diff --git a/addons/mrp/tests/common.py b/addons/mrp/tests/common.py
index 85ef8107520..a6937e6f8f1 100644
--- a/addons/mrp/tests/common.py
+++ b/addons/mrp/tests/common.py
@@ -8,31 +8,31 @@ from odoo.addons.stock.tests import common2
 class TestMrpCommon(common2.TestStockCommon):
 
     @classmethod
-    def generate_mo(self, tracking_final='none', tracking_base_1='none', tracking_base_2='none', qty_final=5, qty_base_1=4, qty_base_2=1, picking_type_id=False, consumption=False):
+    def generate_mo(cls, tracking_final='none', tracking_base_1='none', tracking_base_2='none', qty_final=5, qty_base_1=4, qty_base_2=1, picking_type_id=False, consumption=False):
         """ This function generate a manufacturing order with one final
         product and two consumed product. Arguments allows to choose
         the tracking/qty for each different products. It returns the
         MO, used bom and the tree products.
         """
-        product_to_build = self.env['product.product'].create({
+        product_to_build = cls.env['product.product'].create({
             'name': 'Young Tom',
             'type': 'product',
             'tracking': tracking_final,
         })
-        product_to_use_1 = self.env['product.product'].create({
+        product_to_use_1 = cls.env['product.product'].create({
             'name': 'Botox',
             'type': 'product',
             'tracking': tracking_base_1,
         })
-        product_to_use_2 = self.env['product.product'].create({
+        product_to_use_2 = cls.env['product.product'].create({
             'name': 'Old Tom',
             'type': 'product',
             'tracking': tracking_base_2,
         })
-        bom_1 = self.env['mrp.bom'].create({
+        bom_1 = cls.env['mrp.bom'].create({
             'product_id': product_to_build.id,
             'product_tmpl_id': product_to_build.product_tmpl_id.id,
-            'product_uom_id': self.uom_unit.id,
+            'product_uom_id': cls.uom_unit.id,
             'product_qty': 1.0,
             'type': 'normal',
             'consumption': consumption if consumption else 'flexible',
@@ -40,7 +40,7 @@ class TestMrpCommon(common2.TestStockCommon):
                 (0, 0, {'product_id': product_to_use_2.id, 'product_qty': qty_base_2}),
                 (0, 0, {'product_id': product_to_use_1.id, 'product_qty': qty_base_1})
             ]})
-        mo_form = Form(self.env['mrp.production'])
+        mo_form = Form(cls.env['mrp.production'])
         mo_form.product_id = product_to_build
         if picking_type_id:
             mo_form.picking_type_id = picking_type_id