Lib/test/test_descr.py

import builtins
import gc
import sys
import types
import math
import unittest
import weakref

from copy import deepcopy
from test import support


class OperatorsTest(unittest.TestCase):

    def __init__(self, *args, **kwargs):
        unittest.TestCase.__init__(self, *args, **kwargs)
        self.binops = {
            'add': '+',
            'sub': '-',
            'mul': '*',
            'div': '/',
            'divmod': 'divmod',
            'pow': '**',
            'lshift': '<<',
            'rshift': '>>',
            'and': '&',
            'xor': '^',
            'or': '|',
            'cmp': 'cmp',
            'lt': '<',
            'le': '<=',
            'eq': '==',
            'ne': '!=',
            'gt': '>',
            'ge': '>=',
        }

        for name, expr in list(self.binops.items()):
            if expr.islower():
                expr = expr + "(a, b)"
            else:
                expr = 'a %s b' % expr
            self.binops[name] = expr

        self.unops = {
            'pos': '+',
            'neg': '-',
            'abs': 'abs',
            'invert': '~',
            'int': 'int',
            'float': 'float',
            'oct': 'oct',
            'hex': 'hex',
        }

        for name, expr in list(self.unops.items()):
            if expr.islower():
                expr = expr + "(a)"
            else:
                expr = '%s a' % expr
            self.unops[name] = expr

    def unop_test(self, a, res, expr="len(a)", meth="__len__"):
        d = {'a': a}
        self.assertEqual(eval(expr, d), res)
        t = type(a)
        m = getattr(t, meth)

        # Find method in parent class
        while meth not in t.__dict__:
            t = t.__bases__[0]
        # in some implementations (e.g. PyPy), 'm' can be a regular unbound
        # method object; the getattr() below obtains its underlying function.
        self.assertEqual(getattr(m, 'im_func', m), t.__dict__[meth])
        self.assertEqual(m(a), res)
        bm = getattr(a, meth)
        self.assertEqual(bm(), res)

    def binop_test(self, a, b, res, expr="a+b", meth="__add__"):
        d = {'a': a, 'b': b}

        # XXX Hack so this passes before 2.3 when -Qnew is specified.
        if meth == "__div__" and 1/2 == 0.5:
            meth = "__truediv__"

        if meth == '__divmod__': pass

        self.assertEqual(eval(expr, d), res)
        t = type(a)
        m = getattr(t, meth)
        while meth not in t.__dict__:
            t = t.__bases__[0]
        # in some implementations (e.g. PyPy), 'm' can be a regular unbound
        # method object; the getattr() below obtains its underlying function.
        self.assertEqual(getattr(m, 'im_func', m), t.__dict__[meth])
        self.assertEqual(m(a, b), res)
        bm = getattr(a, meth)
        self.assertEqual(bm(b), res)

    def sliceop_test(self, a, b, c, res, expr="a[b:c]", meth="__getitem__"):
        d = {'a': a, 'b': b, 'c': c}
        self.assertEqual(eval(expr, d), res)
        t = type(a)
        m = getattr(t, meth)
        while meth not in t.__dict__:
            t = t.__bases__[0]
        # in some implementations (e.g. PyPy), 'm' can be a regular unbound
        # method object; the getattr() below obtains its underlying function.
        self.assertEqual(getattr(m, 'im_func', m), t.__dict__[meth])
        self.assertEqual(m(a, slice(b, c)), res)
        bm = getattr(a, meth)
        self.assertEqual(bm(slice(b, c)), res)

    def setop_test(self, a, b, res, stmt="a+=b", meth="__iadd__"):
        d = {'a': deepcopy(a), 'b': b}
        exec(stmt, d)
        self.assertEqual(d['a'], res)
        t = type(a)
        m = getattr(t, meth)
        while meth not in t.__dict__:
            t = t.__bases__[0]
        # in some implementations (e.g. PyPy), 'm' can be a regular unbound
        # method object; the getattr() below obtains its underlying function.
        self.assertEqual(getattr(m, 'im_func', m), t.__dict__[meth])
        d['a'] = deepcopy(a)
        m(d['a'], b)
        self.assertEqual(d['a'], res)
        d['a'] = deepcopy(a)
        bm = getattr(d['a'], meth)
        bm(b)
        self.assertEqual(d['a'], res)

    def set2op_test(self, a, b, c, res, stmt="a[b]=c", meth="__setitem__"):
        d = {'a': deepcopy(a), 'b': b, 'c': c}
        exec(stmt, d)
        self.assertEqual(d['a'], res)
        t = type(a)
        m = getattr(t, meth)
        while meth not in t.__dict__:
            t = t.__bases__[0]
        # in some implementations (e.g. PyPy), 'm' can be a regular unbound
        # method object; the getattr() below obtains its underlying function.
        self.assertEqual(getattr(m, 'im_func', m), t.__dict__[meth])
        d['a'] = deepcopy(a)
        m(d['a'], b, c)
        self.assertEqual(d['a'], res)
        d['a'] = deepcopy(a)
        bm = getattr(d['a'], meth)
        bm(b, c)
        self.assertEqual(d['a'], res)

    def setsliceop_test(self, a, b, c, d, res, stmt="a[b:c]=d", meth="__setitem__"):
        dictionary = {'a': deepcopy(a), 'b': b, 'c': c, 'd': d}
        exec(stmt, dictionary)
        self.assertEqual(dictionary['a'], res)
        t = type(a)
        while meth not in t.__dict__:
            t = t.__bases__[0]
        m = getattr(t, meth)
        # in some implementations (e.g. PyPy), 'm' can be a regular unbound
        # method object; the getattr() below obtains its underlying function.
        self.assertEqual(getattr(m, 'im_func', m), t.__dict__[meth])
        dictionary['a'] = deepcopy(a)
        m(dictionary['a'], slice(b, c), d)
        self.assertEqual(dictionary['a'], res)
        dictionary['a'] = deepcopy(a)
        bm = getattr(dictionary['a'], meth)
        bm(slice(b, c), d)
        self.assertEqual(dictionary['a'], res)

    def test_lists(self):
        # Testing list operations...
        # Asserts are within individual test methods
        self.binop_test([1], [2], [1,2], "a+b", "__add__")
        self.binop_test([1,2,3], 2, 1, "b in a", "__contains__")
        self.binop_test([1,2,3], 4, 0, "b in a", "__contains__")
        self.binop_test([1,2,3], 1, 2, "a[b]", "__getitem__")
        self.sliceop_test([1,2,3], 0, 2, [1,2], "a[b:c]", "__getitem__")
        self.setop_test([1], [2], [1,2], "a+=b", "__iadd__")
        self.setop_test([1,2], 3, [1,2,1,2,1,2], "a*=b", "__imul__")
        self.unop_test([1,2,3], 3, "len(a)", "__len__")
        self.binop_test([1,2], 3, [1,2,1,2,1,2], "a*b", "__mul__")
        self.binop_test([1,2], 3, [1,2,1,2,1,2], "b*a", "__rmul__")
        self.set2op_test([1,2], 1, 3, [1,3], "a[b]=c", "__setitem__")
        self.setsliceop_test([1,2,3,4], 1, 3, [5,6], [1,5,6,4], "a[b:c]=d",
                        "__setitem__")

    def test_dicts(self):
        # Testing dict operations...
        self.binop_test({1:2,3:4}, 1, 1, "b in a", "__contains__")
        self.binop_test({1:2,3:4}, 2, 0, "b in a", "__contains__")
        self.binop_test({1:2,3:4}, 1, 2, "a[b]", "__getitem__")

        d = {1:2, 3:4}
        l1 = []
        for i in list(d.keys()):
            l1.append(i)
        l = []
        for i in iter(d):
            l.append(i)
        self.assertEqual(l, l1)
        l = []
        for i in d.__iter__():
            l.append(i)
        self.assertEqual(l, l1)
        l = []
        for i in dict.__iter__(d):
            l.append(i)
        self.assertEqual(l, l1)
        d = {1:2, 3:4}
        self.unop_test(d, 2, "len(a)", "__len__")
        self.assertEqual(eval(repr(d), {}), d)
        self.assertEqual(eval(d.__repr__(), {}), d)
        self.set2op_test({1:2,3:4}, 2, 3, {1:2,2:3,3:4}, "a[b]=c",
                        "__setitem__")

    # Tests for unary and binary operators
    def number_operators(self, a, b, skip=[]):
        dict = {'a': a, 'b': b}

        for name, expr in list(self.binops.items()):
            if name not in skip:
                name = "__%s__" % name
                if hasattr(a, name):
                    res = eval(expr, dict)
                    self.binop_test(a, b, res, expr, name)

        for name, expr in list(self.unops.items()):
            if name not in skip:
                name = "__%s__" % name
                if hasattr(a, name):
                    res = eval(expr, dict)
                    self.unop_test(a, res, expr, name)

    def test_ints(self):
        # Testing int operations...
        self.number_operators(100, 3)
        # The following crashes in Python 2.2
        self.assertEqual((1).__bool__(), 1)
        self.assertEqual((0).__bool__(), 0)
        # This returns 'NotImplemented' in Python 2.2
        class C(int):
            def __add__(self, other):
                return NotImplemented
        self.assertEqual(C(5), 5)
        try:
            C() + ""
        except TypeError:
            pass
        else:
            self.fail("NotImplemented should have caused TypeError")

    def test_floats(self):
        # Testing float operations...
        self.number_operators(100.0, 3.0)

    def test_complexes(self):
        # Testing complex operations...
        self.number_operators(100.0j, 3.0j, skip=['lt', 'le', 'gt', 'ge',
                                                  'int', 'float',
                                                  'divmod', 'mod'])

        class Number(complex):
            __slots__ = ['prec']
            def __new__(cls, *args, **kwds):
                result = complex.__new__(cls, *args)
                result.prec = kwds.get('prec', 12)
                return result
            def __repr__(self):
                prec = self.prec
                if self.imag == 0.0:
                    return "%.*g" % (prec, self.real)
                if self.real == 0.0:
                    return "%.*gj" % (prec, self.imag)
                return "(%.*g+%.*gj)" % (prec, self.real, prec, self.imag)
            __str__ = __repr__

        a = Number(3.14, prec=6)
        self.assertEqual(repr(a), "3.14")
        self.assertEqual(a.prec, 6)

        a = Number(a, prec=2)
        self.assertEqual(repr(a), "3.1")
        self.assertEqual(a.prec, 2)

        a = Number(234.5)
        self.assertEqual(repr(a), "234.5")
        self.assertEqual(a.prec, 12)

    def test_explicit_reverse_methods(self):
        # see issue 9930
        self.assertEqual(complex.__radd__(3j, 4.0), complex(4.0, 3.0))
        self.assertEqual(float.__rsub__(3.0, 1), -2.0)

    @support.impl_detail("the module 'xxsubtype' is internal")
    def test_spam_lists(self):
        # Testing spamlist operations...
        import copy, xxsubtype as spam

        def spamlist(l, memo=None):
            import xxsubtype as spam
            return spam.spamlist(l)

        # This is an ugly hack:
        copy._deepcopy_dispatch[spam.spamlist] = spamlist

        self.binop_test(spamlist([1]), spamlist([2]), spamlist([1,2]), "a+b",
                       "__add__")
        self.binop_test(spamlist([1,2,3]), 2, 1, "b in a", "__contains__")
        self.binop_test(spamlist([1,2,3]), 4, 0, "b in a", "__contains__")
        self.binop_test(spamlist([1,2,3]), 1, 2, "a[b]", "__getitem__")
        self.sliceop_test(spamlist([1,2,3]), 0, 2, spamlist([1,2]), "a[b:c]",
                          "__getitem__")
        self.setop_test(spamlist([1]), spamlist([2]), spamlist([1,2]), "a+=b",
                        "__iadd__")
        self.setop_test(spamlist([1,2]), 3, spamlist([1,2,1,2,1,2]), "a*=b",
                        "__imul__")
        self.unop_test(spamlist([1,2,3]), 3, "len(a)", "__len__")
        self.binop_test(spamlist([1,2]), 3, spamlist([1,2,1,2,1,2]), "a*b",
                        "__mul__")
        self.binop_test(spamlist([1,2]), 3, spamlist([1,2,1,2,1,2]), "b*a",
                        "__rmul__")
        self.set2op_test(spamlist([1,2]), 1, 3, spamlist([1,3]), "a[b]=c",
                         "__setitem__")
        self.setsliceop_test(spamlist([1,2,3,4]), 1, 3, spamlist([5,6]),
                             spamlist([1,5,6,4]), "a[b:c]=d", "__setitem__")
        # Test subclassing
        class C(spam.spamlist):
            def foo(self): return 1
        a = C()
        self.assertEqual(a, [])
        self.assertEqual(a.foo(), 1)
        a.append(100)
        self.assertEqual(a, [100])
        self.assertEqual(a.getstate(), 0)
        a.setstate(42)
        self.assertEqual(a.getstate(), 42)

    @support.impl_detail("the module 'xxsubtype' is internal")
    def test_spam_dicts(self):
        # Testing spamdict operations...
        import copy, xxsubtype as spam
        def spamdict(d, memo=None):
            import xxsubtype as spam
            sd = spam.spamdict()
            for k, v in list(d.items()):
                sd[k] = v
            return sd
        # This is an ugly hack:
        copy._deepcopy_dispatch[spam.spamdict] = spamdict

        self.binop_test(spamdict({1:2,3:4}), 1, 1, "b in a", "__contains__")
        self.binop_test(spamdict({1:2,3:4}), 2, 0, "b in a", "__contains__")
        self.binop_test(spamdict({1:2,3:4}), 1, 2, "a[b]", "__getitem__")
        d = spamdict({1:2,3:4})
        l1 = []
        for i in list(d.keys()):
            l1.append(i)
        l = []
        for i in iter(d):
            l.append(i)
        self.assertEqual(l, l1)
        l = []
        for i in d.__iter__():
            l.append(i)
        self.assertEqual(l, l1)
        l = []
        for i in type(spamdict({})).__iter__(d):
            l.append(i)
        self.assertEqual(l, l1)
        straightd = {1:2, 3:4}
        spamd = spamdict(straightd)
        self.unop_test(spamd, 2, "len(a)", "__len__")
        self.unop_test(spamd, repr(straightd), "repr(a)", "__repr__")
        self.set2op_test(spamdict({1:2,3:4}), 2, 3, spamdict({1:2,2:3,3:4}),
                   "a[b]=c", "__setitem__")
        # Test subclassing
        class C(spam.spamdict):
            def foo(self): return 1
        a = C()
        self.assertEqual(list(a.items()), [])
        self.assertEqual(a.foo(), 1)
        a['foo'] = 'bar'
        self.assertEqual(list(a.items()), [('foo', 'bar')])
        self.assertEqual(a.getstate(), 0)
        a.setstate(100)
        self.assertEqual(a.getstate(), 100)

class ClassPropertiesAndMethods(unittest.TestCase):

    def test_python_dicts(self):
        # Testing Python subclass of dict...
        self.assertTrue(issubclass(dict, dict))
        self.assertIsInstance({}, dict)
        d = dict()
        self.assertEqual(d, {})
        self.assertTrue(d.__class__ is dict)
        self.assertIsInstance(d, dict)
        class C(dict):
            state = -1
            def __init__(self_local, *a, **kw):
                if a:
                    self.assertEqual(len(a), 1)
                    self_local.state = a[0]
                if kw:
                    for k, v in list(kw.items()):
                        self_local[v] = k
            def __getitem__(self, key):
                return self.get(key, 0)
            def __setitem__(self_local, key, value):
                self.assertIsInstance(key, type(0))
                dict.__setitem__(self_local, key, value)
            def setstate(self, state):
                self.state = state
            def getstate(self):
                return self.state
        self.assertTrue(issubclass(C, dict))
        a1 = C(12)
        self.assertEqual(a1.state, 12)
        a2 = C(foo=1, bar=2)
        self.assertEqual(a2[1] == 'foo' and a2[2], 'bar')
        a = C()
        self.assertEqual(a.state, -1)
        self.assertEqual(a.getstate(), -1)
        a.setstate(0)
        self.assertEqual(a.state, 0)
        self.assertEqual(a.getstate(), 0)
        a.setstate(10)
        self.assertEqual(a.state, 10)
        self.assertEqual(a.getstate(), 10)
        self.assertEqual(a[42], 0)
        a[42] = 24
        self.assertEqual(a[42], 24)
        N = 50
        for i in range(N):
            a[i] = C()
            for j in range(N):
                a[i][j] = i*j
        for i in range(N):
            for j in range(N):
                self.assertEqual(a[i][j], i*j)

    def test_python_lists(self):
        # Testing Python subclass of list...
        class C(list):
            def __getitem__(self, i):
                if isinstance(i, slice):
                    return i.start, i.stop
                return list.__getitem__(self, i) + 100
        a = C()
        a.extend([0,1,2])
        self.assertEqual(a[0], 100)
        self.assertEqual(a[1], 101)
        self.assertEqual(a[2], 102)
        self.assertEqual(a[100:200], (100,200))

    def test_metaclass(self):
        # Testing metaclasses...
        class C(metaclass=type):
            def __init__(self):
                self.__state = 0
            def getstate(self):
                return self.__state
            def setstate(self, state):
                self.__state = state
        a = C()
        self.assertEqual(a.getstate(), 0)
        a.setstate(10)
        self.assertEqual(a.getstate(), 10)
        class _metaclass(type):
            def myself(cls): return cls
        class D(metaclass=_metaclass):
            pass
        self.assertEqual(D.myself(), D)
        d = D()
        self.assertEqual(d.__class__, D)
        class M1(type):
            def __new__(cls, name, bases, dict):
                dict['__spam__'] = 1
                return type.__new__(cls, name, bases, dict)
        class C(metaclass=M1):
            pass
        self.assertEqual(C.__spam__, 1)
        c = C()
        self.assertEqual(c.__spam__, 1)

        class _instance(object):
            pass
        class M2(object):
            @staticmethod
            def __new__(cls, name, bases, dict):
                self = object.__new__(cls)
                self.name = name
                self.bases = bases
                self.dict = dict
                return self
            def __call__(self):
                it = _instance()
                # Early binding of methods
                for key in self.dict:
                    if key.startswith("__"):
                        continue
                    setattr(it, key, self.dict[key].__get__(it, self))
                return it
        class C(metaclass=M2):
            def spam(self):
                return 42
        self.assertEqual(C.name, 'C')
        self.assertEqual(C.bases, ())
        self.assertIn('spam', C.dict)
        c = C()
        self.assertEqual(c.spam(), 42)

