"""Test the binascii C module."""

import unittest
import binascii
import array
import re
from test.support import bigmemtest, _1G, _4G
from test.support.hypothesis_helper import hypothesis


# Note: "*_hex" functions are aliases for "(un)hexlify"
b2a_functions = ['b2a_base64', 'b2a_hex', 'b2a_qp', 'b2a_uu',
                 'hexlify']
a2b_functions = ['a2b_base64', 'a2b_hex', 'a2b_qp', 'a2b_uu',
                 'unhexlify']
all_functions = a2b_functions + b2a_functions + ['crc32', 'crc_hqx']


class BinASCIITest(unittest.TestCase):

    type2test = bytes
    # Create binary test data
    rawdata = b"The quick brown fox jumps over the lazy dog.\r\n"
    # Be slow so we don't depend on other modules
    rawdata += bytes(range(256))
    rawdata += b"\r\nHello world.\n"

    def setUp(self):
        self.data = self.type2test(self.rawdata)

    def assertConversion(self, original, converted, restored, **kwargs):
        self.assertIsInstance(original, bytes)
        self.assertIsInstance(converted, bytes)
        self.assertIsInstance(restored, bytes)
        if converted:
            self.assertLess(max(converted), 128)
        self.assertEqual(original, restored, msg=f'{self.type2test=} {kwargs=}')

    def test_exceptions(self):
        # Check module exceptions
        self.assertIsSubclass(binascii.Error, Exception)
        self.assertIsSubclass(binascii.Incomplete, Exception)

    def test_functions(self):
        # Check presence of all functions
        for name in all_functions:
            self.assertHasAttr(getattr(binascii, name), '__call__')
            self.assertRaises(TypeError, getattr(binascii, name))

    def test_returned_value(self):
        # Limit to the minimum of all limits (b2a_uu)
        MAX_ALL = 45
        raw = self.rawdata[:MAX_ALL]
        for fa, fb in zip(a2b_functions, b2a_functions):
            a2b = getattr(binascii, fa)
            b2a = getattr(binascii, fb)
            try:
                a = b2a(self.type2test(raw))
                res = a2b(self.type2test(a))
            except Exception as err:
                self.fail("{}/{} conversion raises {!r}".format(fb, fa, err))
            self.assertEqual(res, raw, "{}/{} conversion: "
                             "{!r} != {!r}".format(fb, fa, res, raw))
            self.assertConversion(raw, a, res)
        self.assertIsInstance(binascii.crc_hqx(raw, 0), int)
        self.assertIsInstance(binascii.crc32(raw), int)

    def test_base64valid(self):
        # Test base64 with valid data
        MAX_BASE64 = 57
        lines = []
        for i in range(0, len(self.rawdata), MAX_BASE64):
            b = self.type2test(self.rawdata[i:i+MAX_BASE64])
            a = binascii.b2a_base64(b)
            lines.append(a)
        res = bytes()
        for line in lines:
            a = self.type2test(line)
            b = binascii.a2b_base64(a)
            res += b
        self.assertEqual(res, self.rawdata)

    def test_base64invalid(self):
        # Test base64 with random invalid characters sprinkled throughout
        # (This requires a new version of binascii.)
        MAX_BASE64 = 57
        lines = []
        for i in range(0, len(self.data), MAX_BASE64):
            b = self.type2test(self.rawdata[i:i+MAX_BASE64])
            a = binascii.b2a_base64(b)
            lines.append(a)

        fillers = bytearray()
        valid = b"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+/"
        for i in range(256):
            if i not in valid:
                fillers.append(i)
        def addnoise(line):
            noise = fillers
            ratio = len(line) // len(noise)
            res = bytearray()
            while line and noise:
                if len(line) // len(noise) > ratio:
                    c, line = line[0], line[1:]
                else:
                    c, noise = noise[0], noise[1:]
                res.append(c)
            return res + noise + line
        res = bytearray()
        for line in map(addnoise, lines):
            a = self.type2test(line)
            b = binascii.a2b_base64(a)
            res += b
        self.assertEqual(res, self.rawdata)

        # Test base64 with just invalid characters, which should return
        # empty strings. TBD: shouldn't it raise an exception instead ?
        self.assertEqual(binascii.a2b_base64(self.type2test(fillers)), b'')

