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"""Unit tests for __instancecheck__ and __subclasscheck__."""
import unittest
class ABC(type):
def __instancecheck__(cls, inst):
"""Implement isinstance(inst, cls)."""
return any(cls.__subclasscheck__(c)
for c in {type(inst), inst.__class__})
def __subclasscheck__(cls, sub):
"""Implement issubclass(sub, cls)."""
candidates = cls.__dict__.get("__subclass__", set()) | {cls}
return any(c in candidates for c in sub.mro())
class Integer(metaclass=ABC):
__subclass__ = {int}
class SubInt(Integer):
pass
class TypeChecksTest(unittest.TestCase):
def testIsSubclassInternal(self):
self.assertEqual(Integer.__subclasscheck__(int), True)
self.assertEqual(Integer.__subclasscheck__(float), False)
def testIsSubclassBuiltin(self):
self.assertEqual(issubclass(int, Integer), True)
self.assertEqual(issubclass(int, (Integer,)), True)
self.assertEqual(issubclass(float, Integer), False)
self.assertEqual(issubclass(float, (Integer,)), False)
def testIsInstanceBuiltin(self):
self.assertEqual(isinstance(42, Integer), True)
self.assertEqual(isinstance(42, (Integer,)), True)
self.assertEqual(isinstance(3.14, Integer), False)
self.assertEqual(isinstance(3.14, (Integer,)), False)
def testIsInstanceActual(self):
self.assertEqual(isinstance(Integer(), Integer), True)
self.assertEqual(isinstance(Integer(), (Integer,)), True)
def testIsSubclassActual(self):
self.assertEqual(issubclass(Integer, Integer), True)
self.assertEqual(issubclass(Integer, (Integer,)), True)
def testSubclassBehavior(self):
self.assertEqual(issubclass(SubInt, Integer), True)
self.assertEqual(issubclass(SubInt, (Integer,)), True)
self.assertEqual(issubclass(SubInt, SubInt), True)
self.assertEqual(issubclass(SubInt, (SubInt,)), True)
self.assertEqual(issubclass(Integer, SubInt), False)
self.assertEqual(issubclass(Integer, (SubInt,)), False)
self.assertEqual(issubclass(int, SubInt), False)
self.assertEqual(issubclass(int, (SubInt,)), False)
self.assertEqual(isinstance(SubInt(), Integer), True)
self.assertEqual(isinstance(SubInt(), (Integer,)), True)
self.assertEqual(isinstance(SubInt(), SubInt), True)
self.assertEqual(isinstance(SubInt(), (SubInt,)), True)
self.assertEqual(isinstance(42, SubInt), False)
self.assertEqual(isinstance(42, (SubInt,)), False)
if __name__ == "__main__":
unittest.main()
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