        # More metaclass examples

        class autosuper(type):
            # Automatically add __super to the class
            # This trick only works for dynamic classes
            def __new__(metaclass, name, bases, dict):
                cls = super(autosuper, metaclass).__new__(metaclass,
                                                          name, bases, dict)
                # Name mangling for __super removes leading underscores
                while name[:1] == "_":
                    name = name[1:]
                if name:
                    name = "_%s__super" % name
                else:
                    name = "__super"
                setattr(cls, name, super(cls))
                return cls
        class A(metaclass=autosuper):
            def meth(self):
                return "A"
        class B(A):
            def meth(self):
                return "B" + self.__super.meth()
        class C(A):
            def meth(self):
                return "C" + self.__super.meth()
        class D(C, B):
            def meth(self):
                return "D" + self.__super.meth()
        self.assertEqual(D().meth(), "DCBA")
        class E(B, C):
            def meth(self):
                return "E" + self.__super.meth()
        self.assertEqual(E().meth(), "EBCA")

        class autoproperty(type):
            # Automatically create property attributes when methods
            # named _get_x and/or _set_x are found
            def __new__(metaclass, name, bases, dict):
                hits = {}
                for key, val in dict.items():
                    if key.startswith("_get_"):
                        key = key[5:]
                        get, set = hits.get(key, (None, None))
                        get = val
                        hits[key] = get, set
                    elif key.startswith("_set_"):
                        key = key[5:]
                        get, set = hits.get(key, (None, None))
                        set = val
                        hits[key] = get, set
                for key, (get, set) in hits.items():
                    dict[key] = property(get, set)
                return super(autoproperty, metaclass).__new__(metaclass,
                                                            name, bases, dict)
        class A(metaclass=autoproperty):
            def _get_x(self):
                return -self.__x
            def _set_x(self, x):
                self.__x = -x
        a = A()
        self.assertTrue(not hasattr(a, "x"))
        a.x = 12
        self.assertEqual(a.x, 12)
        self.assertEqual(a._A__x, -12)

        class multimetaclass(autoproperty, autosuper):
            # Merge of multiple cooperating metaclasses
            pass
        class A(metaclass=multimetaclass):
            def _get_x(self):
                return "A"
        class B(A):
            def _get_x(self):
                return "B" + self.__super._get_x()
        class C(A):
            def _get_x(self):
                return "C" + self.__super._get_x()
        class D(C, B):
            def _get_x(self):
                return "D" + self.__super._get_x()
        self.assertEqual(D().x, "DCBA")

        # Make sure type(x) doesn't call x.__class__.__init__
        class T(type):
            counter = 0
            def __init__(self, *args):
                T.counter += 1
        class C(metaclass=T):
            pass
        self.assertEqual(T.counter, 1)
        a = C()
        self.assertEqual(type(a), C)
        self.assertEqual(T.counter, 1)

        class C(object): pass
        c = C()
        try: c()
        except TypeError: pass
        else: self.fail("calling object w/o call method should raise "
                        "TypeError")

        # Testing code to find most derived baseclass
        class A(type):
            def __new__(*args, **kwargs):
                return type.__new__(*args, **kwargs)

        class B(object):
            pass

        class C(object, metaclass=A):
            pass

        # The most derived metaclass of D is A rather than type.
        class D(B, C):
            pass
        self.assertIs(A, type(D))

        # issue1294232: correct metaclass calculation
        new_calls = []  # to check the order of __new__ calls
        class AMeta(type):
            @staticmethod
            def __new__(mcls, name, bases, ns):
                new_calls.append('AMeta')
                return super().__new__(mcls, name, bases, ns)
            @classmethod
            def __prepare__(mcls, name, bases):
                return {}

        class BMeta(AMeta):
            @staticmethod
            def __new__(mcls, name, bases, ns):
                new_calls.append('BMeta')
                return super().__new__(mcls, name, bases, ns)
            @classmethod
            def __prepare__(mcls, name, bases):
                ns = super().__prepare__(name, bases)
                ns['BMeta_was_here'] = True
                return ns

        class A(metaclass=AMeta):
            pass
        self.assertEqual(['AMeta'], new_calls)
        new_calls[:] = []

        class B(metaclass=BMeta):
            pass
        # BMeta.__new__ calls AMeta.__new__ with super:
        self.assertEqual(['BMeta', 'AMeta'], new_calls)
        new_calls[:] = []

        class C(A, B):
            pass
        # The most derived metaclass is BMeta:
        self.assertEqual(['BMeta', 'AMeta'], new_calls)
        new_calls[:] = []
        # BMeta.__prepare__ should've been called:
        self.assertIn('BMeta_was_here', C.__dict__)

        # The order of the bases shouldn't matter:
        class C2(B, A):
            pass
        self.assertEqual(['BMeta', 'AMeta'], new_calls)
        new_calls[:] = []
        self.assertIn('BMeta_was_here', C2.__dict__)

        # Check correct metaclass calculation when a metaclass is declared:
        class D(C, metaclass=type):
            pass
        self.assertEqual(['BMeta', 'AMeta'], new_calls)
        new_calls[:] = []
        self.assertIn('BMeta_was_here', D.__dict__)

        class E(C, metaclass=AMeta):
            pass
        self.assertEqual(['BMeta', 'AMeta'], new_calls)
        new_calls[:] = []
        self.assertIn('BMeta_was_here', E.__dict__)

        # Special case: the given metaclass isn't a class,
        # so there is no metaclass calculation.
        marker = object()
        def func(*args, **kwargs):
            return marker
        class X(metaclass=func):
            pass
        class Y(object, metaclass=func):
            pass
        class Z(D, metaclass=func):
            pass
        self.assertIs(marker, X)
        self.assertIs(marker, Y)
        self.assertIs(marker, Z)

        # The given metaclass is a class,
        # but not a descendant of type.
        prepare_calls = []  # to track __prepare__ calls
        class ANotMeta:
            def __new__(mcls, *args, **kwargs):
                new_calls.append('ANotMeta')
                return super().__new__(mcls)
            @classmethod
            def __prepare__(mcls, name, bases):
                prepare_calls.append('ANotMeta')
                return {}
        class BNotMeta(ANotMeta):
            def __new__(mcls, *args, **kwargs):
                new_calls.append('BNotMeta')
                return super().__new__(mcls)
            @classmethod
            def __prepare__(mcls, name, bases):
                prepare_calls.append('BNotMeta')
                return super().__prepare__(name, bases)

        class A(metaclass=ANotMeta):
            pass
        self.assertIs(ANotMeta, type(A))
        self.assertEqual(['ANotMeta'], prepare_calls)
        prepare_calls[:] = []
        self.assertEqual(['ANotMeta'], new_calls)
        new_calls[:] = []

        class B(metaclass=BNotMeta):
            pass
        self.assertIs(BNotMeta, type(B))
        self.assertEqual(['BNotMeta', 'ANotMeta'], prepare_calls)
        prepare_calls[:] = []
        self.assertEqual(['BNotMeta', 'ANotMeta'], new_calls)
        new_calls[:] = []

        class C(A, B):
            pass
        self.assertIs(BNotMeta, type(C))
        self.assertEqual(['BNotMeta', 'ANotMeta'], new_calls)
        new_calls[:] = []
        self.assertEqual(['BNotMeta', 'ANotMeta'], prepare_calls)
        prepare_calls[:] = []

        class C2(B, A):
            pass
        self.assertIs(BNotMeta, type(C2))
        self.assertEqual(['BNotMeta', 'ANotMeta'], new_calls)
        new_calls[:] = []
        self.assertEqual(['BNotMeta', 'ANotMeta'], prepare_calls)
        prepare_calls[:] = []

        # This is a TypeError, because of a metaclass conflict:
        # BNotMeta is neither a subclass, nor a superclass of type
        with self.assertRaises(TypeError):
            class D(C, metaclass=type):
                pass

        class E(C, metaclass=ANotMeta):
            pass
        self.assertIs(BNotMeta, type(E))
        self.assertEqual(['BNotMeta', 'ANotMeta'], new_calls)
        new_calls[:] = []
        self.assertEqual(['BNotMeta', 'ANotMeta'], prepare_calls)
        prepare_calls[:] = []

        class F(object(), C):
            pass
        self.assertIs(BNotMeta, type(F))
        self.assertEqual(['BNotMeta', 'ANotMeta'], new_calls)
        new_calls[:] = []
        self.assertEqual(['BNotMeta', 'ANotMeta'], prepare_calls)
        prepare_calls[:] = []

        class F2(C, object()):
            pass
        self.assertIs(BNotMeta, type(F2))
        self.assertEqual(['BNotMeta', 'ANotMeta'], new_calls)
        new_calls[:] = []
        self.assertEqual(['BNotMeta', 'ANotMeta'], prepare_calls)
        prepare_calls[:] = []

        # TypeError: BNotMeta is neither a
        # subclass, nor a superclass of int
        with self.assertRaises(TypeError):
            class X(C, int()):
                pass
        with self.assertRaises(TypeError):
            class X(int(), C):
                pass

    def test_module_subclasses(self):
        # Testing Python subclass of module...
        log = []
        MT = type(sys)
        class MM(MT):
            def __init__(self, name):
                MT.__init__(self, name)
            def __getattribute__(self, name):
                log.append(("getattr", name))
                return MT.__getattribute__(self, name)
            def __setattr__(self, name, value):
                log.append(("setattr", name, value))
                MT.__setattr__(self, name, value)
            def __delattr__(self, name):
                log.append(("delattr", name))
                MT.__delattr__(self, name)
        a = MM("a")
        a.foo = 12
        x = a.foo
        del a.foo
        self.assertEqual(log, [("setattr", "foo", 12),
                               ("getattr", "foo"),
                               ("delattr", "foo")])

        # http://python.org/sf/1174712
        try:
            class Module(types.ModuleType, str):
                pass
        except TypeError:
            pass
        else:
            self.fail("inheriting from ModuleType and str at the same time "
                      "should fail")

    def test_multiple_inheritance(self):
        # Testing multiple inheritance...
        class C(object):
            def __init__(self):
                self.__state = 0
            def getstate(self):
                return self.__state
            def setstate(self, state):
                self.__state = state
        a = C()
        self.assertEqual(a.getstate(), 0)
        a.setstate(10)
        self.assertEqual(a.getstate(), 10)
        class D(dict, C):
            def __init__(self):
                type({}).__init__(self)
                C.__init__(self)
        d = D()
        self.assertEqual(list(d.keys()), [])
        d["hello"] = "world"
        self.assertEqual(list(d.items()), [("hello", "world")])
        self.assertEqual(d["hello"], "world")
        self.assertEqual(d.getstate(), 0)
        d.setstate(10)
        self.assertEqual(d.getstate(), 10)
        self.assertEqual(D.__mro__, (D, dict, C, object))

        # SF bug #442833
        class Node(object):
            def __int__(self):
                return int(self.foo())
            def foo(self):
                return "23"
        class Frag(Node, list):
            def foo(self):
                return "42"
        self.assertEqual(Node().__int__(), 23)
        self.assertEqual(int(Node()), 23)
        self.assertEqual(Frag().__int__(), 42)
        self.assertEqual(int(Frag()), 42)

    def test_diamond_inheritence(self):
        # Testing multiple inheritance special cases...
        class A(object):
            def spam(self): return "A"
        self.assertEqual(A().spam(), "A")
        class B(A):
            def boo(self): return "B"
            def spam(self): return "B"
        self.assertEqual(B().spam(), "B")
        self.assertEqual(B().boo(), "B")
        class C(A):
            def boo(self): return "C"
        self.assertEqual(C().spam(), "A")
        self.assertEqual(C().boo(), "C")
        class D(B, C): pass
        self.assertEqual(D().spam(), "B")
        self.assertEqual(D().boo(), "B")
        self.assertEqual(D.__mro__, (D, B, C, A, object))
        class E(C, B): pass
        self.assertEqual(E().spam(), "B")
        self.assertEqual(E().boo(), "C")
        self.assertEqual(E.__mro__, (E, C, B, A, object))
        # MRO order disagreement
        try:
            class F(D, E): pass
        except TypeError:
            pass
        else:
            self.fail("expected MRO order disagreement (F)")
        try:
            class G(E, D): pass
        except TypeError:
            pass
        else:
            self.fail("expected MRO order disagreement (G)")

    # see thread python-dev/2002-October/029035.html
    def test_ex5_from_c3_switch(self):
        # Testing ex5 from C3 switch discussion...
        class A(object): pass
        class B(object): pass
        class C(object): pass
        class X(A): pass
        class Y(A): pass
        class Z(X,B,Y,C): pass
        self.assertEqual(Z.__mro__, (Z, X, B, Y, A, C, object))

    # see "A Monotonic Superclass Linearization for Dylan",
    # by Kim Barrett et al. (OOPSLA 1996)
    def test_monotonicity(self):
        # Testing MRO monotonicity...
        class Boat(object): pass
        class DayBoat(Boat): pass
        class WheelBoat(Boat): pass
        class EngineLess(DayBoat): pass
        class SmallMultihull(DayBoat): pass
        class PedalWheelBoat(EngineLess,WheelBoat): pass
        class SmallCatamaran(SmallMultihull): pass
        class Pedalo(PedalWheelBoat,SmallCatamaran): pass

        self.assertEqual(PedalWheelBoat.__mro__,
              (PedalWheelBoat, EngineLess, DayBoat, WheelBoat, Boat, object))
        self.assertEqual(SmallCatamaran.__mro__,
              (SmallCatamaran, SmallMultihull, DayBoat, Boat, object))
        self.assertEqual(Pedalo.__mro__,
              (Pedalo, PedalWheelBoat, EngineLess, SmallCatamaran,
               SmallMultihull, DayBoat, WheelBoat, Boat, object))

    # see "A Monotonic Superclass Linearization for Dylan",
    # by Kim Barrett et al. (OOPSLA 1996)
    def test_consistency_with_epg(self):
        # Testing consistency with EPG...
        class Pane(object): pass
        class ScrollingMixin(object): pass
        class EditingMixin(object): pass
        class ScrollablePane(Pane,ScrollingMixin): pass
        class EditablePane(Pane,EditingMixin): pass
        class EditableScrollablePane(ScrollablePane,EditablePane): pass

        self.assertEqual(EditableScrollablePane.__mro__,
              (EditableScrollablePane, ScrollablePane, EditablePane, Pane,
                ScrollingMixin, EditingMixin, object))

    def test_mro_disagreement(self):
        # Testing error messages for MRO disagreement...
        mro_err_msg = """Cannot create a consistent method resolution
order (MRO) for bases """

        def raises(exc, expected, callable, *args):
            try:
                callable(*args)
            except exc as msg:
                # the exact msg is generally considered an impl detail
                if support.check_impl_detail():
                    if not str(msg).startswith(expected):
                        self.fail("Message %r, expected %r" %
                                  (str(msg), expected))
            else:
                self.fail("Expected %s" % exc)

        class A(object): pass
        class B(A): pass
        class C(object): pass

        # Test some very simple errors
        raises(TypeError, "duplicate base class A",
               type, "X", (A, A), {})
        raises(TypeError, mro_err_msg,
               type, "X", (A, B), {})
        raises(TypeError, mro_err_msg,
               type, "X", (A, C, B), {})
        # Test a slightly more complex error
        class GridLayout(object): pass
        class HorizontalGrid(GridLayout): pass
        class VerticalGrid(GridLayout): pass
        class HVGrid(HorizontalGrid, VerticalGrid): pass
        class VHGrid(VerticalGrid, HorizontalGrid): pass
        raises(TypeError, mro_err_msg,
               type, "ConfusedGrid", (HVGrid, VHGrid), {})

    def test_object_class(self):
        # Testing object class...
        a = object()
        self.assertEqual(a.__class__, object)
        self.assertEqual(type(a), object)
        b = object()
        self.assertNotEqual(a, b)
        self.assertFalse(hasattr(a, "foo"))
        try:
            a.foo = 12
        except (AttributeError, TypeError):
            pass
        else:
            self.fail("object() should not allow setting a foo attribute")
        self.assertFalse(hasattr(object(), "__dict__"))

        class Cdict(object):
            pass
        x = Cdict()
        self.assertEqual(x.__dict__, {})
        x.foo = 1
        self.assertEqual(x.foo, 1)
        self.assertEqual(x.__dict__, {'foo': 1})

    def test_slots(self):
        # Testing __slots__...
        class C0(object):
            __slots__ = []
        x = C0()
        self.assertFalse(hasattr(x, "__dict__"))
        self.assertFalse(hasattr(x, "foo"))

        class C1(object):
            __slots__ = ['a']
        x = C1()
        self.assertFalse(hasattr(x, "__dict__"))
        self.assertFalse(hasattr(x, "a"))
        x.a = 1
        self.assertEqual(x.a, 1)
        x.a = None
        self.assertEqual(x.a, None)
        del x.a
        self.assertFalse(hasattr(x, "a"))

        class C3(object):
            __slots__ = ['a', 'b', 'c']
        x = C3()
        self.assertFalse(hasattr(x, "__dict__"))
        self.assertFalse(hasattr(x, 'a'))
        self.assertFalse(hasattr(x, 'b'))
        self.assertFalse(hasattr(x, 'c'))
        x.a = 1
        x.b = 2
        x.c = 3
        self.assertEqual(x.a, 1)
        self.assertEqual(x.b, 2)
        self.assertEqual(x.c, 3)

        class C4(object):
            """Validate name mangling"""
            __slots__ = ['__a']
            def __init__(self, value):
                self.__a = value
            def get(self):
                return self.__a
        x = C4(5)
        self.assertFalse(hasattr(x, '__dict__'))
        self.assertFalse(hasattr(x, '__a'))
        self.assertEqual(x.get(), 5)
        try:
            x.__a = 6
        except AttributeError:
            pass
        else:
            self.fail("Double underscored names not mangled")

        # Make sure slot names are proper identifiers
        try:
            class C(object):
                __slots__ = [None]
        except TypeError:
            pass
        else:
            self.fail("[None] slots not caught")
        try:
            class C(object):
                __slots__ = ["foo bar"]
        except TypeError:
            pass
        else:
            self.fail("['foo bar'] slots not caught")
        try:
            class C(object):
                __slots__ = ["foo\0bar"]
        except TypeError:
            pass
        else:
            self.fail("['foo\\0bar'] slots not caught")
        try:
            class C(object):
                __slots__ = ["1"]
        except TypeError:
            pass
        else:
            self.fail("['1'] slots not caught")
        try:
            class C(object):
                __slots__ = [""]
        except TypeError:
            pass
        else:
            self.fail("[''] slots not caught")
        class C(object):
            __slots__ = ["a", "a_b", "_a", "A0123456789Z"]
        # XXX(nnorwitz): was there supposed to be something tested
        # from the class above?

