FIX pass scenario test

invoice.py

@@ -149,7 +149,8 @@ class Invoice(metaclass=PoolMeta):
 
         amount = 0
         for tax in self.taxes:
-            if tax.tax.include_347 and tax.tax.recargo_equivalencia:
+            if tax.tax.include_347 and (hasattr(tax.tax, 'recargo_equivalencia')
+                    and tax.tax.recargo_equivalencia):
                 amount += tax.amount
             elif tax.tax.include_347:
                 amount += (tax.base + tax.amount)

tests/scenario_aeat347.rst

@@ -46,8 +46,10 @@ Create chart of accounts::
 Create tax::
 
     >>> tax = create_tax(Decimal('.10'))
+    >>> tax.include_347 = True
     >>> tax.save()
     >>> tax2 = create_tax(Decimal('.10'))
+    >>> tax2.include_347 = True
     >>> tax2.save()
 
 Create party::