1 """Unit tests for __instancecheck__ and __subclasscheck__."""
4 from test import test_support
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__]))
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())
24 __subclass__ = set([int])
27 class SubInt(Integer):
33 def __instancecheck__(self, inst): return False
36 class TypeChecksTest(unittest.TestCase):
38 def testIsSubclassInternal(self):
39 self.assertEqual(Integer.__subclasscheck__(int), True)
40 self.assertEqual(Integer.__subclasscheck__(float), False)
42 def testIsSubclassBuiltin(self):
43 self.assertEqual(issubclass(int, Integer), True)
44 self.assertEqual(issubclass(int, (Integer,)), True)
45 self.assertEqual(issubclass(float, Integer), False)
46 self.assertEqual(issubclass(float, (Integer,)), False)
48 def testIsInstanceBuiltin(self):
49 self.assertEqual(isinstance(42, Integer), True)
50 self.assertEqual(isinstance(42, (Integer,)), True)
51 self.assertEqual(isinstance(3.14, Integer), False)
52 self.assertEqual(isinstance(3.14, (Integer,)), False)
54 def testIsInstanceActual(self):
55 self.assertEqual(isinstance(Integer(), Integer), True)
56 self.assertEqual(isinstance(Integer(), (Integer,)), True)
58 def testIsSubclassActual(self):
59 self.assertEqual(issubclass(Integer, Integer), True)
60 self.assertEqual(issubclass(Integer, (Integer,)), True)
62 def testSubclassBehavior(self):
63 self.assertEqual(issubclass(SubInt, Integer), True)
64 self.assertEqual(issubclass(SubInt, (Integer,)), True)
65 self.assertEqual(issubclass(SubInt, SubInt), True)
66 self.assertEqual(issubclass(SubInt, (SubInt,)), True)
67 self.assertEqual(issubclass(Integer, SubInt), False)
68 self.assertEqual(issubclass(Integer, (SubInt,)), False)
69 self.assertEqual(issubclass(int, SubInt), False)
70 self.assertEqual(issubclass(int, (SubInt,)), False)
71 self.assertEqual(isinstance(SubInt(), Integer), True)
72 self.assertEqual(isinstance(SubInt(), (Integer,)), True)
73 self.assertEqual(isinstance(SubInt(), SubInt), True)
74 self.assertEqual(isinstance(SubInt(), (SubInt,)), True)
75 self.assertEqual(isinstance(42, SubInt), False)
76 self.assertEqual(isinstance(42, (SubInt,)), False)
78 def testInfiniteRecursionCaughtProperly(self):
80 # This invokes isinstance() recursively, until the stack is exhausted.
81 self.assertRaises(RuntimeError, isinstance, e, Evil)
82 # XXX How to check the same situation for issubclass()?
86 test_support.run_unittest(TypeChecksTest)
89 if __name__ == "__main__":