        # Test a single string is not expanded as a sequence.
        class C(object):
            __slots__ = "abc"
        c = C()
        c.abc = 5
        self.assertEqual(c.abc, 5)

        # Test unicode slot names
        # Test a single unicode string is not expanded as a sequence.
        class C(object):
            __slots__ = "abc"
        c = C()
        c.abc = 5
        self.assertEqual(c.abc, 5)

        # _unicode_to_string used to modify slots in certain circumstances
        slots = ("foo", "bar")
        class C(object):
            __slots__ = slots
        x = C()
        x.foo = 5
        self.assertEqual(x.foo, 5)
        self.assertTrue(type(slots[0]) is str)
        # this used to leak references
        try:
            class C(object):
                __slots__ = [chr(128)]
        except (TypeError, UnicodeEncodeError):
            pass
        else:
            raise TestFailed("[chr(128)] slots not caught")

        # Test leaks
        class Counted(object):
            counter = 0    # counts the number of instances alive
            def __init__(self):
                Counted.counter += 1
            def __del__(self):
                Counted.counter -= 1
        class C(object):
            __slots__ = ['a', 'b', 'c']
        x = C()
        x.a = Counted()
        x.b = Counted()
        x.c = Counted()
        self.assertEqual(Counted.counter, 3)
        del x
        support.gc_collect()
        self.assertEqual(Counted.counter, 0)
        class D(C):
            pass
        x = D()
        x.a = Counted()
        x.z = Counted()
        self.assertEqual(Counted.counter, 2)
        del x
        support.gc_collect()
        self.assertEqual(Counted.counter, 0)
        class E(D):
            __slots__ = ['e']
        x = E()
        x.a = Counted()
        x.z = Counted()
        x.e = Counted()
        self.assertEqual(Counted.counter, 3)
        del x
        support.gc_collect()
        self.assertEqual(Counted.counter, 0)

        # Test cyclical leaks [SF bug 519621]
        class F(object):
            __slots__ = ['a', 'b']
        s = F()
        s.a = [Counted(), s]
        self.assertEqual(Counted.counter, 1)
        s = None
        support.gc_collect()
        self.assertEqual(Counted.counter, 0)

        # Test lookup leaks [SF bug 572567]
        if hasattr(gc, 'get_objects'):
            class G(object):
                def __eq__(self, other):
                    return False
            g = G()
            orig_objects = len(gc.get_objects())
            for i in range(10):
                g==g
            new_objects = len(gc.get_objects())
            self.assertEqual(orig_objects, new_objects)

        class H(object):
            __slots__ = ['a', 'b']
            def __init__(self):
                self.a = 1
                self.b = 2
            def __del__(self_):
                self.assertEqual(self_.a, 1)
                self.assertEqual(self_.b, 2)
        with support.captured_output('stderr') as s:
            h = H()
            del h
        self.assertEqual(s.getvalue(), '')

        class X(object):
            __slots__ = "a"
        with self.assertRaises(AttributeError):
            del X().a

    def test_slots_special(self):
        # Testing __dict__ and __weakref__ in __slots__...
        class D(object):
            __slots__ = ["__dict__"]
        a = D()
        self.assertTrue(hasattr(a, "__dict__"))
        self.assertFalse(hasattr(a, "__weakref__"))
        a.foo = 42
        self.assertEqual(a.__dict__, {"foo": 42})

        class W(object):
            __slots__ = ["__weakref__"]
        a = W()
        self.assertTrue(hasattr(a, "__weakref__"))
        self.assertFalse(hasattr(a, "__dict__"))
        try:
            a.foo = 42
        except AttributeError:
            pass
        else:
            self.fail("shouldn't be allowed to set a.foo")

        class C1(W, D):
            __slots__ = []
        a = C1()
        self.assertTrue(hasattr(a, "__dict__"))
        self.assertTrue(hasattr(a, "__weakref__"))
        a.foo = 42
        self.assertEqual(a.__dict__, {"foo": 42})

        class C2(D, W):
            __slots__ = []
        a = C2()
        self.assertTrue(hasattr(a, "__dict__"))
        self.assertTrue(hasattr(a, "__weakref__"))
        a.foo = 42
        self.assertEqual(a.__dict__, {"foo": 42})

    def test_slots_descriptor(self):
        # Issue2115: slot descriptors did not correctly check
        # the type of the given object
        import abc
        class MyABC(metaclass=abc.ABCMeta):
            __slots__ = "a"

        class Unrelated(object):
            pass
        MyABC.register(Unrelated)

        u = Unrelated()
        self.assertIsInstance(u, MyABC)

        # This used to crash
        self.assertRaises(TypeError, MyABC.a.__set__, u, 3)

    def test_dynamics(self):
        # Testing class attribute propagation...
        class D(object):
            pass
        class E(D):
            pass
        class F(D):
            pass
        D.foo = 1
        self.assertEqual(D.foo, 1)
        # Test that dynamic attributes are inherited
        self.assertEqual(E.foo, 1)
        self.assertEqual(F.foo, 1)
        # Test dynamic instances
        class C(object):
            pass
        a = C()
        self.assertFalse(hasattr(a, "foobar"))
        C.foobar = 2
        self.assertEqual(a.foobar, 2)
        C.method = lambda self: 42
        self.assertEqual(a.method(), 42)
        C.__repr__ = lambda self: "C()"
        self.assertEqual(repr(a), "C()")
        C.__int__ = lambda self: 100
        self.assertEqual(int(a), 100)
        self.assertEqual(a.foobar, 2)
        self.assertFalse(hasattr(a, "spam"))
        def mygetattr(self, name):
            if name == "spam":
                return "spam"
            raise AttributeError
        C.__getattr__ = mygetattr
        self.assertEqual(a.spam, "spam")
        a.new = 12
        self.assertEqual(a.new, 12)
        def mysetattr(self, name, value):
            if name == "spam":
                raise AttributeError
            return object.__setattr__(self, name, value)
        C.__setattr__ = mysetattr
        try:
            a.spam = "not spam"
        except AttributeError:
            pass
        else:
            self.fail("expected AttributeError")
        self.assertEqual(a.spam, "spam")
        class D(C):
            pass
        d = D()
        d.foo = 1
        self.assertEqual(d.foo, 1)

        # Test handling of int*seq and seq*int
        class I(int):
            pass
        self.assertEqual("a"*I(2), "aa")
        self.assertEqual(I(2)*"a", "aa")
        self.assertEqual(2*I(3), 6)
        self.assertEqual(I(3)*2, 6)
        self.assertEqual(I(3)*I(2), 6)

        # Test comparison of classes with dynamic metaclasses
        class dynamicmetaclass(type):
            pass
        class someclass(metaclass=dynamicmetaclass):
            pass
        self.assertNotEqual(someclass, object)

    def test_errors(self):
        # Testing errors...
        try:
            class C(list, dict):
                pass
        except TypeError:
            pass
        else:
            self.fail("inheritance from both list and dict should be illegal")

        try:
            class C(object, None):
                pass
        except TypeError:
            pass
        else:
            self.fail("inheritance from non-type should be illegal")
        class Classic:
            pass

        try:
            class C(type(len)):
                pass
        except TypeError:
            pass
        else:
            self.fail("inheritance from CFunction should be illegal")

        try:
            class C(object):
                __slots__ = 1
        except TypeError:
            pass
        else:
            self.fail("__slots__ = 1 should be illegal")

        try:
            class C(object):
                __slots__ = [1]
        except TypeError:
            pass
        else:
            self.fail("__slots__ = [1] should be illegal")

        class M1(type):
            pass
        class M2(type):
            pass
        class A1(object, metaclass=M1):
            pass
        class A2(object, metaclass=M2):
            pass
        try:
            class B(A1, A2):
                pass
        except TypeError:
            pass
        else:
            self.fail("finding the most derived metaclass should have failed")

    def test_classmethods(self):
        # Testing class methods...
        class C(object):
            def foo(*a): return a
            goo = classmethod(foo)
        c = C()
        self.assertEqual(C.goo(1), (C, 1))
        self.assertEqual(c.goo(1), (C, 1))
        self.assertEqual(c.foo(1), (c, 1))
        class D(C):
            pass
        d = D()
        self.assertEqual(D.goo(1), (D, 1))
        self.assertEqual(d.goo(1), (D, 1))
        self.assertEqual(d.foo(1), (d, 1))
        self.assertEqual(D.foo(d, 1), (d, 1))
        # Test for a specific crash (SF bug 528132)
        def f(cls, arg): return (cls, arg)
        ff = classmethod(f)
        self.assertEqual(ff.__get__(0, int)(42), (int, 42))
        self.assertEqual(ff.__get__(0)(42), (int, 42))

        # Test super() with classmethods (SF bug 535444)
        self.assertEqual(C.goo.__self__, C)
        self.assertEqual(D.goo.__self__, D)
        self.assertEqual(super(D,D).goo.__self__, D)
        self.assertEqual(super(D,d).goo.__self__, D)
        self.assertEqual(super(D,D).goo(), (D,))
        self.assertEqual(super(D,d).goo(), (D,))

        # Verify that a non-callable will raise
        meth = classmethod(1).__get__(1)
        self.assertRaises(TypeError, meth)

        # Verify that classmethod() doesn't allow keyword args
        try:
            classmethod(f, kw=1)
        except TypeError:
            pass
        else:
            self.fail("classmethod shouldn't accept keyword args")

    @support.impl_detail("the module 'xxsubtype' is internal")
    def test_classmethods_in_c(self):
        # Testing C-based class methods...
        import xxsubtype as spam
        a = (1, 2, 3)
        d = {'abc': 123}
        x, a1, d1 = spam.spamlist.classmeth(*a, **d)
        self.assertEqual(x, spam.spamlist)
        self.assertEqual(a, a1)
        self.assertEqual(d, d1)
        x, a1, d1 = spam.spamlist().classmeth(*a, **d)
        self.assertEqual(x, spam.spamlist)
        self.assertEqual(a, a1)
        self.assertEqual(d, d1)
        spam_cm = spam.spamlist.__dict__['classmeth']
        x2, a2, d2 = spam_cm(spam.spamlist, *a, **d)
        self.assertEqual(x2, spam.spamlist)
        self.assertEqual(a2, a1)
        self.assertEqual(d2, d1)
        class SubSpam(spam.spamlist): pass
        x2, a2, d2 = spam_cm(SubSpam, *a, **d)
        self.assertEqual(x2, SubSpam)
        self.assertEqual(a2, a1)
        self.assertEqual(d2, d1)
        with self.assertRaises(TypeError):
            spam_cm()
        with self.assertRaises(TypeError):
            spam_cm(spam.spamlist())
        with self.assertRaises(TypeError):
            spam_cm(list)

    def test_staticmethods(self):
        # Testing static methods...
        class C(object):
            def foo(*a): return a
            goo = staticmethod(foo)
        c = C()
        self.assertEqual(C.goo(1), (1,))
        self.assertEqual(c.goo(1), (1,))
        self.assertEqual(c.foo(1), (c, 1,))
        class D(C):
            pass
        d = D()
        self.assertEqual(D.goo(1), (1,))
        self.assertEqual(d.goo(1), (1,))
        self.assertEqual(d.foo(1), (d, 1))
        self.assertEqual(D.foo(d, 1), (d, 1))

    @support.impl_detail("the module 'xxsubtype' is internal")
    def test_staticmethods_in_c(self):
        # Testing C-based static methods...
        import xxsubtype as spam
        a = (1, 2, 3)
        d = {"abc": 123}
        x, a1, d1 = spam.spamlist.staticmeth(*a, **d)
        self.assertEqual(x, None)
        self.assertEqual(a, a1)
        self.assertEqual(d, d1)
        x, a1, d2 = spam.spamlist().staticmeth(*a, **d)
        self.assertEqual(x, None)
        self.assertEqual(a, a1)
        self.assertEqual(d, d1)

    def test_classic(self):
        # Testing classic classes...
        class C:
            def foo(*a): return a
            goo = classmethod(foo)
        c = C()
        self.assertEqual(C.goo(1), (C, 1))
        self.assertEqual(c.goo(1), (C, 1))
        self.assertEqual(c.foo(1), (c, 1))
        class D(C):
            pass
        d = D()
        self.assertEqual(D.goo(1), (D, 1))
        self.assertEqual(d.goo(1), (D, 1))
        self.assertEqual(d.foo(1), (d, 1))
        self.assertEqual(D.foo(d, 1), (d, 1))
        class E: # *not* subclassing from C
            foo = C.foo
        self.assertEqual(E().foo.__func__, C.foo) # i.e., unbound
        self.assertTrue(repr(C.foo.__get__(C())).startswith("<bound method "))

    def test_compattr(self):
        # Testing computed attributes...
        class C(object):
            class computed_attribute(object):
                def __init__(self, get, set=None, delete=None):
                    self.__get = get
                    self.__set = set
                    self.__delete = delete
                def __get__(self, obj, type=None):
                    return self.__get(obj)
                def __set__(self, obj, value):
                    return self.__set(obj, value)
                def __delete__(self, obj):
                    return self.__delete(obj)
            def __init__(self):
                self.__x = 0
            def __get_x(self):
                x = self.__x
                self.__x = x+1
                return x
            def __set_x(self, x):
                self.__x = x
            def __delete_x(self):
                del self.__x
            x = computed_attribute(__get_x, __set_x, __delete_x)
        a = C()
        self.assertEqual(a.x, 0)
        self.assertEqual(a.x, 1)
        a.x = 10
        self.assertEqual(a.x, 10)
        self.assertEqual(a.x, 11)
        del a.x
        self.assertEqual(hasattr(a, 'x'), 0)

    def test_newslots(self):
        # Testing __new__ slot override...
        class C(list):
            def __new__(cls):
                self = list.__new__(cls)
                self.foo = 1
                return self
            def __init__(self):
                self.foo = self.foo + 2
        a = C()
        self.assertEqual(a.foo, 3)
        self.assertEqual(a.__class__, C)
        class D(C):
            pass
        b = D()
        self.assertEqual(b.foo, 3)
        self.assertEqual(b.__class__, D)

    def test_altmro(self):
        # Testing mro() and overriding it...
        class A(object):
            def f(self): return "A"
        class B(A):
            pass
        class C(A):
            def f(self): return "C"
        class D(B, C):
            pass
        self.assertEqual(D.mro(), [D, B, C, A, object])
        self.assertEqual(D.__mro__, (D, B, C, A, object))
        self.assertEqual(D().f(), "C")

        class PerverseMetaType(type):
            def mro(cls):
                L = type.mro(cls)
                L.reverse()
                return L
        class X(D,B,C,A, metaclass=PerverseMetaType):
            pass
        self.assertEqual(X.__mro__, (object, A, C, B, D, X))
        self.assertEqual(X().f(), "A")

        try:
            class _metaclass(type):
                def mro(self):
                    return [self, dict, object]
            class X(object, metaclass=_metaclass):
                pass
            # In CPython, the class creation above already raises
            # TypeError, as a protection against the fact that
            # instances of X would segfault it.  In other Python
            # implementations it would be ok to let the class X
            # be created, but instead get a clean TypeError on the
            # __setitem__ below.
            x = object.__new__(X)
            x[5] = 6
        except TypeError:
            pass
        else:
            self.fail("devious mro() return not caught")

        try:
            class _metaclass(type):
                def mro(self):
                    return [1]
            class X(object, metaclass=_metaclass):
                pass
        except TypeError:
            pass
        else:
            self.fail("non-class mro() return not caught")

        try:
            class _metaclass(type):
                def mro(self):
                    return 1
            class X(object, metaclass=_metaclass):
                pass
        except TypeError:
            pass
        else:
            self.fail("non-sequence mro() return not caught")

    def test_overloading(self):
        # Testing operator overloading...

