[FIX] purchase: tests should not rely on demo data

Fixed the TestPurchaseInvoice.test_double_validation and the setupClass
to use test accounting data in setupClass instead of the demo data.

closes odoo/odoo#89370

X-original-commit: a7546aead36c5d56809fcd9c46b2a552991b5449
Signed-off-by: Steve Van Essche <svs@odoo.com>
Signed-off-by: Paolo Gatti (pgi) <pgi@odoo.com>

addons/purchase/tests/test_access_rights.py

@@ -142,7 +142,16 @@ class TestPurchaseInvoice(AccountTestInvoicingCommon):
         """Only purchase managers can approve a purchase order when double
         validation is enabled"""
         group_purchase_manager = self.env.ref('purchase.group_purchase_manager')
-        order = self.env.ref("purchase.purchase_order_1")
+        order = self.env['purchase.order'].create({
+            "partner_id": self.vendor.id,
+            "order_line": [
+                (0, 0, {
+                    'product_id': self.product.id,
+                    'name': f'{self.product.name} {1:05}',
+                    'price_unit': 79.80,
+                    'product_qty': 15.0,
+                }),
+            ]})
         company = order.sudo().company_id
         company.po_double_validation = 'two_step'
         company.po_double_validation_amount = 0