Files
RustPython/Lib/test/test_struct.py
T
Jeong, YunWonandLee Dogeon afad92bf1b Add OrderedDict, marshal, inspect, and chflags bitflagset (#8780)
* Implement _collections.OrderedDict

Extracted from #6799: native OrderedDict as a dict subclass,
iterator mutation tracking, and mapping-view set operations.

* Add OrderedDict, warnings source lines, and socket sendmsg

Implement _collections.OrderedDict as a dict subclass with a
linked list of insertion-order nodes.

Pack struct F/D as native float/double complex pairs, and report
unexpected __replace__ field names as a list repr.

Register encodings.latin_1 at startup. Reject NUL in input()
prompts. Copy non-exact type dicts in mapping order.

Fetch warning source lines through _bless_my_loader and unicode
splitlines. Keep the last warnings.filters list after deletion.

Snapshot sendmsg sequences before converting buffers, parse
ancillary ints with __index__, and dispatch AF_CAN by protocol.

Store sys.trace and sys.profile on each ThreadSlot so
_settraceallthreads/_setprofileallthreads are visible to
sys.gettrace/getprofile on other threads.

Use <frozen importlib._bootstrap> as frozen importlib
co_filename. Keep HEAPTYPE socket objects GC-tracked.

Assisted-by: Grok:grok-4.6

* Load marshal via readinto and dump sets in dumps order

marshal.load fills a scratch buffer with readinto on a
contiguous writable memoryview, and rejects a returned length
other than the requested size.

set and frozenset dumps write elements in sorted(v,
key=marshal.dumps) order.

Assisted-by: Grok:grok-4.6

* Add classmethod_descriptor and ABC IS_ABSTRACT flags

Give METH_CLASS methods a distinct classmethod_descriptor type.
Store Py_TPFLAGS_IS_ABSTRACT from __abstractmethods__ and look
up that attribute only in the type's own dict.

Expose defaultdict.default_factory as a member descriptor.
Inherit bool's unused number slots from int. Mark set and
frozenset __contains__ as METH_COEXIST.

Parse classmethod, staticmethod, object.__new__, and heap type
text signatures. Register interactive source in linecache.

Assisted-by: Grok:grok-4.6

* address review: odict reuse, descr call, new wrapper

Reuse odict node slots and walk the live list in next_after.
Require both | operands to be dicts. Drop the odict iterator
on GC clear. Bind classmethod descriptors through descr_get
and update IS_ABSTRACT under the type lock. Give odict keys
and items sq_contains. Walk tp_new_wrapper past new_wrapper
so HEAPTYPE socket subclasses can call socket.__new__.
Split FreeBSD Bluetooth protocol constants from Linux values.

Assisted-by: Grok:grok-4.6

* Represent chflags bits with bitflagset

Assisted-by: Grok:grok-4.6

* Represent access and mode bits with bitflagset

Assisted-by: Grok:grok-4.6

* Continue unfinished REPL suites as incomplete input

Assisted-by: Grok:grok-4.6

* Add pickle and os.stat inspect signatures

Give _pickle.Pickler the clinic constructor text signature and
accept fix_imports and buffer_callback as positional-or-keyword.
Allow #[pyfunction(text_signature)] and use it so os.stat reports
(path, *, dir_fd=None, follow_symlinks=True). Uncomment import
_pickle and drop the pickle inspect expectedFailures.

Assisted-by: Grok:grok-4.6

* Add Unpickler, dump/load, and lstat signatures

Give _pickle Unpickler, dump, dumps, load, and loads clinic
text signatures, and os.lstat (path, *, dir_fd=None).

Assisted-by: Grok:grok-4.6

* Complete OrderedDict with insertion-order links

Move the native OrderedDict into ordered_dict.rs and track order
with a linked list of nodes, keeping mapping-view set operations.

Assisted-by: Grok:grok-4.6

* address CI: stat casts, HCI_DATA_DIR, passing xfails

Compare stat permission bits as Mode so Linux clippy does not
flag a u32-to-u32 cast. Export HCI_DATA_DIR with the Bluetooth
socket option values. Drop expectedFailure from tests that now
pass.

Assisted-by: Grok:grok-4.6

* Fix wasm teardown deadlock and bluetooth constants

Assisted-by: Grok:grok-4.6

* Clear process-wide eval breaker bits in STW test

Assisted-by: Grok:grok-4.6

* Drop exclusive-held panic that tripped wasm clippy

Assisted-by: Grok:grok-4.6

* Fix OrderedDict contains and export Windows BDADDR

Assisted-by: Grok:grok-4.6

* Add cmp_to_key and hash-once LRU cache

_functools.cmp_to_key now returns KeyWrapper. LRU lookups store the
key hash on _lru_list_elem so __hash__ is not called again on hits
or eviction.

Assisted-by: Grok:grok-4.6

* Allow subclass keywords on list, tuple, and float

list.__init__ rejects keywords only when tp_new is still list's.
tuple/float.__new__ reject them only when tp_init is still the base's.

Assisted-by: Grok:grok-4.6

* Fix CI lint, test re-export, and structseq members

Drop the duplicate clear_eval_breaker_for_test re-export.
Format structseq imports. Expose struct sequence fields as
readonly members so assignment raises "readonly attribute".

Assisted-by: Grok:grok-4.6

* Allow subclass keywords on itertools and filter

Positional-only constructors ignore extra keywords when a subclass
has replaced tp_init, matching list/tuple/float.

Assisted-by: Grok:grok-4.6

* Remove text_signature derive parameter

Drop the string override on #[pyfunction] and #[pyclass]. Signatures
are generated from the Rust parameter list only. Restore inspect
expectedFailures that depended on the override.

Assisted-by: Grok:grok-4.6

* Rename set contains_method to __contains__

Keep a borrowed contains helper for slots and C-API. The coexist
pymethod is named __contains__.

Assisted-by: Grok:grok-4.6

* Use MonitoringEvent instead of EVENT_* aliases

Drop the unused MonitoringEvents bitflags and the EVENT_PY_START
style mask constants. Call sites use the enum and .mask().

Assisted-by: Grok:grok-4.6

* Store warnings filters as PyListRef

The list already serializes its elements. Drop the extra mutex around
the cached list pointer.