        class B(object):
            "Intermediate class because object doesn't have a __setattr__"

        class C(B):
            def __getattr__(self, name):
                if name == "foo":
                    return ("getattr", name)
                else:
                    raise AttributeError
            def __setattr__(self, name, value):
                if name == "foo":
                    self.setattr = (name, value)
                else:
                    return B.__setattr__(self, name, value)
            def __delattr__(self, name):
                if name == "foo":
                    self.delattr = name
                else:
                    return B.__delattr__(self, name)

            def __getitem__(self, key):
                return ("getitem", key)
            def __setitem__(self, key, value):
                self.setitem = (key, value)
            def __delitem__(self, key):
                self.delitem = key

        a = C()
        self.assertEqual(a.foo, ("getattr", "foo"))
        a.foo = 12
        self.assertEqual(a.setattr, ("foo", 12))
        del a.foo
        self.assertEqual(a.delattr, "foo")

        self.assertEqual(a[12], ("getitem", 12))
        a[12] = 21
        self.assertEqual(a.setitem, (12, 21))
        del a[12]
        self.assertEqual(a.delitem, 12)

        self.assertEqual(a[0:10], ("getitem", slice(0, 10)))
        a[0:10] = "foo"
        self.assertEqual(a.setitem, (slice(0, 10), "foo"))
        del a[0:10]
        self.assertEqual(a.delitem, (slice(0, 10)))

    def test_methods(self):
        # Testing methods...
        class C(object):
            def __init__(self, x):
                self.x = x
            def foo(self):
                return self.x
        c1 = C(1)
        self.assertEqual(c1.foo(), 1)
        class D(C):
            boo = C.foo
            goo = c1.foo
        d2 = D(2)
        self.assertEqual(d2.foo(), 2)
        self.assertEqual(d2.boo(), 2)
        self.assertEqual(d2.goo(), 1)
        class E(object):
            foo = C.foo
        self.assertEqual(E().foo.__func__, C.foo) # i.e., unbound
        self.assertTrue(repr(C.foo.__get__(C(1))).startswith("<bound method "))

    def test_special_method_lookup(self):
        # The lookup of special methods bypasses __getattr__ and
        # __getattribute__, but they still can be descriptors.

        def run_context(manager):
            with manager:
                pass
        def iden(self):
            return self
        def hello(self):
            return b"hello"
        def empty_seq(self):
            return []
        def zero(self):
            return 0
        def complex_num(self):
            return 1j
        def stop(self):
            raise StopIteration
        def return_true(self, thing=None):
            return True
        def do_isinstance(obj):
            return isinstance(int, obj)
        def do_issubclass(obj):
            return issubclass(int, obj)
        def do_dict_missing(checker):
            class DictSub(checker.__class__, dict):
                pass
            self.assertEqual(DictSub()["hi"], 4)
        def some_number(self_, key):
            self.assertEqual(key, "hi")
            return 4
        def swallow(*args): pass
        def format_impl(self, spec):
            return "hello"

        # It would be nice to have every special method tested here, but I'm
        # only listing the ones I can remember outside of typeobject.c, since it
        # does it right.
        specials = [
            ("__bytes__", bytes, hello, set(), {}),
            ("__reversed__", reversed, empty_seq, set(), {}),
            ("__length_hint__", list, zero, set(),
             {"__iter__" : iden, "__next__" : stop}),
            ("__sizeof__", sys.getsizeof, zero, set(), {}),
            ("__instancecheck__", do_isinstance, return_true, set(), {}),
            ("__missing__", do_dict_missing, some_number,
             set(("__class__",)), {}),
            ("__subclasscheck__", do_issubclass, return_true,
             set(("__bases__",)), {}),
            ("__enter__", run_context, iden, set(), {"__exit__" : swallow}),
            ("__exit__", run_context, swallow, set(), {"__enter__" : iden}),
            ("__complex__", complex, complex_num, set(), {}),
            ("__format__", format, format_impl, set(), {}),
            ("__floor__", math.floor, zero, set(), {}),
            ("__trunc__", math.trunc, zero, set(), {}),
            ("__ceil__", math.ceil, zero, set(), {}),
            ("__dir__", dir, empty_seq, set(), {}),
            ]

        class Checker(object):
            def __getattr__(self, attr, test=self):
                test.fail("__getattr__ called with {0}".format(attr))
            def __getattribute__(self, attr, test=self):
                if attr not in ok:
                    test.fail("__getattribute__ called with {0}".format(attr))
                return object.__getattribute__(self, attr)
        class SpecialDescr(object):
            def __init__(self, impl):
                self.impl = impl
            def __get__(self, obj, owner):
                record.append(1)
                return self.impl.__get__(obj, owner)
        class MyException(Exception):
            pass
        class ErrDescr(object):
            def __get__(self, obj, owner):
                raise MyException

        for name, runner, meth_impl, ok, env in specials:
            class X(Checker):
                pass
            for attr, obj in env.items():
                setattr(X, attr, obj)
            setattr(X, name, meth_impl)
            runner(X())

            record = []
            class X(Checker):
                pass
            for attr, obj in env.items():
                setattr(X, attr, obj)
            setattr(X, name, SpecialDescr(meth_impl))
            runner(X())
            self.assertEqual(record, [1], name)

            class X(Checker):
                pass
            for attr, obj in env.items():
                setattr(X, attr, obj)
            setattr(X, name, ErrDescr())
            try:
                runner(X())
            except MyException:
                pass
            else:
                self.fail("{0!r} didn't raise".format(name))

    def test_specials(self):
        # Testing special operators...
        # Test operators like __hash__ for which a built-in default exists

        # Test the default behavior for static classes
        class C(object):
            def __getitem__(self, i):
                if 0 <= i < 10: return i
                raise IndexError
        c1 = C()
        c2 = C()
        self.assertTrue(not not c1) # What?
        self.assertNotEqual(id(c1), id(c2))
        hash(c1)
        hash(c2)
        self.assertEqual(c1, c1)
        self.assertTrue(c1 != c2)
        self.assertTrue(not c1 != c1)
        self.assertTrue(not c1 == c2)
        # Note that the module name appears in str/repr, and that varies
        # depending on whether this test is run standalone or from a framework.
        self.assertTrue(str(c1).find('C object at ') >= 0)
        self.assertEqual(str(c1), repr(c1))
        self.assertNotIn(-1, c1)
        for i in range(10):
            self.assertIn(i, c1)
        self.assertNotIn(10, c1)
        # Test the default behavior for dynamic classes
        class D(object):
            def __getitem__(self, i):
                if 0 <= i < 10: return i
                raise IndexError
        d1 = D()
        d2 = D()
        self.assertTrue(not not d1)
        self.assertNotEqual(id(d1), id(d2))
        hash(d1)
        hash(d2)
        self.assertEqual(d1, d1)
        self.assertNotEqual(d1, d2)
        self.assertTrue(not d1 != d1)
        self.assertTrue(not d1 == d2)
        # Note that the module name appears in str/repr, and that varies
        # depending on whether this test is run standalone or from a framework.
        self.assertTrue(str(d1).find('D object at ') >= 0)
        self.assertEqual(str(d1), repr(d1))
        self.assertNotIn(-1, d1)
        for i in range(10):
            self.assertIn(i, d1)
        self.assertNotIn(10, d1)
        # Test overridden behavior
        class Proxy(object):
            def __init__(self, x):
                self.x = x
            def __bool__(self):
                return not not self.x
            def __hash__(self):
                return hash(self.x)
            def __eq__(self, other):
                return self.x == other
            def __ne__(self, other):
                return self.x != other
            def __ge__(self, other):
                return self.x >= other
            def __gt__(self, other):
                return self.x > other
            def __le__(self, other):
                return self.x <= other
            def __lt__(self, other):
                return self.x < other
            def __str__(self):
                return "Proxy:%s" % self.x
            def __repr__(self):
                return "Proxy(%r)" % self.x
            def __contains__(self, value):
                return value in self.x
        p0 = Proxy(0)
        p1 = Proxy(1)
        p_1 = Proxy(-1)
        self.assertFalse(p0)
        self.assertTrue(not not p1)
        self.assertEqual(hash(p0), hash(0))
        self.assertEqual(p0, p0)
        self.assertNotEqual(p0, p1)
        self.assertTrue(not p0 != p0)
        self.assertEqual(not p0, p1)
        self.assertTrue(p0 < p1)
        self.assertTrue(p0 <= p1)
        self.assertTrue(p1 > p0)
        self.assertTrue(p1 >= p0)
        self.assertEqual(str(p0), "Proxy:0")
        self.assertEqual(repr(p0), "Proxy(0)")
        p10 = Proxy(range(10))
        self.assertNotIn(-1, p10)
        for i in range(10):
            self.assertIn(i, p10)
        self.assertNotIn(10, p10)

    def test_weakrefs(self):
        # Testing weak references...
        import weakref
        class C(object):
            pass
        c = C()
        r = weakref.ref(c)
        self.assertEqual(r(), c)
        del c
        support.gc_collect()
        self.assertEqual(r(), None)
        del r
        class NoWeak(object):
            __slots__ = ['foo']
        no = NoWeak()
        try:
            weakref.ref(no)
        except TypeError as msg:
            self.assertTrue(str(msg).find("weak reference") >= 0)
        else:
            self.fail("weakref.ref(no) should be illegal")
        class Weak(object):
            __slots__ = ['foo', '__weakref__']
        yes = Weak()
        r = weakref.ref(yes)
        self.assertEqual(r(), yes)
        del yes
        support.gc_collect()
        self.assertEqual(r(), None)
        del r

    def test_properties(self):
        # Testing property...
        class C(object):
            def getx(self):
                return self.__x
            def setx(self, value):
                self.__x = value
            def delx(self):
                del self.__x
            x = property(getx, setx, delx, doc="I'm the x property.")
        a = C()
        self.assertFalse(hasattr(a, "x"))
        a.x = 42
        self.assertEqual(a._C__x, 42)
        self.assertEqual(a.x, 42)
        del a.x
        self.assertFalse(hasattr(a, "x"))
        self.assertFalse(hasattr(a, "_C__x"))
        C.x.__set__(a, 100)
        self.assertEqual(C.x.__get__(a), 100)
        C.x.__delete__(a)
        self.assertFalse(hasattr(a, "x"))

        raw = C.__dict__['x']
        self.assertIsInstance(raw, property)

        attrs = dir(raw)
        self.assertIn("__doc__", attrs)
        self.assertIn("fget", attrs)
        self.assertIn("fset", attrs)
        self.assertIn("fdel", attrs)

        self.assertEqual(raw.__doc__, "I'm the x property.")
        self.assertTrue(raw.fget is C.__dict__['getx'])
        self.assertTrue(raw.fset is C.__dict__['setx'])
        self.assertTrue(raw.fdel is C.__dict__['delx'])

        for attr in "__doc__", "fget", "fset", "fdel":
            try:
                setattr(raw, attr, 42)
            except AttributeError as msg:
                if str(msg).find('readonly') < 0:
                    self.fail("when setting readonly attr %r on a property, "
                              "got unexpected AttributeError msg %r" % (attr, str(msg)))
            else:
                self.fail("expected AttributeError from trying to set readonly %r "
                          "attr on a property" % attr)

        class D(object):
            __getitem__ = property(lambda s: 1/0)

        d = D()
        try:
            for i in d:
                str(i)
        except ZeroDivisionError:
            pass
        else:
            self.fail("expected ZeroDivisionError from bad property")

    @unittest.skipIf(sys.flags.optimize >= 2,
                     "Docstrings are omitted with -O2 and above")
    def test_properties_doc_attrib(self):
        class E(object):
            def getter(self):
                "getter method"
                return 0
            def setter(self_, value):
                "setter method"
                pass
            prop = property(getter)
            self.assertEqual(prop.__doc__, "getter method")
            prop2 = property(fset=setter)
            self.assertEqual(prop2.__doc__, None)

    def test_testcapi_no_segfault(self):
        # this segfaulted in 2.5b2
        try:
            import _testcapi
        except ImportError:
            pass
        else:
            class X(object):
                p = property(_testcapi.test_with_docstring)

    def test_properties_plus(self):
        class C(object):
            foo = property(doc="hello")
            @foo.getter
            def foo(self):
                return self._foo
            @foo.setter
            def foo(self, value):
                self._foo = abs(value)
            @foo.deleter
            def foo(self):
                del self._foo
        c = C()
        self.assertEqual(C.foo.__doc__, "hello")
        self.assertFalse(hasattr(c, "foo"))
        c.foo = -42
        self.assertTrue(hasattr(c, '_foo'))
        self.assertEqual(c._foo, 42)
        self.assertEqual(c.foo, 42)
        del c.foo
        self.assertFalse(hasattr(c, '_foo'))
        self.assertFalse(hasattr(c, "foo"))

        class D(C):
            @C.foo.deleter
            def foo(self):
                try:
                    del self._foo
                except AttributeError:
                    pass
        d = D()
        d.foo = 24
        self.assertEqual(d.foo, 24)
        del d.foo
        del d.foo

        class E(object):
            @property
            def foo(self):
                return self._foo
            @foo.setter
            def foo(self, value):
                raise RuntimeError
            @foo.setter
            def foo(self, value):
                self._foo = abs(value)
            @foo.deleter
            def foo(self, value=None):
                del self._foo

        e = E()
        e.foo = -42
        self.assertEqual(e.foo, 42)
        del e.foo

        class F(E):
            @E.foo.deleter
            def foo(self):
                del self._foo
            @foo.setter
            def foo(self, value):
                self._foo = max(0, value)
        f = F()
        f.foo = -10
        self.assertEqual(f.foo, 0)
        del f.foo

    def test_dict_constructors(self):
        # Testing dict constructor ...
        d = dict()
        self.assertEqual(d, {})
        d = dict({})
        self.assertEqual(d, {})
        d = dict({1: 2, 'a': 'b'})
        self.assertEqual(d, {1: 2, 'a': 'b'})
        self.assertEqual(d, dict(list(d.items())))
        self.assertEqual(d, dict(iter(d.items())))
        d = dict({'one':1, 'two':2})
        self.assertEqual(d, dict(one=1, two=2))
        self.assertEqual(d, dict(**d))
        self.assertEqual(d, dict({"one": 1}, two=2))
        self.assertEqual(d, dict([("two", 2)], one=1))
        self.assertEqual(d, dict([("one", 100), ("two", 200)], **d))
        self.assertEqual(d, dict(**d))

        for badarg in 0, 0, 0j, "0", [0], (0,):
            try:
                dict(badarg)
            except TypeError:
                pass
            except ValueError:
                if badarg == "0":
                    # It's a sequence, and its elements are also sequences (gotta
                    # love strings <wink>), but they aren't of length 2, so this
                    # one seemed better as a ValueError than a TypeError.
                    pass
                else:
                    self.fail("no TypeError from dict(%r)" % badarg)
            else:
                self.fail("no TypeError from dict(%r)" % badarg)

        try:
            dict({}, {})
        except TypeError:
            pass
        else:
            self.fail("no TypeError from dict({}, {})")

        class Mapping:
            # Lacks a .keys() method; will be added later.
            dict = {1:2, 3:4, 'a':1j}

        try:
            dict(Mapping())
        except TypeError:
            pass
        else:
            self.fail("no TypeError from dict(incomplete mapping)")

        Mapping.keys = lambda self: list(self.dict.keys())
        Mapping.__getitem__ = lambda self, i: self.dict[i]
        d = dict(Mapping())
        self.assertEqual(d, Mapping.dict)

        # Init from sequence of iterable objects, each producing a 2-sequence.
        class AddressBookEntry:
            def __init__(self, first, last):
                self.first = first
                self.last = last
            def __iter__(self):
                return iter([self.first, self.last])

        d = dict([AddressBookEntry('Tim', 'Warsaw'),
                  AddressBookEntry('Barry', 'Peters'),
                  AddressBookEntry('Tim', 'Peters'),
                  AddressBookEntry('Barry', 'Warsaw')])
        self.assertEqual(d, {'Barry': 'Warsaw', 'Tim': 'Peters'})

        d = dict(zip(range(4), range(1, 5)))
        self.assertEqual(d, dict([(i, i+1) for i in range(4)]))

        # Bad sequence lengths.
        for bad in [('tooshort',)], [('too', 'long', 'by 1')]:
            try:
                dict(bad)
            except ValueError:
                pass
            else:
                self.fail("no ValueError from dict(%r)" % bad)

    def test_dir(self):
        # Testing dir() ...
        junk = 12
        self.assertEqual(dir(), ['junk', 'self'])
        del junk

        # Just make sure these don't blow up!
        for arg in 2, 2, 2j, 2e0, [2], "2", b"2", (2,), {2:2}, type, self.test_dir:
            dir(arg)

        # Test dir on new-style classes.  Since these have object as a
        # base class, a lot more gets sucked in.
        def interesting(strings):
            return [s for s in strings if not s.startswith('_')]

        class C(object):
            Cdata = 1
            def Cmethod(self): pass

        cstuff = ['Cdata', 'Cmethod']
        self.assertEqual(interesting(dir(C)), cstuff)

        c = C()
        self.assertEqual(interesting(dir(c)), cstuff)
        ## self.assertIn('__self__', dir(C.Cmethod))

        c.cdata = 2
        c.cmethod = lambda self: 0
        self.assertEqual(interesting(dir(c)), cstuff + ['cdata', 'cmethod'])
        ## self.assertIn('__self__', dir(c.Cmethod))

        class A(C):
            Adata = 1
            def Amethod(self): pass

        astuff = ['Adata', 'Amethod'] + cstuff
        self.assertEqual(interesting(dir(A)), astuff)
        ## self.assertIn('__self__', dir(A.Amethod))
        a = A()
        self.assertEqual(interesting(dir(a)), astuff)
        a.adata = 42
        a.amethod = lambda self: 3
        self.assertEqual(interesting(dir(a)), astuff + ['adata', 'amethod'])
        ## self.assertIn('__self__', dir(a.Amethod))

        # Try a module subclass.
        class M(type(sys)):
            pass
        minstance = M("m")
        minstance.b = 2
        minstance.a = 1
        names = [x for x in dir(minstance) if x not in ["__name__", "__doc__"]]
        self.assertEqual(names, ['a', 'b'])

        class M2(M):
            def getdict(self):
                return "Not a dict!"
            __dict__ = property(getdict)

        m2instance = M2("m2")
        m2instance.b = 2
        m2instance.a = 1
        self.assertEqual(m2instance.__dict__, "Not a dict!")
        try:
            dir(m2instance)
        except TypeError:
            pass

        # Two essentially featureless objects, just inheriting stuff from
        # object.
        self.assertEqual(dir(NotImplemented), dir(Ellipsis))
        if support.check_impl_detail():
            # None differs in PyPy: it has a __nonzero__
            self.assertEqual(dir(None), dir(Ellipsis))

