[IMP] stock: allow to start inv. adj. with 0 qty

Add an Inventory Adjustment field `prefill_counted_quantity`.
True by default, when it's disabled, the inventory will generate when
inventory lines with 0 as value for `product_qty` field when started.

The purpose is to make simpler the use of barcode scanner to do the
inventory adjustment.

Task #2026952

addons/stock/models/stock_inventory.py

@@ -69,6 +69,9 @@ class Inventory(models.Model):
         help="Specify Products to focus your inventory on particular Products.")
     start_empty = fields.Boolean('Empty Inventory',
         help="Allows to start with an empty inventory.")
+    prefill_counted_quantity = fields.Boolean('Pre-fill counted quantity',
+        help='Pre-fill the counted quantity with on hand quantity for all the '
+        'products included in the inventory adjustment.', default=True)
 
     def unlink(self):
         for inventory in self:
@@ -231,6 +234,8 @@ class Inventory(models.Model):
             for void_field in [item[0] for item in product_data.items() if item[1] is None]:
                 product_data[void_field] = False
             product_data['theoretical_qty'] = product_data['product_qty']
+            if not self.prefill_counted_quantity:
+                product_data['product_qty'] = 0
             if product_data['product_id']:
                 product_data['product_uom_id'] = Product.browse(product_data['product_id']).uom_id.id
                 quant_products |= Product.browse(product_data['product_id'])

addons/stock/tests/test_inventory.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 from odoo.exceptions import ValidationError
-from odoo.tests.common import SavepointCase
+from odoo.tests.common import Form, SavepointCase
 
 
 class TestInventory(SavepointCase):
@@ -311,6 +311,21 @@ class TestInventory(SavepointCase):
         self.assertEqual(len(inventory.line_ids), 1)
         self.assertEqual(inventory.line_ids.theoretical_qty, 2)
 
+    def test_inventory_8(self):
+        """ Check inventory lines product quantity is 0 when inventory is
+        started with `prefill_counted_quantity` disable.
+        """
+        inventory_form = Form(self.env['stock.inventory'].with_context(
+                default_prefill_counted_quantity=False,
+             ), view='stock.view_inventory_form')
+        inventory = inventory_form.save()
+        inventory.action_start()
+        self.assertNotEqual(len(inventory.line_ids), 0)
+        # Checks all inventory lines quantities are correctly set.
+        for line in inventory.line_ids:
+            self.assertEqual(line.product_qty, 0)
+            self.assertNotEqual(line.theoretical_qty, 0)
+
     def test_inventory_outdate_1(self):
         """ Checks that inventory adjustment line is marked as outdated after
         its corresponding quant is modify and its value was correctly updated

addons/stock/views/stock_inventory_views.xml

@@ -181,6 +181,8 @@
                     </group>
                     <group>
                         <field name="company_id" groups="base.group_multi_company" options="{'no_create': True}"/>
+                        <field name="prefill_counted_quantity"
+                               attrs="{'invisible': [('state', '!=', 'draft')]}"/>
                     </group>
                 </group>
                 <div attrs="{'invisible': [('state', '=', 'done')]}">