trade: prevent ZeroDivisionError for 0 quantity when using base_price_per_slice

bt5/erp5_pdm/SkinTemplateItem/portal_skins/erp5_pdm/Resource_getPriceCalculationOperandDict.py

@@ -24,6 +24,7 @@ result = context.getPriceParameterDict(context=movement, **kw)
 if result["slice_base_price"]:
   total_price = 0.
   quantity = movement.getQuantity()
+  if quantity:
     sliced_base_price_list = zip(result["slice_base_price"], result["slice_quantity_range"])
     for slice_price, slice_range in sliced_base_price_list:
       slice_min, slice_max = slice_range
@@ -34,6 +35,8 @@ if result["slice_base_price"]:
       priced_quantity = min(slice_max - 1, quantity) - (slice_min - 1)
       total_price += priced_quantity * slice_price
     result["base_price"] = total_price / quantity
+  else:
+    result["base_price"] = 0.
 
 base_price = result["base_price"]
 if base_price in (None, ""):

bt5/erp5_trade/TestTemplateItem/portal_components/test.erp5.testResource.py

@@ -1338,6 +1338,7 @@ class TestResource(ERP5TypeTestCase):
        {'quantity': 21, 'price': 198./21, 'total_price': 198.},
        {'quantity': 22, 'price': 206./22, 'total_price': 206.},
        {'quantity': 25, 'price': 230./25, 'total_price': 230.},
+       {'quantity': 0., 'price': 0., 'total_price': 0.},
     ]:
       _test(**case)