# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
# Note: each test is run with Python and C versions of ABCMeta. Except for
# test_ABC_helper(), which assures that abc.ABC is an instance of abc.ABCMeta.
"""Unit tests for abc.py."""
import unittest
import abc
import _py_abc
from inspect import isabstract
def test_factory(abc_ABCMeta, abc_get_cache_token):
class TestLegacyAPI(unittest.TestCase):
def test_abstractproperty_basics(self):
@abc.abstractproperty
def foo(self): pass
self.assertTrue(foo.__isabstractmethod__)
def bar(self): pass
self.assertFalse(hasattr(bar, "__isabstractmethod__"))
class C(metaclass=abc_ABCMeta):
@abc.abstractproperty
def foo(self): return 3
self.assertRaises(TypeError, C)
class D(C):
@property
def foo(self): return super().foo
self.assertEqual(D().foo, 3)
self.assertFalse(getattr(D.foo, "__isabstractmethod__", False))
def test_abstractclassmethod_basics(self):
@abc.abstractclassmethod
def foo(cls): pass
self.assertTrue(foo.__isabstractmethod__)
@classmethod
def bar(cls): pass
self.assertFalse(getattr(bar, "__isabstractmethod__", False))
class C(metaclass=abc_ABCMeta):
@abc.abstractclassmethod
def foo(cls): return cls.__name__
self.assertRaises(TypeError, C)
class D(C):
@classmethod
def foo(cls): return super().foo()
self.assertEqual(D.foo(), 'D')
self.assertEqual(D().foo(), 'D')
def test_abstractstaticmethod_basics(self):
@abc.abstractstaticmethod
def foo(): pass
self.assertTrue(foo.__isabstractmethod__)
@staticmethod
def bar(): pass
self.assertFalse(getattr(bar, "__isabstractmethod__", False))
class C(metaclass=abc_ABCMeta):
@abc.abstractstaticmethod
def foo(): return 3
self.assertRaises(TypeError, C)
class D(C):
@staticmethod
def foo(): return 4
self.assertEqual(D.foo(), 4)
self.assertEqual(D().foo(), 4)
class TestABC(unittest.TestCase):
def test_ABC_helper(self):
# create an ABC using the helper class and perform basic checks
class C(abc.ABC):
@classmethod
@abc.abstractmethod
def foo(cls): return cls.__name__
self.assertEqual(type(C), abc.ABCMeta)
self.assertRaises(TypeError, C)
class D(C):
@classmethod
def foo(cls): return super().foo()
self.assertEqual(D.foo(), 'D')
def test_abstractmethod_basics(self):
@abc.abstractmethod
def foo(self): pass
self.assertTrue(foo.__isabstractmethod__)
def bar(self): pass
self.assertFalse(hasattr(bar, "__isabstractmethod__"))
def test_abstractproperty_basics(self):
@property
@abc.abstractmethod
def foo(self): pass
self.assertTrue(foo.__isabstractmethod__)
def bar(self): pass
self.assertFalse(getattr(bar, "__isabstractmethod__", False))
class C(metaclass=abc_ABCMeta):
@property
@abc.abstractmethod
def foo(self): return 3
self.assertRaises(TypeError, C)
class D(C):
@C.foo.getter
def foo(self): return super().foo
self.assertEqual(D().foo, 3)
def test_abstractclassmethod_basics(self):
@classmethod
@abc.abstractmethod
def foo(cls): pass
self.assertTrue(foo.__isabstractmethod__)
@classmethod
def bar(cls): pass
self.assertFalse(getattr(bar, "__isabstractmethod__", False))
class C(metaclass=abc_ABCMeta):
@classmethod
@abc.abstractmethod
def foo(cls): return cls.__name__
self.assertRaises(TypeError, C)
class D(C):
@classmethod
def foo(cls): return super().foo()
self.assertEqual(D.foo(), 'D')
self.assertEqual(D().foo(), 'D')
def test_abstractstaticmethod_basics(self):
@staticmethod
@abc.abstractmethod
def foo(): pass
self.assertTrue(foo.__isabstractmethod__)
@staticmethod
def bar(): pass
