import _codecs
import codecs
import contextlib
import copy
import importlib
import io
import pickle
import os
import sys
import unittest
import encodings
from unittest import mock
import warnings

from test import support
from test.support import os_helper
from test.support import warnings_helper

try:
    import _testlimitedcapi
except ImportError:
    _testlimitedcapi = None
try:
    import _testinternalcapi
except ImportError:
    _testinternalcapi = None


def codecs_open_no_warn(*args, **kwargs):
    """Call codecs.open(*args, **kwargs) ignoring DeprecationWarning."""
    with warnings.catch_warnings():
        warnings.simplefilter("ignore")
        return codecs.open(*args, **kwargs)

def coding_checker(self, coder):
    def check(input, expect):
        self.assertEqual(coder(input), (expect, len(input)))
    return check

# On small versions of Windows like Windows IoT or Windows Nano Server,
# not all codepages are present
def is_code_page_present(cp):
    from ctypes import POINTER, WINFUNCTYPE, WinDLL
    from ctypes.util import struct
    from ctypes.wintypes import BOOL, BYTE, WCHAR, UINT, DWORD

    MAX_LEADBYTES = 12  # 5 ranges, 2 bytes ea., 0 term.
    MAX_DEFAULTCHAR = 2 # single or double byte
    MAX_PATH = 260

    @struct
    class CPINFOEXW:
        MaxCharSize: UINT
        DefaultChar: BYTE * MAX_DEFAULTCHAR
        LeadByte: BYTE * MAX_LEADBYTES
        UnicodeDefaultChar: WCHAR
        CodePage: UINT
        CodePageName: WCHAR * MAX_PATH

    prototype = WINFUNCTYPE(BOOL, UINT, DWORD, POINTER(CPINFOEXW))
    GetCPInfoEx = prototype(("GetCPInfoExW", WinDLL("kernel32")))
    info = CPINFOEXW()
    return GetCPInfoEx(cp, 0, info)

class Queue(object):
    """
    queue: write bytes at one end, read bytes from the other end
    """
    def __init__(self, buffer):
        self._buffer = buffer

    def write(self, chars):
        self._buffer += chars

    def read(self, size=-1):
        if size<0:
            s = self._buffer
            self._buffer = self._buffer[:0] # make empty
            return s
        else:
            s = self._buffer[:size]
            self._buffer = self._buffer[size:]
            return s


class MixInCheckStateHandling:
    def check_state_handling_decode(self, encoding, u, s):
        for i in range(len(s)+1):
            d = codecs.getincrementaldecoder(encoding)()
            part1 = d.decode(s[:i])
            state = d.getstate()
            self.assertIsInstance(state[1], int)
            # Check that the condition stated in the documentation for
            # IncrementalDecoder.getstate() holds
            if not state[1]:
                # reset decoder to the default state without anything buffered
                d.setstate((state[0][:0], 0))
                # Feeding the previous input may not produce any output
                self.assertTrue(not d.decode(state[0]))
                # The decoder must return to the same state
                self.assertEqual(state, d.getstate())
            # Create a new decoder and set it to the state
            # we extracted from the old one
            d = codecs.getincrementaldecoder(encoding)()
            d.setstate(state)
            part2 = d.decode(s[i:], True)
            self.assertEqual(u, part1+part2)

    def check_state_handling_encode(self, encoding, u, s):
        for i in range(len(u)+1):
            d = codecs.getincrementalencoder(encoding)()
            part1 = d.encode(u[:i])
            state = d.getstate()
            d = codecs.getincrementalencoder(encoding)()
            d.setstate(state)
            part2 = d.encode(u[i:], True)
            self.assertEqual(s, part1+part2)


class ReadTest(MixInCheckStateHandling):
    def check_partial(self, input, partialresults):
        # get a StreamReader for the encoding and feed the bytestring version
        # of input to the reader byte by byte. Read everything available from
        # the StreamReader and check that the results equal the appropriate
        # entries from partialresults.
        q = Queue(b"")
        r = codecs.getreader(self.encoding)(q)
        result = ""
        for (c, partialresult) in zip(input.encode(self.encoding), partialresults, strict=True):
            q.write(bytes([c]))
            result += r.read()
            self.assertEqual(result, partialresult)
        # check that there's nothing left in the buffers
        self.assertEqual(r.read(), "")
        self.assertEqual(r.bytebuffer, b"")

        # do the check again, this time using an incremental decoder
        d = codecs.getincrementaldecoder(self.encoding)()
        result = ""
        for (c, partialresult) in zip(input.encode(self.encoding), partialresults, strict=True):
            result += d.decode(bytes([c]))
            self.assertEqual(result, partialresult)
        # check that there's nothing left in the buffers
        self.assertEqual(d.decode(b"", True), "")
        self.assertEqual(d.buffer, b"")

        # Check whether the reset method works properly
        d.reset()
        result = ""
        for (c, partialresult) in zip(input.encode(self.encoding), partialresults, strict=True):
            result += d.decode(bytes([c]))
            self.assertEqual(result, partialresult)
        # check that there's nothing left in the buffers
        self.assertEqual(d.decode(b"", True), "")
        self.assertEqual(d.buffer, b"")

        # check iterdecode()
        encoded = input.encode(self.encoding)
        self.assertEqual(
            input,
            "".join(codecs.iterdecode([bytes([c]) for c in encoded], self.encoding))
        )

    def test_readline(self):
        def getreader(input):
            stream = io.BytesIO(input.encode(self.encoding))
            return codecs.getreader(self.encoding)(stream)

        def readalllines(input, keepends=True, size=None):
            reader = getreader(input)
            lines = []
            while True:
                line = reader.readline(size=size, keepends=keepends)
                if not line:
                    break
                lines.append(line)
            return "|".join(lines)

        s = "foo\nbar\r\nbaz\rspam\u2028eggs"
        sexpected = "foo\n|bar\r\n|baz\r|spam\u2028|eggs"
        sexpectednoends = "foo|bar|baz|spam|eggs"
        self.assertEqual(readalllines(s, True), sexpected)
        self.assertEqual(readalllines(s, False), sexpectednoends)
        self.assertEqual(readalllines(s, True, 10), sexpected)
        self.assertEqual(readalllines(s, False, 10), sexpectednoends)

        lineends = ("\n", "\r\n", "\r", "\u2028")
        # Test long lines (multiple calls to read() in readline())
        vw = []
        vwo = []
        for (i, lineend) in enumerate(lineends):
            vw.append((i*200+200)*"\u3042" + lineend)
            vwo.append((i*200+200)*"\u3042")
        self.assertEqual(readalllines("".join(vw), True), "|".join(vw))
        self.assertEqual(readalllines("".join(vw), False), "|".join(vwo))

        # Test lines where the first read might end with \r, so the
        # reader has to look ahead whether this is a lone \r or a \r\n
        for size in range(80):
            for lineend in lineends:
                s = 10*(size*"a" + lineend + "xxx\n")
                reader = getreader(s)
                for i in range(10):
                    self.assertEqual(
                        reader.readline(keepends=True),
                        size*"a" + lineend,
                    )
                    self.assertEqual(
                        reader.readline(keepends=True),
                        "xxx\n",
                    )
                reader = getreader(s)
                for i in range(10):
                    self.assertEqual(
                        reader.readline(keepends=False),
                        size*"a",
                    )
                    self.assertEqual(
                        reader.readline(keepends=False),
                        "xxx",
                    )

    def test_mixed_readline_and_read(self):
        lines = ["Humpty Dumpty sat on a wall,\n",
                 "Humpty Dumpty had a great fall.\r\n",
                 "All the king's horses and all the king's men\r",
                 "Couldn't put Humpty together again."]
        data = ''.join(lines)
        def getreader():
            stream = io.BytesIO(data.encode(self.encoding))
            return codecs.getreader(self.encoding)(stream)

        # Issue #8260: Test readline() followed by read()
        f = getreader()
        self.assertEqual(f.readline(), lines[0])
        self.assertEqual(f.read(), ''.join(lines[1:]))
        self.assertEqual(f.read(), '')

        # Issue #32110: Test readline() followed by read(n)
        f = getreader()
        self.assertEqual(f.readline(), lines[0])
        self.assertEqual(f.read(1), lines[1][0])
        self.assertEqual(f.read(0), '')
        self.assertEqual(f.read(100), data[len(lines[0]) + 1:][:100])

        # Issue #16636: Test readline() followed by readlines()
        f = getreader()
        self.assertEqual(f.readline(), lines[0])
        self.assertEqual(f.readlines(), lines[1:])
        self.assertEqual(f.read(), '')

        # Test read(n) followed by read()
        f = getreader()
        self.assertEqual(f.read(size=40, chars=5), data[:5])
        self.assertEqual(f.read(), data[5:])
        self.assertEqual(f.read(), '')

        # Issue #32110: Test read(n) followed by read(n)
        f = getreader()
        self.assertEqual(f.read(size=40, chars=5), data[:5])
        self.assertEqual(f.read(1), data[5])
        self.assertEqual(f.read(0), '')
        self.assertEqual(f.read(100), data[6:106])

        # Issue #12446: Test read(n) followed by readlines()
        f = getreader()
        self.assertEqual(f.read(size=40, chars=5), data[:5])
        self.assertEqual(f.readlines(), [lines[0][5:]] + lines[1:])
        self.assertEqual(f.read(), '')

