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from django.utils import unittest
from django.utils.functional import lazy, lazy_property, cached_property
class FunctionalTestCase(unittest.TestCase):
def test_lazy(self):
t = lazy(lambda: tuple(range(3)), list, tuple)
for a, b in zip(t(), range(3)):
self.assertEqual(a, b)
def test_lazy_base_class(self):
"""Test that lazy also finds base class methods in the proxy object"""
class Base(object):
def base_method(self):
pass
class Klazz(Base):
pass
t = lazy(lambda: Klazz(), Klazz)()
self.assertTrue('base_method' in dir(t))
def test_lazy_property(self):
class A(object):
def _get_do(self):
raise NotImplementedError
def _set_do(self, value):
raise NotImplementedError
do = lazy_property(_get_do, _set_do)
class B(A):
def _get_do(self):
return "DO IT"
self.assertRaises(NotImplementedError, lambda: A().do)
self.assertEqual(B().do, 'DO IT')
def test_cached_property(self):
"""
Test that cached_property caches its value,
and that it behaves like a property
"""
class A(object):
@cached_property
def value(self):
return 1, object()
a = A()
# check that it is cached
self.assertEqual(a.value, a.value)
# check that it returns the right thing
self.assertEqual(a.value[0], 1)
# check that state isn't shared between instances
a2 = A()
self.assertNotEqual(a.value, a2.value)
# check that it behaves like a property when there's no instance
self.assertIsInstance(A.value, cached_property)
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