[FIX] purchase_stock: wrong amount in price difference account

1. Activate anglo saxon accounting
2. Create product with automated inventory valuation and standard pricing
3. Set decimal accuracy to 6
4. Set product cost price to 0,01719
5. Create PO for 30.000 items -> price = 0,01782 -> total = 534,6
6. Receive goods -> stock journal entry = 515,7 (based on the cost, ok)
7. Create vendor bill

Price difference is incorrect if you have a tax rate in the vendor bill
`price_unit_val_dif` will be rounded to 0.02
Multiplied by a great quantity the result will be wrong (84.30)
Without using the tax rate the price difference amount is the expected one

This commit partially revert 643d91e
to improve the original fix.

opw-2849074

closes odoo#91621

Signed-off-by: Laurent Smet <[email protected]>

Author: agr-odoo

addons/purchase_stock/models/account_invoice.py

@@ -100,19 +100,16 @@ def _stock_account_prepare_anglo_saxon_in_lines_vals(self):
 
                 price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
                 if line.tax_ids:
-                    if line.discount and line.quantity:
-                        # We do not want to round the price unit since :
-                        # - It does not follow the currency precision
-                        # - It may include a discount
-                        # Since compute_all still rounds the total, we use an ugly workaround:
-                        # multiply then divide the price unit.
-                        price_unit *= line.quantity
-                        price_unit = line.tax_ids.with_context(round=False, force_sign=move._get_tax_force_sign()).compute_all(
-                            price_unit, currency=move.currency_id, quantity=1.0, is_refund=move.move_type == 'in_refund')['total_excluded']
-                        price_unit /= line.quantity
-                    else:
-                        price_unit = line.tax_ids.compute_all(
-                            price_unit, currency=move.currency_id, quantity=1.0, is_refund=move.move_type == 'in_refund')['total_excluded']
+                    # We do not want to round the price unit since :
+                    # - It does not follow the currency precision
+                    # - It may include a discount
+                    # Since compute_all still rounds the total, we use an ugly workaround:
+                    # shift the decimal part using a fixed quantity to avoid rounding issues
+                    prec = 1e+6
+                    price_unit *= prec
+                    price_unit = line.tax_ids.with_context(round=False, force_sign=move._get_tax_force_sign()).compute_all(
+                        price_unit, currency=move.currency_id, quantity=1.0, is_refund=move.move_type == 'in_refund')['total_excluded']
+                    price_unit /= prec
 
                 price_unit_val_dif = price_unit - valuation_price_unit
                 price_subtotal = line.quantity * price_unit_val_dif

addons/purchase_stock/tests/test_stockvaluation.py

@@ -1351,3 +1351,30 @@ def test_anglosaxon_valuation_price_unit_diff_avco(self):
         # Check if something was posted in the price difference account
         price_diff_aml = invoice.line_ids.filtered(lambda l: l.account_id == self.price_diff_account)
         self.assertEqual(len(price_diff_aml), 0, "No line should have been generated in the price difference account.")
+
+    def test_anglosaxon_valuation_price_unit_diff_standard(self):
+        """
+        Check the price unit difference account is hit with the correct amount
+        """
+        self.env.ref("product.decimal_price").digits = 6
+        self.env.company.anglo_saxon_accounting = True
+        self.product1.categ_id.property_cost_method = 'standard'
+        self.product1.categ_id.property_valuation = 'real_time'
+        self.product1.categ_id.property_account_creditor_price_difference_categ = self.price_diff_account
+        self.product1.standard_price = 0.01719
+
+        invoice = self.env['account.move'].create({
+            'move_type': 'in_invoice',
+            'invoice_date': '2022-03-31',
+            'partner_id': self.partner_id.id,
+            'invoice_line_ids': [
+                (0, 0, {'product_id': self.product1.id, 'quantity': 30000, 'price_unit': 0.01782, 'tax_ids': self.tax_purchase_a.ids})
+            ]
+        })
+
+        invoice.action_post()
+
+        # Check if something was posted in the price difference account
+        price_diff_aml = invoice.line_ids.filtered(lambda l: l.account_id == self.price_diff_account)
+        self.assertEqual(len(price_diff_aml), 1, "A line should have been generated in the price difference account.")
+        self.assertAlmostEqual(price_diff_aml.balance, 18.90)