Assisted-by: Grok:grok-4.6

* Re-export clear_eval_breaker_for_test after rebase

Keep the STW test helper visible without bringing back stop_bit_set.

Assisted-by: Grok:grok-4.6

* Fix groupby reentrancy and islice arguments

Give _grouper its own tgtkey and take currvalue after the key
comparison. Accept __index__ on islice bounds, reject step 0, and
drain the source up to stop.

Assisted-by: Grok:grok-4.6

* SETREF warnings filters, onceregistry, and defaultaction

Keep the last list, dict, or str after the module attributes are
deleted by swapping the interpreter cache pointer. Do not store a
None fallback for _warnings_context.

Assisted-by: Grok:grok-4.6

* Iterate OrderedDict inner dict via next_entry

&PyDict is not an iterator after the borrowed-ref signature change.

Assisted-by: Grok:grok-4.6

* Remove expectedFailure from testBluetoothConstants

Linux now exports BTPROTO_HCI and the rest of the set.

Assisted-by: Grok:grok-4.6

* Borrow get_filter arguments as PyObject

Match the warn_explicit call site that passes borrowed
handles after the internal-helper borrow change.

Assisted-by: Grok:grok-4.6

* Fix bool slots and SemHandle safety docs

Leave unused bool number slots unset so inspect reports
__add__ on int. Document SemHandle::from_raw safety.

Assisted-by: Grok:grok-4.6

* Keep sendmsg errors and drop duplicate linecache

Replace sendmsg iterable TypeError only. Register REPL
source in linecache once per compiled input.

