[FIX] purchase: compute unit price with different uom

On a product form, if the purchase UoM is different from the default
UoM, this will lead to an error when creating a RfQ.

To reproduce the error:
(Need stock)
1. In Settings, enable "Unit of Measures"
2. Create a product P:
    - Cost: 100
    - UoM: Units
    - Purchase UoM: Dozens
3. Create a RfQ:
    - Add P

Error: The quantity is 1 and UoM is Dozens, however the unit price is
$14400. The ratio has been applied twice.

When setting the product, an onchange method computes the unit price.
However, the computation is wrong: it first converts the product's
standard price using the purchase UoM of the product. Then, it converts
the result, this time using the UoM of the PO line.

OPW-2519294

closes odoo/odoo#72139

X-original-commit: b37a13d7763e4a69695fdb1567dce5d0f69ff78a
Signed-off-by: Arnold Moyaux <amoyaux@users.noreply.github.com>
Signed-off-by: Adrien Widart <adwid@users.noreply.github.com>

addons/purchase/models/purchase.py

@@ -1125,8 +1125,9 @@ class PurchaseOrderLine(models.Model):
 
         # If not seller, use the standard price. It needs a proper currency conversion.
         if not seller:
+            po_line_uom = self.product_uom or self.product_id.uom_po_id
             price_unit = self.env['account.tax']._fix_tax_included_price_company(
-                self.product_id.uom_id._compute_price(self.product_id.standard_price, self.product_id.uom_po_id),
+                self.product_id.uom_id._compute_price(self.product_id.standard_price, po_line_uom),
                 self.product_id.supplier_taxes_id,
                 self.taxes_id,
                 self.company_id,
@@ -1139,9 +1140,6 @@ class PurchaseOrderLine(models.Model):
                     self.date_order or fields.Date.today(),
                 )
 
-            if self.product_uom:
-                price_unit = self.product_id.uom_id._compute_price(price_unit, self.product_uom)
-
             self.price_unit = price_unit
             return
 

addons/purchase/tests/test_purchase.py

@@ -215,3 +215,36 @@ class TestPurchase(AccountTestInvoicingCommon):
             line.product_packaging_qty = 1.0
         po_form.save()
         self.assertEqual(po.order_line.product_qty, 12)
+
+    def test_with_different_uom(self):
+        """ This test ensures that the unit price is correctly computed"""
+        uom_units = self.env['ir.model.data'].xmlid_to_object('uom.product_uom_unit')
+        uom_dozens = self.env['ir.model.data'].xmlid_to_object('uom.product_uom_dozen')
+        uom_pairs = self.env['uom.uom'].create({
+            'name': 'Pairs',
+            'category_id': uom_units.category_id.id,
+            'uom_type': 'bigger',
+            'factor_inv': 2,
+            'rounding': 1,
+        })
+        product_data = {
+            'name': 'SuperProduct',
+            'type': 'consu',
+            'uom_id': uom_units.id,
+            'uom_po_id': uom_pairs.id,
+            'standard_price': 100
+        }
+        product_01 = self.env['product.product'].create(product_data)
+        product_02 = self.env['product.product'].create(product_data)
+
+        po_form = Form(self.env['purchase.order'])
+        po_form.partner_id = self.partner_a
+        with po_form.order_line.new() as po_line:
+            po_line.product_id = product_01
+        with po_form.order_line.new() as po_line:
+            po_line.product_id = product_02
+            po_line.product_uom = uom_dozens
+        po = po_form.save()
+
+        self.assertEqual(po.order_line[0].price_unit, 200)
+        self.assertEqual(po.order_line[1].price_unit, 1200)