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7e5c6a02eb
containing class objects) are allowed as the second argument. This makes issubclass() more similar to isinstance() where recursive tuples are allowed too.
260 lines
8.9 KiB
Python
260 lines
8.9 KiB
Python
# Tests some corner cases with isinstance() and issubclass(). While these
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# tests use new style classes and properties, they actually do whitebox
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# testing of error conditions uncovered when using extension types.
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import unittest
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from test import test_support
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class TestIsInstanceExceptions(unittest.TestCase):
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# Test to make sure that an AttributeError when accessing the instance's
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# class's bases is masked. This was actually a bug in Python 2.2 and
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# 2.2.1 where the exception wasn't caught but it also wasn't being cleared
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# (leading to an "undetected error" in the debug build). Set up is,
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# isinstance(inst, cls) where:
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#
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# - inst isn't an InstanceType
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# - cls isn't a ClassType, a TypeType, or a TupleType
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# - cls has a __bases__ attribute
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# - inst has a __class__ attribute
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# - inst.__class__ as no __bases__ attribute
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#
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# Sounds complicated, I know, but this mimics a situation where an
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# extension type raises an AttributeError when its __bases__ attribute is
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# gotten. In that case, isinstance() should return False.
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def test_class_has_no_bases(self):
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class I(object):
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def getclass(self):
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# This must return an object that has no __bases__ attribute
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return None
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__class__ = property(getclass)
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class C(object):
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def getbases(self):
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return ()
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__bases__ = property(getbases)
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self.assertEqual(False, isinstance(I(), C()))
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# Like above except that inst.__class__.__bases__ raises an exception
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# other than AttributeError
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def test_bases_raises_other_than_attribute_error(self):
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class E(object):
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def getbases(self):
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raise RuntimeError
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__bases__ = property(getbases)
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class I(object):
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def getclass(self):
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return E()
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__class__ = property(getclass)
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class C(object):
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def getbases(self):
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return ()
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__bases__ = property(getbases)
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self.assertRaises(RuntimeError, isinstance, I(), C())
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# Here's a situation where getattr(cls, '__bases__') raises an exception.
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# If that exception is not AttributeError, it should not get masked
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def test_dont_mask_non_attribute_error(self):
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class I: pass
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class C(object):
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def getbases(self):
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raise RuntimeError
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__bases__ = property(getbases)
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self.assertRaises(RuntimeError, isinstance, I(), C())
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# Like above, except that getattr(cls, '__bases__') raises an
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# AttributeError, which /should/ get masked as a TypeError
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def test_mask_attribute_error(self):
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class I: pass
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class C(object):
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def getbases(self):
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raise AttributeError
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__bases__ = property(getbases)
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self.assertRaises(TypeError, isinstance, I(), C())
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# These tests are similar to above, but tickle certain code paths in
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# issubclass() instead of isinstance() -- really PyObject_IsSubclass()
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# vs. PyObject_IsInstance().
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class TestIsSubclassExceptions(unittest.TestCase):
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def test_dont_mask_non_attribute_error(self):
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class C(object):
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def getbases(self):
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raise RuntimeError
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__bases__ = property(getbases)
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class S(C): pass
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self.assertRaises(RuntimeError, issubclass, C(), S())
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def test_mask_attribute_error(self):
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class C(object):
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def getbases(self):
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raise AttributeError
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__bases__ = property(getbases)
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class S(C): pass
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self.assertRaises(TypeError, issubclass, C(), S())
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# Like above, but test the second branch, where the __bases__ of the
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# second arg (the cls arg) is tested. This means the first arg must
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# return a valid __bases__, and it's okay for it to be a normal --
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# unrelated by inheritance -- class.