Assisted-by: Grok:grok-4.6

* Nest REPL parse or-patterns for clippy

Assisted-by: Grok:grok-4.6

* Mark pydoc os.stat signature test expectedFailure

Assisted-by: Grok:grok-4.6

---------

Co-authored-by: Lee Dogeon <dev.moreal@gmail.com>
2026-09-24 12:21:26 +09:00

1096 lines
45 KiB
Python
Vendored

from collections import abc
from itertools import combinations
import array
import gc
import math
import operator
import unittest
import struct
import sys
import weakref
from test import support
from test.support import import_helper
from test.support.script_helper import assert_python_ok
from test.support.testcase import ComplexesAreIdenticalMixin
ISBIGENDIAN = sys.byteorder == "big"
integer_codes = 'b', 'B', 'h', 'H', 'i', 'I', 'l', 'L', 'q', 'Q', 'n', 'N'
byteorders = '', '@', '=', '<', '>', '!'
INF = float('inf')
NAN = float('nan')
def iter_integer_formats(byteorders=byteorders):
for code in integer_codes:
for byteorder in byteorders:
if (byteorder not in ('', '@') and code in ('n', 'N')):
continue
yield code, byteorder
def string_reverse(s):
return s[::-1]
def bigendian_to_native(value):
if ISBIGENDIAN:
return value
else:
return string_reverse(value)
class StructTest(ComplexesAreIdenticalMixin, unittest.TestCase):
def test_isbigendian(self):
self.assertEqual((struct.pack('=i', 1)[0] == 0), ISBIGENDIAN)
def test_consistence(self):
self.assertRaises(struct.error, struct.calcsize, 'Z')
sz = struct.calcsize('i')
self.assertEqual(sz * 3, struct.calcsize('iii'))
fmt = 'cbxxxxxxhhhhiillffd?'
fmt3 = '3c3b18x12h6i6l6f3d3?'
sz = struct.calcsize(fmt)
sz3 = struct.calcsize(fmt3)
self.assertEqual(sz * 3, sz3)
self.assertRaises(struct.error, struct.pack, 'iii', 3)
self.assertRaises(struct.error, struct.pack, 'i', 3, 3, 3)
self.assertRaises((TypeError, struct.error), struct.pack, 'i', 'foo')
self.assertRaises((TypeError, struct.error), struct.pack, 'P', 'foo')
self.assertRaises(struct.error, struct.unpack, 'd', b'flap')
s = struct.pack('ii', 1, 2)
self.assertRaises(struct.error, struct.unpack, 'iii', s)
self.assertRaises(struct.error, struct.unpack, 'i', s)
def test_transitiveness(self):
c = b'a'
b = 1
h = 255
i = 65535
l = 65536
f = 3.1415
d = 3.1415
t = True
for prefix in ('', '@', '<', '>', '=', '!'):
for format in ('xcbhilfd?', 'xcBHILfd?'):
format = prefix + format
s = struct.pack(format, c, b, h, i, l, f, d, t)
cp, bp, hp, ip, lp, fp, dp, tp = struct.unpack(format, s)
self.assertEqual(cp, c)
self.assertEqual(bp, b)
self.assertEqual(hp, h)
self.assertEqual(ip, i)
self.assertEqual(lp, l)
self.assertEqual(int(100 * fp), int(100 * f))
self.assertEqual(int(100 * dp), int(100 * d))
self.assertEqual(tp, t)
def test_new_features(self):
# Test some of the new features in detail
# (format, argument, big-endian result, little-endian result, asymmetric)
tests = [
('c', b'a', b'a', b'a', 0),
('xc', b'a', b'\0a', b'\0a', 0),
('cx', b'a', b'a\0', b'a\0', 0),
('s', b'a', b'a', b'a', 0),
('0s', b'helloworld', b'', b'', 1),
('1s', b'helloworld', b'h', b'h', 1),
('9s', b'helloworld', b'helloworl', b'helloworl', 1),
('10s', b'helloworld', b'helloworld', b'helloworld', 0),
('11s', b'helloworld', b'helloworld\0', b'helloworld\0', 1),
('20s', b'helloworld', b'helloworld'+10*b'\0', b'helloworld'+10*b'\0', 1),
('0p', b'helloworld', b'', b'', 1),
('1p', b'helloworld', b'\x00', b'\x00', 1),
('2p', b'helloworld', b'\x01h', b'\x01h', 1),
('10p', b'helloworld', b'\x09helloworl', b'\x09helloworl', 1),
('11p', b'helloworld', b'\x0Ahelloworld', b'\x0Ahelloworld', 0),
('12p', b'helloworld', b'\x0Ahelloworld\0', b'\x0Ahelloworld\0', 1),
('20p', b'helloworld', b'\x0Ahelloworld'+9*b'\0', b'\x0Ahelloworld'+9*b'\0', 1),
('b', 7, b'\7', b'\7', 0),
('b', -7, b'\371', b'\371', 0),
('B', 7, b'\7', b'\7', 0),
('B', 249, b'\371', b'\371', 0),
('h', 700, b'\002\274', b'\274\002', 0),
('h', -700, b'\375D', b'D\375', 0),
('H', 700, b'\002\274', b'\274\002', 0),
('H', 0x10000-700, b'\375D', b'D\375', 0),
('i', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('i', -70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('I', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('I', 0x100000000-70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('l', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('l', -70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('L', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('L', 0x100000000-70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('f', 2.0, b'@\000\000\000', b'\000\000\000@', 0),
('d', 2.0, b'@\000\000\000\000\000\000\000',
b'\000\000\000\000\000\000\000@', 0),
('f', -2.0, b'\300\000\000\000', b'\000\000\000\300', 0),
('d', -2.0, b'\300\000\000\000\000\000\000\000',
b'\000\000\000\000\000\000\000\300', 0),
('?', 0, b'\0', b'\0', 0),
('?', 3, b'\1', b'\1', 1),
('?', True, b'\1', b'\1', 0),
('?', [], b'\0', b'\0', 1),
('?', (1,), b'\1', b'\1', 1),
]
for fmt, arg, big, lil, asy in tests:
for (xfmt, exp) in [('>'+fmt, big), ('!'+fmt, big), ('<'+fmt, lil),
('='+fmt, ISBIGENDIAN and big or lil)]:
res = struct.pack(xfmt, arg)
self.assertEqual(res, exp)
self.assertEqual(struct.calcsize(xfmt), len(res))
rev = struct.unpack(xfmt, res)[0]
if rev != arg:
self.assertTrue(asy)
def test_calcsize(self):
expected_size = {
'b': 1, 'B': 1,
'h': 2, 'H': 2,
'i': 4, 'I': 4,
'l': 4, 'L': 4,
'q': 8, 'Q': 8,
}
# standard integer sizes
for code, byteorder in iter_integer_formats(('=', '<', '>', '!')):
format = byteorder+code
size = struct.calcsize(format)
self.assertEqual(size, expected_size[code])
# native integer sizes
native_pairs = 'bB', 'hH', 'iI', 'lL', 'nN', 'qQ'
for format_pair in native_pairs:
for byteorder in '', '@':
signed_size = struct.calcsize(byteorder + format_pair[0])
unsigned_size = struct.calcsize(byteorder + format_pair[1])
self.assertEqual(signed_size, unsigned_size)
