def test_issue31566(self):
     # warn() shouldn't cause an assertion failure in case of a bad
     # __name__ global.
     with original_warnings.catch_warnings(module=self.module):
         self.module.filterwarnings('error', category=UserWarning)
         with support.swap_item(globals(), '__name__', b'foo'), \
              support.swap_item(globals(), '__file__', None):
             self.assertRaises(UserWarning, self.module.warn, 'bar')

 def test_swap_item(self):
     D = {"x":1}
     with support.swap_item(D, "x", 5) as x:
         self.assertEqual(D["x"], 5)
         self.assertEqual(x, 1)
     self.assertEqual(D["x"], 1)
     with support.swap_item(D, "y", 5) as y:
         self.assertEqual(D["y"], 5)
         self.assertIsNone(y)
     self.assertNotIn("y", D)
     with support.swap_item(D, "y", 5):
         del D["y"]
     self.assertNotIn("y", D)

    def customize_compiler(self):
        # make sure AR gets caught
        class compiler:
            compiler_type = 'unix'

            def set_executables(self, **kw):
                self.exes = kw

        sysconfig_vars = {
            'AR': 'sc_ar',
            'CC': 'sc_cc',
            'CXX': 'sc_cxx',
            'ARFLAGS': '--sc-arflags',
            'CFLAGS': '--sc-cflags',
            'CCSHARED': '--sc-ccshared',
            'LDSHARED': 'sc_ldshared',
            'SHLIB_SUFFIX': 'sc_shutil_suffix',
        }

        comp = compiler()
        with contextlib.ExitStack() as cm:
            for key, value in sysconfig_vars.items():
                cm.enter_context(swap_item(sysconfig._config_vars, key, value))
            sysconfig.customize_compiler(comp)

        return comp

    def test_cannot_replace_builtins_dict_between_calls(self):
        def foo():
            return len([1, 2, 3])
        self.configure_func(foo)

        self.assertEqual(foo(), 3)
        with swap_item(globals(), "__builtins__", {"len": lambda x: 7}):
            self.assertEqual(foo(), 3)

 def test_do_not_recreate_annotations(self):
     # Don't rely on the existence of the '__annotations__' global.
     with support.swap_item(globals(), '__annotations__', {}):
         del globals()['__annotations__']
         class C:
             del __annotations__
             with self.assertRaises(NameError):
                 x: int

 def test_load_source(self):
     # Create a temporary module since load_source(name) modifies
     # sys.modules[name] attributes like __loader___
     modname = f"tmp{__name__}"
     mod = type(sys.modules[__name__])(modname)
     with support.swap_item(sys.modules, modname, mod):
         with self.assertRaisesRegex(ValueError, 'embedded null'):
             imp.load_source(modname, __file__ + "\0")

    def test_globals_shadow_builtins(self):
        # Modify globals() to shadow an entry in builtins.
        def foo():
            return len([1, 2, 3])
        self.configure_func(foo)

        self.assertEqual(foo(), 3)
        with swap_item(globals(), "len", lambda x: 7):
            self.assertEqual(foo(), 7)

    def test_cannot_replace_builtins_dict_while_active(self):
        def foo():
            x = range(3)
            yield len(x)
            yield len(x)
        self.configure_func(foo)

        g = foo()
        self.assertEqual(next(g), 3)
        with swap_item(globals(), "__builtins__", {"len": lambda x: 7}):
            self.assertEqual(next(g), 3)

    def test_pickle_roundtrip(self):
        def check(actual, expected):
            self.assertEqual(actual, expected)
            self.assertEqual(actual.is_safe, expected.is_safe)

        with support.swap_item(sys.modules, 'uuid', self.uuid):
            for is_safe in self.uuid.SafeUUID:
                u = self.uuid.UUID('d82579ce6642a0de7ddf490a7aec7aa5',
                                   is_safe=is_safe)
                check(copy.copy(u), u)
                check(copy.deepcopy(u), u)
                for proto in range(pickle.HIGHEST_PROTOCOL + 1):
                    with self.subTest(protocol=proto):
                        check(pickle.loads(pickle.dumps(u, proto)), u)

    def test_override_builtin(self):
        # Test that overriding builtins.__import__ can bypass sys.modules.
        import os

        def foo():
            import os
            return os
        self.assertEqual(foo(), os)  # Quick sanity check.