    @unittest.expectedFailure  # TODO: RUSTPYTHON
    def test_base64_strict_mode(self):
        # Test base64 with strict mode on
        def _assertRegexTemplate(assert_regex: str, data: bytes, non_strict_mode_expected_result: bytes):
            with self.assertRaisesRegex(binascii.Error, assert_regex):
                binascii.a2b_base64(self.type2test(data), strict_mode=True)
            self.assertEqual(binascii.a2b_base64(self.type2test(data), strict_mode=False),
                             non_strict_mode_expected_result)
            self.assertEqual(binascii.a2b_base64(self.type2test(data)),
                             non_strict_mode_expected_result)

        def assertExcessData(data, non_strict_mode_expected_result: bytes):
            _assertRegexTemplate(r'(?i)Excess data', data, non_strict_mode_expected_result)

        def assertNonBase64Data(data, non_strict_mode_expected_result: bytes):
            _assertRegexTemplate(r'(?i)Only base64 data', data, non_strict_mode_expected_result)

        def assertLeadingPadding(data, non_strict_mode_expected_result: bytes):
            _assertRegexTemplate(r'(?i)Leading padding', data, non_strict_mode_expected_result)

        def assertDiscontinuousPadding(data, non_strict_mode_expected_result: bytes):
            _assertRegexTemplate(r'(?i)Discontinuous padding', data, non_strict_mode_expected_result)

        def assertExcessPadding(data, non_strict_mode_expected_result: bytes):
            _assertRegexTemplate(r'(?i)Excess padding', data, non_strict_mode_expected_result)

        # Test excess data exceptions
        assertExcessPadding(b'ab===', b'i')
        assertExcessPadding(b'ab====', b'i')
        assertNonBase64Data(b'ab==:', b'i')
        assertExcessData(b'abc=a', b'i\xb7\x1a')
        assertNonBase64Data(b'abc=:', b'i\xb7')
        assertNonBase64Data(b'ab==\n', b'i')
        assertExcessPadding(b'abc==', b'i\xb7')
        assertExcessPadding(b'abc===', b'i\xb7')
        assertExcessPadding(b'abc====', b'i\xb7')
        assertExcessPadding(b'abc=====', b'i\xb7')

        # Test non-base64 data exceptions
        assertNonBase64Data(b'\nab==', b'i')
        assertNonBase64Data(b'ab:(){:|:&};:==', b'i')
        assertNonBase64Data(b'a\nb==', b'i')
        assertNonBase64Data(b'a\x00b==', b'i')

        # Test malformed padding
        assertLeadingPadding(b'=', b'')
        assertLeadingPadding(b'==', b'')
        assertLeadingPadding(b'===', b'')
        assertLeadingPadding(b'====', b'')
        assertLeadingPadding(b'=====', b'')
        assertDiscontinuousPadding(b'ab=c=', b'i\xb7')
        assertDiscontinuousPadding(b'ab=ab==', b'i\xb6\x9b')
        assertExcessPadding(b'abcd=', b'i\xb7\x1d')
        assertExcessPadding(b'abcd==', b'i\xb7\x1d')
        assertExcessPadding(b'abcd===', b'i\xb7\x1d')
        assertExcessPadding(b'abcd====', b'i\xb7\x1d')
        assertExcessPadding(b'abcd=====', b'i\xb7\x1d')

    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: b'i' != b'i\xb7'
    def test_base64_excess_data(self):
        # Test excess data exceptions
        def assertExcessData(data, expected):
            assert_regex = r'(?i)Excess data'
            data = self.type2test(data)
            with self.assertRaisesRegex(binascii.Error, assert_regex):
                binascii.a2b_base64(data, strict_mode=True)
            self.assertEqual(binascii.a2b_base64(data, strict_mode=False),
                             expected)
            self.assertEqual(binascii.a2b_base64(data), expected)

        assertExcessData(b'ab==c=', b'i\xb7')
        assertExcessData(b'ab==cd', b'i\xb7\x1d')
        assertExcessData(b'abc=d', b'i\xb7\x1d')

    def test_base64errors(self):
        # Test base64 with invalid padding
        def assertIncorrectPadding(data):
            with self.assertRaisesRegex(binascii.Error, r'(?i)Incorrect padding'):
                binascii.a2b_base64(self.type2test(data))

        assertIncorrectPadding(b'ab')
        assertIncorrectPadding(b'ab=')
        assertIncorrectPadding(b'abc')
        assertIncorrectPadding(b'abcdef')
        assertIncorrectPadding(b'abcdef=')
        assertIncorrectPadding(b'abcdefg')
        assertIncorrectPadding(b'a=b=')
        assertIncorrectPadding(b'a\nb=')