# bounds for native integer sizes
self.assertEqual(struct.calcsize('b'), 1)
self.assertLessEqual(2, struct.calcsize('h'))
self.assertLessEqual(4, struct.calcsize('l'))
self.assertLessEqual(struct.calcsize('h'), struct.calcsize('i'))
self.assertLessEqual(struct.calcsize('i'), struct.calcsize('l'))
self.assertLessEqual(8, struct.calcsize('q'))
self.assertLessEqual(struct.calcsize('l'), struct.calcsize('q'))
self.assertGreaterEqual(struct.calcsize('n'), struct.calcsize('i'))
self.assertGreaterEqual(struct.calcsize('n'), struct.calcsize('P'))
def test_cache_bytes_vs_str_bb(self):
# Mixing str and bytes formats must not raise BytesWarning under -bb.
code = (
'import struct\n'
'struct.calcsize(b"!d"); struct.calcsize("!d")\n'
'struct.calcsize(">d"); struct.calcsize(b">d")\n'
'struct.Struct(b"i"); struct.Struct("i")\n'
)
assert_python_ok('-bb', '-c', code)
def test_integers(self):
# Integer tests (bBhHiIlLqQnN).
import binascii
class IntTester(unittest.TestCase):
def __init__(self, format):
super(IntTester, self).__init__(methodName='test_one')
self.format = format
self.code = format[-1]
self.byteorder = format[:-1]
if not self.byteorder in byteorders:
raise ValueError("unrecognized packing byteorder: %s" %
self.byteorder)
self.bytesize = struct.calcsize(format)
self.bitsize = self.bytesize * 8
if self.code in tuple('bhilqn'):
self.signed = True
self.min_value = -(2**(self.bitsize-1))
self.max_value = 2**(self.bitsize-1) - 1
elif self.code in tuple('BHILQN'):
self.signed = False
self.min_value = 0
self.max_value = 2**self.bitsize - 1
else:
raise ValueError("unrecognized format code: %s" %
self.code)
def test_one(self, x, pack=struct.pack,
unpack=struct.unpack,
unhexlify=binascii.unhexlify):
format = self.format
if self.min_value <= x <= self.max_value:
expected = x
if self.signed and x < 0:
expected += 1 << self.bitsize
self.assertGreaterEqual(expected, 0)
expected = '%x' % expected
if len(expected) & 1:
expected = "0" + expected
expected = expected.encode('ascii')
expected = unhexlify(expected)
expected = (b"\x00" * (self.bytesize - len(expected)) +
expected)
if (self.byteorder == '<' or
self.byteorder in ('', '@', '=') and not ISBIGENDIAN):
expected = string_reverse(expected)
self.assertEqual(len(expected), self.bytesize)
# Pack work?
got = pack(format, x)
self.assertEqual(got, expected)
# Unpack work?
retrieved = unpack(format, got)[0]
self.assertEqual(x, retrieved)
# Adding any byte should cause a "too big" error.
self.assertRaises((struct.error, TypeError), unpack, format,
b'\x01' + got)
else:
# x is out of range -- verify pack realizes that.
self.assertRaises((OverflowError, ValueError, struct.error),
pack, format, x)
def run(self):
from random import randrange
# Create all interesting powers of 2.
values = []
for exp in range(self.bitsize + 3):
values.append(1 << exp)
# Add some random values.
for i in range(self.bitsize):
val = 0
for j in range(self.bytesize):
val = (val << 8) | randrange(256)
values.append(val)
# Values absorbed from other tests
values.extend([300, 700000, sys.maxsize*4])
# Try all those, and their negations, and +-1 from
# them. Note that this tests all power-of-2
# boundaries in range, and a few out of range, plus
# +-(2**n +- 1).
for base in values:
for val in -base, base:
for incr in -1, 0, 1:
x = val + incr
self.test_one(x)
# Some error cases.
class NotAnInt:
def __int__(self):
return 42
# Objects with an '__index__' method should be allowed
# to pack as integers. That is assuming the implemented
# '__index__' method returns an 'int'.
class Indexable(object):
def __init__(self, value):
self._value = value
def __index__(self):
return self._value
# If the '__index__' method raises a type error, then
# '__int__' should be used with a deprecation warning.
class BadIndex(object):
def __index__(self):
raise TypeError
def __int__(self):
return 42
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
"a string")
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
randrange)
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
3+42j)
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
NotAnInt())
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
BadIndex())
# Check for legitimate values from '__index__'.
for obj in (Indexable(0), Indexable(10), Indexable(17),
Indexable(42), Indexable(100), Indexable(127)):
try:
struct.pack(format, obj)
except:
self.fail("integer code pack failed on object "
"with '__index__' method")
# Check for bogus values from '__index__'.
for obj in (Indexable(b'a'), Indexable('b'), Indexable(None),
Indexable({'a': 1}), Indexable([1, 2, 3])):
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
obj)
for code, byteorder in iter_integer_formats():
format = byteorder+code
t = IntTester(format)
t.run()
def test_nN_code(self):
# n and N don't exist in standard sizes
def assertStructError(func, *args, **kwargs):
with self.assertRaises(struct.error) as cm:
func(*args, **kwargs)
self.assertIn("bad char in struct format", str(cm.exception))
for code in 'nN':
for byteorder in ('=', '<', '>', '!'):
format = byteorder+code
assertStructError(struct.calcsize, format)
assertStructError(struct.pack, format, 0)
assertStructError(struct.unpack, format, b"")
def test_p_code(self):
# Test p ("Pascal string") code.
for code, input, expected, expectedback in [
('0p', b'abc', b'', b''),
('p', b'abc', b'\x00', b''),
('1p', b'abc', b'\x00', b''),
('2p', b'abc', b'\x01a', b'a'),
('3p', b'abc', b'\x02ab', b'ab'),
('4p', b'abc', b'\x03abc', b'abc'),
('5p', b'abc', b'\x03abc\x00', b'abc'),
('6p', b'abc', b'\x03abc\x00\x00', b'abc'),
('1000p', b'x'*1000, b'\xff' + b'x'*999, b'x'*255)]:
got = struct.pack(code, input)
self.assertEqual(got, expected)
(got,) = struct.unpack(code, got)
self.assertEqual(got, expectedback)
def test_705836(self):