    def test_bug1175396(self):
        s = [
            '<%!--===================================================\r\n',
            '    BLOG index page: show recent articles,\r\n',
            '    today\'s articles, or articles of a specific date.\r\n',
            '========================================================--%>\r\n',
            '<%@inputencoding="ISO-8859-1"%>\r\n',
            '<%@pagetemplate=TEMPLATE.y%>\r\n',
            '<%@import=import frog.util, frog%>\r\n',
            '<%@import=import frog.objects%>\r\n',
            '<%@import=from frog.storageerrors import StorageError%>\r\n',
            '<%\r\n',
            '\r\n',
            'import logging\r\n',
            'log=logging.getLogger("Snakelets.logger")\r\n',
            '\r\n',
            '\r\n',
            'user=self.SessionCtx.user\r\n',
            'storageEngine=self.SessionCtx.storageEngine\r\n',
            '\r\n',
            '\r\n',
            'def readArticlesFromDate(date, count=None):\r\n',
            '    entryids=storageEngine.listBlogEntries(date)\r\n',
            '    entryids.reverse() # descending\r\n',
            '    if count:\r\n',
            '        entryids=entryids[:count]\r\n',
            '    try:\r\n',
            '        return [ frog.objects.BlogEntry.load(storageEngine, date, Id) for Id in entryids ]\r\n',
            '    except StorageError,x:\r\n',
            '        log.error("Error loading articles: "+str(x))\r\n',
            '        self.abort("cannot load articles")\r\n',
            '\r\n',
            'showdate=None\r\n',
            '\r\n',
            'arg=self.Request.getArg()\r\n',
            'if arg=="today":\r\n',
            '    #-------------------- TODAY\'S ARTICLES\r\n',
            '    self.write("<h2>Today\'s articles</h2>")\r\n',
            '    showdate = frog.util.isodatestr() \r\n',
            '    entries = readArticlesFromDate(showdate)\r\n',
            'elif arg=="active":\r\n',
            '    #-------------------- ACTIVE ARTICLES redirect\r\n',
            '    self.Yredirect("active.y")\r\n',
            'elif arg=="login":\r\n',
            '    #-------------------- LOGIN PAGE redirect\r\n',
            '    self.Yredirect("login.y")\r\n',
            'elif arg=="date":\r\n',
            '    #-------------------- ARTICLES OF A SPECIFIC DATE\r\n',
            '    showdate = self.Request.getParameter("date")\r\n',
            '    self.write("<h2>Articles written on %s</h2>"% frog.util.mediumdatestr(showdate))\r\n',
            '    entries = readArticlesFromDate(showdate)\r\n',
            'else:\r\n',
            '    #-------------------- RECENT ARTICLES\r\n',
            '    self.write("<h2>Recent articles</h2>")\r\n',
            '    dates=storageEngine.listBlogEntryDates()\r\n',
            '    if dates:\r\n',
            '        entries=[]\r\n',
            '        SHOWAMOUNT=10\r\n',
            '        for showdate in dates:\r\n',
            '            entries.extend( readArticlesFromDate(showdate, SHOWAMOUNT-len(entries)) )\r\n',
            '            if len(entries)>=SHOWAMOUNT:\r\n',
            '                break\r\n',
            '                \r\n',
        ]
        stream = io.BytesIO("".join(s).encode(self.encoding))
        reader = codecs.getreader(self.encoding)(stream)
        for (i, line) in enumerate(reader):
            self.assertEqual(line, s[i])

    def test_readlinequeue(self):
        q = Queue(b"")
        writer = codecs.getwriter(self.encoding)(q)
        reader = codecs.getreader(self.encoding)(q)

        # No lineends
        writer.write("foo\r")
        self.assertEqual(reader.readline(keepends=False), "foo")
        writer.write("\nbar\r")
        self.assertEqual(reader.readline(keepends=False), "")
        self.assertEqual(reader.readline(keepends=False), "bar")
        writer.write("baz")
        self.assertEqual(reader.readline(keepends=False), "baz")
        self.assertEqual(reader.readline(keepends=False), "")

        # Lineends
        writer.write("foo\r")
        self.assertEqual(reader.readline(keepends=True), "foo\r")
        writer.write("\nbar\r")
        self.assertEqual(reader.readline(keepends=True), "\n")
        self.assertEqual(reader.readline(keepends=True), "bar\r")
        writer.write("baz")
        self.assertEqual(reader.readline(keepends=True), "baz")
        self.assertEqual(reader.readline(keepends=True), "")
        writer.write("foo\r\n")
        self.assertEqual(reader.readline(keepends=True), "foo\r\n")

    def test_bug1098990_a(self):
        s1 = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy\r\n"
        s2 = "offending line: ladfj askldfj klasdj fskla dfzaskdj fasklfj laskd fjasklfzzzzaa%whereisthis!!!\r\n"
        s3 = "next line.\r\n"

        s = (s1+s2+s3).encode(self.encoding)
        stream = io.BytesIO(s)
        reader = codecs.getreader(self.encoding)(stream)
        self.assertEqual(reader.readline(), s1)
        self.assertEqual(reader.readline(), s2)
        self.assertEqual(reader.readline(), s3)
        self.assertEqual(reader.readline(), "")

    def test_bug1098990_b(self):
        s1 = "aaaaaaaaaaaaaaaaaaaaaaaa\r\n"
        s2 = "bbbbbbbbbbbbbbbbbbbbbbbb\r\n"
        s3 = "stillokay:bbbbxx\r\n"
        s4 = "broken!!!!badbad\r\n"
        s5 = "againokay.\r\n"

        s = (s1+s2+s3+s4+s5).encode(self.encoding)
        stream = io.BytesIO(s)
        reader = codecs.getreader(self.encoding)(stream)
        self.assertEqual(reader.readline(), s1)
        self.assertEqual(reader.readline(), s2)
        self.assertEqual(reader.readline(), s3)
        self.assertEqual(reader.readline(), s4)
        self.assertEqual(reader.readline(), s5)
        self.assertEqual(reader.readline(), "")

    ill_formed_sequence_replace = "\ufffd"

    def test_lone_surrogates(self):
        self.assertRaises(UnicodeEncodeError, "\ud800".encode, self.encoding)
        self.assertEqual("[\uDC80]".encode(self.encoding, "backslashreplace"),
                         "[\\udc80]".encode(self.encoding))
        self.assertEqual("[\uDC80]".encode(self.encoding, "namereplace"),
                         "[\\udc80]".encode(self.encoding))
        self.assertEqual("[\uDC80]".encode(self.encoding, "xmlcharrefreplace"),
                         "[&#56448;]".encode(self.encoding))
        self.assertEqual("[\uDC80]".encode(self.encoding, "ignore"),
                         "[]".encode(self.encoding))
        self.assertEqual("[\uDC80]".encode(self.encoding, "replace"),
                         "[?]".encode(self.encoding))

        # sequential surrogate characters
        self.assertEqual("[\uD800\uDC80]".encode(self.encoding, "ignore"),
                         "[]".encode(self.encoding))
        self.assertEqual("[\uD800\uDC80]".encode(self.encoding, "replace"),
                         "[??]".encode(self.encoding))

        bom = "".encode(self.encoding)
        for before, after in [("\U00010fff", "A"), ("[", "]"),
                              ("A", "\U00010fff")]:
            before_sequence = before.encode(self.encoding)[len(bom):]
            after_sequence = after.encode(self.encoding)[len(bom):]
            test_string = before + "\uDC80" + after
            test_sequence = (bom + before_sequence +
                             self.ill_formed_sequence + after_sequence)
            self.assertRaises(UnicodeDecodeError, test_sequence.decode,
                              self.encoding)
            self.assertEqual(test_string.encode(self.encoding,
                                                "surrogatepass"),
                             test_sequence)
            self.assertEqual(test_sequence.decode(self.encoding,
                                                  "surrogatepass"),
                             test_string)
            self.assertEqual(test_sequence.decode(self.encoding, "ignore"),
                             before + after)
            self.assertEqual(test_sequence.decode(self.encoding, "replace"),
                             before + self.ill_formed_sequence_replace + after)
            backslashreplace = ''.join('\\x%02x' % b
                                       for b in self.ill_formed_sequence)
            self.assertEqual(test_sequence.decode(self.encoding, "backslashreplace"),
                             before + backslashreplace + after)

    def test_incremental_surrogatepass(self):
        # Test incremental decoder for surrogatepass handler:
        # see issue #24214
        # High surrogate
        data = '\uD901'.encode(self.encoding, 'surrogatepass')
        for i in range(1, len(data)):
            dec = codecs.getincrementaldecoder(self.encoding)('surrogatepass')
            self.assertEqual(dec.decode(data[:i]), '')
            self.assertEqual(dec.decode(data[i:], True), '\uD901')
        # Low surrogate
        data = '\uDC02'.encode(self.encoding, 'surrogatepass')
        for i in range(1, len(data)):
            dec = codecs.getincrementaldecoder(self.encoding)('surrogatepass')
            self.assertEqual(dec.decode(data[:i]), '')
            self.assertEqual(dec.decode(data[i:]), '\uDC02')


class UTF32Test(ReadTest, unittest.TestCase):
    encoding = "utf-32"
    if sys.byteorder == 'little':
        ill_formed_sequence = b"\x80\xdc\x00\x00"
    else:
        ill_formed_sequence = b"\x00\x00\xdc\x80"

    spamle = (b'\xff\xfe\x00\x00'
              b's\x00\x00\x00p\x00\x00\x00a\x00\x00\x00m\x00\x00\x00'
              b's\x00\x00\x00p\x00\x00\x00a\x00\x00\x00m\x00\x00\x00')
    spambe = (b'\x00\x00\xfe\xff'
              b'\x00\x00\x00s\x00\x00\x00p\x00\x00\x00a\x00\x00\x00m'
              b'\x00\x00\x00s\x00\x00\x00p\x00\x00\x00a\x00\x00\x00m')

    def test_only_one_bom(self):
        _,_,reader,writer = codecs.lookup(self.encoding)
        # encode some stream
        s = io.BytesIO()
        f = writer(s)
        f.write("spam")
        f.write("spam")
        d = s.getvalue()
        # check whether there is exactly one BOM in it
        self.assertTrue(d == self.spamle or d == self.spambe)
        # try to read it back
        s = io.BytesIO(d)
        f = reader(s)
        self.assertEqual(f.read(), "spamspam")

    def test_badbom(self):
        s = io.BytesIO(4*b"\xff")
        f = codecs.getreader(self.encoding)(s)
        self.assertRaises(UnicodeDecodeError, f.read)

        s = io.BytesIO(8*b"\xff")
        f = codecs.getreader(self.encoding)(s)
        self.assertRaises(UnicodeDecodeError, f.read)

    def test_partial(self):
        self.check_partial(
            "\x00\xff\u0100\uffff\U00010000",
            [
                "", # first byte of BOM read
                "", # second byte of BOM read
                "", # third byte of BOM read
                "", # fourth byte of BOM read => byteorder known
                "",
                "",
                "",
                "\x00",
                "\x00",
                "\x00",
                "\x00",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff\U00010000",
            ]
        )

    def test_handlers(self):
        self.assertEqual(('\ufffd', 1),
                         codecs.utf_32_decode(b'\x01', 'replace', True))
        self.assertEqual(('', 1),
                         codecs.utf_32_decode(b'\x01', 'ignore', True))

    def test_errors(self):
        self.assertRaises(UnicodeDecodeError, codecs.utf_32_decode,
                          b"\xff", "strict", True)

    def test_decoder_state(self):
        self.check_state_handling_decode(self.encoding,
                                         "spamspam", self.spamle)
        self.check_state_handling_decode(self.encoding,
                                         "spamspam", self.spambe)

    def test_issue8941(self):
        # Issue #8941: insufficient result allocation when decoding into
        # surrogate pairs on UCS-2 builds.
        encoded_le = b'\xff\xfe\x00\x00' + b'\x00\x00\x01\x00' * 1024
        self.assertEqual('\U00010000' * 1024,
                         codecs.utf_32_decode(encoded_le)[0])
        encoded_be = b'\x00\x00\xfe\xff' + b'\x00\x01\x00\x00' * 1024
        self.assertEqual('\U00010000' * 1024,
                         codecs.utf_32_decode(encoded_be)[0])


class UTF32LETest(ReadTest, unittest.TestCase):
    encoding = "utf-32-le"
    ill_formed_sequence = b"\x80\xdc\x00\x00"

    def test_partial(self):
        self.check_partial(
            "\x00\xff\u0100\uffff\U00010000",
            [
                "",
                "",
                "",
                "\x00",
                "\x00",
                "\x00",
                "\x00",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff\U00010000",
            ]
        )