self.assertFalse(getattr(bar, "__isabstractmethod__", False))
class C(metaclass=abc_ABCMeta):
@staticmethod
@abc.abstractmethod
def foo(): return 3
self.assertRaises(TypeError, C)
class D(C):
@staticmethod
def foo(): return 4
self.assertEqual(D.foo(), 4)
self.assertEqual(D().foo(), 4)
def test_object_new_with_one_abstractmethod(self):
class C(metaclass=abc_ABCMeta):
@abc.abstractmethod
def method_one(self):
pass
msg = r"class C without an implementation for abstract method 'method_one'"
self.assertRaisesRegex(TypeError, msg, C)
def test_object_new_with_many_abstractmethods(self):
class C(metaclass=abc_ABCMeta):
@abc.abstractmethod
def method_one(self):
pass
@abc.abstractmethod
def method_two(self):
pass
msg = r"class C without an implementation for abstract methods 'method_one', 'method_two'"
self.assertRaisesRegex(TypeError, msg, C)
def test_abstractmethod_integration(self):
for abstractthing in [abc.abstractmethod, abc.abstractproperty,
abc.abstractclassmethod,
abc.abstractstaticmethod]:
class C(metaclass=abc_ABCMeta):
@abstractthing
def foo(self): pass # abstract
def bar(self): pass # concrete
self.assertEqual(C.__abstractmethods__, {"foo"})
self.assertRaises(TypeError, C) # because foo is abstract
self.assertTrue(isabstract(C))
class D(C):
def bar(self): pass # concrete override of concrete
self.assertEqual(D.__abstractmethods__, {"foo"})
self.assertRaises(TypeError, D) # because foo is still abstract
self.assertTrue(isabstract(D))
class E(D):
def foo(self): pass
self.assertEqual(E.__abstractmethods__, set())
E() # now foo is concrete, too
self.assertFalse(isabstract(E))
class F(E):
@abstractthing
def bar(self): pass # abstract override of concrete
self.assertEqual(F.__abstractmethods__, {"bar"})
self.assertRaises(TypeError, F) # because bar is abstract now
self.assertTrue(isabstract(F))
def test_descriptors_with_abstractmethod(self):
class C(metaclass=abc_ABCMeta):
@property
@abc.abstractmethod
def foo(self): return 3
@foo.setter
@abc.abstractmethod
def foo(self, val): pass
self.assertRaises(TypeError, C)
class D(C):
@C.foo.getter
def foo(self): return super().foo
self.assertRaises(TypeError, D)
class E(D):
@D.foo.setter
def foo(self, val): pass
self.assertEqual(E().foo, 3)
# check that the property's __isabstractmethod__ descriptor does the
# right thing when presented with a value that fails truth testing:
class NotBool(object):
def __bool__(self):
raise ValueError()
__len__ = __bool__
with self.assertRaises(ValueError):
class F(C):
def bar(self):
pass
bar.__isabstractmethod__ = NotBool()
foo = property(bar)
def test_customdescriptors_with_abstractmethod(self):
class Descriptor:
def __init__(self, fget, fset=None):
self._fget = fget
self._fset = fset
def getter(self, callable):
return Descriptor(callable, self._fget)
def setter(self, callable):
return Descriptor(self._fget, callable)
@property
def __isabstractmethod__(self):
return (getattr(self._fget, '__isabstractmethod__', False)
or getattr(self._fset, '__isabstractmethod__', False))
class C(metaclass=abc_ABCMeta):
@Descriptor
@abc.abstractmethod
def foo(self): return 3
@foo.setter
@abc.abstractmethod
def foo(self, val): pass
self.assertRaises(TypeError, C)
class D(C):
@C.foo.getter
def foo(self): return super().foo
self.assertRaises(TypeError, D)
class E(D):
@D.foo.setter
def foo(self, val): pass
self.assertFalse(E.foo.__isabstractmethod__)
def test_metaclass_abc(self):
