Implement __contains__ for dict_keys and dict_items.
(Not for dict_values, where it can't be done faster than
the default implementation which just iterates the elements.)
diff --git a/Lib/test/test_dictviews.py b/Lib/test/test_dictviews.py
index c0c1da1..4c436f7 100644
--- a/Lib/test/test_dictviews.py
+++ b/Lib/test/test_dictviews.py
@@ -3,17 +3,39 @@
 
 class DictSetTest(unittest.TestCase):
 
+    def test_constructors_not_callable(self):
+        kt = type({}.KEYS())
+        self.assertRaises(TypeError, kt, {})
+        self.assertRaises(TypeError, kt)
+        it = type({}.ITEMS())
+        self.assertRaises(TypeError, it, {})
+        self.assertRaises(TypeError, it)
+        vt = type({}.VALUES())
+        self.assertRaises(TypeError, vt, {})
+        self.assertRaises(TypeError, vt)
+
     def test_dict_keys(self):
         d = {1: 10, "a": "ABC"}
         keys = d.KEYS()
         self.assertEqual(set(keys), {1, "a"})
         self.assertEqual(len(keys), 2)
+        self.assert_(1 in keys)
+        self.assert_("a" in keys)
+        self.assert_(10 not in keys)
+        self.assert_("Z" not in keys)
 
     def test_dict_items(self):
         d = {1: 10, "a": "ABC"}
         items = d.ITEMS()
         self.assertEqual(set(items), {(1, 10), ("a", "ABC")})
         self.assertEqual(len(items), 2)
+        self.assert_((1, 10) in items)
+        self.assert_(("a", "ABC") in items)
+        self.assert_((1, 11) not in items)
+        self.assert_(1 not in items)
+        self.assert_(() not in items)
+        self.assert_((1,) not in items)
+        self.assert_((1, 2, 3) not in items)
 
     def test_dict_values(self):
         d = {1: 10, "a": "ABC"}