Improve the inference of Getattr nodes when dealing with abstract properties from the abc module.

In astroid.bases.Instance._wrap_attr we had a detection
code for properties, which basically inferred whatever
a property returned, passing the results up the stack,
to the igetattr() method. It handled only the builtin property
but the new patch also handles abc.abstractproperty.

3 files changed, 27 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index d8b5b44..3c7f633 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -34,6 +34,15 @@ Change log for the astroid package (used to be astng)
       classes without slots at all. This was changed in order
       to better reflect what's actually happening.
 
+    * Improve the inference of Getattr nodes when dealing with
+      abstract properties from the abc module.
+
+      In astroid.bases.Instance._wrap_attr we had a detection
+      code for properties, which basically inferred whatever
+      a property returned, passing the results up the stack,
+      to the igetattr() method. It handled only the builtin property
+      but the new patch also handles abc.abstractproperty.
+
 
 2015-03-14 -- 1.3.6
 
diff --git a/astroid/bases.py b/astroid/bases.py
index ee8ee1c..7de2c30 100644
--- a/astroid/bases.py
+++ b/astroid/bases.py
@@ -34,6 +34,7 @@ if sys.version_info >= (3, 0):
     BUILTINS = 'builtins'
 else:
     BUILTINS = '__builtin__'
+PROPERTIES = {BUILTINS + '.property', 'abc.abstractproperty'}
 
 
 class Proxy(object):
@@ -205,7 +206,7 @@ class Instance(Proxy):
         """wrap bound methods of attrs in a InstanceMethod proxies"""
         for attr in attrs:
             if isinstance(attr, UnboundMethod):
-                if BUILTINS + '.property' in attr.decoratornames():
+                if PROPERTIES.intersection(attr.decoratornames()):
                     for infered in attr.infer_call_result(self, context):
                         yield infered
                 else:
diff --git a/astroid/tests/unittest_inference.py b/astroid/tests/unittest_inference.py
index 135681c..1ddba4e 100644
--- a/astroid/tests/unittest_inference.py
+++ b/astroid/tests/unittest_inference.py
@@ -121,6 +121,22 @@ class InferenceTest(resources.SysPathSetup, unittest.TestCase):
 
     ast = test_utils.build_module(CODE, __name__)
 
+    def test_infer_abstract_property_return_values(self):
+        module = test_utils.build_module('''
+        import abc
+
+        class A(object):
+            @abc.abstractproperty
+            def test(self):
+                return 42
+
+        a = A()
+        x = a.test
+        ''')
+        inferred = next(module['x'].infer())
+        self.assertIsInstance(inferred, nodes.Const)
+        self.assertEqual(inferred.value, 42)
+
     def test_module_inference(self):
         infered = self.ast.infer()
         obj = next(infered)