# SF bug 705836. "<f" and ">f" had a severe rounding bug, where a carry
# from the low-order discarded bits could propagate into the exponent
# field, causing the result to be wrong by a factor of 2.
for base in range(1, 33):
# smaller <- largest representable float less than base.
delta = 0.5
while base - delta / 2.0 != base:
delta /= 2.0
smaller = base - delta
# Packing this rounds away a solid string of trailing 1 bits.
packed = struct.pack("<f", smaller)
unpacked = struct.unpack("<f", packed)[0]
# This failed at base = 2, 4, and 32, with unpacked = 1, 2, and
# 16, respectively.
self.assertEqual(base, unpacked)
bigpacked = struct.pack(">f", smaller)
self.assertEqual(bigpacked, string_reverse(packed))
unpacked = struct.unpack(">f", bigpacked)[0]
self.assertEqual(base, unpacked)
# Largest finite IEEE single.
big = (1 << 24) - 1
big = math.ldexp(big, 127 - 23)
packed = struct.pack(">f", big)
unpacked = struct.unpack(">f", packed)[0]
self.assertEqual(big, unpacked)
# The same, but tack on a 1 bit so it rounds up to infinity.
big = (1 << 25) - 1
big = math.ldexp(big, 127 - 24)
self.assertRaises(OverflowError, struct.pack, ">f", big)
self.assertRaises(OverflowError, struct.pack, "<f", big)
# same for native format, see gh-145633
self.assertRaises(OverflowError, struct.pack, "f", big)
# And for half-floats
big = (1 << 11) - 1
big = math.ldexp(big, 15 - 10)
packed = struct.pack(">e", big)
unpacked = struct.unpack(">e", packed)[0]
self.assertEqual(big, unpacked)
big = (1 << 12) - 1
big = math.ldexp(big, 15 - 11)
self.assertRaises(OverflowError, struct.pack, ">e", big)
self.assertRaises(OverflowError, struct.pack, "<e", big)
self.assertRaises(OverflowError, struct.pack, "e", big)
def test_1530559(self):
for code, byteorder in iter_integer_formats():
format = byteorder + code
self.assertRaises(struct.error, struct.pack, format, 1.0)
self.assertRaises(struct.error, struct.pack, format, 1.5)
self.assertRaises(struct.error, struct.pack, 'P', 1.0)
self.assertRaises(struct.error, struct.pack, 'P', 1.5)
def test_unpack_from(self):
test_string = b'abcd01234'
fmt = '4s'
s = struct.Struct(fmt)
for cls in (bytes, bytearray):
data = cls(test_string)
self.assertEqual(s.unpack_from(data), (b'abcd',))
self.assertEqual(s.unpack_from(data, 2), (b'cd01',))
self.assertEqual(s.unpack_from(data, 4), (b'0123',))
for i in range(6):
self.assertEqual(s.unpack_from(data, i), (data[i:i+4],))
for i in range(6, len(test_string) + 1):
self.assertRaises(struct.error, s.unpack_from, data, i)
for cls in (bytes, bytearray):
data = cls(test_string)
self.assertEqual(struct.unpack_from(fmt, data), (b'abcd',))
self.assertEqual(struct.unpack_from(fmt, data, 2), (b'cd01',))
self.assertEqual(struct.unpack_from(fmt, data, 4), (b'0123',))
for i in range(6):
self.assertEqual(struct.unpack_from(fmt, data, i), (data[i:i+4],))
for i in range(6, len(test_string) + 1):
self.assertRaises(struct.error, struct.unpack_from, fmt, data, i)
# keyword arguments
self.assertEqual(s.unpack_from(buffer=test_string, offset=2),
(b'cd01',))
def _test_pack_into(self, pack_into):
test_string = b'Reykjavik rocks, eow!'
writable_buf = memoryview(array.array('b', b' '*100))
# Test without offset
pack_into(writable_buf, 0, test_string)
from_buf = writable_buf.tobytes()[:len(test_string)]
self.assertEqual(from_buf, test_string)
# Test with offset.
pack_into(writable_buf, 10, test_string)
from_buf = writable_buf.tobytes()[:len(test_string)+10]
self.assertEqual(from_buf, test_string[:10] + test_string)
# Test with negative offset.
pack_into(writable_buf, -30, test_string)
from_buf = writable_buf.tobytes()[-30:-30+len(test_string)]
self.assertEqual(from_buf, test_string)
# Go beyond boundaries.
small_buf = array.array('b', b' '*10)
with self.assertRaises((ValueError, struct.error)):
pack_into(small_buf, 0, test_string)
with self.assertRaises((ValueError, struct.error)):
pack_into(writable_buf, 90, test_string)
with self.assertRaises((ValueError, struct.error)):
pack_into(writable_buf, -10, test_string)
with self.assertRaises((ValueError, struct.error)):
pack_into(writable_buf, 150, test_string)
with self.assertRaises((ValueError, struct.error)):
pack_into(writable_buf, -150, test_string)
# Test invalid buffer.
self.assertRaises(TypeError, pack_into, b' '*100, 0, test_string)
self.assertRaises(TypeError, pack_into, ' '*100, 0, test_string)
self.assertRaises(TypeError, pack_into, [0]*100, 0, test_string)
self.assertRaises(TypeError, pack_into, None, 0, test_string)
self.assertRaises(TypeError, pack_into, writable_buf[::2], 0, test_string)
self.assertRaises(TypeError, pack_into, writable_buf[::-1], 0, test_string)
# Test bogus offset (issue bpo-3694)
with self.assertRaises(TypeError):
pack_into(writable_buf, None, test_string)
with self.assertRaises(TypeError):
pack_into(writable_buf, 0.0, test_string)
with self.assertRaises((IndexError, OverflowError)):
pack_into(writable_buf, 2**1000, test_string)
with self.assertRaises((IndexError, OverflowError)):
pack_into(writable_buf, -2**1000, test_string)
def test_pack_into(self):
s = struct.Struct('21s')
self._test_pack_into(s.pack_into)
def test_pack_into_fn(self):
pack_into = lambda *args: struct.pack_into('21s', *args)
self._test_pack_into(pack_into)
def test_unpack_with_buffer(self):
# SF bug 1563759: struct.unpack doesn't support buffer protocol objects
data1 = array.array('B', b'\x12\x34\x56\x78')
data2 = memoryview(b'\x12\x34\x56\x78') # XXX b'......XXXX......', 6, 4
for data in [data1, data2]:
value, = struct.unpack('>I', data)
self.assertEqual(value, 0x12345678)
def test_bool(self):
class ExplodingBool(object):
def __bool__(self):
raise OSError
for prefix in tuple("<>!=")+('',):
false = (), [], [], '', 0
true = [1], 'test', 5, -1, 0xffffffff+1, 0xffffffff/2
falseFormat = prefix + '?' * len(false)