    def test_simple(self):
        self.assertEqual("\U00010203".encode(self.encoding), b"\x03\x02\x01\x00")

    def test_errors(self):
        self.assertRaises(UnicodeDecodeError, codecs.utf_32_le_decode,
                          b"\xff", "strict", True)

    def test_issue8941(self):
        # Issue #8941: insufficient result allocation when decoding into
        # surrogate pairs on UCS-2 builds.
        encoded = b'\x00\x00\x01\x00' * 1024
        self.assertEqual('\U00010000' * 1024,
                         codecs.utf_32_le_decode(encoded)[0])


class UTF32BETest(ReadTest, unittest.TestCase):
    encoding = "utf-32-be"
    ill_formed_sequence = b"\x00\x00\xdc\x80"

    def test_partial(self):
        self.check_partial(
            "\x00\xff\u0100\uffff\U00010000",
            [
                "",
                "",
                "",
                "\x00",
                "\x00",
                "\x00",
                "\x00",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff\U00010000",
            ]
        )

    def test_simple(self):
        self.assertEqual("\U00010203".encode(self.encoding), b"\x00\x01\x02\x03")

    def test_errors(self):
        self.assertRaises(UnicodeDecodeError, codecs.utf_32_be_decode,
                          b"\xff", "strict", True)

    def test_issue8941(self):
        # Issue #8941: insufficient result allocation when decoding into
        # surrogate pairs on UCS-2 builds.
        encoded = b'\x00\x01\x00\x00' * 1024
        self.assertEqual('\U00010000' * 1024,
                         codecs.utf_32_be_decode(encoded)[0])


class UTF16Test(ReadTest, unittest.TestCase):
    encoding = "utf-16"
    if sys.byteorder == 'little':
        ill_formed_sequence = b"\x80\xdc"
    else:
        ill_formed_sequence = b"\xdc\x80"

    spamle = b'\xff\xfes\x00p\x00a\x00m\x00s\x00p\x00a\x00m\x00'
    spambe = b'\xfe\xff\x00s\x00p\x00a\x00m\x00s\x00p\x00a\x00m'

    def test_only_one_bom(self):
        _,_,reader,writer = codecs.lookup(self.encoding)
        # encode some stream
        s = io.BytesIO()
        f = writer(s)
        f.write("spam")
        f.write("spam")
        d = s.getvalue()
        # check whether there is exactly one BOM in it
        self.assertTrue(d == self.spamle or d == self.spambe)
        # try to read it back
        s = io.BytesIO(d)
        f = reader(s)
        self.assertEqual(f.read(), "spamspam")

    def test_badbom(self):
        s = io.BytesIO(b"\xff\xff")
        f = codecs.getreader(self.encoding)(s)
        self.assertRaises(UnicodeDecodeError, f.read)

        s = io.BytesIO(b"\xff\xff\xff\xff")
        f = codecs.getreader(self.encoding)(s)
        self.assertRaises(UnicodeDecodeError, f.read)

    def test_partial(self):
        self.check_partial(
            "\x00\xff\u0100\uffff\U00010000",
            [
                "", # first byte of BOM read
                "", # second byte of BOM read => byteorder known
                "",
                "\x00",
                "\x00",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff\U00010000",
            ]
        )

    def test_handlers(self):
        self.assertEqual(('\ufffd', 1),
                         codecs.utf_16_decode(b'\x01', 'replace', True))
        self.assertEqual(('', 1),
                         codecs.utf_16_decode(b'\x01', 'ignore', True))

    def test_errors(self):
        self.assertRaises(UnicodeDecodeError, codecs.utf_16_decode,
                          b"\xff", "strict", True)

    def test_decoder_state(self):
        self.check_state_handling_decode(self.encoding,
                                         "spamspam", self.spamle)
        self.check_state_handling_decode(self.encoding,
                                         "spamspam", self.spambe)

    def test_bug691291(self):
        # If encoding is not None, then
        # files are always opened in binary mode, even if no binary mode was
        # specified.  This means that no automatic conversion of '\n' is done
        # on reading and writing.
        s1 = 'Hello\r\nworld\r\n'

        s = s1.encode(self.encoding)
        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
        with open(os_helper.TESTFN, 'wb') as fp:
            fp.write(s)
        with codecs_open_no_warn(os_helper.TESTFN, 'r',
                         encoding=self.encoding) as reader:
            self.assertEqual(reader.read(), s1)

    def test_invalid_modes(self):
        for mode in ('U', 'rU', 'r+U'):
            with self.assertRaises(ValueError) as cm:
                codecs_open_no_warn(os_helper.TESTFN, mode, encoding=self.encoding)
            self.assertIn('invalid mode', str(cm.exception))

        for mode in ('rt', 'wt', 'at', 'r+t'):
            with self.assertRaises(ValueError) as cm:
                codecs_open_no_warn(os_helper.TESTFN, mode, encoding=self.encoding)
            self.assertIn("can't have text and binary mode at once",
                          str(cm.exception))


class UTF16LETest(ReadTest, unittest.TestCase):
    encoding = "utf-16-le"
    ill_formed_sequence = b"\x80\xdc"

    def test_partial(self):
        self.check_partial(
            "\x00\xff\u0100\uffff\U00010000",
            [
                "",
                "\x00",
                "\x00",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff\U00010000",
            ]
        )

    def test_errors(self):
        tests = [
            (b'\xff', '\ufffd'),
            (b'A\x00Z', 'A\ufffd'),
            (b'A\x00B\x00C\x00D\x00Z', 'ABCD\ufffd'),
            (b'\x00\xd8', '\ufffd'),
            (b'\x00\xd8A', '\ufffd'),
            (b'\x00\xd8A\x00', '\ufffdA'),
            (b'\x00\xdcA\x00', '\ufffdA'),
        ]
        for raw, expected in tests:
            self.assertRaises(UnicodeDecodeError, codecs.utf_16_le_decode,
                              raw, 'strict', True)
            self.assertEqual(raw.decode('utf-16le', 'replace'), expected)

    def test_nonbmp(self):
        self.assertEqual("\U00010203".encode(self.encoding),
                         b'\x00\xd8\x03\xde')
        self.assertEqual(b'\x00\xd8\x03\xde'.decode(self.encoding),
                         "\U00010203")

class UTF16BETest(ReadTest, unittest.TestCase):
    encoding = "utf-16-be"
    ill_formed_sequence = b"\xdc\x80"

    def test_partial(self):
        self.check_partial(
            "\x00\xff\u0100\uffff\U00010000",
            [
                "",
                "\x00",
                "\x00",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff\u0100",
                "\x00\xff\u0100",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff",
                "\x00\xff\u0100\uffff\U00010000",
            ]
        )

    def test_errors(self):
        tests = [
            (b'\xff', '\ufffd'),
            (b'\x00A\xff', 'A\ufffd'),
            (b'\x00A\x00B\x00C\x00DZ', 'ABCD\ufffd'),
            (b'\xd8\x00', '\ufffd'),
            (b'\xd8\x00\xdc', '\ufffd'),
            (b'\xd8\x00\x00A', '\ufffdA'),
            (b'\xdc\x00\x00A', '\ufffdA'),
        ]
        for raw, expected in tests:
            self.assertRaises(UnicodeDecodeError, codecs.utf_16_be_decode,
                              raw, 'strict', True)
            self.assertEqual(raw.decode('utf-16be', 'replace'), expected)

    def test_nonbmp(self):
        self.assertEqual("\U00010203".encode(self.encoding),
                         b'\xd8\x00\xde\x03')
        self.assertEqual(b'\xd8\x00\xde\x03'.decode(self.encoding),
                         "\U00010203")

class UTF8Test(ReadTest, unittest.TestCase):
    encoding = "utf-8"
    ill_formed_sequence = b"\xed\xb2\x80"
    ill_formed_sequence_replace = "\ufffd" * 3
    BOM = b''

    def test_partial(self):
        self.check_partial(
            "\x00\xff\u07ff\u0800\uffff\U00010000",
            [
                "\x00",
                "\x00",
                "\x00\xff",
                "\x00\xff",
                "\x00\xff\u07ff",
                "\x00\xff\u07ff",
                "\x00\xff\u07ff",
                "\x00\xff\u07ff\u0800",
                "\x00\xff\u07ff\u0800",
                "\x00\xff\u07ff\u0800",
                "\x00\xff\u07ff\u0800\uffff",
                "\x00\xff\u07ff\u0800\uffff",
                "\x00\xff\u07ff\u0800\uffff",
                "\x00\xff\u07ff\u0800\uffff",
                "\x00\xff\u07ff\u0800\uffff\U00010000",
            ]
        )

    def test_decoder_state(self):
        u = "\x00\x7f\x80\xff\u0100\u07ff\u0800\uffff\U0010ffff"
        self.check_state_handling_decode(self.encoding,
                                         u, u.encode(self.encoding))

    def test_decode_error(self):
        for data, error_handler, expected in (
            (b'[\x80\xff]', 'ignore', '[]'),
            (b'[\x80\xff]', 'replace', '[\ufffd\ufffd]'),
            (b'[\x80\xff]', 'surrogateescape', '[\udc80\udcff]'),
            (b'[\x80\xff]', 'backslashreplace', '[\\x80\\xff]'),
        ):
            with self.subTest(data=data, error_handler=error_handler,
                              expected=expected):
                self.assertEqual(data.decode(self.encoding, error_handler),
                                 expected)

    def test_lone_surrogates(self):
        super().test_lone_surrogates()
        # not sure if this is making sense for
        # UTF-16 and UTF-32
        self.assertEqual("[\uDC80]".encode(self.encoding, "surrogateescape"),
                         self.BOM + b'[\x80]')

        with self.assertRaises(UnicodeEncodeError) as cm:
            "[\uDC80\uD800\uDFFF]".encode(self.encoding, "surrogateescape")
        exc = cm.exception
        self.assertEqual(exc.object[exc.start:exc.end], '\uD800\uDFFF')

    def test_surrogatepass_handler(self):
        self.assertEqual("abc\ud800def".encode(self.encoding, "surrogatepass"),
                         self.BOM + b"abc\xed\xa0\x80def")
        self.assertEqual("\U00010fff\uD800".encode(self.encoding, "surrogatepass"),
                         self.BOM + b"\xf0\x90\xbf\xbf\xed\xa0\x80")
        self.assertEqual("[\uD800\uDC80]".encode(self.encoding, "surrogatepass"),
                         self.BOM + b'[\xed\xa0\x80\xed\xb2\x80]')

        self.assertEqual(b"abc\xed\xa0\x80def".decode(self.encoding, "surrogatepass"),
                         "abc\ud800def")
        self.assertEqual(b"\xf0\x90\xbf\xbf\xed\xa0\x80".decode(self.encoding, "surrogatepass"),
                         "\U00010fff\uD800")

        self.assertTrue(codecs.lookup_error("surrogatepass"))
        with self.assertRaises(UnicodeDecodeError):
            b"abc\xed\xa0".decode(self.encoding, "surrogatepass")
        with self.assertRaises(UnicodeDecodeError):
            b"abc\xed\xa0z".decode(self.encoding, "surrogatepass")

