281 lines
9.8 KiB
Python
281 lines
9.8 KiB
Python
# Tests some corner cases with isinstance() and issubclass(). While these
|
||
# tests use new style classes and properties, they actually do whitebox
|
||
# testing of error conditions uncovered when using extension types.
|
||
|
||
import unittest
|
||
import sys
|
||
|
||
|
||
|
||
class TestIsInstanceExceptions(unittest.TestCase):
|
||
# Test to make sure that an AttributeError when accessing the instance's
|
||
# class's bases is masked. This was actually a bug in Python 2.2 and
|
||
# 2.2.1 where the exception wasn't caught but it also wasn't being cleared
|
||
# (leading to an "undetected error" in the debug build). Set up is,
|
||
# isinstance(inst, cls) where:
|
||
#
|
||
# - cls isn't a type, or a tuple
|
||
# - cls has a __bases__ attribute
|
||
# - inst has a __class__ attribute
|
||
# - inst.__class__ as no __bases__ attribute
|
||
#
|
||
# Sounds complicated, I know, but this mimics a situation where an
|
||
# extension type raises an AttributeError when its __bases__ attribute is
|
||
# gotten. In that case, isinstance() should return False.
|
||
def test_class_has_no_bases(self):
|
||
class I(object):
|
||
def getclass(self):
|
||
# This must return an object that has no __bases__ attribute
|
||
return None
|
||
__class__ = property(getclass)
|
||
|
||
class C(object):
|
||
def getbases(self):
|
||
return ()
|
||
__bases__ = property(getbases)
|
||
|
||
self.assertEqual(False, isinstance(I(), C()))
|
||
|
||
# Like above except that inst.__class__.__bases__ raises an exception
|
||
# other than AttributeError
|
||
def test_bases_raises_other_than_attribute_error(self):
|
||
class E(object):
|
||
def getbases(self):
|
||
raise RuntimeError
|
||
__bases__ = property(getbases)
|
||
|
||
class I(object):
|
||
def getclass(self):
|
||
return E()
|
||
__class__ = property(getclass)
|
||
|
||
class C(object):
|
||
def getbases(self):
|
||
return ()
|
||
__bases__ = property(getbases)
|
||
|
||
self.assertRaises(RuntimeError, isinstance, I(), C())
|
||
|
||
# Here's a situation where getattr(cls, '__bases__') raises an exception.
|
||
# If that exception is not AttributeError, it should not get masked
|
||
def test_dont_mask_non_attribute_error(self):
|
||
class I: pass
|
||
|
||
class C(object):
|
||
def getbases(self):
|
||
raise RuntimeError
|
||
__bases__ = property(getbases)
|
||
|
||
self.assertRaises(RuntimeError, isinstance, I(), C())
|
||
|
||
# Like above, except that getattr(cls, '__bases__') raises an
|
||
# AttributeError, which /should/ get masked as a TypeError
|
||
def test_mask_attribute_error(self):
|
||
class I: pass
|
||
|
||
class C(object):
|
||
def getbases(self):
|
||
raise AttributeError
|
||
__bases__ = property(getbases)
|
||
|
||
self.assertRaises(TypeError, isinstance, I(), C())
|
||
|
||
# check that we don't mask non AttributeErrors
|
||
# see: http://bugs.python.org/issue1574217
|
||
def test_isinstance_dont_mask_non_attribute_error(self):
|
||
class C(object):
|
||
def getclass(self):
|
||
raise RuntimeError
|
||
__class__ = property(getclass)
|
||
|
||
c = C()
|
||
self.assertRaises(RuntimeError, isinstance, c, bool)
|
||
|
||
# test another code path
|
||
class D: pass
|
||
self.assertRaises(RuntimeError, isinstance, c, D)
