Staging
v0.8.1
v0.8.1
https://github.com/python/cpython
Tip revision: 659fc426531517e09eb53cccc8ab4e861d8e0c22 authored by Barry Warsaw on 01 March 2008, 17:45:23 UTC
Copyright and version tweaks for 3.0a3.
Copyright and version tweaks for 3.0a3.
Tip revision: 659fc42
test_typechecks.py
"""Unit tests for __instancecheck__ and __subclasscheck__."""
import unittest
from test import test_support
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(float, Integer), False)
def testIsInstanceBuiltin(self):
self.assertEqual(isinstance(42, Integer), True)
self.assertEqual(isinstance(3.14, Integer), False)
def testIsInstanceActual(self):
self.assertEqual(isinstance(Integer(), Integer), True)
def testIsSubclassActual(self):
self.assertEqual(issubclass(Integer, Integer), True)
def testSubclassBehavior(self):
self.assertEqual(issubclass(SubInt, Integer), True)
self.assertEqual(issubclass(SubInt, SubInt), True)
self.assertEqual(issubclass(Integer, SubInt), False)
self.assertEqual(issubclass(int, SubInt), False)
self.assertEqual(isinstance(SubInt(), Integer), True)
self.assertEqual(isinstance(SubInt(), SubInt), True)
self.assertEqual(isinstance(42, SubInt), False)
def test_main():
test_support.run_unittest(TypeChecksTest)
if __name__ == "__main__":
unittest.main()