    def test_incremental_errors(self):
        # Test that the incremental decoder can fail with final=False.
        # See issue #24214
        cases = [b'\x80', b'\xBF', b'\xC0', b'\xC1', b'\xF5', b'\xF6', b'\xFF']
        for prefix in (b'\xC2', b'\xDF', b'\xE0', b'\xE0\xA0', b'\xEF',
                       b'\xEF\xBF', b'\xF0', b'\xF0\x90', b'\xF0\x90\x80',
                       b'\xF4', b'\xF4\x8F', b'\xF4\x8F\xBF'):
            for suffix in b'\x7F', b'\xC0':
                cases.append(prefix + suffix)
        cases.extend((b'\xE0\x80', b'\xE0\x9F', b'\xED\xA0\x80',
                      b'\xED\xBF\xBF', b'\xF0\x80', b'\xF0\x8F', b'\xF4\x90'))

        for data in cases:
            with self.subTest(data=data):
                dec = codecs.getincrementaldecoder(self.encoding)()
                self.assertRaises(UnicodeDecodeError, dec.decode, data)


class UTF7Test(ReadTest, unittest.TestCase):
    encoding = "utf-7"

    def test_ascii(self):
        # Set D (directly encoded characters)
        set_d = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                 'abcdefghijklmnopqrstuvwxyz'
                 '0123456789'
                 '\'(),-./:?')
        self.assertEqual(set_d.encode(self.encoding), set_d.encode('ascii'))
        self.assertEqual(set_d.encode('ascii').decode(self.encoding), set_d)
        # Set O (optional direct characters)
        set_o = ' !"#$%&*;<=>@[]^_`{|}'
        self.assertEqual(set_o.encode(self.encoding), set_o.encode('ascii'))
        self.assertEqual(set_o.encode('ascii').decode(self.encoding), set_o)
        # +
        self.assertEqual('a+b'.encode(self.encoding), b'a+-b')
        self.assertEqual(b'a+-b'.decode(self.encoding), 'a+b')
        # White spaces
        ws = ' \t\n\r'
        self.assertEqual(ws.encode(self.encoding), ws.encode('ascii'))
        self.assertEqual(ws.encode('ascii').decode(self.encoding), ws)
        # Other ASCII characters
        other_ascii = ''.join(sorted(set(bytes(range(0x80)).decode()) -
                                     set(set_d + set_o + '+' + ws)))
        self.assertEqual(other_ascii.encode(self.encoding),
                         b'+AAAAAQACAAMABAAFAAYABwAIAAsADAAOAA8AEAARABIAEwAU'
                         b'ABUAFgAXABgAGQAaABsAHAAdAB4AHwBcAH4Afw-')

    def test_partial(self):
        self.check_partial(
            'a+-b\x00c\x80d\u0100e\U00010000f',
            [
                'a',
                'a',
                'a+',
                'a+-',
                'a+-b',
                'a+-b',
                'a+-b',
                'a+-b',
                'a+-b',
                'a+-b\x00',
                'a+-b\x00c',
                'a+-b\x00c',
                'a+-b\x00c',
                'a+-b\x00c',
                'a+-b\x00c',
                'a+-b\x00c\x80',
                'a+-b\x00c\x80d',
                'a+-b\x00c\x80d',
                'a+-b\x00c\x80d',
                'a+-b\x00c\x80d',
                'a+-b\x00c\x80d',
                'a+-b\x00c\x80d\u0100',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e',
                'a+-b\x00c\x80d\u0100e\U00010000',
                'a+-b\x00c\x80d\u0100e\U00010000f',
            ]
        )

    def test_errors(self):
        tests = [
            (b'\xffb', '\ufffdb'),
            (b'a\xffb', 'a\ufffdb'),
            (b'a\xff\xffb', 'a\ufffd\ufffdb'),
            (b'a+IK', 'a\ufffd'),
            (b'a+IK-b', 'a\ufffdb'),
            (b'a+IK,b', 'a\ufffdb'),
            (b'a+IKx', 'a\u20ac\ufffd'),
            (b'a+IKx-b', 'a\u20ac\ufffdb'),
            (b'a+IKwgr', 'a\u20ac\ufffd'),
            (b'a+IKwgr-b', 'a\u20ac\ufffdb'),
            (b'a+IKwgr,', 'a\u20ac\ufffd'),
            (b'a+IKwgr,-b', 'a\u20ac\ufffd-b'),
            (b'a+IKwgrB', 'a\u20ac\u20ac\ufffd'),
            (b'a+IKwgrB-b', 'a\u20ac\u20ac\ufffdb'),
            (b'a+/,+IKw-b', 'a\ufffd\u20acb'),
            (b'a+//,+IKw-b', 'a\ufffd\u20acb'),
            (b'a+///,+IKw-b', 'a\uffff\ufffd\u20acb'),
            (b'a+////,+IKw-b', 'a\uffff\ufffd\u20acb'),
            (b'a+IKw-b\xff', 'a\u20acb\ufffd'),
            (b'a+IKw\xffb', 'a\u20ac\ufffdb'),
            (b'a+@b', 'a\ufffdb'),
        ]
        for raw, expected in tests:
            with self.subTest(raw=raw):
                self.assertRaises(UnicodeDecodeError, codecs.utf_7_decode,
                                raw, 'strict', True)
                self.assertEqual(raw.decode('utf-7', 'replace'), expected)

    def test_nonbmp(self):
        self.assertEqual('\U000104A0'.encode(self.encoding), b'+2AHcoA-')
        self.assertEqual('\ud801\udca0'.encode(self.encoding), b'+2AHcoA-')
        self.assertEqual(b'+2AHcoA-'.decode(self.encoding), '\U000104A0')
        self.assertEqual(b'+2AHcoA'.decode(self.encoding), '\U000104A0')
        self.assertEqual('\u20ac\U000104A0'.encode(self.encoding), b'+IKzYAdyg-')
        self.assertEqual(b'+IKzYAdyg-'.decode(self.encoding), '\u20ac\U000104A0')
        self.assertEqual(b'+IKzYAdyg'.decode(self.encoding), '\u20ac\U000104A0')
        self.assertEqual('\u20ac\u20ac\U000104A0'.encode(self.encoding),
                         b'+IKwgrNgB3KA-')
        self.assertEqual(b'+IKwgrNgB3KA-'.decode(self.encoding),
                         '\u20ac\u20ac\U000104A0')
        self.assertEqual(b'+IKwgrNgB3KA'.decode(self.encoding),
                         '\u20ac\u20ac\U000104A0')

    def test_lone_surrogates(self):
        tests = [
            (b'a+2AE-b', 'a\ud801b'),
            (b'a+2AE\xffb', 'a\ufffdb'),
            (b'a+2AE', 'a\ufffd'),
            (b'a+2AEA-b', 'a\ufffdb'),
            (b'a+2AH-b', 'a\ufffdb'),
            (b'a+IKzYAQ-b', 'a\u20ac\ud801b'),
            (b'a+IKzYAQ\xffb', 'a\u20ac\ufffdb'),
            (b'a+IKzYAQA-b', 'a\u20ac\ufffdb'),
            (b'a+IKzYAd-b', 'a\u20ac\ufffdb'),
            (b'a+IKwgrNgB-b', 'a\u20ac\u20ac\ud801b'),
            (b'a+IKwgrNgB\xffb', 'a\u20ac\u20ac\ufffdb'),
            (b'a+IKwgrNgB', 'a\u20ac\u20ac\ufffd'),
            (b'a+IKwgrNgBA-b', 'a\u20ac\u20ac\ufffdb'),
        ]
        for raw, expected in tests:
            with self.subTest(raw=raw):
                self.assertEqual(raw.decode('utf-7', 'replace'), expected)


class UTF16ExTest(unittest.TestCase):

    def test_errors(self):
        self.assertRaises(UnicodeDecodeError, codecs.utf_16_ex_decode, b"\xff", "strict", 0, True)

    def test_bad_args(self):
        self.assertRaises(TypeError, codecs.utf_16_ex_decode)

class ReadBufferTest(unittest.TestCase):

    def test_array(self):
        import array
        self.assertEqual(
            codecs.readbuffer_encode(array.array("b", b"spam")),
            (b"spam", 4)
        )

    def test_empty(self):
        self.assertEqual(codecs.readbuffer_encode(""), (b"", 0))

    def test_bad_args(self):
        self.assertRaises(TypeError, codecs.readbuffer_encode)
        self.assertRaises(TypeError, codecs.readbuffer_encode, 42)

class UTF8SigTest(UTF8Test, unittest.TestCase):
    encoding = "utf-8-sig"
    BOM = codecs.BOM_UTF8

    def test_partial(self):
        self.check_partial(
            "\ufeff\x00\xff\u07ff\u0800\uffff\U00010000",
            [
                "",
                "",
                "", # First BOM has been read and skipped
                "",
                "",
                "\ufeff", # Second BOM has been read and emitted
                "\ufeff\x00", # "\x00" read and emitted
                "\ufeff\x00", # First byte of encoded "\xff" read
                "\ufeff\x00\xff", # Second byte of encoded "\xff" read
                "\ufeff\x00\xff", # First byte of encoded "\u07ff" read
                "\ufeff\x00\xff\u07ff", # Second byte of encoded "\u07ff" read
                "\ufeff\x00\xff\u07ff",
                "\ufeff\x00\xff\u07ff",
                "\ufeff\x00\xff\u07ff\u0800",
                "\ufeff\x00\xff\u07ff\u0800",
                "\ufeff\x00\xff\u07ff\u0800",
                "\ufeff\x00\xff\u07ff\u0800\uffff",
                "\ufeff\x00\xff\u07ff\u0800\uffff",
                "\ufeff\x00\xff\u07ff\u0800\uffff",
                "\ufeff\x00\xff\u07ff\u0800\uffff",
                "\ufeff\x00\xff\u07ff\u0800\uffff\U00010000",
            ]
        )

    def test_bug1601501(self):
        # SF bug #1601501: check that the codec works with a buffer
        self.assertEqual(str(b"\xef\xbb\xbf", "utf-8-sig"), "")

    def test_bom(self):
        d = codecs.getincrementaldecoder("utf-8-sig")()
        s = "spam"
        self.assertEqual(d.decode(s.encode("utf-8-sig")), s)

    def test_stream_bom(self):
        unistring = "ABC\u00A1\u2200XYZ"
        bytestring = codecs.BOM_UTF8 + b"ABC\xC2\xA1\xE2\x88\x80XYZ"

        reader = codecs.getreader("utf-8-sig")
        for sizehint in [None] + list(range(1, 11)) + \
                        [64, 128, 256, 512, 1024]:
            istream = reader(io.BytesIO(bytestring))
            ostream = io.StringIO()
            while 1:
                if sizehint is not None:
                    data = istream.read(sizehint)
                else:
                    data = istream.read()

