221 lines
6.9 KiB
Python
221 lines
6.9 KiB
Python
from unittest import mock
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from django.test import SimpleTestCase
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from django.utils.functional import cached_property, lazy
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class FunctionalTests(SimpleTestCase):
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def test_lazy(self):
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t = lazy(lambda: tuple(range(3)), list, tuple)
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for a, b in zip(t(), range(3)):
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self.assertEqual(a, b)
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def test_lazy_base_class(self):
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"""lazy also finds base class methods in the proxy object"""
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class Base:
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def base_method(self):
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pass
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class Klazz(Base):
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pass
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t = lazy(lambda: Klazz(), Klazz)()
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self.assertIn('base_method', dir(t))
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def test_lazy_base_class_override(self):
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"""lazy finds the correct (overridden) method implementation"""
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class Base:
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def method(self):
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return 'Base'
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class Klazz(Base):
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def method(self):
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return 'Klazz'
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t = lazy(lambda: Klazz(), Base)()
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self.assertEqual(t.method(), 'Klazz')
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def test_lazy_object_to_string(self):
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class Klazz:
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def __str__(self):
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return "Î am ā Ǩlâzz."
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def __bytes__(self):
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return b"\xc3\x8e am \xc4\x81 binary \xc7\xa8l\xc3\xa2zz."
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t = lazy(lambda: Klazz(), Klazz)()
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self.assertEqual(str(t), "Î am ā Ǩlâzz.")
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self.assertEqual(bytes(t), b"\xc3\x8e am \xc4\x81 binary \xc7\xa8l\xc3\xa2zz.")
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def assertCachedPropertyWorks(self, attr, Class):
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with self.subTest(attr=attr):
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def get(source):
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return getattr(source, attr)
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obj = Class()
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class SubClass(Class):
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pass
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subobj = SubClass()
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# Docstring is preserved.
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self.assertEqual(get(Class).__doc__, 'Here is the docstring...')
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self.assertEqual(get(SubClass).__doc__, 'Here is the docstring...')
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# It's cached.
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self.assertEqual(get(obj), get(obj))
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self.assertEqual(get(subobj), get(subobj))
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# The correct value is returned.
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self.assertEqual(get(obj)[0], 1)
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self.assertEqual(get(subobj)[0], 1)
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# State isn't shared between instances.
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obj2 = Class()
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subobj2 = SubClass()
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self.assertNotEqual(get(obj), get(obj2))
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self.assertNotEqual(get(subobj), get(subobj2))
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# It behaves like a property when there's no instance.
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self.assertIsInstance(get(Class), cached_property)
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self.assertIsInstance(get(SubClass), cached_property)
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# 'other_value' doesn't become a property.
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self.assertTrue(callable(obj.other_value))
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self.assertTrue(callable(subobj.other_value))
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def test_cached_property(self):
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"""cached_property caches its value and behaves like a property."""
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class Class:
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@cached_property
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def value(self):
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"""Here is the docstring..."""
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return 1, object()
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@cached_property
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def __foo__(self):
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"""Here is the docstring..."""
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return 1, object()
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def other_value(self):
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"""Here is the docstring..."""
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return 1, object()
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other = cached_property(other_value, name='other')
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attrs = ['value', 'other', '__foo__']
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for attr in attrs:
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self.assertCachedPropertyWorks(attr, Class)
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def test_cached_property_auto_name(self):
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"""
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cached_property caches its value and behaves like a property
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on mangled methods or when the name kwarg isn't set.
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"""
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class Class:
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@cached_property
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def __value(self):
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"""Here is the docstring..."""
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return 1, object()
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def other_value(self):
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"""Here is the docstring..."""
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return 1, object()
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other = cached_property(other_value)
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other2 = cached_property(other_value, name='different_name')
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attrs = ['_Class__value', 'other']
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for attr in attrs:
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self.assertCachedPropertyWorks(attr, Class)
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# An explicit name is ignored.
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obj = Class()
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obj.other2
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self.assertFalse(hasattr(obj, 'different_name'))
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def test_cached_property_reuse_different_names(self):
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"""Disallow this case because the decorated function wouldn't be cached."""
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with self.assertRaises(RuntimeError) as ctx:
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class ReusedCachedProperty:
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@cached_property
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def a(self):
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pass
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b = a
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self.assertEqual(
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str(ctx.exception.__context__),
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str(TypeError(
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"Cannot assign the same cached_property to two different "
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"names ('a' and 'b')."
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))
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)
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def test_cached_property_reuse_same_name(self):
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"""
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Reusing a cached_property on different classes under the same name is
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allowed.
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"""
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counter = 0
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@cached_property
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def _cp(_self):
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nonlocal counter
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counter += 1
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return counter
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class A:
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cp = _cp
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class B:
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cp = _cp
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a = A()
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b = B()
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self.assertEqual(a.cp, 1)
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self.assertEqual(b.cp, 2)
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self.assertEqual(a.cp, 1)
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def test_cached_property_set_name_not_called(self):
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cp = cached_property(lambda s: None)
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class Foo:
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pass
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Foo.cp = cp
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msg = 'Cannot use cached_property instance without calling __set_name__() on it.'
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with self.assertRaisesMessage(TypeError, msg):
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Foo().cp
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def test_lazy_equality(self):
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"""
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== and != work correctly for Promises.
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"""
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lazy_a = lazy(lambda: 4, int)
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lazy_b = lazy(lambda: 4, int)
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lazy_c = lazy(lambda: 5, int)
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self.assertEqual(lazy_a(), lazy_b())
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self.assertNotEqual(lazy_b(), lazy_c())
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def test_lazy_repr_text(self):
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original_object = 'Lazy translation text'
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lazy_obj = lazy(lambda: original_object, str)
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self.assertEqual(repr(original_object), repr(lazy_obj()))
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def test_lazy_repr_int(self):
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original_object = 15
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lazy_obj = lazy(lambda: original_object, int)
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self.assertEqual(repr(original_object), repr(lazy_obj()))
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def test_lazy_repr_bytes(self):
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original_object = b'J\xc3\xbcst a str\xc3\xadng'
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lazy_obj = lazy(lambda: original_object, bytes)
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self.assertEqual(repr(original_object), repr(lazy_obj()))
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def test_lazy_class_preparation_caching(self):
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# lazy() should prepare the proxy class only once i.e. the first time
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# it's used.
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lazified = lazy(lambda: 0, int)
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__proxy__ = lazified().__class__
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with mock.patch.object(__proxy__, '__prepare_class__') as mocked:
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lazified()
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mocked.assert_not_called()
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