[FIX] test_main_flows: enable MTO route for main flow tests

Enable MTO route at the start of main flow tour since it's used
by it. Also fix a small bug when the form view is open from a
create edit where the route are hidden.

closes odoo/odoo#55790

Signed-off-by: Arnold Moyaux <amoyaux@users.noreply.github.com>

addons/stock/models/product.py

@@ -603,7 +603,8 @@ class ProductTemplate(models.Model):
     location_id = fields.Many2one('stock.location', 'Location', store=False)
     warehouse_id = fields.Many2one('stock.warehouse', 'Warehouse', store=False)
     has_available_route_ids = fields.Boolean(
-        'Routes can be selected on this product', compute='_compute_has_available_route_ids')
+        'Routes can be selected on this product', compute='_compute_has_available_route_ids',
+        default=lambda self: self.env['stock.location.route'].search_count([('product_selectable', '=', True)]))
     route_ids = fields.Many2many(
         'stock.location.route', 'stock_route_product', 'product_id', 'route_id', 'Routes',
         domain=[('product_selectable', '=', True)],

odoo/addons/test_main_flows/tests/test_flow.py

@@ -7,6 +7,9 @@ import unittest
 class BaseTestUi(odoo.tests.HttpCase):
 
     def main_flow_tour(self):
+        # Enable Make to Order
+        self.env.ref('stock.route_warehouse0_mto').active = True
+
         # Define minimal accounting data to run without CoA
         a_expense = self.env['account.account'].create({
             'code': 'X2120',