Class IntTester

Lib/test/test_struct.py:188–331

        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.