[FIX] stock: move: _action_assign and _free_reservation

The code made the assumption that everything brought by in chained move
is available on the quants. This is not always true, for example when x
products are brought by a move in the chain, the user can make an
inventory adjustment that reduce the quantity available. Thus, we
implement a fallback in case the quantity brought by is not available:
do not reserve more than what's really available. If the user make
available some products with the same characteristics (lot/owner/pack)
in the location, they will be used by a new call to _action_assign.
Indeed, the reserved quants are not discernable. This is not an issue in
reality, as the user cannot discern the products himself if they share
the same characteristics.

2 files changed, 116 insertions, 4 deletions

diff --git a/addons/stock/models/stock_move.py b/addons/stock/models/stock_move.py
index 97c29b45aac..b340688bac4 100644
--- a/addons/stock/models/stock_move.py
+++ b/addons/stock/models/stock_move.py
@@ -775,11 +775,21 @@ class StockMove(models.Model):
 
         taken_quantity = min(available_quantity, need)
 
+        quants = []
+        try:
+            quants = self.env['stock.quant']._update_reserved_quantity(
+                self.product_id, location_id, taken_quantity, lot_id=lot_id,
+                package_id=package_id, owner_id=owner_id, strict=strict
+            )
+        except UserError:
+            # If it raises here, it means that the `available_quantity` brought by a done move line
+            # is not available on the quants itself. This could be the result of an inventory
+            # adjustment that removed totally of partially `available_quantity`. When this happens, we
+            # chose to do nothing. This situation could not happen on MTS move, because in this case
+            # `available_quantity` is directly the quantity on the quants themselves.
+            taken_quantity = 0
+
         # Find a candidate move line to update or create a new one.
-        quants = self.env['stock.quant']._update_reserved_quantity(
-            self.product_id, location_id, taken_quantity, lot_id=lot_id,
-            package_id=package_id, owner_id=owner_id, strict=strict
-        )
         for reserved_quant, quantity in quants:
             to_update = self.move_line_ids.filtered(lambda m: m.location_id.id == reserved_quant.location_id.id and m.lot_id.id == reserved_quant.lot_id.id and m.package_id.id == reserved_quant.package_id.id and m.owner_id.id == reserved_quant.owner_id.id)
             if to_update:
diff --git a/addons/stock/tests/test_inventory.py b/addons/stock/tests/test_inventory.py
index f0a2901860a..796fed4bd2d 100644
--- a/addons/stock/tests/test_inventory.py
+++ b/addons/stock/tests/test_inventory.py
@@ -8,6 +8,9 @@ class TestInventory(TransactionCase):
     def setUp(self):
         super(TestInventory, self).setUp()
         self.stock_location = self.env.ref('stock.stock_location_stock')
+        self.pack_location = self.env.ref('stock.location_pack_zone')
+        self.pack_location.active = True
+        self.customer_location = self.env.ref('stock.stock_location_customers')
         self.uom_unit = self.env.ref('product.product_uom_unit')
         self.product1 = self.env['product.product'].create({
             'name': 'Product A',
@@ -165,3 +168,102 @@ class TestInventory(TransactionCase):
         self.assertEqual(len(quant), 1)
         self.assertEqual(quant.quantity, 5)
         self.assertEqual(quant.owner_id.id, owner1.id)
+
+    def test_inventory_6(self):
+        """ Test that for chained moves, making an inventory adjustment to reduce a quantity that
+        has been reserved correctly free the reservation. After that, add products in stock and check
+        that they're used if the user encodes more than what's available through the chain
+        """
+        # add 10 products in stock
+        inventory = self.env['stock.inventory'].create({
+            'name': 'add 10 products 1',
+            'filter': 'product',
+            'location_id': self.stock_location.id,
+            'product_id': self.product1.id,
+            'exhausted': True,  # should be set by an onchange
+        })
+        inventory.action_start()
+        inventory.line_ids.product_qty = 10
+        inventory.action_done()
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.stock_location), 10.0)
+
+        # Make a chain of two moves, validate the first and check that 10 products are reserved
+        # in the second one.
+        move_stock_pack = self.env['stock.move'].create({
+            'name': 'test_link_2_1',
+            'location_id': self.stock_location.id,
+            'location_dest_id': self.pack_location.id,
+            'product_id': self.product1.id,
+            'product_uom': self.uom_unit.id,
+            'product_uom_qty': 10.0,
+        })
+        move_pack_cust = self.env['stock.move'].create({
+            'name': 'test_link_2_2',
+            'location_id': self.pack_location.id,
+            'location_dest_id': self.customer_location.id,
+            'product_id': self.product1.id,
+            'product_uom': self.uom_unit.id,
+            'product_uom_qty': 10.0,
+        })
+        move_stock_pack.write({'move_dest_ids': [(4, move_pack_cust.id, 0)]})
+        move_pack_cust.write({'move_orig_ids': [(4, move_stock_pack.id, 0)]})
+        (move_stock_pack + move_pack_cust)._action_confirm()
+        move_stock_pack._action_assign()
+        self.assertEqual(move_stock_pack.state, 'assigned')
+        move_stock_pack.move_line_ids.qty_done = 10
+        move_stock_pack._action_done()
+        self.assertEqual(move_stock_pack.state, 'done')
+        self.assertEqual(move_pack_cust.state, 'assigned')
+        self.assertEqual(self.env['stock.quant']._gather(self.product1, self.pack_location).quantity, 10.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.pack_location), 0.0)
+
+        # Make and inventory adjustment and remove two products from the pack location. This should
+        # free the reservation of the second move.
+        inventory = self.env['stock.inventory'].create({
+            'name': 'remove 2 products 1',
+            'filter': 'product',
+            'location_id': self.pack_location.id,
+            'product_id': self.product1.id,
+        })
+        inventory.action_start()
+        inventory.line_ids.product_qty = 8
+        inventory.action_done()
+        self.assertEqual(self.env['stock.quant']._gather(self.product1, self.pack_location).quantity, 8.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.pack_location), 0)
+        self.assertEqual(move_pack_cust.state, 'partially_available')
+        self.assertEqual(move_pack_cust.reserved_availability, 8)
+
+        # If the user tries to assign again, only 8 products are available and thus the reservation
+        # state should not change.
+        move_pack_cust._action_assign()
+        self.assertEqual(move_pack_cust.state, 'partially_available')
+        self.assertEqual(move_pack_cust.reserved_availability, 8)
+
+        # Make a new inventory adjustment and bring two now products.
+        inventory = self.env['stock.inventory'].create({
+            'name': 'remove 2 products 1',
+            'filter': 'product',
+            'location_id': self.pack_location.id,
+            'product_id': self.product1.id,
+        })
+        inventory.action_start()
+        inventory.line_ids.product_qty = 10
+        inventory.action_done()
+
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.pack_location), 2)
+
+        # Nothing should have changed for our pack move
+        self.assertEqual(move_pack_cust.state, 'partially_available')
+        self.assertEqual(move_pack_cust.reserved_availability, 8)
+
+        # Running _action_assign will now find the new available quantity. Indeed, as the products
+        # are not discernabl (not lot/pack/owner), even if the new available quantity is not directly
+        # brought by the chain, the system fill take them into account.
+        move_pack_cust._action_assign()
+        self.assertEqual(move_pack_cust.state, 'assigned')
+
+        # move all the things
+        move_pack_cust.move_line_ids.qty_done = 10
+        move_stock_pack._action_done()
+
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.pack_location), 0)