1"""Unit tests for __instancecheck__ and __subclasscheck__."""
2
3import unittest
4from test import test_support
5
6
7class ABC(type):
8
9    def __instancecheck__(cls, inst):
10        """Implement isinstance(inst, cls)."""
11        return any(cls.__subclasscheck__(c)
12                   for c in set([type(inst), inst.__class__]))
13
14    def __subclasscheck__(cls, sub):
15        """Implement issubclass(sub, cls)."""
16        candidates = cls.__dict__.get("__subclass__", set()) | set([cls])
17        return any(c in candidates for c in sub.mro())
18
19
20class Integer:
21
22    __metaclass__ = ABC
23
24    __subclass__ = set([int])
25
26
27class SubInt(Integer):
28
29    pass
30
31
32class TypeChecksTest(unittest.TestCase):
33
34    def testIsSubclassInternal(self):
35        self.assertEqual(Integer.__subclasscheck__(int), True)
36        self.assertEqual(Integer.__subclasscheck__(float), False)
37
38    def testIsSubclassBuiltin(self):
39        self.assertEqual(issubclass(int, Integer), True)
40        self.assertEqual(issubclass(int, (Integer,)), True)
41        self.assertEqual(issubclass(float, Integer), False)
42        self.assertEqual(issubclass(float, (Integer,)), False)
43
44    def testIsInstanceBuiltin(self):
45        self.assertEqual(isinstance(42, Integer), True)
46        self.assertEqual(isinstance(42, (Integer,)), True)
47        self.assertEqual(isinstance(3.14, Integer), False)
48        self.assertEqual(isinstance(3.14, (Integer,)), False)
49
50    def testIsInstanceActual(self):
51        self.assertEqual(isinstance(Integer(), Integer), True)
52        self.assertEqual(isinstance(Integer(), (Integer,)), True)
53
54    def testIsSubclassActual(self):
55        self.assertEqual(issubclass(Integer, Integer), True)
56        self.assertEqual(issubclass(Integer, (Integer,)), True)
57
58    def testSubclassBehavior(self):
59        self.assertEqual(issubclass(SubInt, Integer), True)
60        self.assertEqual(issubclass(SubInt, (Integer,)), True)
61        self.assertEqual(issubclass(SubInt, SubInt), True)
62        self.assertEqual(issubclass(SubInt, (SubInt,)), True)
63        self.assertEqual(issubclass(Integer, SubInt), False)
64        self.assertEqual(issubclass(Integer, (SubInt,)), False)
65        self.assertEqual(issubclass(int, SubInt), False)
66        self.assertEqual(issubclass(int, (SubInt,)), False)
67        self.assertEqual(isinstance(SubInt(), Integer), True)
68        self.assertEqual(isinstance(SubInt(), (Integer,)), True)
69        self.assertEqual(isinstance(SubInt(), SubInt), True)
70        self.assertEqual(isinstance(SubInt(), (SubInt,)), True)
71        self.assertEqual(isinstance(42, SubInt), False)
72        self.assertEqual(isinstance(42, (SubInt,)), False)
73
74    def test_oldstyle(self):
75        # These should just be ignored.
76        class X:
77            def __instancecheck__(self, inst):
78                return True
79            def __subclasscheck__(self, cls):
80                return True
81        class Sub(X): pass
82        self.assertNotIsInstance(3, X)
83        self.assertIsInstance(X(), X)
84        self.assertFalse(issubclass(int, X))
85        self.assertTrue(issubclass(Sub, X))
86
87
88def test_main():
89    test_support.run_unittest(TypeChecksTest)
90
91
92if __name__ == "__main__":
93    unittest.main()
94