diff -r a4b66e51e0bf Lib/idlelib/idle_test/test_delegator.py
--- a/Lib/idlelib/idle_test/test_delegator.py	Mon Apr 13 22:11:34 2015 +0200
+++ b/Lib/idlelib/idle_test/test_delegator.py	Thu Apr 16 18:17:33 2015 -0400
@@ -6,32 +6,49 @@
     def test_mydel(self):
         # test a simple use scenario
 
-        # initialize
+        # create a delegator for the int type
         mydel = Delegator(int)
-        self.assertIs(mydel.delegate, int)
+
+        # "delegate" attr is the same as the original type
+        self.assertIs(mydel.delegate, int,
+            'Delegate should have been for type int but instead was for type %s' % (mydel.delegate.__name__,))
+
+        # Delegator obj must have a cache
+        self.assertEqual(mydel._Delegator__cache, set(),
+            'Delegator object\'s __cache attr should be an empty set, but instead was %s' % (str(mydel._Delegator__cache)[:80],))
+
+        self.assertRaises(AttributeError, mydel.__getattr__, 'ThisAttrDoesNotExist')
+
+        # check that this Delegator obj has the same methods as the int type
+        self.assertIs(mydel.bit_length, int.bit_length,
+            'Delegator object for type int doesn\'t have int\'s bit_length() method.')
+
+        # check that cache cached bit_length correctly
+        self.assertEqual(mydel._Delegator__cache, {'bit_length'})
+
+        mydel.numerator # caches numerator attr
+        self.assertEqual(mydel._Delegator__cache, {'bit_length', 'numerator'})
+
+        # delete the numerator attr (but leaves it in the name cache)
+        del mydel.numerator
+        self.assertNotIn('numerator', mydel.__dict__)
+        self.assertIn('numerator', mydel._Delegator__cache,
+            'Delegator object\'s cache doesn\'t have the numerator() method, but  even after it was deleted from the object\'s namespace.')
+
+        # resetcache() should remove everything from the cache
+        mydel.resetcache()
+        self.assertIs(mydel.delegate, int,
+            'After resetcache() is called, Delegate should still be for type int but instead was for type %s' % (mydel.delegate.__name__,))
+        self.assertEqual(mydel._Delegator__cache, set(),
+            'After resetcache() is called, the cache should be an empty set, but instead was %s' % (str(mydel._Delegator__cache)[:80],))
+
+        # reset by calling setdelegate() (which calls resetcache())
+        mydel.setdelegate(float)
+        self.assertIsNot(mydel.delegate, int,
+            'Delegate is still for int type even after setdelegate(float) was called to change it to be for float type.')
+        self.assertIs(mydel.delegate, float)
         self.assertEqual(mydel._Delegator__cache, set())
 
-        # add an attribute:
-        self.assertRaises(AttributeError, mydel.__getattr__, 'xyz')
-        bl = mydel.bit_length
-        self.assertIs(bl, int.bit_length)
-        self.assertIs(mydel.__dict__['bit_length'], int.bit_length)
-        self.assertEqual(mydel._Delegator__cache, {'bit_length'})
-
-        # add a second attribute
-        mydel.numerator
-        self.assertEqual(mydel._Delegator__cache, {'bit_length', 'numerator'})
-
-        # delete the second (which, however, leaves it in the name cache)
-        del mydel.numerator
-        self.assertNotIn('numerator', mydel.__dict__)
-        self.assertIn('numerator', mydel._Delegator__cache)
-
-        # reset by calling .setdelegate, which calls .resetcache
-        mydel.setdelegate(float)
-        self.assertIs(mydel.delegate, float)
-        self.assertNotIn('bit_length', mydel.__dict__)
-        self.assertEqual(mydel._Delegator__cache, set())
 
 if __name__ == '__main__':
     unittest.main(verbosity=2, exit=2)