                if not data:
                    break
                ostream.write(data)

            got = ostream.getvalue()
            self.assertEqual(got, unistring)

    def test_stream_bare(self):
        unistring = "ABC\u00A1\u2200XYZ"
        bytestring = b"ABC\xC2\xA1\xE2\x88\x80XYZ"

        reader = codecs.getreader("utf-8-sig")
        for sizehint in [None] + list(range(1, 11)) + \
                        [64, 128, 256, 512, 1024]:
            istream = reader(io.BytesIO(bytestring))
            ostream = io.StringIO()
            while 1:
                if sizehint is not None:
                    data = istream.read(sizehint)
                else:
                    data = istream.read()

                if not data:
                    break
                ostream.write(data)

            got = ostream.getvalue()
            self.assertEqual(got, unistring)


class EscapeDecodeTest(unittest.TestCase):
    def test_empty(self):
        self.assertEqual(codecs.escape_decode(b""), (b"", 0))
        self.assertEqual(codecs.escape_decode(bytearray()), (b"", 0))

    def test_raw(self):
        decode = codecs.escape_decode
        for b in range(256):
            b = bytes([b])
            if b != b'\\':
                self.assertEqual(decode(b + b'0'), (b + b'0', 2))

    def test_escape(self):
        decode = codecs.escape_decode
        check = coding_checker(self, decode)
        check(b"[\\\n]", b"[]")
        check(br'[\"]', b'["]')
        check(br"[\']", b"[']")
        check(br"[\\]", b"[\\]")
        check(br"[\a]", b"[\x07]")
        check(br"[\b]", b"[\x08]")
        check(br"[\t]", b"[\x09]")
        check(br"[\n]", b"[\x0a]")
        check(br"[\v]", b"[\x0b]")
        check(br"[\f]", b"[\x0c]")
        check(br"[\r]", b"[\x0d]")
        check(br"[\7]", b"[\x07]")
        check(br"[\78]", b"[\x078]")
        check(br"[\41]", b"[!]")
        check(br"[\418]", b"[!8]")
        check(br"[\101]", b"[A]")
        check(br"[\1010]", b"[A0]")
        check(br"[\x41]", b"[A]")
        check(br"[\x410]", b"[A0]")

    def test_warnings(self):
        decode = codecs.escape_decode
        check = coding_checker(self, decode)
        for i in range(97, 123):
            b = bytes([i])
            if b not in b'abfnrtvx':
                with self.assertWarnsRegex(DeprecationWarning,
                        r'"\\%c" is an invalid escape sequence' % i):
                    check(b"\\" + b, b"\\" + b)
            with self.assertWarnsRegex(DeprecationWarning,
                    r'"\\%c" is an invalid escape sequence' % (i-32)):
                check(b"\\" + b.upper(), b"\\" + b.upper())
        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\8" is an invalid escape sequence'):
            check(br"\8", b"\\8")
        with self.assertWarns(DeprecationWarning):
            check(br"\9", b"\\9")
        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\\xfa" is an invalid escape sequence') as cm:
            check(b"\\\xfa", b"\\\xfa")
        for i in range(0o400, 0o1000):
            with self.assertWarnsRegex(DeprecationWarning,
                    r'"\\%o" is an invalid octal escape sequence' % i):
                check(rb'\%o' % i, bytes([i & 0o377]))

        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\z" is an invalid escape sequence'):
            self.assertEqual(decode(br'\x\z', 'ignore'), (b'\\z', 4))
        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\501" is an invalid octal escape sequence'):
            self.assertEqual(decode(br'\x\501', 'ignore'), (b'A', 6))

    def test_errors(self):
        decode = codecs.escape_decode
        self.assertRaises(ValueError, decode, br"\x")
        self.assertRaises(ValueError, decode, br"[\x]")
        self.assertEqual(decode(br"[\x]\x", "ignore"), (b"[]", 6))
        self.assertEqual(decode(br"[\x]\x", "replace"), (b"[?]?", 6))
        self.assertRaises(ValueError, decode, br"\x0")
        self.assertRaises(ValueError, decode, br"[\x0]")
        self.assertEqual(decode(br"[\x0]\x0", "ignore"), (b"[]", 8))
        self.assertEqual(decode(br"[\x0]\x0", "replace"), (b"[?]?", 8))


# From RFC 3492
punycode_testcases = [
    # A Arabic (Egyptian):
    ("\u0644\u064A\u0647\u0645\u0627\u0628\u062A\u0643\u0644"
     "\u0645\u0648\u0634\u0639\u0631\u0628\u064A\u061F",
     b"egbpdaj6bu4bxfgehfvwxn"),
    # B Chinese (simplified):
    ("\u4ED6\u4EEC\u4E3A\u4EC0\u4E48\u4E0D\u8BF4\u4E2D\u6587",
     b"ihqwcrb4cv8a8dqg056pqjye"),
    # C Chinese (traditional):
    ("\u4ED6\u5011\u7232\u4EC0\u9EBD\u4E0D\u8AAA\u4E2D\u6587",
     b"ihqwctvzc91f659drss3x8bo0yb"),
    # D Czech: Pro<ccaron>prost<ecaron>nemluv<iacute><ccaron>esky
    ("\u0050\u0072\u006F\u010D\u0070\u0072\u006F\u0073\u0074"
     "\u011B\u006E\u0065\u006D\u006C\u0075\u0076\u00ED\u010D"
     "\u0065\u0073\u006B\u0079",
     b"Proprostnemluvesky-uyb24dma41a"),
    # E Hebrew:
    ("\u05DC\u05DE\u05D4\u05D4\u05DD\u05E4\u05E9\u05D5\u05D8"
     "\u05DC\u05D0\u05DE\u05D3\u05D1\u05E8\u05D9\u05DD\u05E2"
     "\u05D1\u05E8\u05D9\u05EA",
     b"4dbcagdahymbxekheh6e0a7fei0b"),
    # F Hindi (Devanagari):
    ("\u092F\u0939\u0932\u094B\u0917\u0939\u093F\u0928\u094D"
     "\u0926\u0940\u0915\u094D\u092F\u094B\u0902\u0928\u0939"
     "\u0940\u0902\u092C\u094B\u0932\u0938\u0915\u0924\u0947"
     "\u0939\u0948\u0902",
     b"i1baa7eci9glrd9b2ae1bj0hfcgg6iyaf8o0a1dig0cd"),

    #(G) Japanese (kanji and hiragana):
    ("\u306A\u305C\u307F\u3093\u306A\u65E5\u672C\u8A9E\u3092"
     "\u8A71\u3057\u3066\u304F\u308C\u306A\u3044\u306E\u304B",
     b"n8jok5ay5dzabd5bym9f0cm5685rrjetr6pdxa"),

    # (H) Korean (Hangul syllables):
    ("\uC138\uACC4\uC758\uBAA8\uB4E0\uC0AC\uB78C\uB4E4\uC774"
     "\uD55C\uAD6D\uC5B4\uB97C\uC774\uD574\uD55C\uB2E4\uBA74"
     "\uC5BC\uB9C8\uB098\uC88B\uC744\uAE4C",
     b"989aomsvi5e83db1d2a355cv1e0vak1dwrv93d5xbh15a0dt30a5j"
     b"psd879ccm6fea98c"),

    # (I) Russian (Cyrillic):
    ("\u043F\u043E\u0447\u0435\u043C\u0443\u0436\u0435\u043E"
     "\u043D\u0438\u043D\u0435\u0433\u043E\u0432\u043E\u0440"
     "\u044F\u0442\u043F\u043E\u0440\u0443\u0441\u0441\u043A"
     "\u0438",
     b"b1abfaaepdrnnbgefbaDotcwatmq2g4l"),

    # (J) Spanish: Porqu<eacute>nopuedensimplementehablarenEspa<ntilde>ol
    ("\u0050\u006F\u0072\u0071\u0075\u00E9\u006E\u006F\u0070"
     "\u0075\u0065\u0064\u0065\u006E\u0073\u0069\u006D\u0070"
     "\u006C\u0065\u006D\u0065\u006E\u0074\u0065\u0068\u0061"
     "\u0062\u006C\u0061\u0072\u0065\u006E\u0045\u0073\u0070"
     "\u0061\u00F1\u006F\u006C",
     b"PorqunopuedensimplementehablarenEspaol-fmd56a"),

    # (K) Vietnamese:
    #  T<adotbelow>isaoh<odotbelow>kh<ocirc>ngth<ecirchookabove>ch\
    #   <ihookabove>n<oacute>iti<ecircacute>ngVi<ecircdotbelow>t
    ("\u0054\u1EA1\u0069\u0073\u0061\u006F\u0068\u1ECD\u006B"
     "\u0068\u00F4\u006E\u0067\u0074\u0068\u1EC3\u0063\u0068"
     "\u1EC9\u006E\u00F3\u0069\u0074\u0069\u1EBF\u006E\u0067"
     "\u0056\u0069\u1EC7\u0074",
     b"TisaohkhngthchnitingVit-kjcr8268qyxafd2f1b9g"),

    #(L) 3<nen>B<gumi><kinpachi><sensei>
    ("\u0033\u5E74\u0042\u7D44\u91D1\u516B\u5148\u751F",
     b"3B-ww4c5e180e575a65lsy2b"),

    # (M) <amuro><namie>-with-SUPER-MONKEYS
    ("\u5B89\u5BA4\u5948\u7F8E\u6075\u002D\u0077\u0069\u0074"
     "\u0068\u002D\u0053\u0055\u0050\u0045\u0052\u002D\u004D"
     "\u004F\u004E\u004B\u0045\u0059\u0053",
     b"-with-SUPER-MONKEYS-pc58ag80a8qai00g7n9n"),

    # (N) Hello-Another-Way-<sorezore><no><basho>
    ("\u0048\u0065\u006C\u006C\u006F\u002D\u0041\u006E\u006F"
     "\u0074\u0068\u0065\u0072\u002D\u0057\u0061\u0079\u002D"
     "\u305D\u308C\u305E\u308C\u306E\u5834\u6240",
     b"Hello-Another-Way--fc4qua05auwb3674vfr0b"),

    # (O) <hitotsu><yane><no><shita>2
    ("\u3072\u3068\u3064\u5C4B\u6839\u306E\u4E0B\u0032",
     b"2-u9tlzr9756bt3uc0v"),

    # (P) Maji<de>Koi<suru>5<byou><mae>
    ("\u004D\u0061\u006A\u0069\u3067\u004B\u006F\u0069\u3059"
     "\u308B\u0035\u79D2\u524D",
     b"MajiKoi5-783gue6qz075azm5e"),

