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284 lines
8.1 KiB
284 lines
8.1 KiB
3 years ago
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import types
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import unittest
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class Test(unittest.TestCase):
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def test_init_subclass(self):
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class A:
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initialized = False
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def __init_subclass__(cls):
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super().__init_subclass__()
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cls.initialized = True
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class B(A):
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pass
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self.assertFalse(A.initialized)
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self.assertTrue(B.initialized)
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def test_init_subclass_dict(self):
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class A(dict):
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initialized = False
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def __init_subclass__(cls):
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super().__init_subclass__()
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cls.initialized = True
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class B(A):
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pass
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self.assertFalse(A.initialized)
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self.assertTrue(B.initialized)
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def test_init_subclass_kwargs(self):
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class A:
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def __init_subclass__(cls, **kwargs):
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cls.kwargs = kwargs
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class B(A, x=3):
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pass
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self.assertEqual(B.kwargs, dict(x=3))
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def test_init_subclass_error(self):
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class A:
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def __init_subclass__(cls):
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raise RuntimeError
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with self.assertRaises(RuntimeError):
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class B(A):
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pass
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def test_init_subclass_wrong(self):
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class A:
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def __init_subclass__(cls, whatever):
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pass
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with self.assertRaises(TypeError):
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class B(A):
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pass
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def test_init_subclass_skipped(self):
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class BaseWithInit:
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def __init_subclass__(cls, **kwargs):
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super().__init_subclass__(**kwargs)
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cls.initialized = cls
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class BaseWithoutInit(BaseWithInit):
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pass
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class A(BaseWithoutInit):
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pass
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self.assertIs(A.initialized, A)
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self.assertIs(BaseWithoutInit.initialized, BaseWithoutInit)
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def test_init_subclass_diamond(self):
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class Base:
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def __init_subclass__(cls, **kwargs):
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super().__init_subclass__(**kwargs)
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cls.calls = []
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class Left(Base):
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pass
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class Middle:
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def __init_subclass__(cls, middle, **kwargs):
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super().__init_subclass__(**kwargs)
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cls.calls += [middle]
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class Right(Base):
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def __init_subclass__(cls, right="right", **kwargs):
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super().__init_subclass__(**kwargs)
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cls.calls += [right]
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class A(Left, Middle, Right, middle="middle"):
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pass
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self.assertEqual(A.calls, ["right", "middle"])
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self.assertEqual(Left.calls, [])
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self.assertEqual(Right.calls, [])
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def test_set_name(self):
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class Descriptor:
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def __set_name__(self, owner, name):
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self.owner = owner
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self.name = name
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class A:
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d = Descriptor()
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self.assertEqual(A.d.name, "d")
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self.assertIs(A.d.owner, A)
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def test_set_name_metaclass(self):
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class Meta(type):
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def __new__(cls, name, bases, ns):
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ret = super().__new__(cls, name, bases, ns)
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self.assertEqual(ret.d.name, "d")
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self.assertIs(ret.d.owner, ret)
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return 0
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class Descriptor:
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def __set_name__(self, owner, name):
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self.owner = owner
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self.name = name
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class A(metaclass=Meta):
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d = Descriptor()
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self.assertEqual(A, 0)
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def test_set_name_error(self):
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class Descriptor:
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def __set_name__(self, owner, name):
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1/0
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with self.assertRaises(RuntimeError) as cm:
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class NotGoingToWork:
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attr = Descriptor()
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exc = cm.exception
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self.assertRegex(str(exc), r'\bNotGoingToWork\b')
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self.assertRegex(str(exc), r'\battr\b')
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self.assertRegex(str(exc), r'\bDescriptor\b')
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self.assertIsInstance(exc.__cause__, ZeroDivisionError)
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def test_set_name_wrong(self):
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class Descriptor:
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def __set_name__(self):
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pass
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with self.assertRaises(RuntimeError) as cm:
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class NotGoingToWork:
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attr = Descriptor()
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exc = cm.exception
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self.assertRegex(str(exc), r'\bNotGoingToWork\b')
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self.assertRegex(str(exc), r'\battr\b')
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self.assertRegex(str(exc), r'\bDescriptor\b')
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self.assertIsInstance(exc.__cause__, TypeError)
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def test_set_name_lookup(self):
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resolved = []
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class NonDescriptor:
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def __getattr__(self, name):
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resolved.append(name)
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class A:
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d = NonDescriptor()
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self.assertNotIn('__set_name__', resolved,
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'__set_name__ is looked up in instance dict')
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def test_set_name_init_subclass(self):
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class Descriptor:
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def __set_name__(self, owner, name):
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self.owner = owner
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self.name = name
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class Meta(type):
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def __new__(cls, name, bases, ns):
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self = super().__new__(cls, name, bases, ns)
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self.meta_owner = self.owner
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self.meta_name = self.name
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return self
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class A:
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def __init_subclass__(cls):
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cls.owner = cls.d.owner
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cls.name = cls.d.name
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class B(A, metaclass=Meta):
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d = Descriptor()
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self.assertIs(B.owner, B)
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self.assertEqual(B.name, 'd')
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self.assertIs(B.meta_owner, B)
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self.assertEqual(B.name, 'd')
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def test_set_name_modifying_dict(self):
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notified = []
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class Descriptor:
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def __set_name__(self, owner, name):
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setattr(owner, name + 'x', None)
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notified.append(name)
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class A:
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a = Descriptor()
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b = Descriptor()
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c = Descriptor()
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d = Descriptor()
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e = Descriptor()
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self.assertCountEqual(notified, ['a', 'b', 'c', 'd', 'e'])
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def test_errors(self):
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class MyMeta(type):
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pass
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with self.assertRaises(TypeError):
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class MyClass(metaclass=MyMeta, otherarg=1):
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pass
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with self.assertRaises(TypeError):
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types.new_class("MyClass", (object,),
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dict(metaclass=MyMeta, otherarg=1))
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types.prepare_class("MyClass", (object,),
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dict(metaclass=MyMeta, otherarg=1))
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class MyMeta(type):
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def __init__(self, name, bases, namespace, otherarg):
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super().__init__(name, bases, namespace)
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with self.assertRaises(TypeError):
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class MyClass(metaclass=MyMeta, otherarg=1):
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pass
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class MyMeta(type):
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def __new__(cls, name, bases, namespace, otherarg):
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return super().__new__(cls, name, bases, namespace)
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def __init__(self, name, bases, namespace, otherarg):
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super().__init__(name, bases, namespace)
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self.otherarg = otherarg
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class MyClass(metaclass=MyMeta, otherarg=1):
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pass
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self.assertEqual(MyClass.otherarg, 1)
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def test_errors_changed_pep487(self):
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# These tests failed before Python 3.6, PEP 487
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class MyMeta(type):
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def __new__(cls, name, bases, namespace):
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return super().__new__(cls, name=name, bases=bases,
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dict=namespace)
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with self.assertRaises(TypeError):
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class MyClass(metaclass=MyMeta):
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pass
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class MyMeta(type):
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def __new__(cls, name, bases, namespace, otherarg):
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self = super().__new__(cls, name, bases, namespace)
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self.otherarg = otherarg
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return self
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class MyClass(metaclass=MyMeta, otherarg=1):
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pass
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self.assertEqual(MyClass.otherarg, 1)
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def test_type(self):
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t = type('NewClass', (object,), {})
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self.assertIsInstance(t, type)
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self.assertEqual(t.__name__, 'NewClass')
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with self.assertRaises(TypeError):
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type(name='NewClass', bases=(object,), dict={})
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if __name__ == "__main__":
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unittest.main()
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