|
||
|
||
|
||
# These tests are similar to above, but tickle certain code paths in
|
||
# issubclass() instead of isinstance() -- really PyObject_IsSubclass()
|
||
# vs. PyObject_IsInstance().
|
||
class TestIsSubclassExceptions(unittest.TestCase):
|
||
def test_dont_mask_non_attribute_error(self):
|
||
class C(object):
|
||
def getbases(self):
|
||
raise RuntimeError
|
||
__bases__ = property(getbases)
|
||
|
||
class S(C): pass
|
||
|
||
self.assertRaises(RuntimeError, issubclass, C(), S())
|
||
|
||
def test_mask_attribute_error(self):
|
||
class C(object):
|
||
def getbases(self):
|
||
raise AttributeError
|
||
__bases__ = property(getbases)
|
||
|
||
class S(C): pass
|
||
|
||
self.assertRaises(TypeError, issubclass, C(), S())
|
||
|
||
# Like above, but test the second branch, where the __bases__ of the
|
||
# second arg (the cls arg) is tested. This means the first arg must
|
||
# return a valid __bases__, and it's okay for it to be a normal --
|
||
# unrelated by inheritance -- class.
|
||
def test_dont_mask_non_attribute_error_in_cls_arg(self):
|
||
class B: pass
|
||
|
||
class C(object):
|
||
def getbases(self):
|
||
raise RuntimeError
|
||
__bases__ = property(getbases)
|
||
|
||
self.assertRaises(RuntimeError, issubclass, B, C())
|
||
|
||
def test_mask_attribute_error_in_cls_arg(self):
|
||
class B: pass
|
||
|
||
class C(object):
|
||
def getbases(self):
|
||
raise AttributeError
|
||
__bases__ = property(getbases)
|
||
|
||
self.assertRaises(TypeError, issubclass, B, C())
|
||
|
||
|
||
|
||
# meta classes for creating abstract classes and instances
|
||
class AbstractClass(object):
|
||
def __init__(self, bases):
|
||
self.bases = bases
|
||
|
||
def getbases(self):
|
||
return self.bases
|
||
__bases__ = property(getbases)
|
||
|
||
def __call__(self):
|
||
return AbstractInstance(self)
|
||
|
||
class AbstractInstance(object):
|
||
def __init__(self, klass):
|
||
self.klass = klass
|
||
|
||
def getclass(self):
|
||
return self.klass
|
||
__class__ = property(getclass)
|
||
|
||
# abstract classes
|
||
AbstractSuper = AbstractClass(bases=())
|
||
|
||
AbstractChild = AbstractClass(bases=(AbstractSuper,))
|
||
|
||
# normal classes
|
||
class Super:
|
||
pass
|
||
|
||
class Child(Super):
|
||
pass
|
||
|
||
# new-style classes
|
||
class NewSuper(object):
|
||
pass
|
||
|
||
class NewChild(NewSuper):
|
||
pass
|
||
|
||
|
||
|
||
class TestIsInstanceIsSubclass(unittest.TestCase):
