from unittest import mock from django.test import SimpleTestCase from django.utils.functional import cached_property, classproperty, lazy class FunctionalTests(SimpleTestCase): 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): """lazy also finds base class methods in the proxy object""" class Base: def base_method(self): pass class Klazz(Base): pass t = lazy(lambda: Klazz(), Klazz)() self.assertIn("base_method", dir(t)) def test_lazy_base_class_override(self): """lazy finds the correct (overridden) method implementation""" class Base: def method(self): return "Base" class Klazz(Base): def method(self): return "Klazz" t = lazy(lambda: Klazz(), Base)() self.assertEqual(t.method(), "Klazz") def test_lazy_object_to_string(self): class Klazz: def __str__(self): return "Î am ā Ǩlâzz." def __bytes__(self): return b"\xc3\x8e am \xc4\x81 binary \xc7\xa8l\xc3\xa2zz." t = lazy(lambda: Klazz(), Klazz)() self.assertEqual(str(t), "Î am ā Ǩlâzz.") self.assertEqual(bytes(t), b"\xc3\x8e am \xc4\x81 binary \xc7\xa8l\xc3\xa2zz.") def assertCachedPropertyWorks(self, attr, Class): with self.subTest(attr=attr): def get(source): return getattr(source, attr) obj = Class() class SubClass(Class): pass subobj = SubClass() # Docstring is preserved. self.assertEqual(get(Class).__doc__, "Here is the docstring...") self.assertEqual(get(SubClass).__doc__, "Here is the docstring...") # It's cached. self.assertEqual(get(obj), get(obj)) self.assertEqual(get(subobj), get(subobj)) # The correct value is returned. self.assertEqual(get(obj)[0], 1) self.assertEqual(get(subobj)[0], 1) # State isn't shared between instances. obj2 = Class() subobj2 = SubClass() self.assertNotEqual(get(obj), get(obj2)) self.assertNotEqual(get(subobj), get(subobj2)) # It behaves like a property when there's no instance. self.assertIsInstance(get(Class), cached_property) self.assertIsInstance(get(SubClass), cached_property) # 'other_value' doesn't become a property. self.assertTrue(callable(obj.other_value)) self.assertTrue(callable(subobj.other_value)) def test_cached_property(self): """cached_property caches its value and behaves like a property.""" class Class: @cached_property def value(self): """Here is the docstring...""" return 1, object() @cached_property def __foo__(self): """Here is the docstring...""" return 1, object() def other_value(self): """Here is the docstring...""" return 1, object() other = cached_property(other_value) attrs = ["value", "other", "__foo__"] for attr in attrs: self.assertCachedPropertyWorks(attr, Class) def test_cached_property_auto_name(self): """ cached_property caches its value and behaves like a property on mangled methods or when the name kwarg isn't set. """ class Class: @cached_property def __value(self): """Here is the docstring...""" return 1, object() def other_value(self): """Here is the docstring...""" return 1, object() other = cached_property(other_value) attrs = ["_Class__value", "other"] for attr in attrs: self.assertCachedPropertyWorks(attr, Class) def test_cached_property_reuse_different_names(self): """Disallow this case because the decorated function wouldn't be cached.""" with self.assertRaises(RuntimeError) as ctx: class ReusedCachedProperty: @cached_property def a(self): pass b = a self.assertEqual( str(ctx.exception.__context__), str( TypeError( "Cannot assign the same cached_property to two different " "names ('a' and 'b')." ) ), ) def test_cached_property_reuse_same_name(self): """ Reusing a cached_property on different classes under the same name is allowed. """ counter = 0 @cached_property def _cp(_self): nonlocal counter counter += 1 return counter class A: cp = _cp class B: cp = _cp a = A() b = B() self.assertEqual(a.cp, 1) self.assertEqual(b.cp, 2) self.assertEqual(a.cp, 1) def test_cached_property_set_name_not_called(self): cp = cached_property(lambda s: None) class Foo: pass Foo.cp = cp msg = ( "Cannot use cached_property instance without calling __set_name__() on it." ) with self.assertRaisesMessage(TypeError, msg): Foo().cp def test_lazy_add(self): lazy_4 = lazy(lambda: 4, int) lazy_5 = lazy(lambda: 5, int) self.assertEqual(lazy_4() + lazy_5(), 9) def test_lazy_equality(self): """ == and != work correctly for Promises. """ lazy_a = lazy(lambda: 4, int) lazy_b = lazy(lambda: 4, int) lazy_c = lazy(lambda: 5, int) self.assertEqual(lazy_a(), lazy_b()) self.assertNotEqual(lazy_b(), lazy_c()) def test_lazy_repr_text(self): original_object = "Lazy translation text" lazy_obj = lazy(lambda: original_object, str) self.assertEqual(repr(original_object), repr(lazy_obj())) def test_lazy_repr_int(self): original_object = 15 lazy_obj = lazy(lambda: original_object, int) self.assertEqual(repr(original_object), repr(lazy_obj())) def test_lazy_repr_bytes(self): original_object = b"J\xc3\xbcst a str\xc3\xadng" lazy_obj = lazy(lambda: original_object, bytes) self.assertEqual(repr(original_object), repr(lazy_obj())) def test_lazy_class_preparation_caching(self): # lazy() should prepare the proxy class only once i.e. the first time # it's used. lazified = lazy(lambda: 0, int) __proxy__ = lazified().__class__ with mock.patch.object(__proxy__, "__prepare_class__") as mocked: lazified() mocked.assert_not_called() def test_lazy_bytes_and_str_result_classes(self): lazy_obj = lazy(lambda: "test", str, bytes) msg = "Cannot call lazy() with both bytes and text return types." with self.assertRaisesMessage(ValueError, msg): lazy_obj() def test_lazy_str_cast_mixed_result_types(self): lazy_value = lazy(lambda: [1], str, list)() self.assertEqual(str(lazy_value), "[1]") def test_classproperty_getter(self): class Foo: foo_attr = 123 def __init__(self): self.foo_attr = 456 @classproperty def foo(cls): return cls.foo_attr class Bar: bar = classproperty() @bar.getter def bar(cls): return 123 self.assertEqual(Foo.foo, 123) self.assertEqual(Foo().foo, 123) self.assertEqual(Bar.bar, 123) self.assertEqual(Bar().bar, 123) def test_classproperty_override_getter(self): class Foo: @classproperty def foo(cls): return 123 @foo.getter def foo(cls): return 456 self.assertEqual(Foo.foo, 456) self.assertEqual(Foo().foo, 456)