[FIX] stock_account: avoid negative values after revaluation

When performing a manual stock revaluation, the value difference is distributed
equally among the available stock. This method breaks down however in case of a
devaluation where some items in stock are already valued less than the unit
cost difference: this results in a negative value.

This commit will prevent such devaluations by raising a UserError whenever the
remaining value of a stock.valuation.layer becomes negative. Additionally, after
a revaluation, the standard_price field will now also be updated for fifo valued
products.

opw-3340298

closes odoo/odoo#143437

X-original-commit: a6db4b48f1d32f1020ee3ad242c77211aa10b3b2
Signed-off-by: Arnold Moyaux (arm) <arm@odoo.com>

addons/stock_account/i18n/stock_account.pot

@@ -1061,3 +1061,8 @@ msgstr ""
 #: model_terms:ir.ui.view,arch_db:stock_account.stock_account_report_invoice_document
 msgid "units"
 msgstr ""
+
+#. module: stock_account
+#: code:addons/stock_account/wizard/stock_valuation_layer_revaluation.py:0
+msgid "'The value of a stock valuation layer cannot be negative. Landed cost could be use to correct a specific transfer."
+msgstr ""

addons/stock_account/tests/test_stockvaluation.py

@@ -4004,3 +4004,46 @@ class TestStockValuation(TransactionCase):
 
         self.product1.write({'standard_price': 7})
         self.assertEqual(self.product1.value_svl, 49)
+
+    def test_average_manual_revaluation(self):
+        self.product1.categ_id.property_cost_method = 'average'
+
+        self._make_in_move(self.product1, 1, unit_cost=20)
+        self._make_in_move(self.product1, 1, unit_cost=30)
+        self.assertEqual(self.product1.standard_price, 25)
+
+        Form(self.env['stock.valuation.layer.revaluation'].with_context({
+            'default_product_id': self.product1.id,
+            'default_company_id': self.env.company.id,
+            'default_account_id': self.stock_valuation_account,
+            'default_added_value': -10.0,
+        })).save().action_validate_revaluation()
+
+        self.assertEqual(self.product1.standard_price, 20)
+
+    def test_fifo_manual_revaluation(self):
+        revaluation_vals = {
+            'default_product_id': self.product1.id,
+            'default_company_id': self.env.company.id,
+            'default_account_id': self.stock_valuation_account,
+        }
+        self.product1.categ_id.property_cost_method = 'fifo'
+
+        self._make_in_move(self.product1, 1, unit_cost=15)
+        self._make_in_move(self.product1, 1, unit_cost=30)
+        self.assertEqual(self.product1.stock_valuation_layer_ids[0].remaining_value, 15)
+
+        Form(self.env['stock.valuation.layer.revaluation'].with_context({
+            **revaluation_vals,
+            'default_added_value': -10.0,
+        })).save().action_validate_revaluation()
+
+        self.assertEqual(self.product1.stock_valuation_layer_ids[0].remaining_value, 10)
+
+        revaluation = Form(self.env['stock.valuation.layer.revaluation'].with_context({
+            **revaluation_vals,
+            'default_added_value': -25.0,
+        })).save()
+
+        with self.assertRaises(UserError):
+            revaluation.action_validate_revaluation()

addons/stock_account/wizard/stock_valuation_layer_revaluation.py

@@ -3,7 +3,7 @@
 
 from odoo import _, api, fields, models
 from odoo.exceptions import UserError
-from odoo.tools import float_is_zero
+from odoo.tools import float_compare, float_is_zero
 
 
 class StockValuationLayerRevaluation(models.TransientModel):
@@ -97,12 +97,15 @@ class StockValuationLayerRevaluation(models.TransientModel):
         remaining_value_unit_cost = self.currency_id.round(remaining_value / remaining_qty)
         for svl in remaining_svls:
             if float_is_zero(svl.remaining_qty - remaining_qty, precision_rounding=self.product_id.uom_id.rounding):
-                svl.remaining_value += remaining_value
+                taken_remaining_value = remaining_value
             else:
                 taken_remaining_value = remaining_value_unit_cost * svl.remaining_qty
-                svl.remaining_value += taken_remaining_value
-                remaining_value -= taken_remaining_value
-                remaining_qty -= svl.remaining_qty
+            if float_compare(svl.remaining_value + taken_remaining_value, 0, precision_rounding=self.product_id.uom_id.rounding) < 0:
+                raise UserError(_('The value of a stock valuation layer cannot be negative. Landed cost could be use to correct a specific transfer.'))
+
+            svl.remaining_value += taken_remaining_value
+            remaining_value -= taken_remaining_value
+            remaining_qty -= svl.remaining_qty
 
         revaluation_svl = self.env['stock.valuation.layer'].create(revaluation_svl_vals)