        # Test base64 with invalid number of valid characters (1 mod 4)
        def assertInvalidLength(data):
            n_data_chars = len(re.sub(br'[^A-Za-z0-9/+]', br'', data))
            expected_errmsg_re = \
                r'(?i)Invalid.+number of data characters.+' + str(n_data_chars)
            with self.assertRaisesRegex(binascii.Error, expected_errmsg_re):
                binascii.a2b_base64(self.type2test(data))

        assertInvalidLength(b'a')
        assertInvalidLength(b'a=')
        assertInvalidLength(b'a==')
        assertInvalidLength(b'a===')
        assertInvalidLength(b'a' * 5)
        assertInvalidLength(b'a' * (4 * 87 + 1))
        assertInvalidLength(b'A\tB\nC ??DE')  # only 5 valid characters

    def test_uu(self):
        MAX_UU = 45
        for backtick in (True, False):
            lines = []
            for i in range(0, len(self.data), MAX_UU):
                b = self.type2test(self.rawdata[i:i+MAX_UU])
                a = binascii.b2a_uu(b, backtick=backtick)
                lines.append(a)
            res = bytes()
            for line in lines:
                a = self.type2test(line)
                b = binascii.a2b_uu(a)
                res += b
            self.assertEqual(res, self.rawdata)

        self.assertEqual(binascii.a2b_uu(b"\x7f"), b"\x00"*31)
        self.assertEqual(binascii.a2b_uu(b"\x80"), b"\x00"*32)
        self.assertEqual(binascii.a2b_uu(b"\xff"), b"\x00"*31)
        self.assertRaises(binascii.Error, binascii.a2b_uu, b"\xff\x00")
        self.assertRaises(binascii.Error, binascii.a2b_uu, b"!!!!")
        self.assertRaises(binascii.Error, binascii.a2b_uu,
                          self.type2test(b""))
        self.assertRaises(binascii.Error, binascii.a2b_uu,
                          self.type2test(b"#86)C")[:0])
        self.assertRaises(binascii.Error, binascii.b2a_uu, 46*b"!")

        # Issue #7701 (crash on a pydebug build)
        self.assertEqual(binascii.b2a_uu(b'x'), b'!>   \n')

        self.assertEqual(binascii.b2a_uu(b''), b' \n')
        self.assertEqual(binascii.b2a_uu(b'', backtick=True), b'`\n')
        self.assertEqual(binascii.a2b_uu(b' \n'), b'')
        self.assertEqual(binascii.a2b_uu(b'`\n'), b'')
        self.assertEqual(binascii.b2a_uu(b'\x00Cat'), b'$ $-A=   \n')
        self.assertEqual(binascii.b2a_uu(b'\x00Cat', backtick=True),
                         b'$`$-A=```\n')
        self.assertEqual(binascii.a2b_uu(b'$`$-A=```\n'),
                         binascii.a2b_uu(b'$ $-A=   \n'))
        with self.assertRaises(TypeError):
            binascii.b2a_uu(b"", True)

    @hypothesis.given(
        binary=hypothesis.strategies.binary(max_size=45),
        backtick=hypothesis.strategies.booleans(),
    )
    def test_b2a_roundtrip(self, binary, backtick):
        converted = binascii.b2a_uu(self.type2test(binary), backtick=backtick)
        restored = binascii.a2b_uu(self.type2test(converted))
        self.assertConversion(binary, converted, restored, backtick=backtick)

    def test_crc_hqx(self):
        crc = binascii.crc_hqx(self.type2test(b"Test the CRC-32 of"), 0)
        crc = binascii.crc_hqx(self.type2test(b" this string."), crc)
        self.assertEqual(crc, 14290)

        self.assertRaises(TypeError, binascii.crc_hqx)
        self.assertRaises(TypeError, binascii.crc_hqx, self.type2test(b''))

        for crc in 0, 1, 0x1234, 0x12345, 0x12345678, -1:
            self.assertEqual(binascii.crc_hqx(self.type2test(b''), crc),
                             crc & 0xffff)

    def test_crc32(self):
        crc = binascii.crc32(self.type2test(b"Test the CRC-32 of"))
        crc = binascii.crc32(self.type2test(b" this string."), crc)
        self.assertEqual(crc, 1571220330)

        self.assertRaises(TypeError, binascii.crc32)

