[FIX] account: prevent taxes on "payment_term" aml

Steps to reproduce:
- Go to Contacts and open any contact (e.g. Contact X)
- Check its configured Account Receivable (e.g. 121000 Account Receivable)
- Configure that account and set a default Sales tax on it (e.g. Tax 15%)
- Create an invoice with Contact X as customer
- Add an invoice line for any amount (e.g. $100) and any tax
- Swith to "Journal Items" tab and display "Taxes" column
A line (with 121000 Account Receivable) has been created automatically to balance the invoice line.
This line has a tax (i.e. Tax 15%): the default one configured on the account.
There should not be a tax for a receivable account.
Another issue is that the tax is set on the aml but not tax line has been created.
- Go back to "Invoice Lines" tab
- Remove the tax on the invoice line
- Save
In "Journal Items" tab, the tax line has been created from the aml with the receivable account.
- Go back to "Invoice Lines" tab
- Add a tax on the invoice line again
- Save
- Remove the tax on the invoice line
- Save
In "Journal Items" tab, there are now 2 tax lines from the aml with the receivable account.
By repeating the previous steps, new tax lines can be created infinitely.

Solution:
To prevent the issue, the default taxes shouldn't be populated on the aml when the account
is a receivable (or payable) one and when the move type is an "invoice" type one.
As "display_type" field of "account.move.line" is set to "payment_term" when the account is
a receivable or a payable one and when "is_invoice" is True on the move, no tax will be set
in "_compute_tax_ids" computed method when "display_type" is "payment_term".

opw-3345953

closes odoo/odoo#131330

X-original-commit: c6076a272cfe997856f3026557900ce9718c45e5
Signed-off-by: Anh Thao Pham (pta) <pta@odoo.com>
Signed-off-by: Brice Bartoletti (bib) <bib@odoo.com>

addons/account/models/account_move_line.py

@@ -843,7 +843,7 @@ class AccountMoveLine(models.Model):
     @api.depends('product_id', 'product_uom_id')
     def _compute_tax_ids(self):
         for line in self:
-            if line.display_type in ('line_section', 'line_note'):
+            if line.display_type in ('line_section', 'line_note', 'payment_term'):
                 continue
             # /!\ Don't remove existing taxes if there is no explicit taxes set on the account.
             if line.product_id or line.account_id.tax_ids or not line.tax_ids:

addons/account/tests/test_account_move_out_invoice.py

@@ -3647,3 +3647,25 @@ class TestAccountMoveOutInvoiceOnchanges(AccountTestInvoicingCommon):
         self.assertEqual(invalid_invoice_2.state, 'draft')
         self.assertEqual(invalid_invoice_2.message_ids[0].body,
                          "<p>The move could not be posted for the following reason: You need to add a line before posting.</p>")
+
+    def test_no_taxes_on_payment_term_line(self):
+        ''' No tax should be set on payment_term lines'''
+
+        receivable_account = self.partner_a.property_account_receivable_id
+        receivable_account.tax_ids = [Command.set(self.company_data['default_tax_sale'].ids)]
+
+        invoice = self.env['account.move'].create({
+            'move_type': 'out_invoice',
+            'partner_id': self.partner_a.id,
+            'invoice_line_ids': [
+                Command.create({
+                    'name': 'test line',
+                    'quantity': 1,
+                    'price_unit': 100,
+                })
+            ],
+        })
+
+        self.assertRecordValues(invoice.line_ids.filtered(lambda l: l.display_type == 'payment_term'), [
+            {'account_id': receivable_account.id, 'tax_ids': []},
+        ])