     # (Q) <pafii>de<runba>
    ("\u30D1\u30D5\u30A3\u30FC\u0064\u0065\u30EB\u30F3\u30D0",
     b"de-jg4avhby1noc0d"),

    # (R) <sono><supiido><de>
    ("\u305D\u306E\u30B9\u30D4\u30FC\u30C9\u3067",
     b"d9juau41awczczp"),

    # (S) -> $1.00 <-
    ("\u002D\u003E\u0020\u0024\u0031\u002E\u0030\u0030\u0020"
     "\u003C\u002D",
     b"-> $1.00 <--")
    ]

for i in punycode_testcases:
    if len(i)!=2:
        print(repr(i))


class PunycodeTest(unittest.TestCase):
    def test_encode(self):
        for uni, puny in punycode_testcases:
            # Need to convert both strings to lower case, since
            # some of the extended encodings use upper case, but our
            # code produces only lower case. Converting just puny to
            # lower is also insufficient, since some of the input characters
            # are upper case.
            self.assertEqual(
                str(uni.encode("punycode"), "ascii").lower(),
                str(puny, "ascii").lower()
            )

    def test_decode(self):
        for uni, puny in punycode_testcases:
            self.assertEqual(uni, puny.decode("punycode"))
            puny = puny.decode("ascii").encode("ascii")
            self.assertEqual(uni, puny.decode("punycode"))

    def test_decode_invalid(self):
        testcases = [
            (b"xn--w&", "strict", UnicodeDecodeError("punycode", b"", 5, 6, "")),
            (b"&egbpdaj6bu4bxfgehfvwxn", "strict", UnicodeDecodeError("punycode", b"", 0, 1, "")),
            (b"egbpdaj6bu&4bx&fgehfvwxn", "strict", UnicodeDecodeError("punycode", b"", 10, 11, "")),
            (b"egbpdaj6bu4bxfgehfvwxn&", "strict", UnicodeDecodeError("punycode", b"", 22, 23, "")),
            (b"\xFFProprostnemluvesky-uyb24dma41a", "strict", UnicodeDecodeError("ascii", b"", 0, 1, "")),
            (b"Pro\xFFprostnemluvesky-uyb24dma41a", "strict", UnicodeDecodeError("ascii", b"", 3, 4, "")),
            (b"Proprost&nemluvesky-uyb24&dma41a", "strict", UnicodeDecodeError("punycode", b"", 25, 26, "")),
            (b"Proprostnemluvesky&-&uyb24dma41a", "strict", UnicodeDecodeError("punycode", b"", 20, 21, "")),
            (b"Proprostnemluvesky-&uyb24dma41a", "strict", UnicodeDecodeError("punycode", b"", 19, 20, "")),
            (b"Proprostnemluvesky-uyb24d&ma41a", "strict", UnicodeDecodeError("punycode", b"", 25, 26, "")),
            (b"Proprostnemluvesky-uyb24dma41a&", "strict", UnicodeDecodeError("punycode", b"", 30, 31, "")),
            (b"xn--w&", "ignore", "xn-"),
        ]
        for puny, errors, expected in testcases:
            with self.subTest(puny=puny, errors=errors):
                if isinstance(expected, Exception):
                    with self.assertRaises(UnicodeDecodeError) as cm:
                        puny.decode("punycode", errors)
                    exc = cm.exception
                    self.assertEqual(exc.encoding, expected.encoding)
                    self.assertEqual(exc.object, puny)
                    self.assertEqual(exc.start, expected.start)
                    self.assertEqual(exc.end, expected.end)
                else:
                    self.assertEqual(puny.decode("punycode", errors), expected)


utf_7_imap_testcases = [
    # (unicode, modified UTF-7)
    ('', b''),
    ('INBOX', b'INBOX'),
    # Printable US-ASCII represents itself.
    ('abcABC123 !#$%()*+,-./:;<=>?@[]^_`{|}~', b'abcABC123 !#$%()*+,-./:;<=>?@[]^_`{|}~'),
    # "&" is escaped as "&-".
    ('&', b'&-'),
    ('&&', b'&-&-'),
    ('A&B', b'A&-B'),
    # "+" and "+-" are literal, unlike in UTF-7 where "+" is the shift character.
    ('+', b'+'),
    ('+-', b'+-'),
    # RFC 3501 section 5.1.3 example.
    ('~peter/mail/台北/日本語',
     b'~peter/mail/&U,BTFw-/&ZeVnLIqe-'),
    # Non-printable ASCII (including TAB) is Base64-encoded, not direct.
    ('a\tb', b'a&AAk-b'),
    ('\x00', b'&AAA-'),
    ('Entw\xfcrfe', b'Entw&APw-rfe'),
    ('ϰ', b'&A,A-'),                     # "," in the Base64 alphabet ("&A/A-" is invalid)
    ('☃', b'&JgM-'),                     # snowman
    ('\U0001f600', b'&2D3eAA-'),              # non-BMP (surrogate pair)
    ('Sent &\N{DELETE}', b'Sent &-&AH8-'),
]

class Utf7ImapTest(unittest.TestCase):
    @support.subTests('uni,encoded', utf_7_imap_testcases)
    def test_encode(self, uni, encoded):
        self.assertEqual(uni.encode('utf-7-imap'), encoded)

    @support.subTests('uni,encoded', utf_7_imap_testcases)
    def test_decode(self, uni, encoded):
        self.assertEqual(encoded.decode('utf-7-imap'), uni)

    # 'start' is the position of the first offending byte in each case.
    @support.subTests('encoded,start', [
        (b'x&', 1),             # "&" just before the end, unterminated
        (b'&AAAA', 0),          # unterminated, though the Base64 is valid
        (b'&AB-', 0),           # Base64 length not a multiple of a code unit
        (b'&A/A-', 0),          # "/" not in the alphabet ("&A,A-" is valid)
        (b'&@@@-', 0),          # invalid Base64
        (b'a\x80b', 1),         # 8-bit byte outside a shift sequence
        (b'a\x1fb', 1),         # control byte outside a shift sequence
    ])
    def test_decode_invalid(self, encoded, start):
        with self.assertRaises(UnicodeDecodeError) as cm:
            encoded.decode('utf-7-imap')
        self.assertEqual(cm.exception.encoding, 'utf-7-imap')
        self.assertEqual(cm.exception.start, start)

    def test_encode_lone_surrogate(self):
        with self.assertRaises(UnicodeEncodeError):
            '\ud800'.encode('utf-7-imap')

    def test_only_strict_errors(self):
        with self.assertRaises(UnicodeError):
            'x'.encode('utf-7-imap', 'replace')
        with self.assertRaises(UnicodeError):
            b'x'.decode('utf-7-imap', 'ignore')

    def test_stateless(self):
        # The codec is registered and exposes the standard interface.
        info = codecs.lookup('utf-7-imap')
        self.assertEqual(info.name, 'utf-7-imap')


# From http://www.gnu.org/software/libidn/draft-josefsson-idn-test-vectors.html
nameprep_tests = [
    # 3.1 Map to nothing.
    (b'foo\xc2\xad\xcd\x8f\xe1\xa0\x86\xe1\xa0\x8bbar'
     b'\xe2\x80\x8b\xe2\x81\xa0baz\xef\xb8\x80\xef\xb8\x88\xef'
     b'\xb8\x8f\xef\xbb\xbf',
     b'foobarbaz'),
    # 3.2 Case folding ASCII U+0043 U+0041 U+0046 U+0045.
    (b'CAFE',
     b'cafe'),
    # 3.3 Case folding 8bit U+00DF (german sharp s).
    # The original test case is bogus; it says \xc3\xdf
    (b'\xc3\x9f',
     b'ss'),
    # 3.4 Case folding U+0130 (turkish capital I with dot).
    (b'\xc4\xb0',
     b'i\xcc\x87'),
    # 3.5 Case folding multibyte U+0143 U+037A.
    (b'\xc5\x83\xcd\xba',
     b'\xc5\x84 \xce\xb9'),
    # 3.6 Case folding U+2121 U+33C6 U+1D7BB.
    # XXX: skip this as it fails in UCS-2 mode
    #('\xe2\x84\xa1\xe3\x8f\x86\xf0\x9d\x9e\xbb',
    # 'telc\xe2\x88\x95kg\xcf\x83'),
    (None, None),
    # 3.7 Normalization of U+006a U+030c U+00A0 U+00AA.
    (b'j\xcc\x8c\xc2\xa0\xc2\xaa',
     b'\xc7\xb0 a'),
    # 3.8 Case folding U+1FB7 and normalization.
    (b'\xe1\xbe\xb7',
     b'\xe1\xbe\xb6\xce\xb9'),
    # 3.9 Self-reverting case folding U+01F0 and normalization.
    # The original test case is bogus, it says `\xc7\xf0'
    (b'\xc7\xb0',
     b'\xc7\xb0'),
    # 3.10 Self-reverting case folding U+0390 and normalization.
    (b'\xce\x90',
     b'\xce\x90'),
    # 3.11 Self-reverting case folding U+03B0 and normalization.
    (b'\xce\xb0',
     b'\xce\xb0'),
    # 3.12 Self-reverting case folding U+1E96 and normalization.
    (b'\xe1\xba\x96',
     b'\xe1\xba\x96'),
    # 3.13 Self-reverting case folding U+1F56 and normalization.
    (b'\xe1\xbd\x96',
     b'\xe1\xbd\x96'),
    # 3.14 ASCII space character U+0020.
    (b' ',
     b' '),
    # 3.15 Non-ASCII 8bit space character U+00A0.
    (b'\xc2\xa0',
     b' '),
    # 3.16 Non-ASCII multibyte space character U+1680.
    (b'\xe1\x9a\x80',
     None),
    # 3.17 Non-ASCII multibyte space character U+2000.
    (b'\xe2\x80\x80',
     b' '),
    # 3.18 Zero Width Space U+200b.
    (b'\xe2\x80\x8b',
     b''),
    # 3.19 Non-ASCII multibyte space character U+3000.
    (b'\xe3\x80\x80',
     b' '),
    # 3.20 ASCII control characters U+0010 U+007F.
    (b'\x10\x7f',
     b'\x10\x7f'),
    # 3.21 Non-ASCII 8bit control character U+0085.
    (b'\xc2\x85',
     None),
    # 3.22 Non-ASCII multibyte control character U+180E.
    (b'\xe1\xa0\x8e',
     None),
    # 3.23 Zero Width No-Break Space U+FEFF.
    (b'\xef\xbb\xbf',
     b''),
    # 3.24 Non-ASCII control character U+1D175.
    (b'\xf0\x9d\x85\xb5',
     None),
    # 3.25 Plane 0 private use character U+F123.
    (b'\xef\x84\xa3',
     None),
    # 3.26 Plane 15 private use character U+F1234.
    (b'\xf3\xb1\x88\xb4',
     None),
    # 3.27 Plane 16 private use character U+10F234.
    (b'\xf4\x8f\x88\xb4',
     None),
    # 3.28 Non-character code point U+8FFFE.
    (b'\xf2\x8f\xbf\xbe',
     None),
    # 3.29 Non-character code point U+10FFFF.
    (b'\xf4\x8f\xbf\xbf',
     None),
    # 3.30 Surrogate code U+DF42.
    (b'\xed\xbd\x82',
     None),
    # 3.31 Non-plain text character U+FFFD.
    (b'\xef\xbf\xbd',
     None),
    # 3.32 Ideographic description character U+2FF5.
    (b'\xe2\xbf\xb5',
     None),
    # 3.33 Display property character U+0341.
    (b'\xcd\x81',
     b'\xcc\x81'),
    # 3.34 Left-to-right mark U+200E.
    (b'\xe2\x80\x8e',
     None),
    # 3.35 Deprecated U+202A.
    (b'\xe2\x80\xaa',
     None),
    # 3.36 Language tagging character U+E0001.
    (b'\xf3\xa0\x80\x81',
     None),
    # 3.37 Language tagging character U+E0042.
    (b'\xf3\xa0\x81\x82',
     None),
    # 3.38 Bidi: RandALCat character U+05BE and LCat characters.
    (b'foo\xd6\xbebar',
     None),
    # 3.39 Bidi: RandALCat character U+FD50 and LCat characters.
    (b'foo\xef\xb5\x90bar',
     None),
    # 3.40 Bidi: RandALCat character U+FB38 and LCat characters.
    (b'foo\xef\xb9\xb6bar',
     b'foo \xd9\x8ebar'),
    # 3.41 Bidi: RandALCat without trailing RandALCat U+0627 U+0031.
    (b'\xd8\xa71',
     None),
    # 3.42 Bidi: RandALCat character U+0627 U+0031 U+0628.
    (b'\xd8\xa71\xd8\xa8',
     b'\xd8\xa71\xd8\xa8'),
    # 3.43 Unassigned code point U+E0002.
    # Skip this test as we allow unassigned
    #(b'\xf3\xa0\x80\x82',
    # None),
    (None, None),
    # 3.44 Larger test (shrinking).
    # Original test case reads \xc3\xdf
    (b'X\xc2\xad\xc3\x9f\xc4\xb0\xe2\x84\xa1j\xcc\x8c\xc2\xa0\xc2'
     b'\xaa\xce\xb0\xe2\x80\x80',
     b'xssi\xcc\x87tel\xc7\xb0 a\xce\xb0 '),
    # 3.45 Larger test (expanding).
    # Original test case reads \xc3\x9f
    (b'X\xc3\x9f\xe3\x8c\x96\xc4\xb0\xe2\x84\xa1\xe2\x92\x9f\xe3\x8c'
     b'\x80',
     b'xss\xe3\x82\xad\xe3\x83\xad\xe3\x83\xa1\xe3\x83\xbc\xe3'
     b'\x83\x88\xe3\x83\xabi\xcc\x87tel\x28d\x29\xe3\x82'
     b'\xa2\xe3\x83\x91\xe3\x83\xbc\xe3\x83\x88')
    ]