    def test_hex(self):
        # test hexlification
        s = b'{s\005\000\000\000worldi\002\000\000\000s\005\000\000\000helloi\001\000\000\0000'
        t = binascii.b2a_hex(self.type2test(s))
        u = binascii.a2b_hex(self.type2test(t))
        self.assertEqual(s, u)
        self.assertRaises(binascii.Error, binascii.a2b_hex, t[:-1])
        self.assertRaises(binascii.Error, binascii.a2b_hex, t[:-1] + b'q')
        self.assertRaises(binascii.Error, binascii.a2b_hex, bytes([255, 255]))
        self.assertRaises(binascii.Error, binascii.a2b_hex, b'0G')
        self.assertRaises(binascii.Error, binascii.a2b_hex, b'0g')
        self.assertRaises(binascii.Error, binascii.a2b_hex, b'G0')
        self.assertRaises(binascii.Error, binascii.a2b_hex, b'g0')

        # Confirm that b2a_hex == hexlify and a2b_hex == unhexlify
        self.assertEqual(binascii.hexlify(self.type2test(s)), t)
        self.assertEqual(binascii.unhexlify(self.type2test(t)), u)

    @hypothesis.given(binary=hypothesis.strategies.binary())
    def test_hex_roundtrip(self, binary):
        converted = binascii.hexlify(self.type2test(binary))
        restored = binascii.unhexlify(self.type2test(converted))
        self.assertConversion(binary, converted, restored)

    def test_hex_separator(self):
        """Test that hexlify and b2a_hex are binary versions of bytes.hex."""
        # Logic of separators is tested in test_bytes.py.  This checks that
        # arg parsing works and exercises the direct to bytes object code
        # path within pystrhex.c.
        s = b'{s\005\000\000\000worldi\002\000\000\000s\005\000\000\000helloi\001\000\000\0000'
        self.assertEqual(binascii.hexlify(self.type2test(s)), s.hex().encode('ascii'))
        expected8 = s.hex('.', 8).encode('ascii')
        self.assertEqual(binascii.hexlify(self.type2test(s), '.', 8), expected8)
        expected1 = s.hex(':').encode('ascii')
        self.assertEqual(binascii.b2a_hex(self.type2test(s), ':'), expected1)

    def test_qp(self):
        type2test = self.type2test
        a2b_qp = binascii.a2b_qp
        b2a_qp = binascii.b2a_qp

        a2b_qp(data=b"", header=False)  # Keyword arguments allowed

        # A test for SF bug 534347 (segfaults without the proper fix)
        try:
            a2b_qp(b"", **{1:1})
        except TypeError:
            pass
        else:
            self.fail("binascii.a2b_qp(**{1:1}) didn't raise TypeError")

        self.assertEqual(a2b_qp(type2test(b"=")), b"")
        self.assertEqual(a2b_qp(type2test(b"= ")), b"= ")
        self.assertEqual(a2b_qp(type2test(b"==")), b"=")
        self.assertEqual(a2b_qp(type2test(b"=\nAB")), b"AB")
        self.assertEqual(a2b_qp(type2test(b"=\r\nAB")), b"AB")
        self.assertEqual(a2b_qp(type2test(b"=\rAB")), b"")  # ?
        self.assertEqual(a2b_qp(type2test(b"=\rAB\nCD")), b"CD")  # ?
        self.assertEqual(a2b_qp(type2test(b"=AB")), b"\xab")
        self.assertEqual(a2b_qp(type2test(b"=ab")), b"\xab")
        self.assertEqual(a2b_qp(type2test(b"=AX")), b"=AX")
        self.assertEqual(a2b_qp(type2test(b"=XA")), b"=XA")
        self.assertEqual(a2b_qp(type2test(b"=AB")[:-1]), b"=A")

        self.assertEqual(a2b_qp(type2test(b'_')), b'_')
        self.assertEqual(a2b_qp(type2test(b'_'), header=True), b' ')

        self.assertRaises(TypeError, b2a_qp, foo="bar")
        self.assertEqual(a2b_qp(type2test(b"=00\r\n=00")), b"\x00\r\n\x00")
        self.assertEqual(b2a_qp(type2test(b"\xff\r\n\xff\n\xff")),
                         b"=FF\r\n=FF\r\n=FF")
        self.assertEqual(b2a_qp(type2test(b"0"*75+b"\xff\r\n\xff\r\n\xff")),
                         b"0"*75+b"=\r\n=FF\r\n=FF\r\n=FF")

