Drop OSCAR_OFFER_BLACKLIST_PRODUCT functionality

It only prevents adding a product to a range; offers can be applied
nonetheless (despite the docs saying otherwise). The same functionality
can be achieved by overriding get_is_discountable, so it can be safely
removed.

docs/source/ref/settings.rst

 Offer settings
 ==============
 
-``OSCAR_OFFER_BLACKLIST_PRODUCT``
----------------------------------
-
-Default: ``None``
-
-A function which takes a product as its sole parameter and returns a boolean
-indicating if the product is blacklisted from offers or not.
-
-Example::
-
-    from decimal import Decimal as D
-
-    def is_expensive(product):
-        if product.has_stockrecord:
-            return product.stockrecord.price_incl_tax > D('1000.00')
-        return False
-
-    # Don't allow expensive products to be in offers
-    OSCAR_OFFER_BLACKLIST_PRODUCT = is_expensive
-
 ``OSCAR_OFFER_ROUNDING_FUNCTION``
 ---------------------------------
 

docs/source/releases/v0.8.rst

   and not running an English locale, you will need to migrate the existing
   data to the English values.
 
+* Support for the ``OSCAR_OFFER_BLACKLIST_PRODUCT`` setting has been removed.
+  It was only partially supported: it prevented products from being
+  added to a range, but offers could be applied to the products nonetheless.
+  To prevent an offer being applied to a product, use ``is_discountable`` or
+  override ``get_is_discountable`` on your product instances.
+
 .. _rewritten: https://github.com/tangentlabs/django-oscar/commit/d8b4dbfed17be90846ea4bc47b5f7b39ad944c24
 
 Basket line stockrecords

oscar/apps/offer/models.py

         """
         Check whether the passed product is part of this range
         """
-        # We look for shortcircuit checks first before
-        # the tests that require more database queries.
-
-        if settings.OSCAR_OFFER_BLACKLIST_PRODUCT and \
-                settings.OSCAR_OFFER_BLACKLIST_PRODUCT(product):
-            return False
-
         # Delegate to a proxy class if one is provided
         if self.proxy_class:
             return load_proxy(self.proxy_class)().contains_product(product)

oscar/defaults.py

 OSCAR_SEND_REGISTRATION_EMAIL = True
 OSCAR_FROM_EMAIL = 'oscar@example.com'
 
-# Offers
-OSCAR_OFFER_BLACKLIST_PRODUCT = None
-
 # Slug handling
 OSCAR_SLUG_FUNCTION = 'oscar.core.utils.default_slugifier'
 OSCAR_SLUG_MAP = {}

tests/integration/offer/range_tests.py

-from django.conf import settings
 from django.test import TestCase
 
 from oscar.apps.offer import models
 from oscar.test.factories import create_product
 
 
-class TestWholeSiteRangeWithGlobalBlacklist(TestCase):
-
-    def setUp(self):
-        self.range = models.Range(
-            name="All products", includes_all_products=True)
-
-    def tearDown(self):
-        settings.OSCAR_OFFER_BLACKLIST_PRODUCT = None
-
-    def test_blacklisting_prevents_products_being_in_range(self):
-        settings.OSCAR_OFFER_BLACKLIST_PRODUCT = lambda p: True
-        prod = create_product()
-        self.assertFalse(self.range.contains_product(prod))
-
-    def test_blacklisting_can_use_product_class(self):
-        settings.OSCAR_OFFER_BLACKLIST_PRODUCT = (
-            lambda p: p.get_product_class().name == 'giftcard')
-        prod = create_product(product_class="giftcard")
-        self.assertFalse(self.range.contains_product(prod))
-
-    def test_blacklisting_doesnt_exlude_everything(self):
-        settings.OSCAR_OFFER_BLACKLIST_PRODUCT = (
-            lambda p: p.get_product_class().name == 'giftcard')
-        prod = create_product(product_class="book")
-        self.assertTrue(self.range.contains_product(prod))
-
-
 class TestWholeSiteRange(TestCase):
 
     def setUp(self):
         self.assertFalse(self.range.contains_product(self.prod))
 
 
-class TestRangeModle(TestCase):
+class TestRangeModel(TestCase):
 
     def test_ensures_unique_slugs_are_used(self):
         first_range = models.Range.objects.create(name="Foo")