amount, Decimal('10.00'))
 
+    def test_lot_invoice_default_final_fee_display_ignores_padding(self):
+        'initial final fee display reads amount without padding'
+        class FeeStub:
+            state = 'invoiced'
+            add_padding = True
+
+            @property
+            def amount(self):
+                if Transaction().context.get(
+                        '_purchase_trade_ignore_fee_padding'):
+                    return Decimal('14970')
+                return Decimal('14985')
+
+        fee = FeeStub()
+
+        self.assertEqual(
+            lot_module.LotInvoice._fee_display_amount(fee, 'final'),
+            Decimal('14970'))
+
     def test_fee_get_non_cog_returns_zero_without_move_lines(self):
         'fee non-cog amount is zero before any accounting move line exists'
         fee = fee_module.Fee()