[FIX] purchase_stock: price diff on vendor bill

Steps to reproduce:

• Create Record: Product Category
- Costing Method: Average
- Inventory Valuation: Automated
- Specify a price difference account (may create new account).
- Ensure Stock Interim (Received) account is reconcilable.

• Create Record: Product
- Product Type: Storable
- Cost Price: 1.01
- Product Category: New Product Category

• Create bill with this product, for a quantity of 10.5

-> The is price difference of 0.1

Issue comes from this commit 286ea6b681e9ba77357f91b546052449f6342f20
which doesn't round if there is a discount.

With this commit we isolate the latter case in order to keep the
price unit rounded if there is no discount.

closes odoo/odoo#88734

X-original-commit: 643d91ef5ebfb29fde142294ced82c470d42c136
Signed-off-by: Florian Gilbert <flg@odoo.com>

addons/purchase_stock/models/account_invoice.py

@@ -99,16 +99,20 @@ class AccountMove(models.Model):
 
 
                 price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
-                if line.tax_ids 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
+                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']
 
                 price_unit_val_dif = price_unit - valuation_price_unit
                 price_subtotal = line.quantity * price_unit_val_dif

addons/purchase_stock/tests/test_stockvaluation.py

@@ -1276,3 +1276,28 @@ class TestStockValuationWithCOA(AccountTestInvoicingCommon):
         self.assertEqual(len(input_aml), 2, "Only two lines should have been generated in stock input account: one when receiving the product, one when making the invoice.")
         self.assertAlmostEqual(sum(input_aml.mapped('debit')), 90, "Total debit value on stock input account should be equal to the original PO price of the product.")
         self.assertAlmostEqual(sum(input_aml.mapped('credit')), 90, "Total credit value on stock input account should be equal to the original PO price of the product.")
+
+    def test_anglosaxon_valuation_price_unit_diff_avco(self):
+        """
+        Inv: price unit: 100
+        """
+        self.env.company.anglo_saxon_accounting = True
+        self.product1.categ_id.property_cost_method = 'average'
+        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 = 1.01
+
+        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': 10.50, 'price_unit': 1.01, '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), 0, "No line should have been generated in the price difference account.")