class NameprepTest(unittest.TestCase):
    def test_nameprep(self):
        from encodings.idna import nameprep
        for pos, (orig, prepped) in enumerate(nameprep_tests):
            if orig is None:
                # Skipped
                continue
            # The Unicode strings are given in UTF-8
            orig = str(orig, "utf-8", "surrogatepass")
            if prepped is None:
                # Input contains prohibited characters
                self.assertRaises(UnicodeEncodeError, nameprep, orig)
            else:
                prepped = str(prepped, "utf-8", "surrogatepass")
                try:
                    self.assertEqual(nameprep(orig), prepped)
                except Exception as e:
                    raise support.TestFailed("Test 3.%d: %s" % (pos+1, str(e)))


class IDNACodecTest(unittest.TestCase):

    invalid_decode_testcases = [
        (b"\xFFpython.org", UnicodeDecodeError("idna", b"\xFFpython.org", 0, 1, "")),
        (b"pyt\xFFhon.org", UnicodeDecodeError("idna", b"pyt\xFFhon.org", 3, 4, "")),
        (b"python\xFF.org", UnicodeDecodeError("idna", b"python\xFF.org", 6, 7, "")),
        (b"python.\xFForg", UnicodeDecodeError("idna", b"python.\xFForg", 7, 8, "")),
        (b"python.o\xFFrg", UnicodeDecodeError("idna", b"python.o\xFFrg", 8, 9, "")),
        (b"python.org\xFF", UnicodeDecodeError("idna", b"python.org\xFF", 10, 11, "")),
        (b"xn--pythn-&mua.org", UnicodeDecodeError("idna", b"xn--pythn-&mua.org", 10, 11, "")),
        (b"xn--pythn-m&ua.org", UnicodeDecodeError("idna", b"xn--pythn-m&ua.org", 11, 12, "")),
        (b"xn--pythn-mua&.org", UnicodeDecodeError("idna", b"xn--pythn-mua&.org", 13, 14, "")),
    ]
    invalid_encode_testcases = [
        (f"foo.{'\xff'*60}", UnicodeEncodeError("idna", f"foo.{'\xff'*60}", 4, 64, "")),
        ("あさ.\u034f", UnicodeEncodeError("idna", "あさ.\u034f", 3, 4, "")),
    ]

    def test_builtin_decode(self):
        self.assertEqual(str(b"python.org", "idna"), "python.org")
        self.assertEqual(str(b"python.org.", "idna"), "python.org.")
        self.assertEqual(str(b"xn--pythn-mua.org", "idna"), "pyth\xf6n.org")
        self.assertEqual(str(b"xn--pythn-mua.org.", "idna"), "pyth\xf6n.org.")
        self.assertEqual(str(b"XN--pythn-mua.org.", "idna"), "pyth\xf6n.org.")
        self.assertEqual(str(b"xN--pythn-mua.org.", "idna"), "pyth\xf6n.org.")
        self.assertEqual(str(b"Xn--pythn-mua.org.", "idna"), "pyth\xf6n.org.")
        self.assertEqual(str(b"bugs.xn--pythn-mua.org.", "idna"),
                         "bugs.pyth\xf6n.org.")
        self.assertEqual(str(b"bugs.XN--pythn-mua.org.", "idna"),
                         "bugs.pyth\xf6n.org.")

    def test_builtin_decode_invalid(self):
        for case, expected in self.invalid_decode_testcases:
            with self.subTest(case=case, expected=expected):
                with self.assertRaises(UnicodeDecodeError) as cm:
                    case.decode("idna")
                exc = cm.exception
                self.assertEqual(exc.encoding, expected.encoding)
                self.assertEqual(exc.object, expected.object)
                self.assertEqual(exc.start, expected.start, msg=f'reason: {exc.reason}')
                self.assertEqual(exc.end, expected.end)

    def test_builtin_encode(self):
        self.assertEqual("python.org".encode("idna"), b"python.org")
        self.assertEqual("python.org.".encode("idna"), b"python.org.")
        self.assertEqual("pyth\xf6n.org".encode("idna"), b"xn--pythn-mua.org")
        self.assertEqual("pyth\xf6n.org.".encode("idna"), b"xn--pythn-mua.org.")

    @support.subTests(['unicode', 'encoded'], [
        ('\N{CHEROKEE LETTER A}\N{CHEROKEE LETTER A}', b"xn--58da"),
        ('\N{GEORGIAN CAPITAL LETTER AN}.', b"xn--7md."),
        ('\N{CYRILLIC LETTER PALOCHKA}.example', b"xn--d5a.example"),
        ('\N{ROMAN NUMERAL REVERSED ONE HUNDRED}.example.', b"xn--q5g.example."),
    ])
    def test_new_unicode_case_folding(self, unicode, encoded):
        self.assertEqual(unicode.encode("idna"), encoded)

    def test_builtin_encode_invalid(self):
        for case, expected in self.invalid_encode_testcases:
            with self.subTest(case=case, expected=expected):
                with self.assertRaises(UnicodeEncodeError) as cm:
                    case.encode("idna")
                exc = cm.exception
                self.assertEqual(exc.encoding, expected.encoding)
                self.assertEqual(exc.object, expected.object)
                self.assertEqual(exc.start, expected.start)
                self.assertEqual(exc.end, expected.end)

    def test_builtin_decode_length_limit(self):
        with self.assertRaisesRegex(UnicodeDecodeError, "way too long"):
            (b"xn--016c"+b"a"*1100).decode("idna")
        with self.assertRaisesRegex(UnicodeDecodeError, "too long"):
            (b"xn--016c"+b"a"*70).decode("idna")

    def test_stream(self):
        r = codecs.getreader("idna")(io.BytesIO(b"abc"))
        r.read(3)
        self.assertEqual(r.read(), "")

    def test_incremental_decode(self):
        self.assertEqual(
            "".join(codecs.iterdecode((bytes([c]) for c in b"python.org"), "idna")),
            "python.org"
        )
        self.assertEqual(
            "".join(codecs.iterdecode((bytes([c]) for c in b"python.org."), "idna")),
            "python.org."
        )
        self.assertEqual(
            "".join(codecs.iterdecode((bytes([c]) for c in b"xn--pythn-mua.org."), "idna")),
            "pyth\xf6n.org."
        )
        self.assertEqual(
            "".join(codecs.iterdecode((bytes([c]) for c in b"xn--pythn-mua.org."), "idna")),
            "pyth\xf6n.org."
        )

        decoder = codecs.getincrementaldecoder("idna")()
        self.assertEqual(decoder.decode(b"xn--xam", ), "")
        self.assertEqual(decoder.decode(b"ple-9ta.o", ), "\xe4xample.")
        self.assertEqual(decoder.decode(b"rg"), "")
        self.assertEqual(decoder.decode(b"", True), "org")

        decoder.reset()
        self.assertEqual(decoder.decode(b"xn--xam", ), "")
        self.assertEqual(decoder.decode(b"ple-9ta.o", ), "\xe4xample.")
        self.assertEqual(decoder.decode(b"rg."), "org.")
        self.assertEqual(decoder.decode(b"", True), "")

    def test_incremental_decode_invalid(self):
        iterdecode_testcases = [
            (b"\xFFpython.org", UnicodeDecodeError("idna", b"\xFF", 0, 1, "")),
            (b"pyt\xFFhon.org", UnicodeDecodeError("idna", b"pyt\xFF", 3, 4, "")),
            (b"python\xFF.org", UnicodeDecodeError("idna", b"python\xFF", 6, 7, "")),
            (b"python.\xFForg", UnicodeDecodeError("idna", b"\xFF", 0, 1, "")),
            (b"python.o\xFFrg", UnicodeDecodeError("idna", b"o\xFF", 1, 2, "")),
            (b"python.org\xFF", UnicodeDecodeError("idna", b"org\xFF", 3, 4, "")),
            (b"xn--pythn-&mua.org", UnicodeDecodeError("idna", b"xn--pythn-&mua.", 10, 11, "")),
            (b"xn--pythn-m&ua.org", UnicodeDecodeError("idna", b"xn--pythn-m&ua.", 11, 12, "")),
            (b"xn--pythn-mua&.org", UnicodeDecodeError("idna", b"xn--pythn-mua&.", 13, 14, "")),
        ]
        for case, expected in iterdecode_testcases:
            with self.subTest(case=case, expected=expected):
                with self.assertRaises(UnicodeDecodeError) as cm:
                    list(codecs.iterdecode((bytes([c]) for c in case), "idna"))
                exc = cm.exception
                self.assertEqual(exc.encoding, expected.encoding)
                self.assertEqual(exc.object, expected.object)
                self.assertEqual(exc.start, expected.start)
                self.assertEqual(exc.end, expected.end)

