# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Unit tests for abc.py."""
import unittest, weakref
from test import test_support
import abc
from inspect import isabstract
class TestABC(unittest.TestCase):
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):
@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
class D(C):
@property
def foo(self): return super(D, self).foo
self.assertEqual(D().foo, 3)
def test_abstractmethod_integration(self):
for abstractthing in [abc.abstractmethod, abc.abstractproperty]:
class C:
__metaclass__ = abc.ABCMeta
@abstractthing
def foo(self): pass # abstract
def bar(self): pass # concrete
self.assertEqual(C.__abstractmethods__, set(["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__, set(["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__, set(["bar"]))
self.assertRaises(TypeError, F) # because bar is abstract now
self.assertTrue(isabstract(F))
def test_subclass_oldstyle_class(self):
class A:
__metaclass__ = abc.ABCMeta
class OldstyleClass:
pass
self.assertFalse(issubclass(OldstyleClass, A))
self.assertFalse(issubclass(A, OldstyleClass))
def test_isinstance_class(self):
class A:
__metaclass__ = abc.ABCMeta
class OldstyleClass:
pass
self.assertFalse(isinstance(OldstyleClass, A))
self.assertTrue(isinstance(OldstyleClass, type(OldstyleClass)))
self.assertFalse(isinstance(A, OldstyleClass))
# This raises a recursion depth error, but is low-priority:
# self.assertTrue(isinstance(A, abc.ABCMeta))
def test_registration_basics(self):
class A:
__metaclass__ = abc.ABCMeta
class B(object):
pass
b = B()
self.assertFalse(issubclass(B, A))
self.assertFalse(issubclass(B, (A,)))
self.assertNotIsInstance(b, A)
self.assertNotIsInstance(b, (A,))
A.register(B)
self.assertTrue(issubclass(B, A))
self.assertTrue(issubclass(B, (A,)))
self.assertIsInstance(b, A)
self.assertIsInstance(b, (A,))
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_isinstance_invalidation(self):
class A:
__metaclass__ = abc.ABCMeta
class B(object):
pass
b = B()
self.assertFalse(isinstance(b, A))
self.assertFalse(isinstance(b, (A,)))
A.register(B)
self.assertTrue(isinstance(b, A))
self.assertTrue(isinstance(b, (A,)))
def test_registration_builtins(self):
class A:
__metaclass__ = abc.ABCMeta
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(basestring)
self.assertIsInstance("", A)
self.assertIsInstance("", (A,))
self.assertTrue(issubclass(str, A))
self.assertTrue(issubclass(str, (A,)))
def test_registration_edge_cases(self):
class A:
__metaclass__ = abc.ABCMeta
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(object):
__metaclass__ = abc.ABCMeta
self.assertRaisesRegexp(TypeError, "Can only register classes",
A.register, 4)
def test_registration_transitiveness(self):
class A:
__metaclass__ = abc.ABCMeta
self.assertTrue(issubclass(A, A))
self.assertTrue(issubclass(A, (A,)))
class B:
__metaclass__ = abc.ABCMeta
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
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_all_new_methods_are_called(self):
class A:
__metaclass__ = abc.ABCMeta
class B(object):
counter = 0
def __new__(cls):
B.counter += 1
return super(B, cls).__new__(cls)
class C(A, B):
pass
self.assertEqual(B.counter, 0)
C()
self.assertEqual(B.counter, 1)
def test_cache_leak(self):
# See issue #2521.
class A(object):
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def f(self):
pass
class C(A):
def f(self):
A.f(self)
r = weakref.ref(C)
# Trigger cache.
C().f()
del C
test_support.gc_collect()
self.assertEqual(r(), None)
def test_main():
test_support.run_unittest(TestABC)
if __name__ == "__main__":
unittest.main()