# Metaclasses can be ABCs, too.
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def x(self):
pass
self.assertEqual(A.__abstractmethods__, {"x"})
class meta(type, A):
def x(self):
return 1
class C(metaclass=meta):
pass
def test_registration_basics(self):
class A(metaclass=abc_ABCMeta):
pass
class B(object):
pass
b = B()
self.assertFalse(issubclass(B, A))
self.assertFalse(issubclass(B, (A,)))
self.assertNotIsInstance(b, A)
self.assertNotIsInstance(b, (A,))
B1 = A.register(B)
self.assertTrue(issubclass(B, A))
self.assertTrue(issubclass(B, (A,)))
self.assertIsInstance(b, A)
self.assertIsInstance(b, (A,))
self.assertIs(B1, B)
class C(B):
pass
c = C()
self.assertTrue(issubclass(C, A))
self.assertTrue(issubclass(C, (A,)))
self.assertIsInstance(c, A)
self.assertIsInstance(c, (A,))
def test_register_as_class_deco(self):
class A(metaclass=abc_ABCMeta):
pass
@A.register
class B(object):
pass
b = B()
self.assertTrue(issubclass(B, A))
self.assertTrue(issubclass(B, (A,)))
self.assertIsInstance(b, A)
self.assertIsInstance(b, (A,))
@A.register
class C(B):
pass
c = C()
self.assertTrue(issubclass(C, A))
self.assertTrue(issubclass(C, (A,)))
self.assertIsInstance(c, A)
self.assertIsInstance(c, (A,))
self.assertIs(C, A.register(C))
def test_isinstance_invalidation(self):
class A(metaclass=abc_ABCMeta):
pass
class B:
pass
b = B()
self.assertFalse(isinstance(b, A))
self.assertFalse(isinstance(b, (A,)))
token_old = abc_get_cache_token()
A.register(B)
token_new = abc_get_cache_token()
self.assertGreater(token_new, token_old)
self.assertTrue(isinstance(b, A))
self.assertTrue(isinstance(b, (A,)))
def test_registration_builtins(self):
class A(metaclass=abc_ABCMeta):
pass
A.register(int)
self.assertIsInstance(42, A)
self.assertIsInstance(42, (A,))
self.assertTrue(issubclass(int, A))
self.assertTrue(issubclass(int, (A,)))
class B(A):
pass
B.register(str)
class C(str): pass
self.assertIsInstance("", A)
self.assertIsInstance("", (A,))
self.assertTrue(issubclass(str, A))
self.assertTrue(issubclass(str, (A,)))
self.assertTrue(issubclass(C, A))
self.assertTrue(issubclass(C, (A,)))
def test_registration_edge_cases(self):
class A(metaclass=abc_ABCMeta):
pass
A.register(A) # should pass silently
class A1(A):
pass
self.assertRaises(RuntimeError, A1.register, A) # cycles not allowed
class B(object):
pass
A1.register(B) # ok
A1.register(B) # should pass silently
class C(A):
pass
A.register(C) # should pass silently
self.assertRaises(RuntimeError, C.register, A) # cycles not allowed
C.register(B) # ok
def test_register_non_class(self):
class A(metaclass=abc_ABCMeta):
pass
self.assertRaisesRegex(TypeError, "Can only register classes",
A.register, 4)
def test_registration_transitiveness(self):
class A(metaclass=abc_ABCMeta):
pass
self.assertTrue(issubclass(A, A))
self.assertTrue(issubclass(A, (A,)))
class B(metaclass=abc_ABCMeta):
pass
self.assertFalse(issubclass(A, B))