        # Nasty test case for proxied objects
        class Wrapper(object):
            def __init__(self, obj):
                self.__obj = obj
            def __repr__(self):
                return "Wrapper(%s)" % repr(self.__obj)
            def __getitem__(self, key):
                return Wrapper(self.__obj[key])
            def __len__(self):
                return len(self.__obj)
            def __getattr__(self, name):
                return Wrapper(getattr(self.__obj, name))

        class C(object):
            def __getclass(self):
                return Wrapper(type(self))
            __class__ = property(__getclass)

        dir(C()) # This used to segfault

    def test_supers(self):
        # Testing super...

        class A(object):
            def meth(self, a):
                return "A(%r)" % a

        self.assertEqual(A().meth(1), "A(1)")

        class B(A):
            def __init__(self):
                self.__super = super(B, self)
            def meth(self, a):
                return "B(%r)" % a + self.__super.meth(a)

        self.assertEqual(B().meth(2), "B(2)A(2)")

        class C(A):
            def meth(self, a):
                return "C(%r)" % a + self.__super.meth(a)
        C._C__super = super(C)

        self.assertEqual(C().meth(3), "C(3)A(3)")

        class D(C, B):
            def meth(self, a):
                return "D(%r)" % a + super(D, self).meth(a)

        self.assertEqual(D().meth(4), "D(4)C(4)B(4)A(4)")

        # Test for subclassing super

        class mysuper(super):
            def __init__(self, *args):
                return super(mysuper, self).__init__(*args)

        class E(D):
            def meth(self, a):
                return "E(%r)" % a + mysuper(E, self).meth(a)

        self.assertEqual(E().meth(5), "E(5)D(5)C(5)B(5)A(5)")

        class F(E):
            def meth(self, a):
                s = self.__super # == mysuper(F, self)
                return "F(%r)[%s]" % (a, s.__class__.__name__) + s.meth(a)
        F._F__super = mysuper(F)

        self.assertEqual(F().meth(6), "F(6)[mysuper]E(6)D(6)C(6)B(6)A(6)")

        # Make sure certain errors are raised

        try:
            super(D, 42)
        except TypeError:
            pass
        else:
            self.fail("shouldn't allow super(D, 42)")

        try:
            super(D, C())
        except TypeError:
            pass
        else:
            self.fail("shouldn't allow super(D, C())")

        try:
            super(D).__get__(12)
        except TypeError:
            pass
        else:
            self.fail("shouldn't allow super(D).__get__(12)")

        try:
            super(D).__get__(C())
        except TypeError:
            pass
        else:
            self.fail("shouldn't allow super(D).__get__(C())")

        # Make sure data descriptors can be overridden and accessed via super
        # (new feature in Python 2.3)

        class DDbase(object):
            def getx(self): return 42
            x = property(getx)

        class DDsub(DDbase):
            def getx(self): return "hello"
            x = property(getx)

        dd = DDsub()
        self.assertEqual(dd.x, "hello")
        self.assertEqual(super(DDsub, dd).x, 42)

        # Ensure that super() lookup of descriptor from classmethod
        # works (SF ID# 743627)

        class Base(object):
            aProp = property(lambda self: "foo")

        class Sub(Base):
            @classmethod
            def test(klass):
                return super(Sub,klass).aProp

        self.assertEqual(Sub.test(), Base.aProp)

        # Verify that super() doesn't allow keyword args
        try:
            super(Base, kw=1)
        except TypeError:
            pass
        else:
            self.assertEqual("super shouldn't accept keyword args")

    def test_basic_inheritance(self):
        # Testing inheritance from basic types...

        class hexint(int):
            def __repr__(self):
                return hex(self)
            def __add__(self, other):
                return hexint(int.__add__(self, other))
            # (Note that overriding __radd__ doesn't work,
            # because the int type gets first dibs.)
        self.assertEqual(repr(hexint(7) + 9), "0x10")
        self.assertEqual(repr(hexint(1000) + 7), "0x3ef")
        a = hexint(12345)
        self.assertEqual(a, 12345)
        self.assertEqual(int(a), 12345)
        self.assertTrue(int(a).__class__ is int)
        self.assertEqual(hash(a), hash(12345))
        self.assertTrue((+a).__class__ is int)
        self.assertTrue((a >> 0).__class__ is int)
        self.assertTrue((a << 0).__class__ is int)
        self.assertTrue((hexint(0) << 12).__class__ is int)
        self.assertTrue((hexint(0) >> 12).__class__ is int)

        class octlong(int):
            __slots__ = []
            def __str__(self):
                return oct(self)
            def __add__(self, other):
                return self.__class__(super(octlong, self).__add__(other))
            __radd__ = __add__
        self.assertEqual(str(octlong(3) + 5), "0o10")
        # (Note that overriding __radd__ here only seems to work
        # because the example uses a short int left argument.)
        self.assertEqual(str(5 + octlong(3000)), "0o5675")
        a = octlong(12345)
        self.assertEqual(a, 12345)
        self.assertEqual(int(a), 12345)
        self.assertEqual(hash(a), hash(12345))
        self.assertTrue(int(a).__class__ is int)
        self.assertTrue((+a).__class__ is int)
        self.assertTrue((-a).__class__ is int)
        self.assertTrue((-octlong(0)).__class__ is int)
        self.assertTrue((a >> 0).__class__ is int)
        self.assertTrue((a << 0).__class__ is int)
        self.assertTrue((a - 0).__class__ is int)
        self.assertTrue((a * 1).__class__ is int)
        self.assertTrue((a ** 1).__class__ is int)
        self.assertTrue((a // 1).__class__ is int)
        self.assertTrue((1 * a).__class__ is int)
        self.assertTrue((a | 0).__class__ is int)
        self.assertTrue((a ^ 0).__class__ is int)
        self.assertTrue((a & -1).__class__ is int)
        self.assertTrue((octlong(0) << 12).__class__ is int)
        self.assertTrue((octlong(0) >> 12).__class__ is int)
        self.assertTrue(abs(octlong(0)).__class__ is int)

        # Because octlong overrides __add__, we can't check the absence of +0
        # optimizations using octlong.
        class longclone(int):
            pass
        a = longclone(1)
        self.assertTrue((a + 0).__class__ is int)
        self.assertTrue((0 + a).__class__ is int)

        # Check that negative clones don't segfault
        a = longclone(-1)
        self.assertEqual(a.__dict__, {})
        self.assertEqual(int(a), -1)  # self.assertTrue PyNumber_Long() copies the sign bit

        class precfloat(float):
            __slots__ = ['prec']
            def __init__(self, value=0.0, prec=12):
                self.prec = int(prec)
            def __repr__(self):
                return "%.*g" % (self.prec, self)
        self.assertEqual(repr(precfloat(1.1)), "1.1")
        a = precfloat(12345)
        self.assertEqual(a, 12345.0)
        self.assertEqual(float(a), 12345.0)
        self.assertTrue(float(a).__class__ is float)
        self.assertEqual(hash(a), hash(12345.0))
        self.assertTrue((+a).__class__ is float)

        class madcomplex(complex):
            def __repr__(self):
                return "%.17gj%+.17g" % (self.imag, self.real)
        a = madcomplex(-3, 4)
        self.assertEqual(repr(a), "4j-3")
        base = complex(-3, 4)
        self.assertEqual(base.__class__, complex)
        self.assertEqual(a, base)
        self.assertEqual(complex(a), base)
        self.assertEqual(complex(a).__class__, complex)
        a = madcomplex(a)  # just trying another form of the constructor
        self.assertEqual(repr(a), "4j-3")
        self.assertEqual(a, base)
        self.assertEqual(complex(a), base)
        self.assertEqual(complex(a).__class__, complex)
        self.assertEqual(hash(a), hash(base))
        self.assertEqual((+a).__class__, complex)
        self.assertEqual((a + 0).__class__, complex)
        self.assertEqual(a + 0, base)
        self.assertEqual((a - 0).__class__, complex)
        self.assertEqual(a - 0, base)
        self.assertEqual((a * 1).__class__, complex)
        self.assertEqual(a * 1, base)
        self.assertEqual((a / 1).__class__, complex)
        self.assertEqual(a / 1, base)

        class madtuple(tuple):
            _rev = None
            def rev(self):
                if self._rev is not None:
                    return self._rev
                L = list(self)
                L.reverse()
                self._rev = self.__class__(L)
                return self._rev
        a = madtuple((1,2,3,4,5,6,7,8,9,0))
        self.assertEqual(a, (1,2,3,4,5,6,7,8,9,0))
        self.assertEqual(a.rev(), madtuple((0,9,8,7,6,5,4,3,2,1)))
        self.assertEqual(a.rev().rev(), madtuple((1,2,3,4,5,6,7,8,9,0)))
        for i in range(512):
            t = madtuple(range(i))
            u = t.rev()
            v = u.rev()
            self.assertEqual(v, t)
        a = madtuple((1,2,3,4,5))
        self.assertEqual(tuple(a), (1,2,3,4,5))
        self.assertTrue(tuple(a).__class__ is tuple)
        self.assertEqual(hash(a), hash((1,2,3,4,5)))
        self.assertTrue(a[:].__class__ is tuple)
        self.assertTrue((a * 1).__class__ is tuple)
        self.assertTrue((a * 0).__class__ is tuple)
        self.assertTrue((a + ()).__class__ is tuple)
        a = madtuple(())
        self.assertEqual(tuple(a), ())
        self.assertTrue(tuple(a).__class__ is tuple)
        self.assertTrue((a + a).__class__ is tuple)
        self.assertTrue((a * 0).__class__ is tuple)
        self.assertTrue((a * 1).__class__ is tuple)
        self.assertTrue((a * 2).__class__ is tuple)
        self.assertTrue(a[:].__class__ is tuple)

        class madstring(str):
            _rev = None
            def rev(self):
                if self._rev is not None:
                    return self._rev
                L = list(self)
                L.reverse()
                self._rev = self.__class__("".join(L))
                return self._rev
        s = madstring("abcdefghijklmnopqrstuvwxyz")
        self.assertEqual(s, "abcdefghijklmnopqrstuvwxyz")
        self.assertEqual(s.rev(), madstring("zyxwvutsrqponmlkjihgfedcba"))
        self.assertEqual(s.rev().rev(), madstring("abcdefghijklmnopqrstuvwxyz"))
        for i in range(256):
            s = madstring("".join(map(chr, range(i))))
            t = s.rev()
            u = t.rev()
            self.assertEqual(u, s)
        s = madstring("12345")
        self.assertEqual(str(s), "12345")
        self.assertTrue(str(s).__class__ is str)

        base = "\x00" * 5
        s = madstring(base)
        self.assertEqual(s, base)
        self.assertEqual(str(s), base)
        self.assertTrue(str(s).__class__ is str)
        self.assertEqual(hash(s), hash(base))
        self.assertEqual({s: 1}[base], 1)
        self.assertEqual({base: 1}[s], 1)
        self.assertTrue((s + "").__class__ is str)
        self.assertEqual(s + "", base)
        self.assertTrue(("" + s).__class__ is str)
        self.assertEqual("" + s, base)
        self.assertTrue((s * 0).__class__ is str)
        self.assertEqual(s * 0, "")
        self.assertTrue((s * 1).__class__ is str)
        self.assertEqual(s * 1, base)
        self.assertTrue((s * 2).__class__ is str)
        self.assertEqual(s * 2, base + base)
        self.assertTrue(s[:].__class__ is str)
        self.assertEqual(s[:], base)
        self.assertTrue(s[0:0].__class__ is str)
        self.assertEqual(s[0:0], "")
        self.assertTrue(s.strip().__class__ is str)
        self.assertEqual(s.strip(), base)
        self.assertTrue(s.lstrip().__class__ is str)
        self.assertEqual(s.lstrip(), base)
        self.assertTrue(s.rstrip().__class__ is str)
        self.assertEqual(s.rstrip(), base)
        identitytab = {}
        self.assertTrue(s.translate(identitytab).__class__ is str)
        self.assertEqual(s.translate(identitytab), base)
        self.assertTrue(s.replace("x", "x").__class__ is str)
        self.assertEqual(s.replace("x", "x"), base)
        self.assertTrue(s.ljust(len(s)).__class__ is str)
        self.assertEqual(s.ljust(len(s)), base)
        self.assertTrue(s.rjust(len(s)).__class__ is str)
        self.assertEqual(s.rjust(len(s)), base)
        self.assertTrue(s.center(len(s)).__class__ is str)
        self.assertEqual(s.center(len(s)), base)
        self.assertTrue(s.lower().__class__ is str)
        self.assertEqual(s.lower(), base)

        class madunicode(str):
            _rev = None
            def rev(self):
                if self._rev is not None:
                    return self._rev
                L = list(self)
                L.reverse()
                self._rev = self.__class__("".join(L))
                return self._rev
        u = madunicode("ABCDEF")
        self.assertEqual(u, "ABCDEF")
        self.assertEqual(u.rev(), madunicode("FEDCBA"))
        self.assertEqual(u.rev().rev(), madunicode("ABCDEF"))
        base = "12345"
        u = madunicode(base)
        self.assertEqual(str(u), base)
        self.assertTrue(str(u).__class__ is str)
        self.assertEqual(hash(u), hash(base))
        self.assertEqual({u: 1}[base], 1)
        self.assertEqual({base: 1}[u], 1)
        self.assertTrue(u.strip().__class__ is str)
        self.assertEqual(u.strip(), base)
        self.assertTrue(u.lstrip().__class__ is str)
        self.assertEqual(u.lstrip(), base)
        self.assertTrue(u.rstrip().__class__ is str)
        self.assertEqual(u.rstrip(), base)
        self.assertTrue(u.replace("x", "x").__class__ is str)
        self.assertEqual(u.replace("x", "x"), base)
        self.assertTrue(u.replace("xy", "xy").__class__ is str)
        self.assertEqual(u.replace("xy", "xy"), base)
        self.assertTrue(u.center(len(u)).__class__ is str)
        self.assertEqual(u.center(len(u)), base)
        self.assertTrue(u.ljust(len(u)).__class__ is str)
        self.assertEqual(u.ljust(len(u)), base)
        self.assertTrue(u.rjust(len(u)).__class__ is str)
        self.assertEqual(u.rjust(len(u)), base)
        self.assertTrue(u.lower().__class__ is str)
        self.assertEqual(u.lower(), base)
        self.assertTrue(u.upper().__class__ is str)
        self.assertEqual(u.upper(), base)
        self.assertTrue(u.capitalize().__class__ is str)
        self.assertEqual(u.capitalize(), base)
        self.assertTrue(u.title().__class__ is str)
        self.assertEqual(u.title(), base)
        self.assertTrue((u + "").__class__ is str)
        self.assertEqual(u + "", base)
        self.assertTrue(("" + u).__class__ is str)
        self.assertEqual("" + u, base)
        self.assertTrue((u * 0).__class__ is str)
        self.assertEqual(u * 0, "")
        self.assertTrue((u * 1).__class__ is str)
        self.assertEqual(u * 1, base)
        self.assertTrue((u * 2).__class__ is str)
        self.assertEqual(u * 2, base + base)
        self.assertTrue(u[:].__class__ is str)
        self.assertEqual(u[:], base)
        self.assertTrue(u[0:0].__class__ is str)
        self.assertEqual(u[0:0], "")

        class sublist(list):
            pass
        a = sublist(range(5))
        self.assertEqual(a, list(range(5)))
        a.append("hello")
        self.assertEqual(a, list(range(5)) + ["hello"])
        a[5] = 5
        self.assertEqual(a, list(range(6)))
        a.extend(range(6, 20))
        self.assertEqual(a, list(range(20)))
        a[-5:] = []
        self.assertEqual(a, list(range(15)))
        del a[10:15]
        self.assertEqual(len(a), 10)
        self.assertEqual(a, list(range(10)))
        self.assertEqual(list(a), list(range(10)))
        self.assertEqual(a[0], 0)
        self.assertEqual(a[9], 9)
        self.assertEqual(a[-10], 0)
        self.assertEqual(a[-1], 9)
        self.assertEqual(a[:5], list(range(5)))

        ## class CountedInput(file):
        ##    """Counts lines read by self.readline().
        ##
        ##     self.lineno is the 0-based ordinal of the last line read, up to
        ##     a maximum of one greater than the number of lines in the file.
        ##
        ##     self.ateof is true if and only if the final "" line has been read,
        ##     at which point self.lineno stops incrementing, and further calls
        ##     to readline() continue to return "".
        ##     """
        ##
        ##     lineno = 0
        ##     ateof = 0
        ##     def readline(self):
        ##         if self.ateof:
        ##             return ""
        ##         s = file.readline(self)
        ##         # Next line works too.
        ##         # s = super(CountedInput, self).readline()
        ##         self.lineno += 1
        ##         if s == "":
        ##             self.ateof = 1
        ##        return s
        ##
        ## f = file(name=support.TESTFN, mode='w')
        ## lines = ['a\n', 'b\n', 'c\n']
        ## try:
        ##     f.writelines(lines)
        ##     f.close()
        ##     f = CountedInput(support.TESTFN)
        ##     for (i, expected) in zip(range(1, 5) + [4], lines + 2 * [""]):
        ##         got = f.readline()
        ##         self.assertEqual(expected, got)
        ##         self.assertEqual(f.lineno, i)
        ##         self.assertEqual(f.ateof, (i > len(lines)))
        ##     f.close()
        ## finally:
        ##     try:
        ##         f.close()
        ##     except:
        ##         pass
        ##     support.unlink(support.TESTFN)

    def test_keywords(self):
        # Testing keyword args to basic type constructors ...
        self.assertEqual(int(x=1), 1)
        self.assertEqual(float(x=2), 2.0)
        self.assertEqual(int(x=3), 3)
        self.assertEqual(complex(imag=42, real=666), complex(666, 42))
        self.assertEqual(str(object=500), '500')
        self.assertEqual(str(object=b'abc', errors='strict'), 'abc')
        self.assertEqual(tuple(sequence=range(3)), (0, 1, 2))
        self.assertEqual(list(sequence=(0, 1, 2)), list(range(3)))
        # note: as of Python 2.3, dict() no longer has an "items" keyword arg

        for constructor in (int, float, int, complex, str, str,
                            tuple, list):
            try:
                constructor(bogus_keyword_arg=1)
            except TypeError:
                pass
            else:
                self.fail("expected TypeError from bogus keyword argument to %r"
                            % constructor)

    def test_str_subclass_as_dict_key(self):
        # Testing a str subclass used as dict key ..

        class cistr(str):
            """Sublcass of str that computes __eq__ case-insensitively.

