1"""Unit tests for __instancecheck__ and __subclasscheck__."""
2
3import unittest
4
5
6class ABC(type):
7
8    def __instancecheck__(cls, inst):
9        """Implement isinstance(inst, cls)."""
10        return any(cls.__subclasscheck__(c)
11                   for c in {type(inst), inst.__class__})
12
13    def __subclasscheck__(cls, sub):
14        """Implement issubclass(sub, cls)."""
15        candidates = cls.__dict__.get("__subclass__", set()) | {cls}
16        return any(c in candidates for c in sub.mro())
17
18
19class Integer(metaclass=ABC):
20    __subclass__ = {int}
21
22
23class SubInt(Integer):
24    pass
25
26
27class TypeChecksTest(unittest.TestCase):
28
29    def testIsSubclassInternal(self):
30        self.assertEqual(Integer.__subclasscheck__(int), True)
31        self.assertEqual(Integer.__subclasscheck__(float), False)
32
33    def testIsSubclassBuiltin(self):
34        self.assertEqual(issubclass(int, Integer), True)
35        self.assertEqual(issubclass(int, (Integer,)), True)
36        self.assertEqual(issubclass(float, Integer), False)
37        self.assertEqual(issubclass(float, (Integer,)), False)
38
39    def testIsInstanceBuiltin(self):
40        self.assertEqual(isinstance(42, Integer), True)
41        self.assertEqual(isinstance(42, (Integer,)), True)
42        self.assertEqual(isinstance(3.14, Integer), False)
43        self.assertEqual(isinstance(3.14, (Integer,)), False)
44
45    def testIsInstanceActual(self):
46        self.assertEqual(isinstance(Integer(), Integer), True)
47        self.assertEqual(isinstance(Integer(), (Integer,)), True)
48
49    def testIsSubclassActual(self):
50        self.assertEqual(issubclass(Integer, Integer), True)
51        self.assertEqual(issubclass(Integer, (Integer,)), True)
52
53    def testSubclassBehavior(self):
54        self.assertEqual(issubclass(SubInt, Integer), True)
55        self.assertEqual(issubclass(SubInt, (Integer,)), True)
56        self.assertEqual(issubclass(SubInt, SubInt), True)
57        self.assertEqual(issubclass(SubInt, (SubInt,)), True)
58        self.assertEqual(issubclass(Integer, SubInt), False)
59        self.assertEqual(issubclass(Integer, (SubInt,)), False)
60        self.assertEqual(issubclass(int, SubInt), False)
61        self.assertEqual(issubclass(int, (SubInt,)), False)
62        self.assertEqual(isinstance(SubInt(), Integer), True)
63        self.assertEqual(isinstance(SubInt(), (Integer,)), True)
64        self.assertEqual(isinstance(SubInt(), SubInt), True)
65        self.assertEqual(isinstance(SubInt(), (SubInt,)), True)
66        self.assertEqual(isinstance(42, SubInt), False)
67        self.assertEqual(isinstance(42, (SubInt,)), False)
68
69
70if __name__ == "__main__":
71    unittest.main()
72