Fix taxes calculation and override in a proper way

account_invoice_triple_discount/models/__init__.py

@@ -1,3 +1,4 @@
 # -*- coding: utf-8 -*-
 
+from . import account_invoice
 from . import account_invoice_line

account_invoice_triple_discount/models/account_invoice.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Tecnativa - David Vidal
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import models
+
+
+class AccountInvoice(models.Model):
+    _inherit = "account.invoice"
+
+    def get_taxes_values(self):
+        prices = {}
+        discount = {}
+        for line in self.invoice_line_ids:
+            prices[line.id] = line.price_unit
+            discount[line.id] = line.discount
+            line.price_unit *= (1 - (line.discount or 0.0) / 100.0)
+            line.price_unit *= (1 - (line.discount2 or 0.0) / 100.0)
+            line.price_unit *= (1 - (line.discount3 or 0.0) / 100.0)
+            line['discount'] = 0.0
+        tax_grouped = super(AccountInvoice, self).get_taxes_values()
+        for line in self.invoice_line_ids:
+            line['price_unit'] = prices[line.id]
+            line['discount'] = discount[line.id]
+        return tax_grouped

account_invoice_triple_discount/models/account_invoice_line.py

@@ -27,26 +27,12 @@ class AccountInvoiceLine(models.Model):
                  'invoice_id.company_id', 'invoice_id.date_invoice')
     def _compute_price(self):
         for line in self:
-            currency = line.invoice_id and line.invoice_id.currency_id or None
-            price = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
-            price *= (1 - (line.discount2 or 0.0) / 100.0)
-            price *= (1 - (line.discount3 or 0.0) / 100.0)
-            taxes = False
-            if line.invoice_line_tax_ids:
-                taxes = line.invoice_line_tax_ids.compute_all(
-                    price, currency, line.quantity, product=line.product_id,
-                    partner=line.invoice_id.partner_id)
-            line.price_subtotal = price_subtotal_signed = taxes[
-                'total_excluded'] if taxes else line.quantity * price
-            if (line.invoice_id.currency_id and
-                    line.invoice_id.company_id and
-                    line.invoice_id.currency_id !=
-                    line.invoice_id.company_id.currency_id):
-                price_subtotal_signed = \
-                    line.invoice_id.currency_id.with_context(
-                        date=line.invoice_id.date_invoice).compute(
-                            price_subtotal_signed,
-                            line.invoice_id.company_id.currency_id)
-            sign = line.invoice_id.type in ['in_refund',
-                                            'out_refund'] and -1 or 1
-            line.price_subtotal_signed = price_subtotal_signed * sign
+            price = line.price_unit
+            discount = line.discount
+            line.price_unit *= (1 - (line.discount or 0.0) / 100.0)
+            line.price_unit *= (1 - (line.discount2 or 0.0) / 100.0)
+            line.price_unit *= (1 - (line.discount3 or 0.0) / 100.0)
+            line['discount'] = 0.0
+            super(AccountInvoiceLine, line)._compute_price()
+            line['price_unit'] = price
+            line['discount'] = discount

account_invoice_triple_discount/tests/test_invoice_triple_discount.py

@@ -11,6 +11,12 @@ class TestInvoiceTripleDiscount(SavepointCase):
     def setUpClass(cls):
         super(TestInvoiceTripleDiscount, cls).setUpClass()
         cls.partner = cls.env['res.partner'].create({'name': 'Test'})
+        cls.tax = cls.env['account.tax'].create({
+            'name': 'TAX 15%',
+            'amount_type': 'percent',
+            'type_tax_use': 'purchase',
+            'amount': 15.0,
+        })
         cls.account_type = cls.env['account.account.type'].create({
             'name': 'Test',
             'type': 'receivable',
@@ -34,40 +40,44 @@ def setUpClass(cls):
             'name': 'Line 1',
             'price_unit': 200.0,
             'account_id': cls.account.id,
+            'invoice_line_tax_ids': [(6, 0, [cls.tax.id])],
         })
+        cls.invoice._onchange_invoice_line_ids()
 
-    def test_discounts(self):
+    def test_01_discounts(self):
+        """ Tests multiple discounts in line with taxes """
         # Adds a first discount
         self.invoice_line1.discount = 50.0
-        self.invoice._compute_amount()
-        self.assertEqual(self.invoice.amount_total, 100.0)
+        self.invoice._onchange_invoice_line_ids()
+        self.assertEqual(self.invoice.amount_total, 115.0)
         # Adds a second discount over the price calculated before
         self.invoice_line1.discount2 = 40.0
-        self.invoice._compute_amount()
-        self.assertEqual(self.invoice.amount_total, 60.0)
+        self.invoice._onchange_invoice_line_ids()
+        self.assertEqual(self.invoice.amount_total, 69.0)
         # Adds a third discount over the price calculated before
         self.invoice_line1.discount3 = 50.0
-        self.invoice._compute_amount()
-        self.assertEqual(self.invoice.amount_total, 30.0)
+        self.invoice._onchange_invoice_line_ids()
+        self.assertEqual(self.invoice.amount_total, 34.5)
         # Deletes first discount
         self.invoice_line1.discount = 0.0
-        self.invoice._compute_amount()
-        self.assertEqual(self.invoice.amount_total, 60.0)
+        self.invoice._onchange_invoice_line_ids()
+        self.assertEqual(self.invoice.amount_total, 69.0)
         # Charge 5% over price:
         self.invoice_line1.discount = -5.0
-        self.invoice._compute_amount()
-        self.assertEqual(self.invoice.amount_total, 63.0)
+        self.invoice._onchange_invoice_line_ids()
+        self.assertEqual(self.invoice.amount_total, 72.45)
 
-    def test_discounts_multiple_lines(self):
+    def test_02_discounts_multiple_lines(self):
+        """ Tests multiple lines with mixed taxes """
         self.invoice_line2 = self.invoice_line.create({
             'invoice_id': self.invoice.id,
             'name': 'Line 1',
             'price_unit': 500.0,
             'account_id': self.account.id,
         })
         self.invoice_line2.discount3 = 50.0
-        self.invoice._compute_amount()
-        self.assertEqual(self.invoice.amount_total, 450.0)
+        self.invoice._onchange_invoice_line_ids()
+        self.assertEqual(self.invoice.amount_total, 480.0)
         self.invoice_line1.discount = 50.0
-        self.invoice._compute_amount()
-        self.assertEqual(self.invoice.amount_total, 350.0)
+        self.invoice._onchange_invoice_line_ids()
+        self.assertEqual(self.invoice.amount_total, 365.0)