packedFalse = struct.pack(falseFormat, *false)
unpackedFalse = struct.unpack(falseFormat, packedFalse)
trueFormat = prefix + '?' * len(true)
packedTrue = struct.pack(trueFormat, *true)
unpackedTrue = struct.unpack(trueFormat, packedTrue)
self.assertEqual(len(true), len(unpackedTrue))
self.assertEqual(len(false), len(unpackedFalse))
for t in unpackedFalse:
self.assertFalse(t)
for t in unpackedTrue:
self.assertTrue(t)
packed = struct.pack(prefix+'?', 1)
self.assertEqual(len(packed), struct.calcsize(prefix+'?'))
if len(packed) != 1:
self.assertFalse(prefix, msg='encoded bool is not one byte: %r'
%packed)
try:
struct.pack(prefix + '?', ExplodingBool())
except OSError:
pass
else:
self.fail("Expected OSError: struct.pack(%r, "
"ExplodingBool())" % (prefix + '?'))
for c in [b'\x01', b'\x7f', b'\xff', b'\x0f', b'\xf0']:
self.assertTrue(struct.unpack('>?', c)[0])
self.assertTrue(struct.unpack('<?', c)[0])
self.assertTrue(struct.unpack('=?', c)[0])
self.assertTrue(struct.unpack('@?', c)[0])
def test_count_overflow(self):
hugecount = '{}b'.format(sys.maxsize+1)
self.assertRaises(struct.error, struct.calcsize, hugecount)
hugecount2 = '{}b{}H'.format(sys.maxsize//2, sys.maxsize//2)
self.assertRaises(struct.error, struct.calcsize, hugecount2)
hugecount3 = '{}i{}q'.format(sys.maxsize // 4, sys.maxsize // 8)
self.assertRaises(struct.error, struct.calcsize, hugecount3)
hugecount4 = '{}?s'.format(sys.maxsize)
self.assertRaises(struct.error, struct.calcsize, hugecount4)
hugecount5 = '{}?p'.format(sys.maxsize)
self.assertRaises(struct.error, struct.calcsize, hugecount5)
def test_trailing_counter(self):
store = array.array('b', b' '*100)
# format lists containing only count spec should result in an error
self.assertRaises(struct.error, struct.pack, '12345')
self.assertRaises(struct.error, struct.unpack, '12345', b'')
self.assertRaises(struct.error, struct.pack_into, '12345', store, 0)
self.assertRaises(struct.error, struct.unpack_from, '12345', store, 0)
# Format lists with trailing count spec should result in an error
self.assertRaises(struct.error, struct.pack, 'c12345', 'x')
self.assertRaises(struct.error, struct.unpack, 'c12345', b'x')
self.assertRaises(struct.error, struct.pack_into, 'c12345', store, 0,
'x')
self.assertRaises(struct.error, struct.unpack_from, 'c12345', store,
0)
# Mixed format tests
self.assertRaises(struct.error, struct.pack, '14s42', 'spam and eggs')
self.assertRaises(struct.error, struct.unpack, '14s42',
b'spam and eggs')
self.assertRaises(struct.error, struct.pack_into, '14s42', store, 0,
'spam and eggs')
self.assertRaises(struct.error, struct.unpack_from, '14s42', store, 0)
def test_Struct_reinitialization(self):
# Issue 9422: there was a memory leak when reinitializing a
# Struct instance. This test can be used to detect the leak
# when running with regrtest -L.
s = struct.Struct('>h')
s.__init__('>hh')
self.assertEqual(s.format, '>hh')
packed = b'\x00\x01\x00\x02'
self.assertEqual(s.pack(1, 2), packed)
self.assertEqual(s.unpack(packed), (1, 2))
with self.assertRaises(UnicodeEncodeError):
s.__init__('\udc00')
self.assertEqual(s.format, '>hh')
self.assertEqual(s.pack(1, 2), packed)
self.assertEqual(s.unpack(packed), (1, 2))
with self.assertRaises(struct.error):
s.__init__('$')
self.assertEqual(s.format, '>hh')
self.assertEqual(s.pack(1, 2), packed)
self.assertEqual(s.unpack(packed), (1, 2))
def check_sizeof(self, format_str, number_of_codes):
# The size of 'PyStructObject'
totalsize = support.calcobjsize('2n3P')
# The size taken up by the 'formatcode' dynamic array
totalsize += struct.calcsize('P3n0P') * (number_of_codes + 1)
support.check_sizeof(self, struct.Struct(format_str), totalsize)
@support.cpython_only
def test__sizeof__(self):
for code in integer_codes:
self.check_sizeof(code, 1)
self.check_sizeof('BHILfdspP', 9)
self.check_sizeof('B' * 1234, 1234)
self.check_sizeof('fd', 2)
self.check_sizeof('xxxxxxxxxxxxxx', 0)
self.check_sizeof('100H', 1)
self.check_sizeof('187s', 1)
self.check_sizeof('20p', 1)
self.check_sizeof('0s', 1)
self.check_sizeof('0p', 1)
self.check_sizeof('0c', 0)
def test_boundary_error_message(self):
regex1 = (
r'pack_into requires a buffer of at least 6 '
r'bytes for packing 1 bytes at offset 5 '
r'\(actual buffer size is 1\)'
)
with self.assertRaisesRegex(struct.error, regex1):
struct.pack_into('b', bytearray(1), 5, 1)
regex2 = (
r'unpack_from requires a buffer of at least 6 '
r'bytes for unpacking 1 bytes at offset 5 '
r'\(actual buffer size is 1\)'
)
with self.assertRaisesRegex(struct.error, regex2):
struct.unpack_from('b', bytearray(1), 5)
def test_boundary_error_message_with_negative_offset(self):
byte_list = bytearray(10)
with self.assertRaisesRegex(
struct.error,
r'no space to pack 4 bytes at offset -2'):
struct.pack_into('<I', byte_list, -2, 123)
with self.assertRaisesRegex(
struct.error,
'offset -11 out of range for 10-byte buffer'):
struct.pack_into('<B', byte_list, -11, 123)
with self.assertRaisesRegex(
struct.error,
r'not enough data to unpack 4 bytes at offset -2'):
struct.unpack_from('<I', byte_list, -2)
with self.assertRaisesRegex(
struct.error,
"offset -11 out of range for 10-byte buffer"):
struct.unpack_from('<B', byte_list, -11)
def test_boundary_error_message_with_large_offset(self):
# Test overflows cause by large offset and value size (issue 30245)
regex1 = (
r'pack_into requires a buffer of at least ' + str(sys.maxsize + 4) +
r' bytes for packing 4 bytes at offset ' + str(sys.maxsize) +
r' \(actual buffer size is 10\)'
)
with self.assertRaisesRegex(struct.error, regex1):
struct.pack_into('<I', bytearray(10), sys.maxsize, 1)
regex2 = (
r'unpack_from requires a buffer of at least ' + str(sys.maxsize + 4) +
r' bytes for unpacking 4 bytes at offset ' + str(sys.maxsize) +
r' \(actual buffer size is 10\)'
)
with self.assertRaisesRegex(struct.error, regex2):
