[FIX] point_of_sale: show discount information from pricelist in invoice

When the discount policy of a pricelist was set to `without_discount`, the discount information was shown in the order line of the product screen and on the receipt but not in the invoice.

task-2492631

addons/point_of_sale/models/pos_order.py

@@ -9,7 +9,7 @@ import pytz
 import re
 
 from odoo import api, fields, models, tools, _
-from odoo.tools import float_is_zero, float_round
+from odoo.tools import float_is_zero, float_round, float_repr
 from odoo.exceptions import ValidationError, UserError
 from odoo.http import request
 from odoo.osv.expression import AND
@@ -202,12 +202,20 @@ class PosOrder(models.Model):
         invoice_lines = []
         for line in self.lines:
             invoice_lines.append((0, None, self._prepare_invoice_line(line)))
+            if line.order_id.pricelist_id.discount_policy == 'without_discount' and line.price_unit != line.product_id.lst_price:
+                invoice_lines.append((0, None, {
+                    'name': _('Price discount from %s -> %s',
+                              float_repr(line.product_id.lst_price, self.currency_id.decimal_places),
+                              float_repr(line.price_unit, self.currency_id.decimal_places)),
+                    'display_type': 'line_note',
+                }))
             if line.customer_note:
                 invoice_lines.append((0, None, {
                     'name': line.customer_note,
                     'display_type': 'line_note',
                 }))
 
+
         return invoice_lines
 
     def _get_pos_anglo_saxon_price_unit(self, product, partner_id, quantity):