            Also computes a hash code of the string in canonical form.
            """

            def __init__(self, value):
                self.canonical = value.lower()
                self.hashcode = hash(self.canonical)

            def __eq__(self, other):
                if not isinstance(other, cistr):
                    other = cistr(other)
                return self.canonical == other.canonical

            def __hash__(self):
                return self.hashcode

        self.assertEqual(cistr('ABC'), 'abc')
        self.assertEqual('aBc', cistr('ABC'))
        self.assertEqual(str(cistr('ABC')), 'ABC')

        d = {cistr('one'): 1, cistr('two'): 2, cistr('tHree'): 3}
        self.assertEqual(d[cistr('one')], 1)
        self.assertEqual(d[cistr('tWo')], 2)
        self.assertEqual(d[cistr('THrEE')], 3)
        self.assertIn(cistr('ONe'), d)
        self.assertEqual(d.get(cistr('thrEE')), 3)

    def test_classic_comparisons(self):
        # Testing classic comparisons...
        class classic:
            pass

        for base in (classic, int, object):
            class C(base):
                def __init__(self, value):
                    self.value = int(value)
                def __eq__(self, other):
                    if isinstance(other, C):
                        return self.value == other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value == other
                    return NotImplemented
                def __ne__(self, other):
                    if isinstance(other, C):
                        return self.value != other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value != other
                    return NotImplemented
                def __lt__(self, other):
                    if isinstance(other, C):
                        return self.value < other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value < other
                    return NotImplemented
                def __le__(self, other):
                    if isinstance(other, C):
                        return self.value <= other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value <= other
                    return NotImplemented
                def __gt__(self, other):
                    if isinstance(other, C):
                        return self.value > other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value > other
                    return NotImplemented
                def __ge__(self, other):
                    if isinstance(other, C):
                        return self.value >= other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value >= other
                    return NotImplemented

            c1 = C(1)
            c2 = C(2)
            c3 = C(3)
            self.assertEqual(c1, 1)
            c = {1: c1, 2: c2, 3: c3}
            for x in 1, 2, 3:
                for y in 1, 2, 3:
                    for op in "<", "<=", "==", "!=", ">", ">=":
                        self.assertTrue(eval("c[x] %s c[y]" % op) ==
                                     eval("x %s y" % op),
                                     "x=%d, y=%d" % (x, y))
                        self.assertTrue(eval("c[x] %s y" % op) ==
                                     eval("x %s y" % op),
                                     "x=%d, y=%d" % (x, y))
                        self.assertTrue(eval("x %s c[y]" % op) ==
                                     eval("x %s y" % op),
                                     "x=%d, y=%d" % (x, y))

    def test_rich_comparisons(self):
        # Testing rich comparisons...
        class Z(complex):
            pass
        z = Z(1)
        self.assertEqual(z, 1+0j)
        self.assertEqual(1+0j, z)
        class ZZ(complex):
            def __eq__(self, other):
                try:
                    return abs(self - other) <= 1e-6
                except:
                    return NotImplemented
        zz = ZZ(1.0000003)
        self.assertEqual(zz, 1+0j)
        self.assertEqual(1+0j, zz)

        class classic:
            pass
        for base in (classic, int, object, list):
            class C(base):
                def __init__(self, value):
                    self.value = int(value)
                def __cmp__(self_, other):
                    self.fail("shouldn't call __cmp__")
                def __eq__(self, other):
                    if isinstance(other, C):
                        return self.value == other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value == other
                    return NotImplemented
                def __ne__(self, other):
                    if isinstance(other, C):
                        return self.value != other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value != other
                    return NotImplemented
                def __lt__(self, other):
                    if isinstance(other, C):
                        return self.value < other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value < other
                    return NotImplemented
                def __le__(self, other):
                    if isinstance(other, C):
                        return self.value <= other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value <= other
                    return NotImplemented
                def __gt__(self, other):
                    if isinstance(other, C):
                        return self.value > other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value > other
                    return NotImplemented
                def __ge__(self, other):
                    if isinstance(other, C):
                        return self.value >= other.value
                    if isinstance(other, int) or isinstance(other, int):
                        return self.value >= other
                    return NotImplemented
            c1 = C(1)
            c2 = C(2)
            c3 = C(3)
            self.assertEqual(c1, 1)
            c = {1: c1, 2: c2, 3: c3}
            for x in 1, 2, 3:
                for y in 1, 2, 3:
                    for op in "<", "<=", "==", "!=", ">", ">=":
                        self.assertTrue(eval("c[x] %s c[y]" % op) == eval("x %s y" % op),
                               "x=%d, y=%d" % (x, y))
                        self.assertTrue(eval("c[x] %s y" % op) == eval("x %s y" % op),
                               "x=%d, y=%d" % (x, y))
                        self.assertTrue(eval("x %s c[y]" % op) == eval("x %s y" % op),
                               "x=%d, y=%d" % (x, y))

    def test_descrdoc(self):
        # Testing descriptor doc strings...
        from _io import FileIO
        def check(descr, what):
            self.assertEqual(descr.__doc__, what)
        check(FileIO.closed, "True if the file is closed") # getset descriptor
        check(complex.real, "the real part of a complex number") # member descriptor

    def test_doc_descriptor(self):
        # Testing __doc__ descriptor...
        # SF bug 542984
        class DocDescr(object):
            def __get__(self, object, otype):
                if object:
                    object = object.__class__.__name__ + ' instance'
                if otype:
                    otype = otype.__name__
                return 'object=%s; type=%s' % (object, otype)
        class OldClass:
            __doc__ = DocDescr()
        class NewClass(object):
            __doc__ = DocDescr()
        self.assertEqual(OldClass.__doc__, 'object=None; type=OldClass')
        self.assertEqual(OldClass().__doc__, 'object=OldClass instance; type=OldClass')
        self.assertEqual(NewClass.__doc__, 'object=None; type=NewClass')
        self.assertEqual(NewClass().__doc__, 'object=NewClass instance; type=NewClass')

    def test_set_class(self):
        # Testing __class__ assignment...
        class C(object): pass
        class D(object): pass
        class E(object): pass
        class F(D, E): pass
        for cls in C, D, E, F:
            for cls2 in C, D, E, F:
                x = cls()
                x.__class__ = cls2
                self.assertTrue(x.__class__ is cls2)
                x.__class__ = cls
                self.assertTrue(x.__class__ is cls)
        def cant(x, C):
            try:
                x.__class__ = C
            except TypeError:
                pass
            else:
                self.fail("shouldn't allow %r.__class__ = %r" % (x, C))
            try:
                delattr(x, "__class__")
            except (TypeError, AttributeError):
                pass
            else:
                self.fail("shouldn't allow del %r.__class__" % x)
        cant(C(), list)
        cant(list(), C)
        cant(C(), 1)
        cant(C(), object)
        cant(object(), list)
        cant(list(), object)
        class Int(int): __slots__ = []
        cant(2, Int)
        cant(Int(), int)
        cant(True, int)
        cant(2, bool)
        o = object()
        cant(o, type(1))
        cant(o, type(None))
        del o
        class G(object):
            __slots__ = ["a", "b"]
        class H(object):
            __slots__ = ["b", "a"]
        class I(object):
            __slots__ = ["a", "b"]
        class J(object):
            __slots__ = ["c", "b"]
        class K(object):
            __slots__ = ["a", "b", "d"]
        class L(H):
            __slots__ = ["e"]
        class M(I):
            __slots__ = ["e"]
        class N(J):
            __slots__ = ["__weakref__"]
        class P(J):
            __slots__ = ["__dict__"]
        class Q(J):
            pass
        class R(J):
            __slots__ = ["__dict__", "__weakref__"]

        for cls, cls2 in ((G, H), (G, I), (I, H), (Q, R), (R, Q)):
            x = cls()
            x.a = 1
            x.__class__ = cls2
            self.assertTrue(x.__class__ is cls2,
                   "assigning %r as __class__ for %r silently failed" % (cls2, x))
            self.assertEqual(x.a, 1)
            x.__class__ = cls
            self.assertTrue(x.__class__ is cls,
                   "assigning %r as __class__ for %r silently failed" % (cls, x))
            self.assertEqual(x.a, 1)
        for cls in G, J, K, L, M, N, P, R, list, Int:
            for cls2 in G, J, K, L, M, N, P, R, list, Int:
                if cls is cls2:
                    continue
                cant(cls(), cls2)

        # Issue5283: when __class__ changes in __del__, the wrong
        # type gets DECREF'd.
        class O(object):
            pass
        class A(object):
            def __del__(self):
                self.__class__ = O
        l = [A() for x in range(100)]
        del l

    def test_set_dict(self):
        # Testing __dict__ assignment...
        class C(object): pass
        a = C()
        a.__dict__ = {'b': 1}
        self.assertEqual(a.b, 1)
        def cant(x, dict):
            try:
                x.__dict__ = dict
            except (AttributeError, TypeError):
                pass
            else:
                self.fail("shouldn't allow %r.__dict__ = %r" % (x, dict))
        cant(a, None)
        cant(a, [])
        cant(a, 1)
        del a.__dict__ # Deleting __dict__ is allowed

        class Base(object):
            pass
        def verify_dict_readonly(x):
            """
            x has to be an instance of a class inheriting from Base.
            """
            cant(x, {})
            try:
                del x.__dict__
            except (AttributeError, TypeError):
                pass
            else:
                self.fail("shouldn't allow del %r.__dict__" % x)
            dict_descr = Base.__dict__["__dict__"]
            try:
                dict_descr.__set__(x, {})
            except (AttributeError, TypeError):
                pass
            else:
                self.fail("dict_descr allowed access to %r's dict" % x)

        # Classes don't allow __dict__ assignment and have readonly dicts
        class Meta1(type, Base):
            pass
        class Meta2(Base, type):
            pass
        class D(object, metaclass=Meta1):
            pass
        class E(object, metaclass=Meta2):
            pass
        for cls in C, D, E:
            verify_dict_readonly(cls)
            class_dict = cls.__dict__
            try:
                class_dict["spam"] = "eggs"
            except TypeError:
                pass
            else:
                self.fail("%r's __dict__ can be modified" % cls)

        # Modules also disallow __dict__ assignment
        class Module1(types.ModuleType, Base):
            pass
        class Module2(Base, types.ModuleType):
            pass
        for ModuleType in Module1, Module2:
            mod = ModuleType("spam")
            verify_dict_readonly(mod)
            mod.__dict__["spam"] = "eggs"

        # Exception's __dict__ can be replaced, but not deleted
        # (at least not any more than regular exception's __dict__ can
        # be deleted; on CPython it is not the case, whereas on PyPy they
        # can, just like any other new-style instance's __dict__.)
        def can_delete_dict(e):
            try:
                del e.__dict__
            except (TypeError, AttributeError):
                return False
            else:
                return True
        class Exception1(Exception, Base):
            pass
        class Exception2(Base, Exception):
            pass
        for ExceptionType in Exception, Exception1, Exception2:
            e = ExceptionType()
            e.__dict__ = {"a": 1}
            self.assertEqual(e.a, 1)
            self.assertEqual(can_delete_dict(e), can_delete_dict(ValueError()))

    def test_pickles(self):
        # Testing pickling and copying new-style classes and objects...
        import pickle

        def sorteditems(d):
            L = list(d.items())
            L.sort()
            return L

        global C
        class C(object):
            def __init__(self, a, b):
                super(C, self).__init__()
                self.a = a
                self.b = b
            def __repr__(self):
                return "C(%r, %r)" % (self.a, self.b)

        global C1
        class C1(list):
            def __new__(cls, a, b):
                return super(C1, cls).__new__(cls)
            def __getnewargs__(self):
                return (self.a, self.b)
            def __init__(self, a, b):
                self.a = a
                self.b = b
            def __repr__(self):
                return "C1(%r, %r)<%r>" % (self.a, self.b, list(self))

        global C2
        class C2(int):
            def __new__(cls, a, b, val=0):
                return super(C2, cls).__new__(cls, val)
            def __getnewargs__(self):
                return (self.a, self.b, int(self))
            def __init__(self, a, b, val=0):
                self.a = a
                self.b = b
            def __repr__(self):
                return "C2(%r, %r)<%r>" % (self.a, self.b, int(self))

        global C3
        class C3(object):
            def __init__(self, foo):
                self.foo = foo
            def __getstate__(self):
                return self.foo
            def __setstate__(self, foo):
                self.foo = foo

        global C4classic, C4
        class C4classic: # classic
            pass
        class C4(C4classic, object): # mixed inheritance
            pass

        for bin in 0, 1:
            for cls in C, C1, C2:
                s = pickle.dumps(cls, bin)
                cls2 = pickle.loads(s)
                self.assertTrue(cls2 is cls)

            a = C1(1, 2); a.append(42); a.append(24)
            b = C2("hello", "world", 42)
            s = pickle.dumps((a, b), bin)
            x, y = pickle.loads(s)
            self.assertEqual(x.__class__, a.__class__)
            self.assertEqual(sorteditems(x.__dict__), sorteditems(a.__dict__))
            self.assertEqual(y.__class__, b.__class__)
            self.assertEqual(sorteditems(y.__dict__), sorteditems(b.__dict__))
            self.assertEqual(repr(x), repr(a))
            self.assertEqual(repr(y), repr(b))
            # Test for __getstate__ and __setstate__ on new style class
            u = C3(42)
            s = pickle.dumps(u, bin)
            v = pickle.loads(s)
            self.assertEqual(u.__class__, v.__class__)
            self.assertEqual(u.foo, v.foo)
            # Test for picklability of hybrid class
            u = C4()
            u.foo = 42
            s = pickle.dumps(u, bin)
            v = pickle.loads(s)
            self.assertEqual(u.__class__, v.__class__)
            self.assertEqual(u.foo, v.foo)

        # Testing copy.deepcopy()
        import copy
        for cls in C, C1, C2:
            cls2 = copy.deepcopy(cls)
            self.assertTrue(cls2 is cls)

        a = C1(1, 2); a.append(42); a.append(24)
        b = C2("hello", "world", 42)
        x, y = copy.deepcopy((a, b))
        self.assertEqual(x.__class__, a.__class__)
        self.assertEqual(sorteditems(x.__dict__), sorteditems(a.__dict__))
        self.assertEqual(y.__class__, b.__class__)
        self.assertEqual(sorteditems(y.__dict__), sorteditems(b.__dict__))
        self.assertEqual(repr(x), repr(a))
        self.assertEqual(repr(y), repr(b))

    def test_pickle_slots(self):
        # Testing pickling of classes with __slots__ ...
        import pickle
        # Pickling of classes with __slots__ but without __getstate__ should fail
        # (if using protocol 0 or 1)
        global B, C, D, E
        class B(object):
            pass
        for base in [object, B]:
            class C(base):
                __slots__ = ['a']
            class D(C):
                pass
            try:
                pickle.dumps(C(), 0)
            except TypeError:
                pass
            else:
                self.fail("should fail: pickle C instance - %s" % base)
            try:
                pickle.dumps(C(), 0)
            except TypeError:
                pass
            else:
                self.fail("should fail: pickle D instance - %s" % base)
            # Give C a nice generic __getstate__ and __setstate__
            class C(base):
                __slots__ = ['a']
                def __getstate__(self):
                    try:
                        d = self.__dict__.copy()
                    except AttributeError:
                        d = {}
                    for cls in self.__class__.__mro__:
                        for sn in cls.__dict__.get('__slots__', ()):
                            try:
                                d[sn] = getattr(self, sn)
                            except AttributeError:
                                pass
                    return d
                def __setstate__(self, d):
                    for k, v in list(d.items()):
                        setattr(self, k, v)
            class D(C):
                pass
            # Now it should work
            x = C()
            y = pickle.loads(pickle.dumps(x))
            self.assertEqual(hasattr(y, 'a'), 0)
            x.a = 42
            y = pickle.loads(pickle.dumps(x))
            self.assertEqual(y.a, 42)
            x = D()
            x.a = 42
            x.b = 100
            y = pickle.loads(pickle.dumps(x))
            self.assertEqual(y.a + y.b, 142)
            # A subclass that adds a slot should also work
            class E(C):
                __slots__ = ['b']
            x = E()
            x.a = 42
            x.b = "foo"
            y = pickle.loads(pickle.dumps(x))
            self.assertEqual(y.a, x.a)
            self.assertEqual(y.b, x.b)

    def test_binary_operator_override(self):
        # Testing overrides of binary operations...
        class I(int):
            def __repr__(self):
                return "I(%r)" % int(self)
            def __add__(self, other):
                return I(int(self) + int(other))
            __radd__ = __add__
            def __pow__(self, other, mod=None):
                if mod is None:
                    return I(pow(int(self), int(other)))
                else:
                    return I(pow(int(self), int(other), int(mod)))
            def __rpow__(self, other, mod=None):
                if mod is None:
                    return I(pow(int(other), int(self), mod))
                else:
                    return I(pow(int(other), int(self), int(mod)))

        self.assertEqual(repr(I(1) + I(2)), "I(3)")
        self.assertEqual(repr(I(1) + 2), "I(3)")
        self.assertEqual(repr(1 + I(2)), "I(3)")
        self.assertEqual(repr(I(2) ** I(3)), "I(8)")
        self.assertEqual(repr(2 ** I(3)), "I(8)")
        self.assertEqual(repr(I(2) ** 3), "I(8)")
        self.assertEqual(repr(pow(I(2), I(3), I(5))), "I(3)")
        class S(str):
            def __eq__(self, other):
                return self.lower() == other.lower()

    def test_subclass_propagation(self):
        # Testing propagation of slot functions to subclasses...
        class A(object):
            pass
        class B(A):
            pass
        class C(A):
            pass
        class D(B, C):
            pass
        d = D()
        orig_hash = hash(d) # related to id(d) in platform-dependent ways
        A.__hash__ = lambda self: 42
        self.assertEqual(hash(d), 42)
        C.__hash__ = lambda self: 314
        self.assertEqual(hash(d), 314)
        B.__hash__ = lambda self: 144
        self.assertEqual(hash(d), 144)
        D.__hash__ = lambda self: 100
        self.assertEqual(hash(d), 100)
        D.__hash__ = None
        self.assertRaises(TypeError, hash, d)
        del D.__hash__
        self.assertEqual(hash(d), 144)
        B.__hash__ = None
        self.assertRaises(TypeError, hash, d)
        del B.__hash__
        self.assertEqual(hash(d), 314)
        C.__hash__ = None
        self.assertRaises(TypeError, hash, d)
        del C.__hash__
        self.assertEqual(hash(d), 42)
        A.__hash__ = None
        self.assertRaises(TypeError, hash, d)
        del A.__hash__
        self.assertEqual(hash(d), orig_hash)
        d.foo = 42
        d.bar = 42
        self.assertEqual(d.foo, 42)
        self.assertEqual(d.bar, 42)
        def __getattribute__(self, name):
            if name == "foo":
                return 24
            return object.__getattribute__(self, name)
        A.__getattribute__ = __getattribute__
        self.assertEqual(d.foo, 24)
        self.assertEqual(d.bar, 42)
        def __getattr__(self, name):
            if name in ("spam", "foo", "bar"):
                return "hello"
            raise AttributeError(name)
        B.__getattr__ = __getattr__
        self.assertEqual(d.spam, "hello")
        self.assertEqual(d.foo, 24)
        self.assertEqual(d.bar, 42)
        del A.__getattribute__
        self.assertEqual(d.foo, 42)
        del d.foo
        self.assertEqual(d.foo, "hello")
        self.assertEqual(d.bar, 42)
        del B.__getattr__
        try:
            d.foo
        except AttributeError:
            pass
        else:
            self.fail("d.foo should be undefined now")

