Deprecate scrapy.item.BaseItem

scrapy/item.py

@@ -28,7 +28,12 @@ class BaseItem(object_ref):
     Unlike instances of :class:`dict`, instances of :class:`BaseItem` may be
     :ref:`tracked <topics-leaks-trackrefs>` to debug memory leaks.
     """
-    pass
+
+    def __new__(cls, *args, **kwargs):
+        if issubclass(cls, BaseItem) and not (issubclass(cls, Item) or issubclass(cls, DictItem)):
+            warn('scrapy.item.BaseItem is deprecated, please use scrapy.item.Item instead',
+                 ScrapyDeprecationWarning, stacklevel=2)
+        return super(BaseItem, cls).__new__(cls, *args, **kwargs)
 
 
 class Field(dict):

tests/test_item.py

@@ -4,7 +4,7 @@ from unittest import mock
 from warnings import catch_warnings
 
 from scrapy.exceptions import ScrapyDeprecationWarning
-from scrapy.item import ABCMeta, DictItem, Field, Item, ItemMeta
+from scrapy.item import ABCMeta, BaseItem, DictItem, Field, Item, ItemMeta
 
 
 PY36_PLUS = (sys.version_info.major >= 3) and (sys.version_info.minor >= 6)
@@ -131,12 +131,12 @@ class ItemTest(unittest.TestCase):
         self.assertSortedEqual(list(item.values()), [u'New'])
 
     def test_metaclass_inheritance(self):
-        class BaseItem(Item):
+        class ParentItem(Item):
             name = Field()
             keys = Field()
             values = Field()
 
-        class TestItem(BaseItem):
+        class TestItem(ParentItem):
             keys = Field()
 
         i = TestItem()
@@ -321,13 +321,28 @@ class DictItemTest(unittest.TestCase):
 
     def test_deprecation_warning(self):
         with catch_warnings(record=True) as warnings:
-            dict_item = DictItem()
+            DictItem()
             self.assertEqual(len(warnings), 1)
             self.assertEqual(warnings[0].category, ScrapyDeprecationWarning)
         with catch_warnings(record=True) as warnings:
             class SubclassedDictItem(DictItem):
                 pass
-            subclassed_dict_item = SubclassedDictItem()
+            SubclassedDictItem()
+            self.assertEqual(len(warnings), 1)
+            self.assertEqual(warnings[0].category, ScrapyDeprecationWarning)
+
+
+class BaseItemTest(unittest.TestCase):
+
+    def test_deprecation_warning(self):
+        with catch_warnings(record=True) as warnings:
+            BaseItem()
+            self.assertEqual(len(warnings), 1)
+            self.assertEqual(warnings[0].category, ScrapyDeprecationWarning)
+        with catch_warnings(record=True) as warnings:
+            class SubclassedBaseItem(BaseItem):
+                pass
+            SubclassedBaseItem()
             self.assertEqual(len(warnings), 1)
             self.assertEqual(warnings[0].category, ScrapyDeprecationWarning)