core: handle price 0 or None in Inventory API

The methods used in indexing did not make a difference between the case
where the price is None (ie. price is not set) or where the price is
set to 0 - in both cases this was saved as NULL in stock.total_price
column. This is incorrect, we need to keep the distinction between
these two cases also for inventory calculation.
We had some places where we select IFNULL(stock.total_price, 0) to work
around this, we don't plan to change the existing ones for now, but
while discussing on nexedi/erp5!1974
we concluded that a newly idenfified case of a problem consequence of
these NULL should be handled by fixing the indexation. To benefit from
the fix, impacted instances will have to reindex documents present in
the stock table with stock.total_price is null.

product/ERP5/bootstrap/erp5_core/DocumentTemplateItem/portal_components/document.erp5.Movement.py

@@ -422,7 +422,7 @@ class Movement(XMLObject, Amount, CompositionMixin, AmountGeneratorMixin):
     quantity = self.getQuantity()
     if quantity :
       source_asset_price = self.getSourceAssetPrice()
-      if source_asset_price :
+      if source_asset_price is not None:
         return source_asset_price * - quantity
     return None
 
@@ -466,7 +466,7 @@ class Movement(XMLObject, Amount, CompositionMixin, AmountGeneratorMixin):
     quantity = self.getQuantity()
     if quantity :
       destination_asset_price = self.getDestinationAssetPrice()
-      if destination_asset_price :
+      if destination_asset_price is not None:
         return destination_asset_price * quantity
     return None
 
@@ -520,7 +520,7 @@ class Movement(XMLObject, Amount, CompositionMixin, AmountGeneratorMixin):
 
   def _getAssetPrice(self,section,date):
     price = self.getPrice()
-    if section is None or not price or getattr(
+    if section is None or price is None or getattr(
       section.aq_base, 'getPriceCurrencyValue', None
     ) is None:
       return price

product/ERP5/tests/testInventoryAPI.py

@@ -1708,7 +1708,7 @@ class TestMovementHistoryList(InventoryAPITestCase):
     # default is an empty list
     self.assertEqual(0, len(mvt_history_list))
 
-  def testDefault0(self):
+  def testDefaultNone(self):
     self._makeMovement()
     getMovementHistoryList = self.getSimulationTool().getMovementHistoryList
     mvt_history_list = getMovementHistoryList(
@@ -1718,6 +1718,32 @@ class TestMovementHistoryList(InventoryAPITestCase):
     # If a movement have no price, None is returned
     self.assertEqual(None, mvt_history_list[0].total_price)
 
+  def testPriceZero(self):
+    self._makeMovement(quantity=1, price=0)
+    getMovementHistoryList = self.getSimulationTool().getMovementHistoryList
+    self.assertEqual(
+      [(b.total_quantity, b.total_price) for b in getMovementHistoryList(section_uid=self.section.getUid())],
+      [(1, 0), ]
+    )
+    self.assertEqual(
+      [(b.total_quantity, b.total_price) for b in getMovementHistoryList(section_uid=self.mirror_section.getUid())],
+      [(-1, 0), ]
+    )
+
+  def testPriceNone(self):
+    self._makeMovement(quantity=1, price=None)
+    getMovementHistoryList = self.getSimulationTool().getMovementHistoryList
+    mvt_history_list = getMovementHistoryList(
+      section_uid=self.section.getUid(),)
+    self.assertEqual(
+      [(b.total_quantity, b.total_price) for b in getMovementHistoryList(section_uid=self.section.getUid())],
+      [(1, None), ]
+    )
+    self.assertEqual(
+      [(b.total_quantity, b.total_price) for b in getMovementHistoryList(section_uid=self.mirror_section.getUid())],
+      [(-1, None), ]
+    )
+
   def testMovementBothSides(self):
     """Movement History List returns movement from both sides"""
     getMovementHistoryList = self.getSimulationTool().getMovementHistoryList