struct.unpack_from('<I', bytearray(10), sys.maxsize)
def test_issue29802(self):
# When the second argument of struct.unpack() was of wrong type
# the Struct object was decrefed twice and the reference to
# deallocated object was left in a cache.
with self.assertRaises(TypeError):
struct.unpack('b', 0)
# Shouldn't crash.
self.assertEqual(struct.unpack('b', b'a'), (b'a'[0],))
def test_format_attr(self):
s = struct.Struct('=i2H')
self.assertEqual(s.format, '=i2H')
# use a bytes string
s2 = struct.Struct(s.format.encode())
self.assertEqual(s2.format, s.format)
def test_struct_cleans_up_at_runtime_shutdown(self):
code = """if 1:
import struct
class C:
def __init__(self):
self.pack = struct.pack
def __del__(self):
self.pack('I', -42)
struct.x = C()
"""
rc, stdout, stderr = assert_python_ok("-c", code)
self.assertEqual(rc, 0)
self.assertEqual(stdout.rstrip(), b"")
self.assertIn(b"Exception ignored while calling deallocator", stderr)
self.assertIn(b"C.__del__", stderr)
def test__struct_reference_cycle_cleaned_up(self):
# Regression test for python/cpython#94207.
# When we create a new struct module, trigger use of its cache,
# and then delete it ...
_struct_module = import_helper.import_fresh_module("_struct")
module_ref = weakref.ref(_struct_module)
_struct_module.calcsize("b")
del _struct_module
# Then the module should have been garbage collected.
gc.collect()
self.assertIsNone(
module_ref(), "_struct module was not garbage collected")
@support.cpython_only
def test__struct_types_immutable(self):
# See https://github.com/python/cpython/issues/94254
Struct = struct.Struct
unpack_iterator = type(struct.iter_unpack("b", b'x'))
for cls in (Struct, unpack_iterator):
with self.subTest(cls=cls):
with self.assertRaises(TypeError):
cls.x = 1
def test_issue35714(self):
# Embedded null characters should not be allowed in format strings.
for s in '\0', '2\0i', b'\0':
with self.assertRaisesRegex(struct.error,
'embedded null character'):
struct.calcsize(s)
@support.cpython_only
def test_issue98248(self):
def test_error_msg(prefix, int_type, is_unsigned):
fmt_str = prefix + int_type
size = struct.calcsize(fmt_str)
if is_unsigned:
max_ = 2 ** (size * 8) - 1
min_ = 0
else:
max_ = 2 ** (size * 8 - 1) - 1
min_ = -2 ** (size * 8 - 1)
error_msg = f"'{int_type}' format requires {min_} <= number <= {max_}"
for number in [int(-1e50), min_ - 1, max_ + 1, int(1e50)]:
with self.subTest(format_str=fmt_str, number=number):
with self.assertRaisesRegex(struct.error, error_msg):
struct.pack(fmt_str, number)
error_msg = "required argument is not an integer"
not_number = ""
with self.subTest(format_str=fmt_str, number=not_number):
with self.assertRaisesRegex(struct.error, error_msg):
struct.pack(fmt_str, not_number)
for prefix in '@=<>':
for int_type in 'BHILQ':
test_error_msg(prefix, int_type, True)
for int_type in 'bhilq':
test_error_msg(prefix, int_type, False)
int_type = 'N'
test_error_msg('@', int_type, True)
int_type = 'n'
test_error_msg('@', int_type, False)
@support.cpython_only
def test_issue98248_error_propagation(self):
class Div0:
def __index__(self):
1 / 0
def test_error_propagation(fmt_str):
with self.subTest(format_str=fmt_str, exception="ZeroDivisionError"):
with self.assertRaises(ZeroDivisionError):
struct.pack(fmt_str, Div0())
for prefix in '@=<>':
for int_type in 'BHILQbhilq':
test_error_propagation(prefix + int_type)
test_error_propagation('N')
test_error_propagation('n')
def test_struct_subclass_instantiation(self):
# Regression test for https://github.com/python/cpython/issues/112358
class MyStruct(struct.Struct):
def __init__(self):
super().__init__('>h')
my_struct = MyStruct()
self.assertEqual(my_struct.pack(12345), b'\x30\x39')
def test_repr(self):
s = struct.Struct('=i2H')
self.assertEqual(repr(s), f'Struct({s.format!r})')
def test_c_complex_round_trip(self):
values = [complex(*_) for _ in combinations([1, -1, 0.0, -0.0, 2,
-3, INF, -INF, NAN], 2)]
for z in values:
for f in ['F', 'D', '>F', '>D', '<F', '<D']:
with self.subTest(z=z, format=f):
round_trip = struct.unpack(f, struct.pack(f, z))[0]
self.assertComplexesAreIdentical(z, round_trip)
@unittest.skipIf(
support.is_android or support.is_apple_mobile,
"Subinterpreters are not supported on Android and iOS"
)
def test_endian_table_init_subinterpreters(self):
# Verify that the _struct extension module can be initialized
# concurrently in subinterpreters (gh-140260).
try:
from concurrent.futures import InterpreterPoolExecutor
except ImportError:
raise unittest.SkipTest("InterpreterPoolExecutor not available")
code = "import struct"
with InterpreterPoolExecutor(max_workers=5) as executor:
results = executor.map(exec, [code] * 5)
self.assertListEqual(list(results), [None] * 5)
def test_operations_on_half_initialized_Struct(self):
S = struct.Struct.__new__(struct.Struct)
spam = array.array('b', b' ')
self.assertRaises(RuntimeError, S.iter_unpack, spam)
self.assertRaises(RuntimeError, S.pack, 1)
self.assertRaises(RuntimeError, S.pack_into, spam, 1)
self.assertRaises(RuntimeError, S.unpack, spam)
self.assertRaises(RuntimeError, S.unpack_from, spam)
self.assertRaises(RuntimeError, getattr, S, 'format')
self.assertRaises(RuntimeError, S.__sizeof__)
self.assertRaises(RuntimeError, repr, S)
self.assertEqual(S.size, -1)
def test_float_round_trip(self):
for format in (
"f", "<f", ">f",
"d", "<d", ">d",
"e", "<e", ">e",
):
with self.subTest(format=format):
f = struct.unpack(format, struct.pack(format, 1.5))[0]
self.assertEqual(f, 1.5)
f = struct.unpack(format, struct.pack(format, NAN))[0]
self.assertTrue(math.isnan(f), f)
f = struct.unpack(format, struct.pack(format, INF))[0]
self.assertTrue(math.isinf(f), f)
self.assertEqual(math.copysign(1.0, f), 1.0)
f = struct.unpack(format, struct.pack(format, -INF))[0]
self.assertTrue(math.isinf(f), f)
