[IMP] mrp: suggest correct serial number in next work order

When producing multiple products tracked by serial number only the
serial number was only set for the first one in every work order. This
makes it so that when you create SN1, SN2 and SN3 in the first work
order they show up as default in the following work orders.

4 files changed, 76 insertions, 3 deletions

diff --git a/addons/mrp/models/__init__.py b/addons/mrp/models/__init__.py
index 7b3b3958084..295d045c1e8 100644
--- a/addons/mrp/models/__init__.py
+++ b/addons/mrp/models/__init__.py
@@ -16,5 +16,6 @@ from . import product
 from . import res_company
 from . import stock_move
 from . import stock_picking
+from . import stock_production_lot
 from . import stock_scrap
 from . import stock_warehouse
diff --git a/addons/mrp/models/mrp_workorder.py b/addons/mrp/models/mrp_workorder.py
index 723f4c8f75a..4e8244da860 100644
--- a/addons/mrp/models/mrp_workorder.py
+++ b/addons/mrp/models/mrp_workorder.py
@@ -271,6 +271,10 @@ class MrpWorkorder(models.Model):
                     'location_dest_id': move.location_dest_id.id,
                     })
 
+    def _assign_default_final_lot_id(self):
+        self.final_lot_id = self.env['stock.production.lot'].search([('use_next_on_work_order_id', '=', self.id)],
+                                                                    order='create_date', limit=1)
+
     @api.multi
     def record_production(self):
         self.ensure_one()
@@ -308,8 +312,6 @@ class MrpWorkorder(models.Model):
         # One a piece is produced, you can launch the next work order
         if self.next_work_order_id.state == 'pending':
             self.next_work_order_id.state = 'ready'
-        if self.next_work_order_id and self.final_lot_id and not self.next_work_order_id.final_lot_id:
-            self.next_work_order_id.final_lot_id = self.final_lot_id.id
 
         self.move_line_ids.filtered(
             lambda move_line: not move_line.done_move and not move_line.lot_produced_id and move_line.qty_done > 0
@@ -342,18 +344,24 @@ class MrpWorkorder(models.Model):
         # Update workorder quantity produced
         self.qty_produced += self.qty_producing
 
+        if self.final_lot_id:
+            self.final_lot_id.use_next_on_work_order_id = self.next_work_order_id
+            self.final_lot_id = False
+
         # Set a qty producing
         if self.qty_produced >= self.production_id.product_qty:
             self.qty_producing = 0
         elif self.production_id.product_id.tracking == 'serial':
+            self._assign_default_final_lot_id()
             self.qty_producing = 1.0
             self._generate_lot_ids()
         else:
             self.qty_producing = self.production_id.product_qty - self.qty_produced
             self._generate_lot_ids()
 
-        self.final_lot_id = False
         if self.qty_produced >= self.production_id.product_qty:
+            if self.next_work_order_id and self.production_id.product_id.tracking != 'none':
+                self.next_work_order_id._assign_default_final_lot_id()
             self.button_finish()
         return True
 
diff --git a/addons/mrp/models/stock_production_lot.py b/addons/mrp/models/stock_production_lot.py
new file mode 100644
index 00000000000..9c2470c64ef
--- /dev/null
+++ b/addons/mrp/models/stock_production_lot.py
@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import api, exceptions, fields, models, _
+
+
+class StockProductionLot(models.Model):
+    _inherit = 'stock.production.lot'
+
+    use_next_on_work_order_id = fields.Many2one('mrp.workorder',
+        help='Technical: used to figure out default serial number on work orders')
diff --git a/addons/mrp/tests/test_workorder_operation.py b/addons/mrp/tests/test_workorder_operation.py
index 15adcd236c8..bbbd8efd08d 100644
--- a/addons/mrp/tests/test_workorder_operation.py
+++ b/addons/mrp/tests/test_workorder_operation.py
@@ -408,3 +408,56 @@ class TestWorkOrderProcess(common.TransactionCase):
 #         self.assertEqual(move_product_b.quant_ids.qty, move_product_b.product_qty)
 #         self.assertEqual(move_product_c.quant_ids.qty, 3)
 #         self.assertEqual(move_product_c.quant_ids.product_uom_id.id, kg)
+
+    def test_03_test_serial_number_defaults(self):
+        """ Test that the correct serial number is suggested on consecutive work orders. """
+        laptop = self.env.ref("product.product_product_25")
+        graphics_card = self.env.ref("product.product_product_24")
+        unit = self.env.ref("product.product_uom_unit")
+        three_step_routing = self.env.ref("mrp.mrp_routing_1")
+
+        laptop.tracking = 'serial'
+
+        bom_laptop = self.env['mrp.bom'].create({
+            'product_tmpl_id': laptop.product_tmpl_id.id,
+            'product_qty': 1,
+            'product_uom_id': unit.id,
+            'bom_line_ids': [(0, 0, {
+                'product_id': graphics_card.id,
+                'product_qty': 1,
+                'product_uom_id': unit.id
+            })],
+            'routing_id': three_step_routing.id
+        })
+
+        mo_laptop = self.env['mrp.production'].create({
+            'product_id': laptop.id,
+            'product_qty': 3,
+            'product_uom_id': unit.id,
+            'bom_id': bom_laptop.id
+        })
+
+        mo_laptop.button_plan()
+        workorders = mo_laptop.workorder_ids
+        self.assertEqual(len(workorders), 3)
+
+        workorders[0].button_start()
+        serial_a = self.env['stock.production.lot'].create({'product_id': laptop.id})
+        workorders[0].final_lot_id = serial_a
+        workorders[0].record_production()
+        serial_b = self.env['stock.production.lot'].create({'product_id': laptop.id})
+        workorders[0].final_lot_id = serial_b
+        workorders[0].record_production()
+        serial_c = self.env['stock.production.lot'].create({'product_id': laptop.id})
+        workorders[0].final_lot_id = serial_c
+        workorders[0].record_production()
+        self.assertEqual(workorders[0].state, 'done')
+
+        for workorder in workorders - workorders[0]:
+            self.assertEqual(workorder.final_lot_id, serial_a)
+            workorder.record_production()
+            self.assertEqual(workorder.final_lot_id, serial_b)
+            workorder.record_production()
+            self.assertEqual(workorder.final_lot_id, serial_c)
+            workorder.record_production()
+            self.assertEqual(workorder.state, 'done')