Class.getattr('__mro__') returns the actual MRO.

Also, Class.getattr('__bases__') returns actual bases.
It previously didn't work correctly, because it was putting the
entire ancestors into the Tuple object and it put those classes
into the wrong attribute.
Closes issue #128.

3 files changed, 34 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 88e4aa2..6b93e83 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,9 @@ Change log for the astroid package (used to be astng)
 =====================================================
 
 --
+
+    * Class.getattr('__mro__') returns the actual MRO. Closes issue #128.
+
     * The logilab-common dependency is not needed anymore as the needed code
       was integrated into astroid.
 
diff --git a/astroid/scoped_nodes.py b/astroid/scoped_nodes.py
index 31fc2f8..e6e3324 100644
--- a/astroid/scoped_nodes.py
+++ b/astroid/scoped_nodes.py
@@ -1359,14 +1359,16 @@ class ClassDef(mixins.FilterStmtsMixin, LocalsDictNodeNG,
         if name in self.special_attributes:
             if name == '__module__':
                 return [node_classes.const_factory(self.root().qname())] + values
-            # FIXME: do we really need the actual list of ancestors?
-            # returning [Tuple()] + values don't break any test
-            # this is ticket http://www.logilab.org/ticket/52785
-            # XXX need proper meta class handling + MRO implementation
-            if name == '__bases__' or (name == '__mro__' and self.newstyle):
+            if name == '__bases__':
                 node = node_classes.Tuple()
-                node.items = self.ancestors(recurs=True, context=context)
+                elts = list(self._inferred_bases(context))
+                node.postinit(elts=elts)
                 return [node] + values
+            if name == '__mro__' and self.newstyle:
+                mro = self.mro()
+                node = node_classes.Tuple()
+                node.postinit(elts=mro)
+                return [node]
             return std_special_attributes(self, name)
         # don't modify the list in self.locals!
         values = list(values)
diff --git a/astroid/tests/unittest_scoped_nodes.py b/astroid/tests/unittest_scoped_nodes.py
index bf090da..8e82290 100644
--- a/astroid/tests/unittest_scoped_nodes.py
+++ b/astroid/tests/unittest_scoped_nodes.py
@@ -584,6 +584,29 @@ class ClassNodeTest(ModuleLoader, unittest.TestCase):
             self.assertEqual(len(cls.getattr('__dict__')), 1)
             self.assertEqual(len(cls.getattr('__mro__')), 1)
 
+    def test__mro__attribute(self):
+        node = test_utils.extract_node('''
+        class A(object): pass
+        class B(object): pass
+        class C(A, B): pass        
+        ''')
+        mro = node.getattr('__mro__')[0]
+        self.assertIsInstance(mro, nodes.Tuple)
+        self.assertEqual(mro.elts, node.mro())
+
+    def test__bases__attribute(self):
+        node = test_utils.extract_node('''
+        class A(object): pass
+        class B(object): pass
+        class C(A, B): pass
+        class D(C): pass
+        ''')
+        bases = node.getattr('__bases__')[0]
+        self.assertIsInstance(bases, nodes.Tuple)
+        self.assertEqual(len(bases.elts), 1)
+        self.assertIsInstance(bases.elts[0], nodes.ClassDef)
+        self.assertEqual(bases.elts[0].name, 'C')        
+
     def test_cls_special_attributes_2(self):
         astroid = builder.parse('''
             class A: pass