Update basket stock records when strategy changes

requirements.txt

@@ -3,7 +3,19 @@
 # development
 django-debug-toolbar>=2.2,<4.3
 django-extensions>=2.2,<3.3
+django-extra-views>=0.14
+django-haystack>=3.2.1
+django-phonenumber-field>=7.1
+django_tables2>=2.6
+django-treebeard>=4.7
+django-widget-tweaks>=1.5
+babel>=2.12.1
+factory_boy>=3.3.0
+phonenumbers>=8.13
 psycopg2-binary>=2.8,<2.10
+purl>=1.6
+sorl_thumbnail>=12
+easy_thumbnails>=2.8
 
 # Sandbox
 Whoosh>=2.7,<2.8
@@ -12,7 +24,8 @@ django-redis>=4.12,<5.4
 pysolr>=3.9,<3.10
 redis>=3.5,<5.1
 requests>=2.25,<3
-uWSGI>=2.0.19
+# Does not build on Windows
+# uWSGI>=2.0.19
 whitenoise>=5.2,<6.6
 
 # Linting

src/oscar/apps/basket/abstract_models.py

@@ -325,17 +325,23 @@ def reset_offer_applications(self):
         self.offer_applications = OfferApplications()
         self._lines = None
 
-    def merge_line(self, line, add_quantities=True):
+    def merge_line(self, line, add_quantities=True, strategy=None):
         """
         For transferring a line from another basket to this one.
 
         This is used with the "Saved" basket functionality.
         """
+        # TODO: If the login causes the strategy to be None, the line won't save.
+        # IntegrityError at /checkout/
+        # (1048, "Column 'stockrecord_id' cannot be null")
+        # We'll need to display a message if that's the case.
         try:
             existing_line = self.lines.get(line_reference=line.line_reference)
         except ObjectDoesNotExist:
             # Line does not already exist - reassign its basket
             line.basket = self
+            if strategy:
+                line.stockrecord = strategy.fetch_for_product(line.product).stockrecord
             line.save()
         else:
             # Line already exists - assume the max quantity is correct and
@@ -344,14 +350,17 @@ def merge_line(self, line, add_quantities=True):
                 existing_line.quantity += line.quantity
             else:
                 existing_line.quantity = max(existing_line.quantity, line.quantity)
+
+            if strategy:
+                existing_line.stockrecord = strategy.fetch_for_product(existing_line.product).stockrecord
             existing_line.save()
             line.delete()
         finally:
             self._lines = None
 
     merge_line.alters_data = True
 
-    def merge(self, basket, add_quantities=True):
+    def merge(self, basket, add_quantities=True, strategy=None):
         """
         Merges another basket with this one.
 
@@ -361,7 +370,7 @@ def merge(self, basket, add_quantities=True):
         # Use basket.lines.all instead of all_lines as this function is called
         # before a strategy has been assigned.
         for line_to_merge in basket.lines.all():
-            self.merge_line(line_to_merge, add_quantities)
+            self.merge_line(line_to_merge, add_quantities=add_quantities, strategy=strategy)
         basket.status = self.MERGED
         basket.date_merged = now()
         basket._lines = None

src/oscar/apps/basket/middleware.py

@@ -155,7 +155,7 @@ def get_basket(self, request):
                 old_baskets = list(manager.filter(owner=request.user))
                 basket = old_baskets[0]
                 for other_basket in old_baskets[1:]:
-                    self.merge_baskets(basket, other_basket)
+                    self.merge_baskets(basket, other_basket, strategy=request.strategy)
                     # count number of items that have been merged
                     num_items_merged += other_basket.num_items
 
@@ -166,7 +166,7 @@ def get_basket(self, request):
             if cookie_basket:
                 # count number of items in the basket
                 num_items_merged += cookie_basket.num_items
-                self.merge_baskets(basket, cookie_basket)
+                self.merge_baskets(basket, cookie_basket, strategy=request.strategy)
                 request.cookies_to_delete.append(cookie_key)
 
         elif cookie_basket:
@@ -197,13 +197,13 @@ def get_basket(self, request):
 
         return basket
 
-    def merge_baskets(self, master, slave):
+    def merge_baskets(self, master, slave, strategy=None):
         """
         Merge one basket into another.
 
         This is its own method to allow it to be overridden
         """
-        master.merge(slave, add_quantities=False)
+        master.merge(slave, add_quantities=False, strategy=strategy)
 
     # pylint: disable=unused-argument
     def get_cookie_basket(self, cookie_key, request, manager):

tests/integration/partner/test_strategy.py

@@ -2,13 +2,16 @@
 
 from django.test import TestCase
 
+from oscar.apps.basket.models import Basket
 from oscar.apps.basket.models import Line
 from oscar.apps.catalogue import models
 from oscar.apps.partner import strategy
 from oscar.test import factories
 
 
 class TestDefaultStrategy(TestCase):
+    strategy = None
+
     def setUp(self):
         self.strategy = strategy.Default()
 
@@ -58,6 +61,42 @@ def test_availability_does_not_require_price(self):
         self.assertTrue(info.availability.is_available_to_buy)
 
 
+class UK2(strategy.UK):
+    def select_stockrecord(self, product):
+        try:
+            return product.stockrecords.all()[1]
+        except IndexError:
+            pass
+
+
+class TestStrategyChange(TestCase):
+    basket = None
+    product = None
+    strategy = None
+
+    def setUp(self):
+        self.product = factories.create_product()
+        factories.create_stockrecord(product=self.product, partner_sku="1", price=1)
+        factories.create_stockrecord(product=self.product, partner_sku="2", price=2)
+        self.strategy = strategy.Default()
+        self.basket = Basket.objects.create()
+        self.basket.strategy = strategy.UK()
+        self.basket.add_product(self.product, 1)
+
+    def test_basket_price_changes_when_strategy_does(self):
+        self.assertEqual(self.basket.all_lines()[0].stockrecord.partner_sku, "1")
+        self.basket.strategy = UK2()
+        self.basket.freeze()
+        self.assertEqual(self.basket.total_excl_tax, 2)
+
+    def test_basket_stockrecord_does_not_change_when_strategy_does(self):
+        self.assertEqual(self.basket.all_lines()[0].stockrecord.partner_sku, "1")
+        self.basket.strategy = UK2()
+        self.basket.freeze()
+        self.assertEqual(self.basket.all_lines()[0].stockrecord.partner_sku, "1")
+        self.assertEqual(self.basket.total_excl_tax, 2)
+
+
 class TestDefaultStrategyForParentProductWhoseVariantsHaveNoStockRecords(TestCase):
     def setUp(self):
         self.strategy = strategy.Default()
@@ -127,4 +166,4 @@ def test_pricing_policy_unavailable_if_no_price_excl_tax(self):
         product = factories.ProductFactory(stockrecords=[])
         factories.StockRecordFactory(price=None, product=product)
         info = strategy.US().fetch_for_product(product)
-        self.assertFalse(info.price.exists)
+        self.assertFalse(info.price.exists)