Simplify test method.

Just use use category.

product/ERP5/tests/testTradeModelLine.py

@@ -138,7 +138,7 @@ class TestTradeModelLineMixin(TestBPMMixin, UserDict):
              successor='trade_state/accounted',
              delivery_builder=['portal_deliveries/purchase_invoice_transaction_trade_model_builder',
                                'portal_deliveries/sale_invoice_transaction_trade_model_builder'],
-             test_tales_expression="python: context.BusinessLink_testDeliveryLink('Trade Model Simulation Rule') and context.getResourceValue() is not None and context.getResourceValue().getUse() == 'discount'",
+             test_tales_expression="python: context.getResourceValue() is not None and context.getResourceValue().getUse() == 'discount'",
         ),
         dict(reference='tax',
              trade_phase='default/tax',
@@ -154,7 +154,7 @@ class TestTradeModelLineMixin(TestBPMMixin, UserDict):
              successor='trade_state/accounted',
              delivery_builder=['portal_deliveries/purchase_invoice_transaction_trade_model_builder',
                                'portal_deliveries/sale_invoice_transaction_trade_model_builder'],
-             test_tales_expression="python: context.BusinessLink_testDeliveryLink('Trade Model Simulation Rule') and context.getResourceValue() is not None and context.getResourceValue().getUse() == 'tax'",
+             test_tales_expression="python: context.getResourceValue() is not None and context.getResourceValue().getUse() == 'tax'",
         ),
       ]
       for business_link in business_link_list: