[FIX] mrp: duplicate lot when auto-generate serial.

To reproduce:
1. Manually create lot "0000001" for a lot product
2. Create a MO for this product and click generate-serial button.
Validation error raised since we are trying to generate lot/sn "0000001"
again.

When useing action_generate_serial, ir.sequence always try create a
lot/sn in form "00000dd". If user already created the same one, the
generation will fail.

We already tried to avoid this issue for sn in _get_next_serial() by
finding the latest sn and create new one base on it.

To fix, we also allow _get_next_serial to be applied to lot.

Part of Tast-3187003

closes odoo/odoo#118481

X-original-commit: dc69748ea2698077782d839cf7da48e987f17ffc
Signed-off-by: William Henrotin (whe) <whe@odoo.com>
Signed-off-by: Yuchen Huang (yhu) <yhu@odoo.com>

addons/mrp/tests/test_traceability.py

@@ -613,3 +613,25 @@ class TestTraceability(TestMrpCommon):
             {'product_id': self.bom_4.product_id.id, 'lot_id': False, 'qty_done': 1},
             {'product_id': component.id, 'lot_id': serial_number.id, 'qty_done': 1},
         ])
+
+    def test_generate_serial_button(self):
+        """Test if lot in form "00000dd" is manually created, the generate serial
+        button can skip it and create the next one.
+        """
+        mo, _bom, p_final, _p1, _p2 = self.generate_mo(qty_base_1=1, qty_base_2=1, qty_final=1, tracking_final='lot')
+
+        # generate lot lot_0 on MO
+        mo.action_generate_serial()
+        lot_0 = mo.lot_producing_id.name
+        # manually create lot_1 (lot_0 + 1)
+        lot_1 = self.env['stock.lot'].create({
+            'name': str(int(lot_0) + 1).zfill(7),
+            'product_id': p_final.id,
+            'company_id': self.env.company.id,
+        }).name
+        # generate lot lot_2 on a new MO
+        mo = mo.copy()
+        mo.action_confirm()
+        mo.action_generate_serial()
+        lot_2 = mo.lot_producing_id.name
+        self.assertEqual(lot_2, str(int(lot_1) + 1).zfill(7))

addons/stock/models/stock_lot.py

@@ -63,7 +63,7 @@ class StockLot(models.Model):
     @api.model
     def _get_next_serial(self, company, product):
         """Return the next serial number to be attributed to the product."""
-        if product.tracking == "serial":
+        if product.tracking != "none":
             last_serial = self.env['stock.lot'].search(
                 [('company_id', '=', company.id), ('product_id', '=', product.id)],
                 limit=1, order='id DESC')