        self.assertEqual(b2a_qp(type2test(b'\x7f')), b'=7F')
        self.assertEqual(b2a_qp(type2test(b'=')), b'=3D')

        self.assertEqual(b2a_qp(type2test(b'_')), b'_')
        self.assertEqual(b2a_qp(type2test(b'_'), header=True), b'=5F')
        self.assertEqual(b2a_qp(type2test(b'x y'), header=True), b'x_y')
        self.assertEqual(b2a_qp(type2test(b'x '), header=True), b'x=20')
        self.assertEqual(b2a_qp(type2test(b'x y'), header=True, quotetabs=True),
                         b'x=20y')
        self.assertEqual(b2a_qp(type2test(b'x\ty'), header=True), b'x\ty')

        self.assertEqual(b2a_qp(type2test(b' ')), b'=20')
        self.assertEqual(b2a_qp(type2test(b'\t')), b'=09')
        self.assertEqual(b2a_qp(type2test(b' x')), b' x')
        self.assertEqual(b2a_qp(type2test(b'\tx')), b'\tx')
        self.assertEqual(b2a_qp(type2test(b' x')[:-1]), b'=20')
        self.assertEqual(b2a_qp(type2test(b'\tx')[:-1]), b'=09')
        self.assertEqual(b2a_qp(type2test(b'\0')), b'=00')

        self.assertEqual(b2a_qp(type2test(b'\0\n')), b'=00\n')
        self.assertEqual(b2a_qp(type2test(b'\0\n'), quotetabs=True), b'=00\n')

        self.assertEqual(b2a_qp(type2test(b'x y\tz')), b'x y\tz')
        self.assertEqual(b2a_qp(type2test(b'x y\tz'), quotetabs=True),
                         b'x=20y=09z')
        self.assertEqual(b2a_qp(type2test(b'x y\tz'), istext=False),
                         b'x y\tz')
        self.assertEqual(b2a_qp(type2test(b'x \ny\t\n')),
                         b'x=20\ny=09\n')
        self.assertEqual(b2a_qp(type2test(b'x \ny\t\n'), quotetabs=True),
                         b'x=20\ny=09\n')
        self.assertEqual(b2a_qp(type2test(b'x \ny\t\n'), istext=False),
                         b'x =0Ay\t=0A')
        self.assertEqual(b2a_qp(type2test(b'x \ry\t\r')),
                         b'x \ry\t\r')
        self.assertEqual(b2a_qp(type2test(b'x \ry\t\r'), quotetabs=True),
                         b'x=20\ry=09\r')
        self.assertEqual(b2a_qp(type2test(b'x \ry\t\r'), istext=False),
                         b'x =0Dy\t=0D')
        self.assertEqual(b2a_qp(type2test(b'x \r\ny\t\r\n')),
                         b'x=20\r\ny=09\r\n')
        self.assertEqual(b2a_qp(type2test(b'x \r\ny\t\r\n'), quotetabs=True),
                         b'x=20\r\ny=09\r\n')
        self.assertEqual(b2a_qp(type2test(b'x \r\ny\t\r\n'), istext=False),
                         b'x =0D=0Ay\t=0D=0A')

        self.assertEqual(b2a_qp(type2test(b'x \r\n')[:-1]), b'x \r')
        self.assertEqual(b2a_qp(type2test(b'x\t\r\n')[:-1]), b'x\t\r')
        self.assertEqual(b2a_qp(type2test(b'x \r\n')[:-1], quotetabs=True),
                         b'x=20\r')
        self.assertEqual(b2a_qp(type2test(b'x\t\r\n')[:-1], quotetabs=True),
                         b'x=09\r')
        self.assertEqual(b2a_qp(type2test(b'x \r\n')[:-1], istext=False),
                         b'x =0D')
        self.assertEqual(b2a_qp(type2test(b'x\t\r\n')[:-1], istext=False),
                         b'x\t=0D')

        self.assertEqual(b2a_qp(type2test(b'.')), b'=2E')
        self.assertEqual(b2a_qp(type2test(b'.\n')), b'=2E\n')
        self.assertEqual(b2a_qp(type2test(b'.\r')), b'=2E\r')
        self.assertEqual(b2a_qp(type2test(b'.\0')), b'=2E=00')
        self.assertEqual(b2a_qp(type2test(b'a.\n')), b'a.\n')
        self.assertEqual(b2a_qp(type2test(b'.a')[:-1]), b'=2E')

