[FIX] stock: no tracking for service product

Steps to reproduce the bug:
- Create a storable “P1”:
   - tracking= serial
   - save
- Change the type of product to service

Problem:
some fields for tracked products are not hidden, because the product
tracking is not updated.

Solution:
Convert _onchange_type into compute methods.
The tracking is updated even if the change type is applied from the
"product.product" form.

opw-3499976

closes odoo/odoo#136738

X-original-commit: 22fe0ee4764705e55e81f62e07d29fc9bd8296e1
Signed-off-by: William Henrotin (whe) <whe@odoo.com>
Signed-off-by: Djamel Touati (otd) <otd@odoo.com>

addons/stock/models/product.py

@@ -826,7 +826,7 @@ class ProductTemplate(models.Model):
     @api.depends('type')
     def _compute_tracking(self):
         self.filtered(
-            lambda t: not t.tracking or t.type == 'consu' and t.tracking != 'none'
+            lambda t: not t.tracking or t.type in ('consu', 'service')  and t.tracking != 'none'
         ).tracking = 'none'
 
     @api.onchange('type')

addons/stock/tests/test_product.py

@@ -325,3 +325,23 @@ class TestVirtualAvailable(TestStockCommon):
         ]:
             product_qty = self.product_3.with_context(warehouse=wh, location=loc).qty_available
             self.assertEqual(product_qty, expected)
+
+    def test_change_type_tracked_product(self):
+        product = self.env['product.template'].create({
+            'name': 'Brand new product',
+            'type': 'product',
+            'tracking': 'serial',
+        })
+        product_form = Form(product)
+        product_form.detailed_type = 'service'
+        product = product_form.save()
+        self.assertEqual(product.tracking, 'none')
+
+        product.detailed_type = 'product'
+        product.tracking = 'serial'
+        self.assertEqual(product.tracking, 'serial')
+        # change the type from "product.product" form
+        product_form = Form(product.product_variant_id)
+        product_form.detailed_type = 'service'
+        product = product_form.save()
+        self.assertEqual(product.tracking, 'none')