text: from collections import abc
  import array
  import operator
  import unittest
  import struct
  import sys
  
  from test import support
  
  ISBIGENDIAN = sys.byteorder == "big"
  
  integer_codes = 'b', 'B', 'h', 'H', 'i', 'I', 'l', 'L', 'q', 'Q', 'n', 'N'
  byteorders = '', '@', '=', '<', '>', '!'
  
  def iter_integer_formats(byteorders=byteorders):
      for code in integer_codes:
          for byteorder in byteorders:
              if (byteorder in ('', '@') and code in ('q', 'Q') and
                  not HAVE_LONG_LONG):
                  continue
              if (byteorder not in ('', '@') and code in ('n', 'N')):
                  continue
              yield code, byteorder
  
  # Native 'q' packing isn't available on systems that don't have the C
  # long long type.
  try:
      struct.pack('q', 5)
  except struct.error:
      HAVE_LONG_LONG = False
  else:
      HAVE_LONG_LONG = True
  
  def string_reverse(s):
      return s[::-1]
  
  def bigendian_to_native(value):
      if ISBIGENDIAN:
          return value
      else:
          return string_reverse(value)
  
  class StructTest(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),
              ('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'
          if HAVE_LONG_LONG:
              native_pairs += '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'))
          if HAVE_LONG_LONG:
              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_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 [
                  ('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.
          import math
  
          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)
  
      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)
  
      def test_pack_into(self):
          test_string = b'Reykjavik rocks, eow!'
          writable_buf = array.array('b', b' '*100)
          fmt = '21s'
          s = struct.Struct(fmt)
  
          # Test without offset
          s.pack_into(writable_buf, 0, test_string)
          from_buf = writable_buf.tobytes()[:len(test_string)]
          self.assertEqual(from_buf, test_string)
  
          # Test with offset.
          s.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)
  
          # Go beyond boundaries.
          small_buf = array.array('b', b' '*10)
          self.assertRaises((ValueError, struct.error), s.pack_into, small_buf, 0,
                            test_string)
          self.assertRaises((ValueError, struct.error), s.pack_into, small_buf, 2,
                            test_string)
  
          # Test bogus offset (issue 3694)
          sb = small_buf
          self.assertRaises((TypeError, struct.error), struct.pack_into, b'', sb,
                            None)
  
      def test_pack_into_fn(self):
          test_string = b'Reykjavik rocks, eow!'
          writable_buf = array.array('b', b' '*100)
          fmt = '21s'
          pack_into = lambda *args: struct.pack_into(fmt, *args)
  
          # 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)
  
          # Go beyond boundaries.
          small_buf = array.array('b', b' '*10)
          self.assertRaises((ValueError, struct.error), pack_into, small_buf, 0,
                            test_string)
          self.assertRaises((ValueError, struct.error), pack_into, small_buf, 2,
                            test_string)
  
      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])
  
      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)
  
      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', '')
          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', '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',
                            '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('i')
          s.__init__('ii')
  
      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('0c', 0)
  
  
  @unittest.skipIf(sys.implementation.name == "ironpython", "not implemented")
  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_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_main():
      support.run_unittest(__name__)
  
  if __name__ == '__main__':
      test_main()
  