[FIX] mrp: update BoM on scrap when product is changed

Problem: When a user changes the product on a scrap order, the bom_id field
does not get updated. If they update the product from a product that has BoM
to a product that doesn’t have one, then the bom_id field is hidden and remains
set. This will cause the scrap quantity to be set to 0 when they validate the scrap.
However, the product move actually happens for the correct quantity causing an
inconsistency.

Purpose: This will either set the bom_id field to False if the new product doesn’t
have a valid BoM, or it will update it to the first available BoM.

Steps to Reproduce on Runbot:

1. Create a scrap order for a product that has a kit type BoM and set the kit field.
2. Change the product to a product without a kit type BoM.
3. Validate the scrap order.
4. Observe the quantity field is set to 0, but there are product moves for the
   correct quantity.

opw-5122880

closes odoo#234050

X-original-commit: 07a6b28
Signed-off-by: Steve Van Essche <[email protected]>

Author: prri-odoo

addons/mrp/models/stock_scrap.py

@@ -64,6 +64,13 @@ def _onchange_serial_number(self):
             else:
                 return super()._onchange_serial_number()
 
+    @api.onchange('product_id')
+    def _onchange_product_id(self):
+        if self.product_is_kit:
+            self.bom_id = self.env['mrp.bom']._bom_find(self.product_id, company_id=self.company_id.id, bom_type='phantom')[self.product_id]
+        else:
+            self.bom_id = False
+
     @api.depends('move_ids', 'move_ids.move_line_ids.quantity', 'product_id')
     def _compute_scrap_qty(self):
         self.scrap_qty = 1

addons/mrp/tests/test_stock.py

@@ -736,3 +736,37 @@ def test_search_kit_on_quantity(self):
         self.assertNotIn(self.kit_1, products)  # 12
         self.assertIn(self.kit_2, products)     # 6
         self.assertNotIn(self.kit_3, products)  # 3
+
+    def test_scrap_change_product(self):
+        """ Ensure a scrap order automatically updates the BoM when its product is changed,
+        selecting the product's first BoM if it's a kit or set the field empty otherwise."""
+        bom_a = self.bom_1
+        bom_a.type = 'phantom'
+        product_a = bom_a.product_id
+
+        bom_b = self.bom_3
+        bom_b.type = 'phantom'
+        product_b = bom_b.product_id
+
+        product_c = self.env['product.product'].create({'name': 'product_c', 'is_storable': True})
+
+        form = Form(self.env['stock.scrap'])
+        form.product_id = product_a
+        form.bom_id = bom_a
+        form.scrap_qty = 1
+        scrap = form.save()
+
+        # assert the scrap's bom_id is set to bom_a
+        self.assertEqual(scrap.bom_id, bom_a)
+
+        form.product_id = product_b
+        scrap = form.save()
+
+        # assert the scrap's bom_id is set to bom_b after updating the product
+        self.assertEqual(scrap.bom_id, bom_b)
+
+        form.product_id = product_c
+        scrap = form.save()
+
+        # assert the scrap's bom_id is updated to False after updating the product
+        self.assertFalse(scrap.bom_id)