[FIX] account: clear epd discount tax

Set "Cash Discount Tax Reduction" to "Always"
Have Tax A and Tax B
Create an invoice with a payment term having a discount (example: 2/7 Net 30)
Add the following lines
1) Any prod, Tax A
2) Any prod, Tax B
In journal items tab we will see 2 line for the product,
2 for tax, 3 for epd, 2 for epd tax discount, 1 for payment
Delete line 2)
Check journal items

Issue: epd discount for tax B is still there
This occurs because:
- When calculating the epd vals we don't actually
issue a clear command
- Due to a `_sync_dynamic_line` optimization
we may write on a line scheduled for delete instead of creating a new
one
As result an old tax may be left in the overwritten line

opw-3285534

closes odoo/odoo#123697

X-original-commit: bc83baf7d6be3a9ab25da90ddf1882c1cb95217e
Signed-off-by: Grazioso Andrea (agr) <agr@odoo.com>
Signed-off-by: William André (wan) <wan@odoo.com>

addons/account/models/account_move_line.py

@@ -1005,7 +1005,7 @@ class AccountMoveLine(models.Model):
                     'amount_currency': 0.0,
                     'balance': 0.0,
                     'price_subtotal': 0.0,
-                    'tax_ids': [],
+                    'tax_ids': [Command.clear()],
                 },
             )
             epd_needed_vals['amount_currency'] += line.amount_currency * percentage

addons/account/tests/test_early_payment_discount.py

@@ -581,3 +581,30 @@ class TestAccountEarlyPaymentDiscount(AccountTestInvoicingCommon):
         self.assertEqual(len(inv.line_ids), 3) # 1 prod, 1 tax, 1 payment terms
         inv.write({'invoice_payment_term_id': self.early_pay_10_percents_10_days.id})
         self.assertEqual(len(inv.line_ids), 6)
+
+    def test_mixed_epd_with_tax_deleted_line(self):
+        self.early_pay_10_percents_10_days.write({'early_pay_discount_computation': 'mixed'})
+        tax_a = self.env['account.tax'].create({
+             'name': 'Test A',
+             'amount': 10,
+        })
+        tax_b = self.env['account.tax'].create({
+             'name': 'Test B',
+             'amount': 15,
+        })
+
+        inv = self.env['account.move'].create({
+            'move_type': 'out_invoice',
+            'partner_id': self.partner_a.id,
+            'invoice_date': '2019-01-01',
+            'date': '2019-01-01',
+            'invoice_line_ids': [
+                Command.create({'name': 'line', 'price_unit': 100.0, 'tax_ids': [Command.set(tax_a.ids)]}),
+                Command.create({'name': 'line2', 'price_unit': 100.0, 'tax_ids': [Command.set(tax_b.ids)]}),
+            ],
+            'invoice_payment_term_id': self.early_pay_10_percents_10_days.id,
+        })
+        self.assertEqual(len(inv.line_ids), 10) # 2 prod, 2 tax, 3 epd, 2 epd tax discount, 1 payment terms
+        inv.invoice_line_ids[1].unlink()
+        self.assertEqual(len(inv.line_ids), 6) # 1 prod, 1 tax, 2 epd, 1 epd tax discount, 1 payment terms
+        self.assertEqual(inv.amount_tax, 9.00) # $100.0 @ 10% tax (-10% epd)