self.assertEqual(math.copysign(1.0, f), -1.0)
class UnpackIteratorTest(unittest.TestCase):
"""
Tests for iterative unpacking (struct.Struct.iter_unpack).
"""
def test_construct(self):
def _check_iterator(it):
self.assertIsInstance(it, abc.Iterator)
self.assertIsInstance(it, abc.Iterable)
s = struct.Struct('>ibcp')
it = s.iter_unpack(b"")
_check_iterator(it)
it = s.iter_unpack(b"1234567")
_check_iterator(it)
# Wrong bytes length
with self.assertRaises(struct.error):
s.iter_unpack(b"123456")
with self.assertRaises(struct.error):
s.iter_unpack(b"12345678")
# Zero-length struct
s = struct.Struct('>')
with self.assertRaises(struct.error):
s.iter_unpack(b"")
with self.assertRaises(struct.error):
s.iter_unpack(b"12")
def test_uninstantiable(self):
iter_unpack_type = type(struct.Struct(">ibcp").iter_unpack(b""))
self.assertRaises(TypeError, iter_unpack_type)
def test_iterate(self):
s = struct.Struct('>IB')
b = bytes(range(1, 16))
it = s.iter_unpack(b)
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertEqual(next(it), (0x0b0c0d0e, 15))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_arbitrary_buffer(self):
s = struct.Struct('>IB')
b = bytes(range(1, 11))
it = s.iter_unpack(memoryview(b))
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_length_hint(self):
lh = operator.length_hint
s = struct.Struct('>IB')
b = bytes(range(1, 16))
it = s.iter_unpack(b)
self.assertEqual(lh(it), 3)
next(it)
self.assertEqual(lh(it), 2)
next(it)
self.assertEqual(lh(it), 1)
next(it)
self.assertEqual(lh(it), 0)
self.assertRaises(StopIteration, next, it)
self.assertEqual(lh(it), 0)
def test_module_func(self):
# Sanity check for the global struct.iter_unpack()
it = struct.iter_unpack('>IB', bytes(range(1, 11)))
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_half_float(self):
_testcapi = import_helper.import_module('_testcapi')
# Little-endian examples from:
# http://en.wikipedia.org/wiki/Half_precision_floating-point_format
format_bits_float__cleanRoundtrip_list = [
(b'\x00\x3c', 1.0),
(b'\x00\xc0', -2.0),
(b'\xff\x7b', 65504.0), # (max half precision)
(b'\x00\x04', 2**-14), # ~= 6.10352 * 10**-5 (min pos normal)
(b'\x01\x00', 2**-24), # ~= 5.96046 * 10**-8 (min pos subnormal)
(b'\x00\x00', 0.0),
(b'\x00\x80', -0.0),
(b'\x00\x7c', float('+inf')),
(b'\x00\xfc', float('-inf')),
(b'\x55\x35', 0.333251953125), # ~= 1/3
]
for le_bits, f in format_bits_float__cleanRoundtrip_list:
be_bits = le_bits[::-1]
self.assertEqual(f, struct.unpack('<e', le_bits)[0])
self.assertEqual(le_bits, struct.pack('<e', f))
self.assertEqual(f, struct.unpack('>e', be_bits)[0])
self.assertEqual(be_bits, struct.pack('>e', f))
if sys.byteorder == 'little':
self.assertEqual(f, struct.unpack('e', le_bits)[0])
self.assertEqual(le_bits, struct.pack('e', f))
else:
self.assertEqual(f, struct.unpack('e', be_bits)[0])
self.assertEqual(be_bits, struct.pack('e', f))
# Check for NaN handling:
format_bits__nan_list = [
('<e', b'\x01\xfc'),
('<e', b'\x00\xfe'),
('<e', b'\xff\xff'),
('<e', b'\x01\x7c'),
('<e', b'\x00\x7e'),
('<e', b'\xff\x7f'),
]
for formatcode, bits in format_bits__nan_list:
self.assertTrue(math.isnan(struct.unpack('<e', bits)[0]))
self.assertTrue(math.isnan(struct.unpack('>e', bits[::-1])[0]))
# Check that packing produces a bit pattern representing a quiet NaN:
# all exponent bits and the msb of the fraction should all be 1.
if _testcapi.nan_msb_is_signaling:
# HP PA RISC and some MIPS CPUs use 0 for quiet, see:
# https://en.wikipedia.org/wiki/NaN#Encoding
expected = 0x7c
else:
expected = 0x7e
packed = struct.pack('<e', math.nan)
self.assertEqual(packed[1] & 0x7e, expected)
packed = struct.pack('<e', -math.nan)
self.assertEqual(packed[1] & 0x7e, expected)
# Checks for round-to-even behavior
format_bits_float__rounding_list = [
('>e', b'\x00\x01', 2.0**-25 + 2.0**-35), # Rounds to minimum subnormal
('>e', b'\x00\x00', 2.0**-25), # Underflows to zero (nearest even mode)
('>e', b'\x00\x00', 2.0**-26), # Underflows to zero
('>e', b'\x03\xff', 2.0**-14 - 2.0**-24), # Largest subnormal.
('>e', b'\x03\xff', 2.0**-14 - 2.0**-25 - 2.0**-65),
('>e', b'\x04\x00', 2.0**-14 - 2.0**-25),
('>e', b'\x04\x00', 2.0**-14), # Smallest normal.
('>e', b'\x3c\x01', 1.0+2.0**-11 + 2.0**-16), # rounds to 1.0+2**(-10)
('>e', b'\x3c\x00', 1.0+2.0**-11), # rounds to 1.0 (nearest even mode)
('>e', b'\x3c\x00', 1.0+2.0**-12), # rounds to 1.0
('>e', b'\x7b\xff', 65504), # largest normal
('>e', b'\x7b\xff', 65519), # rounds to 65504
('>e', b'\x80\x01', -2.0**-25 - 2.0**-35), # Rounds to minimum subnormal
('>e', b'\x80\x00', -2.0**-25), # Underflows to zero (nearest even mode)
('>e', b'\x80\x00', -2.0**-26), # Underflows to zero
('>e', b'\xbc\x01', -1.0-2.0**-11 - 2.0**-16), # rounds to 1.0+2**(-10)
('>e', b'\xbc\x00', -1.0-2.0**-11), # rounds to 1.0 (nearest even mode)
('>e', b'\xbc\x00', -1.0-2.0**-12), # rounds to 1.0
('>e', b'\xfb\xff', -65519), # rounds to 65504
]
for formatcode, bits, f in format_bits_float__rounding_list:
self.assertEqual(bits, struct.pack(formatcode, f))
# This overflows, and so raises an error
format_bits_float__roundingError_list = [
# Values that round to infinity.
('>e', 65520.0),
('>e', 65536.0),
('>e', 1e300),
('>e', -65520.0),
('>e', -65536.0),
('>e', -1e300),
('<e', 65520.0),
('<e', 65536.0),
('<e', 1e300),
('<e', -65520.0),
('<e', -65536.0),
('<e', -1e300),
]
for formatcode, f in format_bits_float__roundingError_list:
self.assertRaises(OverflowError, struct.pack, formatcode, f)
# Double rounding
format_bits_float__doubleRoundingError_list = [
('>e', b'\x67\xff', 0x1ffdffffff * 2**-26), # should be 2047, if double-rounded 64>32>16, becomes 2048
]
for formatcode, bits, f in format_bits_float__doubleRoundingError_list:
self.assertEqual(bits, struct.pack(formatcode, f))
if __name__ == '__main__':
unittest.main()