[FIX] account: error in Base amount tax

opw-1917605

Before this commit, when accounting is set to global rounding, the base
amount per tax is not correctly calculated.

Now, the Base amount per tax is calculated adding the rounded lines.

To test this issue, you need to set to global rounding and create a
customer invoice with the following lines :
line 1 = Qty:40; unit price:2.27; tax:15%; discount: 10%
line 2 = Qty:21; unit price:2.77; tax:15%; discount: 10%
line 3 = Qty:21; unit price:2.77; tax:15%; discount: 10%

When the invoce is printed, you would notice that the amount is 186.43
and it should be 186.42.

closes odoo#30021

addons/account/models/account_invoice.py

@@ -642,6 +642,7 @@ def _prepare_tax_line_vals(self, line, tax):
     @api.multi
     def get_taxes_values(self):
         tax_grouped = {}
+        round_curr = self.currency_id.round
         for line in self.invoice_line_ids:
             price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
             taxes = line.invoice_line_tax_ids.compute_all(price_unit, self.currency_id, line.quantity, line.product_id, self.partner_id)['taxes']
@@ -651,9 +652,10 @@ def get_taxes_values(self):
 
                 if key not in tax_grouped:
                     tax_grouped[key] = val
+                    tax_grouped[key]['base'] = round_curr(val['base'])
                 else:
                     tax_grouped[key]['amount'] += val['amount']
-                    tax_grouped[key]['base'] += val['base']
+                    tax_grouped[key]['base'] += round_curr(val['base'])
         return tax_grouped
 
     @api.multi

addons/account/tests/test_account_customer_invoice.py

@@ -107,3 +107,66 @@ def test_customer_invoice(self):
 
         # I clicked on refund button.
         self.account_invoice_refund_0.invoice_refund()
+
+    def test_customer_invoice_tax(self):
+
+        self.env.user.company_id.tax_calculation_rounding_method = 'round_globally'
+
+        payment_term = self.env.ref('account.account_payment_term_advance')
+        journalrec = self.env['account.journal'].search([('type', '=', 'sale')])[0]
+        partner3 = self.env.ref('base.res_partner_3')
+        account_id = self.env['account.account'].search([('user_type_id', '=', self.env.ref('account.data_account_type_revenue').id)], limit=1).id
+
+        tax = self.env['account.tax'].create({
+            'name': 'Tax 15.0',
+            'amount': 15.0,
+            'amount_type': 'percent',
+            'type_tax_use': 'sale',
+        })
+
+        invoice_line_data = [
+            (0, 0,
+                {
+                    'product_id': self.env.ref('product.product_product_1').id,
+                    'quantity': 40.0,
+                    'account_id': account_id,
+                    'name': 'product test 1',
+                    'discount' : 10.00,
+                    'price_unit': 2.27,
+                    'invoice_line_tax_ids': [(6, 0, [tax.id])],
+                }
+             ),
+              (0, 0,
+                {
+                    'product_id': self.env.ref('product.product_product_2').id,
+                    'quantity': 21.0,
+                    'account_id': self.env['account.account'].search([('user_type_id', '=', self.env.ref('account.data_account_type_revenue').id)], limit=1).id,
+                    'name': 'product test 2',
+                    'discount' : 10.00,
+                    'price_unit': 2.77,
+                    'invoice_line_tax_ids': [(6, 0, [tax.id])],
+                }
+             ),
+             (0, 0,
+                {
+                    'product_id': self.env.ref('product.product_product_3').id,
+                    'quantity': 21.0,
+                    'account_id': self.env['account.account'].search([('user_type_id', '=', self.env.ref('account.data_account_type_revenue').id)], limit=1).id,
+                    'name': 'product test 3',
+                    'discount' : 10.00,
+                    'price_unit': 2.77,
+                    'invoice_line_tax_ids': [(6, 0, [tax.id])],
+                }
+             )
+        ]
+
+        invoice = self.env['account.invoice'].create(dict(
+            name="Test Customer Invoice",
+            reference_type="none",
+            payment_term_id=payment_term.id,
+            journal_id=journalrec.id,
+            partner_id=partner3.id,
+            invoice_line_ids=invoice_line_data
+        ))
+
+        self.assertEquals(invoice.amount_untaxed, sum([x.base for x in invoice.tax_line_ids]))