self.assertFalse(issubclass(A, (B,)))
self.assertFalse(issubclass(B, A))
self.assertFalse(issubclass(B, (A,)))
class C(metaclass=abc_ABCMeta):
pass
A.register(B)
class B1(B):
pass
self.assertTrue(issubclass(B1, A))
self.assertTrue(issubclass(B1, (A,)))
class C1(C):
pass
B1.register(C1)
self.assertFalse(issubclass(C, B))
self.assertFalse(issubclass(C, (B,)))
self.assertFalse(issubclass(C, B1))
self.assertFalse(issubclass(C, (B1,)))
self.assertTrue(issubclass(C1, A))
self.assertTrue(issubclass(C1, (A,)))
self.assertTrue(issubclass(C1, B))
self.assertTrue(issubclass(C1, (B,)))
self.assertTrue(issubclass(C1, B1))
self.assertTrue(issubclass(C1, (B1,)))
C1.register(int)
class MyInt(int):
pass
self.assertTrue(issubclass(MyInt, A))
self.assertTrue(issubclass(MyInt, (A,)))
self.assertIsInstance(42, A)
self.assertIsInstance(42, (A,))
def test_issubclass_bad_arguments(self):
class A(metaclass=abc_ABCMeta):
pass
with self.assertRaises(TypeError):
issubclass({}, A) # unhashable
with self.assertRaises(TypeError):
issubclass(42, A) # No __mro__
# Python version supports any iterable as __mro__.
# But it's implementation detail and don't emulate it in C version.
class C:
__mro__ = 42 # __mro__ is not tuple
with self.assertRaises(TypeError):
issubclass(C(), A)
# bpo-34441: Check that issubclass() doesn't crash on bogus
# classes.
bogus_subclasses = [
None,
lambda x: [],
lambda: 42,
lambda: [42],
]
for i, func in enumerate(bogus_subclasses):
class S(metaclass=abc_ABCMeta):
__subclasses__ = func
with self.subTest(i=i):
with self.assertRaises(TypeError):
issubclass(int, S)
# Also check that issubclass() propagates exceptions raised by
# __subclasses__.
class CustomError(Exception): ...
exc_msg = "exception from __subclasses__"
def raise_exc():
raise CustomError(exc_msg)
class S(metaclass=abc_ABCMeta):
__subclasses__ = raise_exc
with self.assertRaisesRegex(CustomError, exc_msg):
issubclass(int, S)
def test_subclasshook(self):
class A(metaclass=abc.ABCMeta):
@classmethod
def __subclasshook__(cls, C):
if cls is A:
return 'foo' in C.__dict__
return NotImplemented
self.assertFalse(issubclass(A, A))
self.assertFalse(issubclass(A, (A,)))
class B:
foo = 42
self.assertTrue(issubclass(B, A))
self.assertTrue(issubclass(B, (A,)))
class C:
spam = 42
self.assertFalse(issubclass(C, A))
self.assertFalse(issubclass(C, (A,)))
def test_all_new_methods_are_called(self):
class A(metaclass=abc_ABCMeta):
pass
class B(object):
counter = 0
def __new__(cls):
B.counter += 1
return super().__new__(cls)
class C(A, B):
pass
self.assertEqual(B.counter, 0)
C()
self.assertEqual(B.counter, 1)
def test_ABC_has___slots__(self):
self.assertTrue(hasattr(abc.ABC, '__slots__'))
def test_tricky_new_works(self):
def with_metaclass(meta, *bases):
class metaclass(type):
def __new__(cls, name, this_bases, d):
return meta(name, bases, d)
return type.__new__(metaclass, 'temporary_class', (), {})
class A: ...
class B: ...