        with swap_attr(builtins, "__import__", lambda *x: 5):
            self.assertEqual(foo(), 5)

        # Test what happens when we shadow __import__ in globals(); this
        # currently does not impact the import process, but if this changes,
        # other code will need to change, so keep this test as a tripwire.
        with swap_item(globals(), "__import__", lambda *x: 5):
            self.assertEqual(foo(), os)

 def copy(self, obj, proto):
     with support.swap_item(sys.modules, 'operator', self.module):
         pickled = pickle.dumps(obj, proto)
     with support.swap_item(sys.modules, 'operator', self.module2):
         return pickle.loads(pickled)

 def test_swap_item(self):
     D = {"item":1}
     with support.swap_item(D, "item", 5):
         self.assertEqual(D["item"], 5)
     self.assertEqual(D["item"], 1)

#.........这里部分代码省略.........
            # Python 3.6, protocol 1
            b'ccopy_reg\n_reconstructor\n(cuuid\nUUID\nc__builtin__\nobject\nN'
            b'tR}X\x03\x00\x00\x00intL287307832597519156748809049798316161701L'
            b'\nsb.',
            # Python 3.6, protocol 2
            b'\x80\x02cuuid\nUUID\n)\x81}X\x03\x00\x00\x00int\x8a\x11\xa5z\xec'
            b'z\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00sb.',
            # Python 3.6, protocol 3
            b'\x80\x03cuuid\nUUID\n)\x81}X\x03\x00\x00\x00int\x8a\x11\xa5z\xec'
            b'z\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00sb.',
            # Python 3.6, protocol 4
            b'\x80\x04\x95+\x00\x00\x00\x00\x00\x00\x00\x8c\x04uuid\x8c\x04UUI'
            b'D\x93)\x81}\x8c\x03int\x8a\x11\xa5z\xecz\nI\xdf}\xde\xa0Bf\xcey%'
            b'\xd8\x00sb.',
            # Python 3.7, protocol 0
            b'ccopy_reg\n_reconstructor\n(cuuid\nUUID\nc__builtin__\nobject\nN'
            b'tR(dVint\nL287307832597519156748809049798316161701L\nsVis_safe\n'
            b'cuuid\nSafeUUID\n(NtRsb.',
            # Python 3.7, protocol 1
            b'ccopy_reg\n_reconstructor\n(cuuid\nUUID\nc__builtin__\nobject\nN'
            b'tR}(X\x03\x00\x00\x00intL287307832597519156748809049798316161701'
            b'L\nX\x07\x00\x00\x00is_safecuuid\nSafeUUID\n(NtRub.',
            # Python 3.7, protocol 2
            b'\x80\x02cuuid\nUUID\n)\x81}(X\x03\x00\x00\x00int\x8a\x11\xa5z'
            b'\xecz\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00X\x07\x00\x00\x00is_safecuu'
            b'id\nSafeUUID\nN\x85Rub.',
            # Python 3.7, protocol 3
            b'\x80\x03cuuid\nUUID\n)\x81}(X\x03\x00\x00\x00int\x8a\x11\xa5z'
            b'\xecz\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00X\x07\x00\x00\x00is_safecuu'
            b'id\nSafeUUID\nN\x85Rub.',
            # Python 3.7, protocol 4
            b'\x80\x04\x95F\x00\x00\x00\x00\x00\x00\x00\x8c\x04uuid\x94\x8c'
            b'\x04UUID\x93)\x81}(\x8c\x03int\x8a\x11\xa5z\xecz\nI\xdf}\xde\xa0'
            b'Bf\xcey%\xd8\x00\x8c\x07is_safeh\x00\x8c\x08SafeUUID\x93N\x85Rub'
            b'.',
        ]
        pickled_uuids_safe = [
            # Python 3.7, protocol 0
            b'ccopy_reg\n_reconstructor\n(cuuid\nUUID\nc__builtin__\nobject\nN'
            b'tR(dVint\nL287307832597519156748809049798316161701L\nsVis_safe\n'
            b'cuuid\nSafeUUID\n(I0\ntRsb.',
            # Python 3.7, protocol 1
