diff options
Diffstat (limited to 'Lib/test/test_subclassinit.py')
| -rw-r--r-- | Lib/test/test_subclassinit.py | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/Lib/test/test_subclassinit.py b/Lib/test/test_subclassinit.py new file mode 100644 index 0000000000..3c331bb98f --- /dev/null +++ b/Lib/test/test_subclassinit.py @@ -0,0 +1,284 @@ +import sys +import types +import unittest + + +class Test(unittest.TestCase): + def test_init_subclass(self): + class A: + initialized = False + + def __init_subclass__(cls): + super().__init_subclass__() + cls.initialized = True + + class B(A): + pass + + self.assertFalse(A.initialized) + self.assertTrue(B.initialized) + + def test_init_subclass_dict(self): + class A(dict): + initialized = False + + def __init_subclass__(cls): + super().__init_subclass__() + cls.initialized = True + + class B(A): + pass + + self.assertFalse(A.initialized) + self.assertTrue(B.initialized) + + def test_init_subclass_kwargs(self): + class A: + def __init_subclass__(cls, **kwargs): + cls.kwargs = kwargs + + class B(A, x=3): + pass + + self.assertEqual(B.kwargs, dict(x=3)) + + def test_init_subclass_error(self): + class A: + def __init_subclass__(cls): + raise RuntimeError + + with self.assertRaises(RuntimeError): + class B(A): + pass + + def test_init_subclass_wrong(self): + class A: + def __init_subclass__(cls, whatever): + pass + + with self.assertRaises(TypeError): + class B(A): + pass + + def test_init_subclass_skipped(self): + class BaseWithInit: + def __init_subclass__(cls, **kwargs): + super().__init_subclass__(**kwargs) + cls.initialized = cls + + class BaseWithoutInit(BaseWithInit): + pass + + class A(BaseWithoutInit): + pass + + self.assertIs(A.initialized, A) + self.assertIs(BaseWithoutInit.initialized, BaseWithoutInit) + + def test_init_subclass_diamond(self): + class Base: + def __init_subclass__(cls, **kwargs): + super().__init_subclass__(**kwargs) + cls.calls = [] + + class Left(Base): + pass + + class Middle: + def __init_subclass__(cls, middle, **kwargs): + super().__init_subclass__(**kwargs) + cls.calls += [middle] + + class Right(Base): + def __init_subclass__(cls, right="right", **kwargs): + super().__init_subclass__(**kwargs) + cls.calls += [right] + + class A(Left, Middle, Right, middle="middle"): + pass + + self.assertEqual(A.calls, ["right", "middle"]) + self.assertEqual(Left.calls, []) + self.assertEqual(Right.calls, []) + + def test_set_name(self): + class Descriptor: + def __set_name__(self, owner, name): + self.owner = owner + self.name = name + + class A: + d = Descriptor() + + self.assertEqual(A.d.name, "d") + self.assertIs(A.d.owner, A) + + def test_set_name_metaclass(self): + class Meta(type): + def __new__(cls, name, bases, ns): + ret = super().__new__(cls, name, bases, ns) + self.assertEqual(ret.d.name, "d") + self.assertIs(ret.d.owner, ret) + return 0 + + class Descriptor: + def __set_name__(self, owner, name): + self.owner = owner + self.name = name + + class A(metaclass=Meta): + d = Descriptor() + self.assertEqual(A, 0) + + def test_set_name_error(self): + class Descriptor: + def __set_name__(self, owner, name): + 1/0 + + with self.assertRaises(RuntimeError) as cm: + class NotGoingToWork: + attr = Descriptor() + + exc = cm.exception + self.assertRegex(str(exc), r'\bNotGoingToWork\b') + self.assertRegex(str(exc), r'\battr\b') + self.assertRegex(str(exc), r'\bDescriptor\b') + self.assertIsInstance(exc.__cause__, ZeroDivisionError) + + def test_set_name_wrong(self): + class Descriptor: + def __set_name__(self): + pass + + with self.assertRaises(RuntimeError) as cm: + class NotGoingToWork: + attr = Descriptor() + + exc = cm.exception + self.assertRegex(str(exc), r'\bNotGoingToWork\b') + self.assertRegex(str(exc), r'\battr\b') + self.assertRegex(str(exc), r'\bDescriptor\b') + self.assertIsInstance(exc.__cause__, TypeError) + + def test_set_name_lookup(self): + resolved = [] + class NonDescriptor: + def __getattr__(self, name): + resolved.append(name) + + class A: + d = NonDescriptor() + + self.assertNotIn('__set_name__', resolved, + '__set_name__ is looked up in instance dict') + + def test_set_name_init_subclass(self): + class Descriptor: + def __set_name__(self, owner, name): + self.owner = owner + self.name = name + + class Meta(type): + def __new__(cls, name, bases, ns): + self = super().__new__(cls, name, bases, ns) + self.meta_owner = self.owner + self.meta_name = self.name + return self + + class A: + def __init_subclass__(cls): + cls.owner = cls.d.owner + cls.name = cls.d.name + + class B(A, metaclass=Meta): + d = Descriptor() + + self.assertIs(B.owner, B) + self.assertEqual(B.name, 'd') + self.assertIs(B.meta_owner, B) + self.assertEqual(B.name, 'd') + + def test_set_name_modifying_dict(self): + notified = [] + class Descriptor: + def __set_name__(self, owner, name): + setattr(owner, name + 'x', None) + notified.append(name) + + class A: + a = Descriptor() + b = Descriptor() + c = Descriptor() + d = Descriptor() + e = Descriptor() + + self.assertCountEqual(notified, ['a', 'b', 'c', 'd', 'e']) + + def test_errors(self): + class MyMeta(type): + pass + + with self.assertRaises(TypeError): + class MyClass(metaclass=MyMeta, otherarg=1): + pass + + with self.assertRaises(TypeError): + types.new_class("MyClass", (object,), + dict(metaclass=MyMeta, otherarg=1)) + types.prepare_class("MyClass", (object,), + dict(metaclass=MyMeta, otherarg=1)) + + class MyMeta(type): + def __init__(self, name, bases, namespace, otherarg): + super().__init__(name, bases, namespace) + + with self.assertRaises(TypeError): + class MyClass(metaclass=MyMeta, otherarg=1): + pass + + class MyMeta(type): + def __new__(cls, name, bases, namespace, otherarg): + return super().__new__(cls, name, bases, namespace) + + def __init__(self, name, bases, namespace, otherarg): + super().__init__(name, bases, namespace) + self.otherarg = otherarg + + class MyClass(metaclass=MyMeta, otherarg=1): + pass + + self.assertEqual(MyClass.otherarg, 1) + + def test_errors_changed_pep487(self): + # These tests failed before Python 3.6, PEP 487 + class MyMeta(type): + def __new__(cls, name, bases, namespace): + return super().__new__(cls, name=name, bases=bases, + dict=namespace) + + with self.assertRaises(TypeError): + class MyClass(metaclass=MyMeta): + pass + + class MyMeta(type): + def __new__(cls, name, bases, namespace, otherarg): + self = super().__new__(cls, name, bases, namespace) + self.otherarg = otherarg + return self + + class MyClass(metaclass=MyMeta, otherarg=1): + pass + + self.assertEqual(MyClass.otherarg, 1) + + def test_type(self): + t = type('NewClass', (object,), {}) + self.assertIsInstance(t, type) + self.assertEqual(t.__name__, 'NewClass') + + with self.assertRaises(TypeError): + type(name='NewClass', bases=(object,), dict={}) + + +if __name__ == "__main__": + unittest.main() |