class C(with_metaclass(abc_ABCMeta, A, B)):
pass
self.assertEqual(C.__class__, abc_ABCMeta)
def test_update_del(self):
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def foo(self):
pass
del A.foo
self.assertEqual(A.__abstractmethods__, {'foo'})
self.assertFalse(hasattr(A, 'foo'))
abc.update_abstractmethods(A)
self.assertEqual(A.__abstractmethods__, set())
A()
def test_update_new_abstractmethods(self):
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def bar(self):
pass
@abc.abstractmethod
def updated_foo(self):
pass
A.foo = updated_foo
abc.update_abstractmethods(A)
self.assertEqual(A.__abstractmethods__, {'foo', 'bar'})
msg = "class A without an implementation for abstract methods 'bar', 'foo'"
self.assertRaisesRegex(TypeError, msg, A)
def test_update_implementation(self):
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def foo(self):
pass
class B(A):
pass
msg = "class B without an implementation for abstract method 'foo'"
self.assertRaisesRegex(TypeError, msg, B)
self.assertEqual(B.__abstractmethods__, {'foo'})
B.foo = lambda self: None
abc.update_abstractmethods(B)
B()
self.assertEqual(B.__abstractmethods__, set())
def test_update_as_decorator(self):
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def foo(self):
pass
def class_decorator(cls):
cls.foo = lambda self: None
return cls
@abc.update_abstractmethods
@class_decorator
class B(A):
pass
B()
self.assertEqual(B.__abstractmethods__, set())
def test_update_non_abc(self):
class A:
pass
@abc.abstractmethod
def updated_foo(self):
pass
A.foo = updated_foo
abc.update_abstractmethods(A)
A()
self.assertFalse(hasattr(A, '__abstractmethods__'))
def test_update_del_implementation(self):
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def foo(self):
pass
class B(A):
def foo(self):
pass
B()
del B.foo
abc.update_abstractmethods(B)
msg = "class B without an implementation for abstract method 'foo'"
self.assertRaisesRegex(TypeError, msg, B)
def test_update_layered_implementation(self):
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def foo(self):
pass
class B(A):
pass
class C(B):
def foo(self):
pass
C()
del C.foo
abc.update_abstractmethods(C)
msg = "class C without an implementation for abstract method 'foo'"
self.assertRaisesRegex(TypeError, msg, C)
def test_update_multi_inheritance(self):
class A(metaclass=abc_ABCMeta):
@abc.abstractmethod
def foo(self):
pass
class B(metaclass=abc_ABCMeta):
def foo(self):
pass
class C(B, A):
@abc.abstractmethod
def foo(self):
pass
self.assertEqual(C.__abstractmethods__, {'foo'})
del C.foo
abc.update_abstractmethods(C)
self.assertEqual(C.__abstractmethods__, set())
C()
class TestABCWithInitSubclass(unittest.TestCase):
def test_works_with_init_subclass(self):
class abc_ABC(metaclass=abc_ABCMeta):
__slots__ = ()
saved_kwargs = {}
class ReceivesClassKwargs:
def __init_subclass__(cls, **kwargs):
super().__init_subclass__()
saved_kwargs.update(kwargs)
class Receiver(ReceivesClassKwargs, abc_ABC, x=1, y=2, z=3):
pass
self.assertEqual(saved_kwargs, dict(x=1, y=2, z=3))
def test_positional_only_and_kwonlyargs_with_init_subclass(self):
saved_kwargs = {}
class A:
def __init_subclass__(cls, **kwargs):
super().__init_subclass__()
saved_kwargs.update(kwargs)
class B(A, metaclass=abc_ABCMeta, name="test"):
pass
self.assertEqual(saved_kwargs, dict(name="test"))
return TestLegacyAPI, TestABC, TestABCWithInitSubclass
TestLegacyAPI_Py, TestABC_Py, TestABCWithInitSubclass_Py = test_factory(abc.ABCMeta,
abc.get_cache_token)
TestLegacyAPI_C, TestABC_C, TestABCWithInitSubclass_C = test_factory(_py_abc.ABCMeta,
_py_abc.get_cache_token)
if __name__ == "__main__":
unittest.main()
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