    @hypothesis.given(
        binary=hypothesis.strategies.binary(),
        quotetabs=hypothesis.strategies.booleans(),
        istext=hypothesis.strategies.booleans(),
        header=hypothesis.strategies.booleans(),
    )
    def test_b2a_qp_a2b_qp_round_trip(self, binary, quotetabs, istext, header):
        converted = binascii.b2a_qp(
            self.type2test(binary),
            quotetabs=quotetabs, istext=istext, header=header,
        )
        restored = binascii.a2b_qp(self.type2test(converted), header=header)
        self.assertConversion(binary, converted, restored,
                              quotetabs=quotetabs, istext=istext, header=header)

    def test_empty_string(self):
        # A test for SF bug #1022953.  Make sure SystemError is not raised.
        empty = self.type2test(b'')
        for func in all_functions:
            if func == 'crc_hqx':
                # crc_hqx needs 2 arguments
                binascii.crc_hqx(empty, 0)
                continue
            f = getattr(binascii, func)
            if func == 'a2b_uu':
                self.assertRaises(binascii.Error, f, empty)
                continue
            try:
                f(empty)
            except Exception as err:
                self.fail("{}({!r}) raises {!r}".format(func, empty, err))

    def test_unicode_b2a(self):
        # Unicode strings are not accepted by b2a_* functions.
        for func in set(all_functions) - set(a2b_functions):
            try:
                self.assertRaises(TypeError, getattr(binascii, func), "test")
            except Exception as err:
                self.fail('{}("test") raises {!r}'.format(func, err))
        # crc_hqx needs 2 arguments
        self.assertRaises(TypeError, binascii.crc_hqx, "test", 0)

    def test_unicode_a2b(self):
        # Unicode strings are accepted by a2b_* functions.
        MAX_ALL = 45
        raw = self.rawdata[:MAX_ALL]
        for fa, fb in zip(a2b_functions, b2a_functions):
            a2b = getattr(binascii, fa)
            b2a = getattr(binascii, fb)
            try:
                a = b2a(self.type2test(raw))
                binary_res = a2b(a)
                a = a.decode('ascii')
                res = a2b(a)
            except Exception as err:
                self.fail("{}/{} conversion raises {!r}".format(fb, fa, err))
            self.assertEqual(res, raw, "{}/{} conversion: "
                             "{!r} != {!r}".format(fb, fa, res, raw))
            self.assertEqual(res, binary_res)
            self.assertIsInstance(res, bytes)
            # non-ASCII string
            self.assertRaises(ValueError, a2b, "\x80")

    def test_b2a_base64_newline(self):
        # Issue #25357: test newline parameter
        b = self.type2test(b'hello')
        self.assertEqual(binascii.b2a_base64(b),
                         b'aGVsbG8=\n')
        self.assertEqual(binascii.b2a_base64(b, newline=True),
                         b'aGVsbG8=\n')
        self.assertEqual(binascii.b2a_base64(b, newline=False),
                         b'aGVsbG8=')

    @hypothesis.given(
        binary=hypothesis.strategies.binary(),
        newline=hypothesis.strategies.booleans(),
    )
    def test_base64_roundtrip(self, binary, newline):
        converted = binascii.b2a_base64(self.type2test(binary), newline=newline)
        restored = binascii.a2b_base64(self.type2test(converted))
        self.assertConversion(binary, converted, restored, newline=newline)

    def test_c_contiguity(self):
        m = memoryview(bytearray(b'noncontig'))
        noncontig_writable = m[::-2]
        with self.assertRaises(BufferError):
            binascii.b2a_hex(noncontig_writable)


class ArrayBinASCIITest(BinASCIITest):
    def type2test(self, s):
        return array.array('B', list(s))


class BytearrayBinASCIITest(BinASCIITest):
    type2test = bytearray


class MemoryviewBinASCIITest(BinASCIITest):
    type2test = memoryview

class ChecksumBigBufferTestCase(unittest.TestCase):
    """bpo-38256 - check that inputs >=4 GiB are handled correctly."""

    @bigmemtest(size=_4G + 4, memuse=1, dry_run=False)
    def test_big_buffer(self, size):
        data = b"nyan" * (_1G + 1)
        self.assertEqual(binascii.crc32(data), 1044521549)


if __name__ == "__main__":
    unittest.main()
