test if the tax rule will actually do something before applying it

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@20557 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/TaxRule.py

@@ -105,3 +105,13 @@ class TaxRule(DeliveryRule):
     # Pass to base class
     Rule.expand(self, applied_rule, force=force, **kw)
 
+  def test(self, context, *args, **kw):
+    """Test if this rule can be applied.
+
+    We return false immediatly if the rule won't create any simulation
+    movement, to prevent creating an empty applied rule.
+    """
+    if not (context.DeliveryMovement_getCorrespondingTaxLineList()):
+      return False
+    return DeliveryRule.test(self, context, *args, **kw)
+