            b'ccopy_reg\n_reconstructor\n(cuuid\nUUID\nc__builtin__\nobject\nN'
            b'tR}(X\x03\x00\x00\x00intL287307832597519156748809049798316161701'
            b'L\nX\x07\x00\x00\x00is_safecuuid\nSafeUUID\n(K\x00tRub.',
            # Python 3.7, protocol 2
            b'\x80\x02cuuid\nUUID\n)\x81}(X\x03\x00\x00\x00int\x8a\x11\xa5z'
            b'\xecz\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00X\x07\x00\x00\x00is_safecuu'
            b'id\nSafeUUID\nK\x00\x85Rub.',
            # Python 3.7, protocol 3
            b'\x80\x03cuuid\nUUID\n)\x81}(X\x03\x00\x00\x00int\x8a\x11\xa5z'
            b'\xecz\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00X\x07\x00\x00\x00is_safecuu'
            b'id\nSafeUUID\nK\x00\x85Rub.',
            # Python 3.7, protocol 4
            b'\x80\x04\x95G\x00\x00\x00\x00\x00\x00\x00\x8c\x04uuid\x94\x8c'
            b'\x04UUID\x93)\x81}(\x8c\x03int\x8a\x11\xa5z\xecz\nI\xdf}\xde\xa0'
            b'Bf\xcey%\xd8\x00\x8c\x07is_safeh\x00\x8c\x08SafeUUID\x93K\x00'
            b'\x85Rub.',
        ]
        pickled_uuids_unsafe = [
            # Python 3.7, protocol 0
            b'ccopy_reg\n_reconstructor\n(cuuid\nUUID\nc__builtin__\nobject\nN'
            b'tR(dVint\nL287307832597519156748809049798316161701L\nsVis_safe\n'
            b'cuuid\nSafeUUID\n(I-1\ntRsb.',
            # Python 3.7, protocol 1
            b'ccopy_reg\n_reconstructor\n(cuuid\nUUID\nc__builtin__\nobject\nN'
            b'tR}(X\x03\x00\x00\x00intL287307832597519156748809049798316161701'
            b'L\nX\x07\x00\x00\x00is_safecuuid\nSafeUUID\n(J\xff\xff\xff\xfftR'
            b'ub.',
            # Python 3.7, protocol 2
            b'\x80\x02cuuid\nUUID\n)\x81}(X\x03\x00\x00\x00int\x8a\x11\xa5z'
            b'\xecz\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00X\x07\x00\x00\x00is_safecuu'
            b'id\nSafeUUID\nJ\xff\xff\xff\xff\x85Rub.',
            # Python 3.7, protocol 3
            b'\x80\x03cuuid\nUUID\n)\x81}(X\x03\x00\x00\x00int\x8a\x11\xa5z'
            b'\xecz\nI\xdf}\xde\xa0Bf\xcey%\xd8\x00X\x07\x00\x00\x00is_safecuu'
            b'id\nSafeUUID\nJ\xff\xff\xff\xff\x85Rub.',
            # Python 3.7, protocol 4
            b'\x80\x04\x95J\x00\x00\x00\x00\x00\x00\x00\x8c\x04uuid\x94\x8c'
            b'\x04UUID\x93)\x81}(\x8c\x03int\x8a\x11\xa5z\xecz\nI\xdf}\xde\xa0'
            b'Bf\xcey%\xd8\x00\x8c\x07is_safeh\x00\x8c\x08SafeUUID\x93J\xff'
            b'\xff\xff\xff\x85Rub.',
        ]

        u = self.uuid.UUID('d82579ce6642a0de7ddf490a7aec7aa5')
        u_safe = self.uuid.UUID('d82579ce6642a0de7ddf490a7aec7aa5',
                                is_safe=self.uuid.SafeUUID.safe)
        u_unsafe = self.uuid.UUID('d82579ce6642a0de7ddf490a7aec7aa5',
                                  is_safe=self.uuid.SafeUUID.unsafe)

        with support.swap_item(sys.modules, 'uuid', self.uuid):
            for pickled in pickled_uuids:
                # is_safe was added in 3.7.  When unpickling values from older
                # versions, is_safe will be missing, so it should be set to
                # SafeUUID.unknown.
                check(pickle.loads(pickled), u)
            for pickled in pickled_uuids_safe:
                check(pickle.loads(pickled), u_safe)
            for pickled in pickled_uuids_unsafe:
                check(pickle.loads(pickled), u_unsafe)