From 31dd3dc4a1060e5e2ab053270e31529aa60819c6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Gra=C3=B1a?= <dangra@gmail.com>
Date: Fri, 10 Jan 2014 17:42:52 -0200
Subject: [PATCH] allow deprecation of subclasses of already deprecated classes

---
 scrapy/tests/test_utils_deprecate.py | 24 ++++++++++++++++++++++++
 scrapy/utils/deprecate.py            |  3 +--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/scrapy/tests/test_utils_deprecate.py b/scrapy/tests/test_utils_deprecate.py
index 8cc3a26f1..75a53b2bf 100644
--- a/scrapy/tests/test_utils_deprecate.py
+++ b/scrapy/tests/test_utils_deprecate.py
@@ -201,3 +201,27 @@ class WarnWhenSubclassedTest(unittest.TestCase):
         Meta1 = type('Meta1', (type,), {})
         New = Meta1('New', (), {})
         Deprecated = create_deprecated_class('Deprecated', New)
+
+    def test_deprecate_subclass_of_deprecated_class(self):
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('always')
+            Deprecated = create_deprecated_class('Deprecated', NewName,
+                                                 warn_category=MyWarning)
+            AlsoDeprecated = create_deprecated_class('AlsoDeprecated', Deprecated,
+                                                     new_class_path='foo.Bar',
+                                                     warn_category=MyWarning)
+
+        w = self._mywarnings(w)
+        self.assertEqual(len(w), 0, str(map(str, w)))
+
+        with warnings.catch_warnings(record=True) as w:
+            AlsoDeprecated()
+            class UserClass(AlsoDeprecated):
+                pass
+
+        w = self._mywarnings(w)
+        self.assertEqual(len(w), 2)
+        self.assertIn('AlsoDeprecated', str(w[0].message))
+        self.assertIn('foo.Bar', str(w[0].message))
+        self.assertIn('AlsoDeprecated', str(w[1].message))
+        self.assertIn('foo.Bar', str(w[1].message))
diff --git a/scrapy/utils/deprecate.py b/scrapy/utils/deprecate.py
index 47d97e9cb..edaecc3d3 100644
--- a/scrapy/utils/deprecate.py
+++ b/scrapy/utils/deprecate.py
@@ -87,8 +87,7 @@ def create_deprecated_class(name, new_class, clsdict=None,
             return any(c in candidates for c in mro)
 
         def __call__(cls, *args, **kwargs):
-            meta = cls.__class__
-            old = meta.deprecated_class
+            old = DeprecatedClass.deprecated_class
             if cls is old:
                 msg = instance_warn_message.format(cls=_clspath(cls, old_class_path),
                                                    new=_clspath(new_class, new_class_path))