        # Test a nasty bug in recurse_down_subclasses()
        class A(object):
            pass
        class B(A):
            pass
        del B
        support.gc_collect()
        A.__setitem__ = lambda *a: None # crash

    def test_buffer_inheritance(self):
        # Testing that buffer interface is inherited ...

        import binascii
        # SF bug [#470040] ParseTuple t# vs subclasses.

        class MyBytes(bytes):
            pass
        base = b'abc'
        m = MyBytes(base)
        # b2a_hex uses the buffer interface to get its argument's value, via
        # PyArg_ParseTuple 't#' code.
        self.assertEqual(binascii.b2a_hex(m), binascii.b2a_hex(base))

        class MyInt(int):
            pass
        m = MyInt(42)
        try:
            binascii.b2a_hex(m)
            self.fail('subclass of int should not have a buffer interface')
        except TypeError:
            pass

    def test_str_of_str_subclass(self):
        # Testing __str__ defined in subclass of str ...
        import binascii
        import io

        class octetstring(str):
            def __str__(self):
                return binascii.b2a_hex(self.encode('ascii')).decode("ascii")
            def __repr__(self):
                return self + " repr"

        o = octetstring('A')
        self.assertEqual(type(o), octetstring)
        self.assertEqual(type(str(o)), str)
        self.assertEqual(type(repr(o)), str)
        self.assertEqual(ord(o), 0x41)
        self.assertEqual(str(o), '41')
        self.assertEqual(repr(o), 'A repr')
        self.assertEqual(o.__str__(), '41')
        self.assertEqual(o.__repr__(), 'A repr')

        capture = io.StringIO()
        # Calling str() or not exercises different internal paths.
        print(o, file=capture)
        print(str(o), file=capture)
        self.assertEqual(capture.getvalue(), '41\n41\n')
        capture.close()

    def test_keyword_arguments(self):
        # Testing keyword arguments to __init__, __call__...
        def f(a): return a
        self.assertEqual(f.__call__(a=42), 42)
        a = []
        list.__init__(a, sequence=[0, 1, 2])
        self.assertEqual(a, [0, 1, 2])

    def test_recursive_call(self):
        # Testing recursive __call__() by setting to instance of class...
        class A(object):
            pass

        A.__call__ = A()
        try:
            A()()
        except RuntimeError:
            pass
        else:
            self.fail("Recursion limit should have been reached for __call__()")

    def test_delete_hook(self):
        # Testing __del__ hook...
        log = []
        class C(object):
            def __del__(self):
                log.append(1)
        c = C()
        self.assertEqual(log, [])
        del c
        support.gc_collect()
        self.assertEqual(log, [1])

        class D(object): pass
        d = D()
        try: del d[0]
        except TypeError: pass
        else: self.fail("invalid del() didn't raise TypeError")

    def test_hash_inheritance(self):
        # Testing hash of mutable subclasses...

        class mydict(dict):
            pass
        d = mydict()
        try:
            hash(d)
        except TypeError:
            pass
        else:
            self.fail("hash() of dict subclass should fail")

        class mylist(list):
            pass
        d = mylist()
        try:
            hash(d)
        except TypeError:
            pass
        else:
            self.fail("hash() of list subclass should fail")

    def test_str_operations(self):
        try: 'a' + 5
        except TypeError: pass
        else: self.fail("'' + 5 doesn't raise TypeError")

        try: ''.split('')
        except ValueError: pass
        else: self.fail("''.split('') doesn't raise ValueError")

        try: ''.join([0])
        except TypeError: pass
        else: self.fail("''.join([0]) doesn't raise TypeError")

        try: ''.rindex('5')
        except ValueError: pass
        else: self.fail("''.rindex('5') doesn't raise ValueError")

        try: '%(n)s' % None
        except TypeError: pass
        else: self.fail("'%(n)s' % None doesn't raise TypeError")

        try: '%(n' % {}
        except ValueError: pass
        else: self.fail("'%(n' % {} '' doesn't raise ValueError")

        try: '%*s' % ('abc')
        except TypeError: pass
        else: self.fail("'%*s' % ('abc') doesn't raise TypeError")

        try: '%*.*s' % ('abc', 5)
        except TypeError: pass
        else: self.fail("'%*.*s' % ('abc', 5) doesn't raise TypeError")

        try: '%s' % (1, 2)
        except TypeError: pass
        else: self.fail("'%s' % (1, 2) doesn't raise TypeError")

        try: '%' % None
        except ValueError: pass
        else: self.fail("'%' % None doesn't raise ValueError")

        self.assertEqual('534253'.isdigit(), 1)
        self.assertEqual('534253x'.isdigit(), 0)
        self.assertEqual('%c' % 5, '\x05')
        self.assertEqual('%c' % '5', '5')

    def test_deepcopy_recursive(self):
        # Testing deepcopy of recursive objects...
        class Node:
            pass
        a = Node()
        b = Node()
        a.b = b
        b.a = a
        z = deepcopy(a) # This blew up before

    def test_unintialized_modules(self):
        # Testing uninitialized module objects...
        from types import ModuleType as M
        m = M.__new__(M)
        str(m)
        self.assertEqual(hasattr(m, "__name__"), 0)
        self.assertEqual(hasattr(m, "__file__"), 0)
        self.assertEqual(hasattr(m, "foo"), 0)
        self.assertFalse(m.__dict__)   # None or {} are both reasonable answers
        m.foo = 1
        self.assertEqual(m.__dict__, {"foo": 1})

    def test_funny_new(self):
        # Testing __new__ returning something unexpected...
        class C(object):
            def __new__(cls, arg):
                if isinstance(arg, str): return [1, 2, 3]
                elif isinstance(arg, int): return object.__new__(D)
                else: return object.__new__(cls)
        class D(C):
            def __init__(self, arg):
                self.foo = arg
        self.assertEqual(C("1"), [1, 2, 3])
        self.assertEqual(D("1"), [1, 2, 3])
        d = D(None)
        self.assertEqual(d.foo, None)
        d = C(1)
        self.assertIsInstance(d, D)
        self.assertEqual(d.foo, 1)
        d = D(1)
        self.assertIsInstance(d, D)
        self.assertEqual(d.foo, 1)

    def test_imul_bug(self):
        # Testing for __imul__ problems...
        # SF bug 544647
        class C(object):
            def __imul__(self, other):
                return (self, other)
        x = C()
        y = x
        y *= 1.0
        self.assertEqual(y, (x, 1.0))
        y = x
        y *= 2
        self.assertEqual(y, (x, 2))
        y = x
        y *= 3
        self.assertEqual(y, (x, 3))
        y = x
        y *= 1<<100
        self.assertEqual(y, (x, 1<<100))
        y = x
        y *= None
        self.assertEqual(y, (x, None))
        y = x
        y *= "foo"
        self.assertEqual(y, (x, "foo"))

    def test_copy_setstate(self):
        # Testing that copy.*copy() correctly uses __setstate__...
        import copy
        class C(object):
            def __init__(self, foo=None):
                self.foo = foo
                self.__foo = foo
            def setfoo(self, foo=None):
                self.foo = foo
            def getfoo(self):
                return self.__foo
            def __getstate__(self):
                return [self.foo]
            def __setstate__(self_, lst):
                self.assertEqual(len(lst), 1)
                self_.__foo = self_.foo = lst[0]
        a = C(42)
        a.setfoo(24)
        self.assertEqual(a.foo, 24)
        self.assertEqual(a.getfoo(), 42)
        b = copy.copy(a)
        self.assertEqual(b.foo, 24)
        self.assertEqual(b.getfoo(), 24)
        b = copy.deepcopy(a)
        self.assertEqual(b.foo, 24)
        self.assertEqual(b.getfoo(), 24)

    def test_slices(self):
        # Testing cases with slices and overridden __getitem__ ...

        # Strings
        self.assertEqual("hello"[:4], "hell")
        self.assertEqual("hello"[slice(4)], "hell")
        self.assertEqual(str.__getitem__("hello", slice(4)), "hell")
        class S(str):
            def __getitem__(self, x):
                return str.__getitem__(self, x)
        self.assertEqual(S("hello")[:4], "hell")
        self.assertEqual(S("hello")[slice(4)], "hell")
        self.assertEqual(S("hello").__getitem__(slice(4)), "hell")
        # Tuples
        self.assertEqual((1,2,3)[:2], (1,2))
        self.assertEqual((1,2,3)[slice(2)], (1,2))
        self.assertEqual(tuple.__getitem__((1,2,3), slice(2)), (1,2))
        class T(tuple):
            def __getitem__(self, x):
                return tuple.__getitem__(self, x)
        self.assertEqual(T((1,2,3))[:2], (1,2))
        self.assertEqual(T((1,2,3))[slice(2)], (1,2))
        self.assertEqual(T((1,2,3)).__getitem__(slice(2)), (1,2))
        # Lists
        self.assertEqual([1,2,3][:2], [1,2])
        self.assertEqual([1,2,3][slice(2)], [1,2])
        self.assertEqual(list.__getitem__([1,2,3], slice(2)), [1,2])
        class L(list):
            def __getitem__(self, x):
                return list.__getitem__(self, x)
        self.assertEqual(L([1,2,3])[:2], [1,2])
        self.assertEqual(L([1,2,3])[slice(2)], [1,2])
        self.assertEqual(L([1,2,3]).__getitem__(slice(2)), [1,2])
        # Now do lists and __setitem__
        a = L([1,2,3])
        a[slice(1, 3)] = [3,2]
        self.assertEqual(a, [1,3,2])
        a[slice(0, 2, 1)] = [3,1]
        self.assertEqual(a, [3,1,2])
        a.__setitem__(slice(1, 3), [2,1])
        self.assertEqual(a, [3,2,1])
        a.__setitem__(slice(0, 2, 1), [2,3])
        self.assertEqual(a, [2,3,1])

    def test_subtype_resurrection(self):
        # Testing resurrection of new-style instance...

        class C(object):
            container = []

            def __del__(self):
                # resurrect the instance
                C.container.append(self)

        c = C()
        c.attr = 42

        # The most interesting thing here is whether this blows up, due to
        # flawed GC tracking logic in typeobject.c's call_finalizer() (a 2.2.1
        # bug).
        del c

        # If that didn't blow up, it's also interesting to see whether clearing
        # the last container slot works: that will attempt to delete c again,
        # which will cause c to get appended back to the container again
        # "during" the del.  (On non-CPython implementations, however, __del__
        # is typically not called again.)
        support.gc_collect()
        self.assertEqual(len(C.container), 1)
        del C.container[-1]
        if support.check_impl_detail():
            support.gc_collect()
            self.assertEqual(len(C.container), 1)
            self.assertEqual(C.container[-1].attr, 42)

        # Make c mortal again, so that the test framework with -l doesn't report
        # it as a leak.
        del C.__del__

    def test_slots_trash(self):
        # Testing slot trash...
        # Deallocating deeply nested slotted trash caused stack overflows
        class trash(object):
            __slots__ = ['x']
            def __init__(self, x):
                self.x = x
        o = None
        for i in range(50000):
            o = trash(o)
        del o

    def test_slots_multiple_inheritance(self):
        # SF bug 575229, multiple inheritance w/ slots dumps core
        class A(object):
            __slots__=()
        class B(object):
            pass
        class C(A,B) :
            __slots__=()
        if support.check_impl_detail():
            self.assertEqual(C.__basicsize__, B.__basicsize__)
        self.assertTrue(hasattr(C, '__dict__'))
        self.assertTrue(hasattr(C, '__weakref__'))
        C().x = 2

    def test_rmul(self):
        # Testing correct invocation of __rmul__...
        # SF patch 592646
        class C(object):
            def __mul__(self, other):
                return "mul"
            def __rmul__(self, other):
                return "rmul"
        a = C()
        self.assertEqual(a*2, "mul")
        self.assertEqual(a*2.2, "mul")
        self.assertEqual(2*a, "rmul")
        self.assertEqual(2.2*a, "rmul")

    def test_ipow(self):
        # Testing correct invocation of __ipow__...
        # [SF bug 620179]
        class C(object):
            def __ipow__(self, other):
                pass
        a = C()
        a **= 2

    def test_mutable_bases(self):
        # Testing mutable bases...

        # stuff that should work:
        class C(object):
            pass
        class C2(object):
            def __getattribute__(self, attr):
                if attr == 'a':
                    return 2
                else:
                    return super(C2, self).__getattribute__(attr)
            def meth(self):
                return 1
        class D(C):
            pass
        class E(D):
            pass
        d = D()
        e = E()
        D.__bases__ = (C,)
        D.__bases__ = (C2,)
        self.assertEqual(d.meth(), 1)
        self.assertEqual(e.meth(), 1)
        self.assertEqual(d.a, 2)
        self.assertEqual(e.a, 2)
        self.assertEqual(C2.__subclasses__(), [D])

        try:
            del D.__bases__
        except (TypeError, AttributeError):
            pass
        else:
            self.fail("shouldn't be able to delete .__bases__")

        try:
            D.__bases__ = ()
        except TypeError as msg:
            if str(msg) == "a new-style class can't have only classic bases":
                self.fail("wrong error message for .__bases__ = ()")
        else:
            self.fail("shouldn't be able to set .__bases__ to ()")

        try:
            D.__bases__ = (D,)
        except TypeError:
            pass
        else:
            # actually, we'll have crashed by here...
            self.fail("shouldn't be able to create inheritance cycles")

        try:
            D.__bases__ = (C, C)
        except TypeError:
            pass
        else:
            self.fail("didn't detect repeated base classes")

        try:
            D.__bases__ = (E,)
        except TypeError:
            pass
        else:
            self.fail("shouldn't be able to create inheritance cycles")

    def test_builtin_bases(self):
        # Make sure all the builtin types can have their base queried without
        # segfaulting. See issue #5787.
        builtin_types = [tp for tp in builtins.__dict__.values()
                         if isinstance(tp, type)]
        for tp in builtin_types:
            object.__getattribute__(tp, "__bases__")
            if tp is not object:
                self.assertEqual(len(tp.__bases__), 1, tp)

        class L(list):
            pass

        class C(object):
            pass

        class D(C):
            pass

        try:
            L.__bases__ = (dict,)
        except TypeError:
            pass
        else:
            self.fail("shouldn't turn list subclass into dict subclass")

        try:
            list.__bases__ = (dict,)
        except TypeError:
            pass
        else:
            self.fail("shouldn't be able to assign to list.__bases__")

        try:
            D.__bases__ = (C, list)
        except TypeError:
            pass
        else:
            assert 0, "best_base calculation found wanting"


    def test_mutable_bases_with_failing_mro(self):
        # Testing mutable bases with failing mro...
        class WorkOnce(type):
            def __new__(self, name, bases, ns):
                self.flag = 0
                return super(WorkOnce, self).__new__(WorkOnce, name, bases, ns)
            def mro(self):
                if self.flag > 0:
                    raise RuntimeError("bozo")
                else:
                    self.flag += 1
                    return type.mro(self)

        class WorkAlways(type):
            def mro(self):
                # this is here to make sure that .mro()s aren't called
                # with an exception set (which was possible at one point).
                # An error message will be printed in a debug build.
                # What's a good way to test for this?
                return type.mro(self)

        class C(object):
            pass

        class C2(object):
            pass

        class D(C):
            pass

        class E(D):
            pass

        class F(D, metaclass=WorkOnce):
            pass

        class G(D, metaclass=WorkAlways):
            pass

        # Immediate subclasses have their mro's adjusted in alphabetical
        # order, so E's will get adjusted before adjusting F's fails.  We
        # check here that E's gets restored.

