Add test for dict_dir method in utils.wildcard

IPython/utils/tests/test_wildcard.py

@@ -131,3 +131,18 b' class Tests (unittest.TestCase):'
                                         show_all=True).keys()
             a.sort()
             self.assertEqual(a, res)
+    
+    def test_dict_dir(self):
+        class A(object):
+            def __init__(self):
+                self.a = 1
+                self.b = 2
+            def __getattribute__(self, name):
+                if name=="a":
+                    raise AttributeError
+                return object.__getattribute__(self, name)
+                
+        a = A()
+        adict = wildcard.dict_dir(a)
+        assert "a" not in adict # change to assertNotIn method in >= 2.7
+        self.assertEqual(adict["b"], 2)