1import unittest
2from idlelib.delegator import Delegator
3
4class DelegatorTest(unittest.TestCase):
5
6    def test_mydel(self):
7        # Test a simple use scenario.
8
9        # Initialize an int delegator.
10        mydel = Delegator(int)
11        self.assertIs(mydel.delegate, int)
12        self.assertEqual(mydel._Delegator__cache, set())
13        # Trying to access a non-attribute of int fails.
14        self.assertRaises(AttributeError, mydel.__getattr__, 'xyz')
15
16        # Add real int attribute 'bit_length' by accessing it.
17        bl = mydel.bit_length
18        self.assertIs(bl, int.bit_length)
19        self.assertIs(mydel.__dict__['bit_length'], int.bit_length)
20        self.assertEqual(mydel._Delegator__cache, {'bit_length'})
21
22        # Add attribute 'numerator'.
23        mydel.numerator
24        self.assertEqual(mydel._Delegator__cache, {'bit_length', 'numerator'})
25
26        # Delete 'numerator'.
27        del mydel.numerator
28        self.assertNotIn('numerator', mydel.__dict__)
29        # The current implementation leaves  it in the name cache.
30        # self.assertIn('numerator', mydel._Delegator__cache)
31        # However, this is not required and not part of the specification
32
33        # Change delegate to float, first resetting the attributes.
34        mydel.setdelegate(float)  # calls resetcache
35        self.assertNotIn('bit_length', mydel.__dict__)
36        self.assertEqual(mydel._Delegator__cache, set())
37        self.assertIs(mydel.delegate, float)
38
39if __name__ == '__main__':
40    unittest.main(verbosity=2, exit=2)
41