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def test_dont_mask_non_attribute_error_in_cls_arg(self):
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class B: pass
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class C(object):
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def getbases(self):
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raise RuntimeError
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__bases__ = property(getbases)
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self.assertRaises(RuntimeError, issubclass, B, C())
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def test_mask_attribute_error_in_cls_arg(self):
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class B: pass
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class C(object):
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def getbases(self):
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raise AttributeError
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__bases__ = property(getbases)
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self.assertRaises(TypeError, issubclass, B, C())
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# meta classes for creating abstract classes and instances
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class AbstractClass(object):
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def __init__(self, bases):
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self.bases = bases
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def getbases(self):
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return self.bases
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__bases__ = property(getbases)
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def __call__(self):
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return AbstractInstance(self)
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class AbstractInstance(object):
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def __init__(self, klass):
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self.klass = klass
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def getclass(self):
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return self.klass
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__class__ = property(getclass)
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# abstract classes
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AbstractSuper = AbstractClass(bases=())
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AbstractChild = AbstractClass(bases=(AbstractSuper,))
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# normal classes
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class Super:
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pass
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class Child(Super):
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pass
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# new-style classes
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class NewSuper(object):
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pass
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class NewChild(NewSuper):
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pass
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class TestIsInstanceIsSubclass(unittest.TestCase):
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# Tests to ensure that isinstance and issubclass work on abstract
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# classes and instances. Before the 2.2 release, TypeErrors were
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# raised when boolean values should have been returned. The bug was
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# triggered by mixing 'normal' classes and instances were with
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# 'abstract' classes and instances. This case tries to test all
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# combinations.
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def test_isinstance_normal(self):
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# normal instances
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self.assertEqual(True, isinstance(Super(), Super))
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self.assertEqual(False, isinstance(Super(), Child))
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self.assertEqual(False, isinstance(Super(), AbstractSuper))
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self.assertEqual(False, isinstance(Super(), AbstractChild))
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self.assertEqual(True, isinstance(Child(), Super))
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self.assertEqual(False, isinstance(Child(), AbstractSuper))
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def test_isinstance_abstract(self):
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# abstract instances
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self.assertEqual(True, isinstance(AbstractSuper(), AbstractSuper))
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self.assertEqual(False, isinstance(AbstractSuper(), AbstractChild))
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self.assertEqual(False, isinstance(AbstractSuper(), Super))
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self.assertEqual(False, isinstance(AbstractSuper(), Child))
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self.assertEqual(True, isinstance(AbstractChild(), AbstractChild))
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self.assertEqual(True, isinstance(AbstractChild(), AbstractSuper))
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self.assertEqual(False, isinstance(AbstractChild(), Super))
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self.assertEqual(False, isinstance(AbstractChild(), Child))
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def test_subclass_normal(self):
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# normal classes
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self.assertEqual(True, issubclass(Super, Super))
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self.assertEqual(False, issubclass(Super, AbstractSuper))
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self.assertEqual(False, issubclass(Super, Child))
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self.assertEqual(True, issubclass(Child, Child))
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self.assertEqual(True, issubclass(Child, Super))
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self.assertEqual(False, issubclass(Child, AbstractSuper))
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def test_subclass_abstract(self):
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# abstract classes
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self.assertEqual(True, issubclass(AbstractSuper, AbstractSuper))
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self.assertEqual(False, issubclass(AbstractSuper, AbstractChild))
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self.assertEqual(False, issubclass(AbstractSuper, Child))
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self.assertEqual(True, issubclass(AbstractChild, AbstractChild))
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self.assertEqual(True, issubclass(AbstractChild, AbstractSuper))
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self.assertEqual(False, issubclass(AbstractChild, Super))
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self.assertEqual(False, issubclass(AbstractChild, Child))
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def test_subclass_tuple(self):
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# test with a tuple as the second argument classes
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self.assertEqual(True, issubclass(Child, (Child,)))
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self.assertEqual(True, issubclass(Child, (Super,)))
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self.assertEqual(False, issubclass(Super, (Child,)))
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self.assertEqual(True, issubclass(Super, (Child, Super)))
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self.assertEqual(False, issubclass(Child, ()))
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self.assertEqual(True, issubclass(Super, (Child, (Super,))))
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self.assertEqual(True, issubclass(NewChild, (NewChild,)))
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self.assertEqual(True, issubclass(NewChild, (NewSuper,)))
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self.assertEqual(False, issubclass(NewSuper, (NewChild,)))
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self.assertEqual(True, issubclass(NewSuper, (NewChild, NewSuper)))
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self.assertEqual(False, issubclass(NewChild, ()))
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self.assertEqual(True, issubclass(NewSuper, (NewChild, (NewSuper,))))
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self.assertEqual(True, issubclass(int, (long, (float, int))))
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self.assertEqual(True, issubclass(str, (unicode, (Child, NewChild, basestring))))
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def test_main():
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suite = unittest.TestSuite()
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suite.addTest(unittest.makeSuite(TestIsInstanceExceptions))
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suite.addTest(unittest.makeSuite(TestIsSubclassExceptions))
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suite.addTest(unittest.makeSuite(TestIsInstanceIsSubclass))
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test_support.run_suite(suite)
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if __name__ == '__main__':
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test_main()
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