|
||
# Tests to ensure that isinstance and issubclass work on abstract
|
||
# classes and instances. Before the 2.2 release, TypeErrors were
|
||
# raised when boolean values should have been returned. The bug was
|
||
# triggered by mixing 'normal' classes and instances were with
|
||
# 'abstract' classes and instances. This case tries to test all
|
||
# combinations.
|
||
|
||
def test_isinstance_normal(self):
|
||
# normal instances
|
||
self.assertEqual(True, isinstance(Super(), Super))
|
||
self.assertEqual(False, isinstance(Super(), Child))
|
||
self.assertEqual(False, isinstance(Super(), AbstractSuper))
|
||
self.assertEqual(False, isinstance(Super(), AbstractChild))
|
||
|
||
self.assertEqual(True, isinstance(Child(), Super))
|
||
self.assertEqual(False, isinstance(Child(), AbstractSuper))
|
||
|
||
def test_isinstance_abstract(self):
|
||
# abstract instances
|
||
self.assertEqual(True, isinstance(AbstractSuper(), AbstractSuper))
|
||
self.assertEqual(False, isinstance(AbstractSuper(), AbstractChild))
|
||
self.assertEqual(False, isinstance(AbstractSuper(), Super))
|
||
self.assertEqual(False, isinstance(AbstractSuper(), Child))
|
||
|
||
self.assertEqual(True, isinstance(AbstractChild(), AbstractChild))
|
||
self.assertEqual(True, isinstance(AbstractChild(), AbstractSuper))
|
||
self.assertEqual(False, isinstance(AbstractChild(), Super))
|
||
self.assertEqual(False, isinstance(AbstractChild(), Child))
|
||
|
||
def test_subclass_normal(self):
|
||
# normal classes
|
||
self.assertEqual(True, issubclass(Super, Super))
|
||
self.assertEqual(False, issubclass(Super, AbstractSuper))
|
||
self.assertEqual(False, issubclass(Super, Child))
|
||
|
||
self.assertEqual(True, issubclass(Child, Child))
|
||
self.assertEqual(True, issubclass(Child, Super))
|
||
self.assertEqual(False, issubclass(Child, AbstractSuper))
|
||
|
||
def test_subclass_abstract(self):
|
||
# abstract classes
|
||
self.assertEqual(True, issubclass(AbstractSuper, AbstractSuper))
|
||
self.assertEqual(False, issubclass(AbstractSuper, AbstractChild))
|
||
self.assertEqual(False, issubclass(AbstractSuper, Child))
|
||
|
||
self.assertEqual(True, issubclass(AbstractChild, AbstractChild))
|
||
self.assertEqual(True, issubclass(AbstractChild, AbstractSuper))
|
||
self.assertEqual(False, issubclass(AbstractChild, Super))
|
||
self.assertEqual(False, issubclass(AbstractChild, Child))
|
||
|
||
def test_subclass_tuple(self):
|
||
# test with a tuple as the second argument classes
|
||
self.assertEqual(True, issubclass(Child, (Child,)))
|
||
self.assertEqual(True, issubclass(Child, (Super,)))
|
||
self.assertEqual(False, issubclass(Super, (Child,)))
|
||
self.assertEqual(True, issubclass(Super, (Child, Super)))
|
||
self.assertEqual(False, issubclass(Child, ()))
|
||
self.assertEqual(True, issubclass(Super, (Child, (Super,))))
|
||
|
||
self.assertEqual(True, issubclass(NewChild, (NewChild,)))
|
||
self.assertEqual(True, issubclass(NewChild, (NewSuper,)))
|
||
self.assertEqual(False, issubclass(NewSuper, (NewChild,)))
|
||
self.assertEqual(True, issubclass(NewSuper, (NewChild, NewSuper)))
|
||
self.assertEqual(False, issubclass(NewChild, ()))
|
||
self.assertEqual(True, issubclass(NewSuper, (NewChild, (NewSuper,))))
|
||
|
||
self.assertEqual(True, issubclass(int, (int, (float, int))))
|
||
self.assertEqual(True, issubclass(str, (str, (Child, NewChild, str))))
|
||
|
||
def test_subclass_recursion_limit(self):
|
||
# make sure that issubclass raises RuntimeError before the C stack is
|
||
# blown
|
||
self.assertRaises(RuntimeError, blowstack, issubclass, str, str)
|
||
|
||
def test_isinstance_recursion_limit(self):
|
||
# make sure that issubclass raises RuntimeError before the C stack is
|
||
# blown
|
||
self.assertRaises(RuntimeError, blowstack, isinstance, '', str)
|
||
|
||
def blowstack(fxn, arg, compare_to):
|
||
# Make sure that calling isinstance with a deeply nested tuple for its
|
||
# argument will raise RuntimeError eventually.
|
||
tuple_arg = (compare_to,)
|
||
for cnt in range(sys.getrecursionlimit()+5):
|
||
tuple_arg = (tuple_arg,)
|
||
fxn(arg, tuple_arg)
|
||
|
||
|
||
if __name__ == '__main__':
|
||
unittest.main()
|