        E_mro_before = E.__mro__
        D_mro_before = D.__mro__

        try:
            D.__bases__ = (C2,)
        except RuntimeError:
            self.assertEqual(E.__mro__, E_mro_before)
            self.assertEqual(D.__mro__, D_mro_before)
        else:
            self.fail("exception not propagated")

    def test_mutable_bases_catch_mro_conflict(self):
        # Testing mutable bases catch mro conflict...
        class A(object):
            pass

        class B(object):
            pass

        class C(A, B):
            pass

        class D(A, B):
            pass

        class E(C, D):
            pass

        try:
            C.__bases__ = (B, A)
        except TypeError:
            pass
        else:
            self.fail("didn't catch MRO conflict")

    def test_mutable_names(self):
        # Testing mutable names...
        class C(object):
            pass

        # C.__module__ could be 'test_descr' or '__main__'
        mod = C.__module__

        C.__name__ = 'D'
        self.assertEqual((C.__module__, C.__name__), (mod, 'D'))

        C.__name__ = 'D.E'
        self.assertEqual((C.__module__, C.__name__), (mod, 'D.E'))

    def test_subclass_right_op(self):
        # Testing correct dispatch of subclass overloading __r<op>__...

        # This code tests various cases where right-dispatch of a subclass
        # should be preferred over left-dispatch of a base class.

        # Case 1: subclass of int; this tests code in abstract.c::binary_op1()

        class B(int):
            def __floordiv__(self, other):
                return "B.__floordiv__"
            def __rfloordiv__(self, other):
                return "B.__rfloordiv__"

        self.assertEqual(B(1) // 1, "B.__floordiv__")
        self.assertEqual(1 // B(1), "B.__rfloordiv__")

        # Case 2: subclass of object; this is just the baseline for case 3

        class C(object):
            def __floordiv__(self, other):
                return "C.__floordiv__"
            def __rfloordiv__(self, other):
                return "C.__rfloordiv__"

        self.assertEqual(C() // 1, "C.__floordiv__")
        self.assertEqual(1 // C(), "C.__rfloordiv__")

        # Case 3: subclass of new-style class; here it gets interesting

        class D(C):
            def __floordiv__(self, other):
                return "D.__floordiv__"
            def __rfloordiv__(self, other):
                return "D.__rfloordiv__"

        self.assertEqual(D() // C(), "D.__floordiv__")
        self.assertEqual(C() // D(), "D.__rfloordiv__")

        # Case 4: this didn't work right in 2.2.2 and 2.3a1

        class E(C):
            pass

        self.assertEqual(E.__rfloordiv__, C.__rfloordiv__)

        self.assertEqual(E() // 1, "C.__floordiv__")
        self.assertEqual(1 // E(), "C.__rfloordiv__")
        self.assertEqual(E() // C(), "C.__floordiv__")
        self.assertEqual(C() // E(), "C.__floordiv__") # This one would fail

    @support.impl_detail("testing an internal kind of method object")
    def test_meth_class_get(self):
        # Testing __get__ method of METH_CLASS C methods...
        # Full coverage of descrobject.c::classmethod_get()

        # Baseline
        arg = [1, 2, 3]
        res = {1: None, 2: None, 3: None}
        self.assertEqual(dict.fromkeys(arg), res)
        self.assertEqual({}.fromkeys(arg), res)

        # Now get the descriptor
        descr = dict.__dict__["fromkeys"]

        # More baseline using the descriptor directly
        self.assertEqual(descr.__get__(None, dict)(arg), res)
        self.assertEqual(descr.__get__({})(arg), res)

        # Now check various error cases
        try:
            descr.__get__(None, None)
        except TypeError:
            pass
        else:
            self.fail("shouldn't have allowed descr.__get__(None, None)")
        try:
            descr.__get__(42)
        except TypeError:
            pass
        else:
            self.fail("shouldn't have allowed descr.__get__(42)")
        try:
            descr.__get__(None, 42)
        except TypeError:
            pass
        else:
            self.fail("shouldn't have allowed descr.__get__(None, 42)")
        try:
            descr.__get__(None, int)
        except TypeError:
            pass
        else:
            self.fail("shouldn't have allowed descr.__get__(None, int)")

    def test_isinst_isclass(self):
        # Testing proxy isinstance() and isclass()...
        class Proxy(object):
            def __init__(self, obj):
                self.__obj = obj
            def __getattribute__(self, name):
                if name.startswith("_Proxy__"):
                    return object.__getattribute__(self, name)
                else:
                    return getattr(self.__obj, name)
        # Test with a classic class
        class C:
            pass
        a = C()
        pa = Proxy(a)
        self.assertIsInstance(a, C)  # Baseline
        self.assertIsInstance(pa, C) # Test
        # Test with a classic subclass
        class D(C):
            pass
        a = D()
        pa = Proxy(a)
        self.assertIsInstance(a, C)  # Baseline
        self.assertIsInstance(pa, C) # Test
        # Test with a new-style class
        class C(object):
            pass
        a = C()
        pa = Proxy(a)
        self.assertIsInstance(a, C)  # Baseline
        self.assertIsInstance(pa, C) # Test
        # Test with a new-style subclass
        class D(C):
            pass
        a = D()
        pa = Proxy(a)
        self.assertIsInstance(a, C)  # Baseline
        self.assertIsInstance(pa, C) # Test

    def test_proxy_super(self):
        # Testing super() for a proxy object...
        class Proxy(object):
            def __init__(self, obj):
                self.__obj = obj
            def __getattribute__(self, name):
                if name.startswith("_Proxy__"):
                    return object.__getattribute__(self, name)
                else:
                    return getattr(self.__obj, name)

        class B(object):
            def f(self):
                return "B.f"

        class C(B):
            def f(self):
                return super(C, self).f() + "->C.f"

        obj = C()
        p = Proxy(obj)
        self.assertEqual(C.__dict__["f"](p), "B.f->C.f")

    def test_carloverre(self):
        # Testing prohibition of Carlo Verre's hack...
        try:
            object.__setattr__(str, "foo", 42)
        except TypeError:
            pass
        else:
            self.fail("Carlo Verre __setattr__ succeeded!")
        try:
            object.__delattr__(str, "lower")
        except TypeError:
            pass
        else:
            self.fail("Carlo Verre __delattr__ succeeded!")

    def test_weakref_segfault(self):
        # Testing weakref segfault...
        # SF 742911
        import weakref

        class Provoker:
            def __init__(self, referrent):
                self.ref = weakref.ref(referrent)

            def __del__(self):
                x = self.ref()

        class Oops(object):
            pass

        o = Oops()
        o.whatever = Provoker(o)
        del o

    def test_wrapper_segfault(self):
        # SF 927248: deeply nested wrappers could cause stack overflow
        f = lambda:None
        for i in range(1000000):
            f = f.__call__
        f = None

    def test_file_fault(self):
        # Testing sys.stdout is changed in getattr...
        test_stdout = sys.stdout
        class StdoutGuard:
            def __getattr__(self, attr):
                sys.stdout = sys.__stdout__
                raise RuntimeError("Premature access to sys.stdout.%s" % attr)
        sys.stdout = StdoutGuard()
        try:
            print("Oops!")
        except RuntimeError:
            pass
        finally:
            sys.stdout = test_stdout

    def test_vicious_descriptor_nonsense(self):
        # Testing vicious_descriptor_nonsense...

        # A potential segfault spotted by Thomas Wouters in mail to
        # python-dev 2003-04-17, turned into an example & fixed by Michael
        # Hudson just less than four months later...

        class Evil(object):
            def __hash__(self):
                return hash('attr')
            def __eq__(self, other):
                del C.attr
                return 0

        class Descr(object):
            def __get__(self, ob, type=None):
                return 1

        class C(object):
            attr = Descr()

        c = C()
        c.__dict__[Evil()] = 0

        self.assertEqual(c.attr, 1)
        # this makes a crash more likely:
        support.gc_collect()
        self.assertEqual(hasattr(c, 'attr'), False)

    def test_init(self):
        # SF 1155938
        class Foo(object):
            def __init__(self):
                return 10
        try:
            Foo()
        except TypeError:
            pass
        else:
            self.fail("did not test __init__() for None return")

    def test_method_wrapper(self):
        # Testing method-wrapper objects...
        # <type 'method-wrapper'> did not support any reflection before 2.5

        # XXX should methods really support __eq__?

        l = []
        self.assertEqual(l.__add__, l.__add__)
        self.assertEqual(l.__add__, [].__add__)
        self.assertTrue(l.__add__ != [5].__add__)
        self.assertTrue(l.__add__ != l.__mul__)
        self.assertTrue(l.__add__.__name__ == '__add__')
        if hasattr(l.__add__, '__self__'):
            # CPython
            self.assertTrue(l.__add__.__self__ is l)
            self.assertTrue(l.__add__.__objclass__ is list)
        else:
            # Python implementations where [].__add__ is a normal bound method
            self.assertTrue(l.__add__.im_self is l)
            self.assertTrue(l.__add__.im_class is list)
        self.assertEqual(l.__add__.__doc__, list.__add__.__doc__)
        try:
            hash(l.__add__)
        except TypeError:
            pass
        else:
            self.fail("no TypeError from hash([].__add__)")

        t = ()
        t += (7,)
        self.assertEqual(t.__add__, (7,).__add__)
        self.assertEqual(hash(t.__add__), hash((7,).__add__))

    def test_not_implemented(self):
        # Testing NotImplemented...
        # all binary methods should be able to return a NotImplemented
        import operator

        def specialmethod(self, other):
            return NotImplemented

        def check(expr, x, y):
            try:
                exec(expr, {'x': x, 'y': y, 'operator': operator})
            except TypeError:
                pass
            else:
                self.fail("no TypeError from %r" % (expr,))

        N1 = sys.maxsize + 1    # might trigger OverflowErrors instead of
                                # TypeErrors
        N2 = sys.maxsize         # if sizeof(int) < sizeof(long), might trigger
                                #   ValueErrors instead of TypeErrors
        for name, expr, iexpr in [
                ('__add__',      'x + y',                   'x += y'),
                ('__sub__',      'x - y',                   'x -= y'),
                ('__mul__',      'x * y',                   'x *= y'),
                ('__truediv__',  'operator.truediv(x, y)',  None),
                ('__floordiv__', 'operator.floordiv(x, y)', None),
                ('__div__',      'x / y',                   'x /= y'),
                ('__mod__',      'x % y',                   'x %= y'),
                ('__divmod__',   'divmod(x, y)',            None),
                ('__pow__',      'x ** y',                  'x **= y'),
                ('__lshift__',   'x << y',                  'x <<= y'),
                ('__rshift__',   'x >> y',                  'x >>= y'),
                ('__and__',      'x & y',                   'x &= y'),
                ('__or__',       'x | y',                   'x |= y'),
                ('__xor__',      'x ^ y',                   'x ^= y')]:
            rname = '__r' + name[2:]
            A = type('A', (), {name: specialmethod})
            a = A()
            check(expr, a, a)
            check(expr, a, N1)
            check(expr, a, N2)
            if iexpr:
                check(iexpr, a, a)
                check(iexpr, a, N1)
                check(iexpr, a, N2)
                iname = '__i' + name[2:]
                C = type('C', (), {iname: specialmethod})
                c = C()
                check(iexpr, c, a)
                check(iexpr, c, N1)
                check(iexpr, c, N2)

    def test_assign_slice(self):
        # ceval.c's assign_slice used to check for
        # tp->tp_as_sequence->sq_slice instead of
        # tp->tp_as_sequence->sq_ass_slice

        class C(object):
            def __setitem__(self, idx, value):
                self.value = value

        c = C()
        c[1:2] = 3
        self.assertEqual(c.value, 3)

    def test_set_and_no_get(self):
        # See
        # http://mail.python.org/pipermail/python-dev/2010-January/095637.html
        class Descr(object):

            def __init__(self, name):
                self.name = name

            def __set__(self, obj, value):
                obj.__dict__[self.name] = value
        descr = Descr("a")

        class X(object):
            a = descr

        x = X()
        self.assertIs(x.a, descr)
        x.a = 42
        self.assertEqual(x.a, 42)

        # Also check type_getattro for correctness.
        class Meta(type):
            pass
        class X(object):
            __metaclass__ = Meta
        X.a = 42
        Meta.a = Descr("a")
        self.assertEqual(X.a, 42)

    def test_getattr_hooks(self):
        # issue 4230

        class Descriptor(object):
            counter = 0
            def __get__(self, obj, objtype=None):
                def getter(name):
                    self.counter += 1
                    raise AttributeError(name)
                return getter

        descr = Descriptor()
        class A(object):
            __getattribute__ = descr
        class B(object):
            __getattr__ = descr
        class C(object):
            __getattribute__ = descr
            __getattr__ = descr

        self.assertRaises(AttributeError, getattr, A(), "attr")
        self.assertEqual(descr.counter, 1)
        self.assertRaises(AttributeError, getattr, B(), "attr")
        self.assertEqual(descr.counter, 2)
        self.assertRaises(AttributeError, getattr, C(), "attr")
        self.assertEqual(descr.counter, 4)

        class EvilGetattribute(object):
            # This used to segfault
            def __getattr__(self, name):
                raise AttributeError(name)
            def __getattribute__(self, name):
                del EvilGetattribute.__getattr__
                for i in range(5):
                    gc.collect()
                raise AttributeError(name)

        self.assertRaises(AttributeError, getattr, EvilGetattribute(), "attr")

    def test_type___getattribute__(self):
        self.assertRaises(TypeError, type.__getattribute__, list, type)

    def test_abstractmethods(self):
        # type pretends not to have __abstractmethods__.
        self.assertRaises(AttributeError, getattr, type, "__abstractmethods__")
        class meta(type):
            pass
        self.assertRaises(AttributeError, getattr, meta, "__abstractmethods__")
        class X(object):
            pass
        with self.assertRaises(AttributeError):
            del X.__abstractmethods__

    def test_proxy_call(self):
        class FakeStr:
            __class__ = str

        fake_str = FakeStr()
        # isinstance() reads __class__
        self.assertTrue(isinstance(fake_str, str))

        # call a method descriptor
        with self.assertRaises(TypeError):
            str.split(fake_str)

        # call a slot wrapper descriptor
        with self.assertRaises(TypeError):
            str.__add__(fake_str, "abc")

    def test_repr_as_str(self):
        # Issue #11603: crash or infinite loop when rebinding __str__ as
        # __repr__.
        class Foo:
            pass
        Foo.__repr__ = Foo.__str__
        foo = Foo()
        self.assertRaises(RuntimeError, str, foo)
        self.assertRaises(RuntimeError, repr, foo)

    def test_mixing_slot_wrappers(self):
        class X(dict):
            __setattr__ = dict.__setitem__
        x = X()
        x.y = 42
        self.assertEqual(x["y"], 42)

    def test_cycle_through_dict(self):
        # See bug #1469629
        class X(dict):
            def __init__(self):
                dict.__init__(self)
                self.__dict__ = self
        x = X()
        x.attr = 42
        wr = weakref.ref(x)
        del x
        support.gc_collect()
        self.assertIsNone(wr())
        for o in gc.get_objects():
            self.assertIsNot(type(o), X)

class DictProxyTests(unittest.TestCase):
    def setUp(self):
        class C(object):
            def meth(self):
                pass
        self.C = C

    def test_iter_keys(self):
        # Testing dict-proxy keys...
        it = self.C.__dict__.keys()
        self.assertNotIsInstance(it, list)
        keys = list(it)
        keys.sort()
        self.assertEqual(keys, ['__dict__', '__doc__', '__module__',
            '__weakref__', 'meth'])

    def test_iter_values(self):
        # Testing dict-proxy values...
        it = self.C.__dict__.values()
        self.assertNotIsInstance(it, list)
        values = list(it)
        self.assertEqual(len(values), 5)

    def test_iter_items(self):
        # Testing dict-proxy iteritems...
        it = self.C.__dict__.items()
        self.assertNotIsInstance(it, list)
        keys = [item[0] for item in it]
        keys.sort()
        self.assertEqual(keys, ['__dict__', '__doc__', '__module__',
            '__weakref__', 'meth'])

    def test_dict_type_with_metaclass(self):
        # Testing type of __dict__ when metaclass set...
        class B(object):
            pass
        class M(type):
            pass
        class C(metaclass=M):
            # In 2.3a1, C.__dict__ was a real dict rather than a dict proxy
            pass
        self.assertEqual(type(C.__dict__), type(B.__dict__))

    def test_repr(self):
        # Testing dict_proxy.__repr__
        def sorted_dict_repr(repr_):
            # Given the repr of a dict, sort the keys
            assert repr_.startswith('{')
            assert repr_.endswith('}')
            kvs = repr_[1:-1].split(', ')
            return '{' + ', '.join(sorted(kvs)) + '}'
        dict_ = {k: v for k, v in self.C.__dict__.items()}
        repr_ = repr(self.C.__dict__)
        self.assertTrue(repr_.startswith('dict_proxy('))
        self.assertTrue(repr_.endswith(')'))
        self.assertEqual(sorted_dict_repr(repr_[len('dict_proxy('):-len(')')]),
                         sorted_dict_repr('{!r}'.format(dict_)))


class PTypesLongInitTest(unittest.TestCase):
    # This is in its own TestCase so that it can be run before any other tests.
    def test_pytype_long_ready(self):
        # Testing SF bug 551412 ...

        # This dumps core when SF bug 551412 isn't fixed --
        # but only when test_descr.py is run separately.
        # (That can't be helped -- as soon as PyType_Ready()
        # is called for PyLong_Type, the bug is gone.)
        class UserLong(object):
            def __pow__(self, *args):
                pass
        try:
            pow(0, UserLong(), 0)
        except:
            pass

        # Another segfault only when run early
        # (before PyType_Ready(tuple) is called)
        type.mro(tuple)


def test_main():
    # Run all local test cases, with PTypesLongInitTest first.
    support.run_unittest(PTypesLongInitTest, OperatorsTest,
                              ClassPropertiesAndMethods, DictProxyTests)

if __name__ == "__main__":
    test_main()