Include the minimal input/output quantity the same day as input in the average quantity for the turnover

Such quantity should be accounted as staying 1 day in the warehouse otherwise
we may have more quantity leaving than the average stock.

Closes #15014

modules/stock/stock_reporting.py

@@ -583,11 +583,12 @@ class InventoryTurnover(ModelSQL, ModelView):
             inventory_from_date = _SQLite_JulianDay(inventory_from_date)
             inventory_to_date = _SQLite_JulianDay(inventory_to_date)
         average_quantity = (
-            Sum(Case(
-                    (inventory.quantity >= 0, inventory.quantity),
-                    else_=0)
+            (Sum(Greatest(inventory.quantity, 0)
                 * (inventory_to_date - inventory_from_date
                     + Case((inventory.to_date == to_date, 1), else_=0)))
+                + Sum(Least(
+                        Greatest(inventory.input_quantity, 0),
+                        Greatest(inventory.output_quantity, 0))))
             / days)
 
         def round_sql(expression, digits=2):

modules/stock/tests/scenario_stock_reporting_inventory.rst

@@ -244,3 +244,31 @@ Check Inventory turnover::
     >>> turnover.turnover
     0.045
     >>> assertEqual(turnover.product_reference.__class__.__name__, product_type)
+
+    >>> with config.set_context(
+    ...         location=warehouse_loc.id,
+    ...         from_date=dt.date(2025, 1, 1),
+    ...         to_date=dt.date(2025, 1, 1),
+    ...         product_type=product_type):
+    ...     turnover, = InventoryTurnover.find([])
+
+    >>> turnover.output_quantity
+    1.0
+    >>> turnover.average_quantity
+    10.0
+    >>> turnover.turnover
+    0.1
+
+    >>> with config.set_context(
+    ...         location=warehouse_loc.id,
+    ...         from_date=dt.date(2025, 1, 1),
+    ...         to_date=dt.date(2025, 1, 5),
+    ...         product_type=product_type):
+    ...     turnover, = InventoryTurnover.find([])
+
+    >>> turnover.output_quantity
+    0.2
+    >>> turnover.average_quantity
+    9.2
+    >>> turnover.turnover
+    0.022