        decoder = codecs.getincrementaldecoder("idna")()
        for case, expected in self.invalid_decode_testcases:
            with self.subTest(case=case, expected=expected):
                with self.assertRaises(UnicodeDecodeError) as cm:
                    decoder.decode(case)
                exc = cm.exception
                self.assertEqual(exc.encoding, expected.encoding)
                self.assertEqual(exc.object, expected.object)
                self.assertEqual(exc.start, expected.start)
                self.assertEqual(exc.end, expected.end)

    def test_incremental_encode(self):
        self.assertEqual(
            b"".join(codecs.iterencode("python.org", "idna")),
            b"python.org"
        )
        self.assertEqual(
            b"".join(codecs.iterencode("python.org.", "idna")),
            b"python.org."
        )
        self.assertEqual(
            b"".join(codecs.iterencode("pyth\xf6n.org.", "idna")),
            b"xn--pythn-mua.org."
        )
        self.assertEqual(
            b"".join(codecs.iterencode("pyth\xf6n.org.", "idna")),
            b"xn--pythn-mua.org."
        )

        encoder = codecs.getincrementalencoder("idna")()
        self.assertEqual(encoder.encode("\xe4x"), b"")
        self.assertEqual(encoder.encode("ample.org"), b"xn--xample-9ta.")
        self.assertEqual(encoder.encode("", True), b"org")

        encoder.reset()
        self.assertEqual(encoder.encode("\xe4x"), b"")
        self.assertEqual(encoder.encode("ample.org."), b"xn--xample-9ta.org.")
        self.assertEqual(encoder.encode("", True), b"")

    def test_incremental_encode_invalid(self):
        iterencode_testcases = [
            (f"foo.{'\xff'*60}", UnicodeEncodeError("idna", f"{'\xff'*60}", 0, 60, "")),
            ("あさ.\u034f", UnicodeEncodeError("idna", "\u034f", 0, 1, "")),
        ]
        for case, expected in iterencode_testcases:
            with self.subTest(case=case, expected=expected):
                with self.assertRaises(UnicodeEncodeError) as cm:
                    list(codecs.iterencode(case, "idna"))
                exc = cm.exception
                self.assertEqual(exc.encoding, expected.encoding)
                self.assertEqual(exc.object, expected.object)
                self.assertEqual(exc.start, expected.start)
                self.assertEqual(exc.end, expected.end)

        # codecs.getincrementalencoder.encode() does not throw an error

    def test_errors(self):
        """Only supports "strict" error handler"""
        "python.org".encode("idna", "strict")
        b"python.org".decode("idna", "strict")
        for errors in ("ignore", "replace", "backslashreplace",
                "surrogateescape"):
            self.assertRaises(Exception, "python.org".encode, "idna", errors)
            self.assertRaises(Exception,
                b"python.org".decode, "idna", errors)


class CodecsModuleTest(unittest.TestCase):

    def test_decode(self):
        self.assertEqual(codecs.decode(b'\xe4\xf6\xfc', 'latin-1'),
                         '\xe4\xf6\xfc')
        self.assertRaises(TypeError, codecs.decode)
        self.assertEqual(codecs.decode(b'abc'), 'abc')
        self.assertRaises(UnicodeDecodeError, codecs.decode, b'\xff', 'ascii')

        # test keywords
        self.assertEqual(codecs.decode(obj=b'\xe4\xf6\xfc', encoding='latin-1'),
                         '\xe4\xf6\xfc')
        self.assertEqual(codecs.decode(b'[\xff]', 'ascii', errors='ignore'),
                         '[]')

    def test_encode(self):
        self.assertEqual(codecs.encode('\xe4\xf6\xfc', 'latin-1'),
                         b'\xe4\xf6\xfc')
        self.assertRaises(TypeError, codecs.encode)
        self.assertRaises(LookupError, codecs.encode, "foo", "__spam__")
        self.assertEqual(codecs.encode('abc'), b'abc')
        self.assertRaises(UnicodeEncodeError, codecs.encode, '\xffff', 'ascii')

        # test keywords
        self.assertEqual(codecs.encode(obj='\xe4\xf6\xfc', encoding='latin-1'),
                         b'\xe4\xf6\xfc')
        self.assertEqual(codecs.encode('[\xff]', 'ascii', errors='ignore'),
                         b'[]')

    def test_register(self):
        self.assertRaises(TypeError, codecs.register)
        self.assertRaises(TypeError, codecs.register, 42)

    def test_unregister(self):
        name = "nonexistent_codec_name"
        search_function = mock.Mock()
        codecs.register(search_function)
        self.assertRaises(TypeError, codecs.lookup, name)
        search_function.assert_called_with(name)
        search_function.reset_mock()

        codecs.unregister(search_function)
        self.assertRaises(LookupError, codecs.lookup, name)
        search_function.assert_not_called()

    def test_lookup(self):
        self.assertRaises(TypeError, codecs.lookup)
        self.assertRaises(LookupError, codecs.lookup, "__spam__")
        self.assertRaises(LookupError, codecs.lookup, " ")

    def test_getencoder(self):
        self.assertRaises(TypeError, codecs.getencoder)
        self.assertRaises(LookupError, codecs.getencoder, "__spam__")

    def test_getdecoder(self):
        self.assertRaises(TypeError, codecs.getdecoder)
        self.assertRaises(LookupError, codecs.getdecoder, "__spam__")

    def test_getreader(self):
        self.assertRaises(TypeError, codecs.getreader)
        self.assertRaises(LookupError, codecs.getreader, "__spam__")

    def test_getwriter(self):
        self.assertRaises(TypeError, codecs.getwriter)
        self.assertRaises(LookupError, codecs.getwriter, "__spam__")

    @support.run_with_locale('LC_CTYPE', 'tr_TR')
    def test_lookup_issue1813(self):
        # Issue #1813: under Turkish locales, lookup of some codecs failed
        # because 'I' is lowercased as "ı" (dotless i)
        c = codecs.lookup('ASCII')
        self.assertEqual(c.name, 'ascii')

    def test_all(self):
        api = (
            "encode", "decode",
            "register", "CodecInfo", "Codec", "IncrementalEncoder",
            "IncrementalDecoder", "StreamReader", "StreamWriter", "lookup",
            "getencoder", "getdecoder", "getincrementalencoder",
            "getincrementaldecoder", "getreader", "getwriter",
            "register_error", "lookup_error",
            "strict_errors", "replace_errors", "ignore_errors",
            "xmlcharrefreplace_errors", "backslashreplace_errors",
            "namereplace_errors",
            "open", "EncodedFile",
            "iterencode", "iterdecode",
            "BOM", "BOM_BE", "BOM_LE",
            "BOM_UTF8", "BOM_UTF16", "BOM_UTF16_BE", "BOM_UTF16_LE",
            "BOM_UTF32", "BOM_UTF32_BE", "BOM_UTF32_LE",
            "BOM32_BE", "BOM32_LE", "BOM64_BE", "BOM64_LE",  # Undocumented
            "StreamReaderWriter", "StreamRecoder",
        )
        self.assertCountEqual(api, codecs.__all__)
        for api in codecs.__all__:
            getattr(codecs, api)

    def test_open(self):
        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
        for mode in ('w', 'r', 'r+', 'w+', 'a', 'a+'):
            with self.subTest(mode), self.assertWarns(DeprecationWarning):
                with codecs.open(os_helper.TESTFN, mode, 'ascii') as file:
                    self.assertIsInstance(file, codecs.StreamReaderWriter)

    def test_undefined(self):
        self.assertRaises(UnicodeError, codecs.encode, 'abc', 'undefined')
        self.assertRaises(UnicodeError, codecs.decode, b'abc', 'undefined')
        self.assertRaises(UnicodeError, codecs.encode, '', 'undefined')
        self.assertRaises(UnicodeError, codecs.decode, b'', 'undefined')
        for errors in ('strict', 'ignore', 'replace', 'backslashreplace'):
            self.assertRaises(UnicodeError,
                codecs.encode, 'abc', 'undefined', errors)
            self.assertRaises(UnicodeError,
                codecs.decode, b'abc', 'undefined', errors)

    def test_file_closes_if_lookup_error_raised(self):
        mock_open = mock.mock_open()
        with mock.patch('builtins.open', mock_open) as file:
            with self.assertRaises(LookupError):
                codecs_open_no_warn(os_helper.TESTFN, 'wt', 'invalid-encoding')

            file().close.assert_called()

    def test_copy(self):
        orig = codecs.lookup('utf-8')
        dup = copy.copy(orig)
        self.assertIsNot(dup, orig)
        self.assertEqual(dup, orig)
        self.assertTrue(orig._is_text_encoding)
        self.assertIsInstance(orig._expat_decoding_table, tuple)
        self.assertEqual(dup.encode, orig.encode)
        self.assertEqual(dup.name, orig.name)
        self.assertEqual(dup.incrementalencoder, orig.incrementalencoder)
        self.assertIs(dup._expat_decoding_table, orig._expat_decoding_table)

        # Test a CodecInfo with _is_text_encoding equal to false.
        orig = codecs.lookup("base64")
        dup = copy.copy(orig)
        self.assertIsNot(dup, orig)
        self.assertEqual(dup, orig)
        self.assertFalse(orig._is_text_encoding)
        self.assertNotHasAttr(orig, '_expat_decoding_table')
        self.assertEqual(dup.encode, orig.encode)
        self.assertEqual(dup.name, orig.name)
        self.assertEqual(dup.incrementalencoder, orig.incrementalencoder)
        self.assertNotHasAttr(dup, '_expat_decoding_table')

    def test_deepcopy(self):
        orig = codecs.lookup('utf-8')
        dup = copy.deepcopy(orig)
        self.assertIsNot(dup, orig)
        self.assertEqual(dup, orig)
        self.assertTrue(orig._is_text_encoding)
        self.assertIsInstance(orig._expat_decoding_table, tuple)
        self.assertEqual(dup.encode, orig.encode)
        self.assertEqual(dup.name, orig.name)
        self.assertEqual(dup.incrementalencoder, orig.incrementalencoder)
        self.assertIs(dup._expat_decoding_table, orig._expat_decoding_table)

        # Test a CodecInfo with _is_text_encoding equal to false.
        orig = codecs.lookup("base64")
        dup = copy.deepcopy(orig)
        self.assertIsNot(dup, orig)
        self.assertEqual(dup, orig)
        self.assertFalse(orig._is_text_encoding)
        self.assertNotHasAttr(orig, '_expat_decoding_table')
        self.assertEqual(dup.encode, orig.encode)
        self.assertEqual(dup.name, orig.name)
        self.assertEqual(dup.incrementalencoder, orig.incrementalencoder)
        self.assertNotHasAttr(dup, '_expat_decoding_table')

    def test_pickle(self):
        codec_info = codecs.lookup('utf-8')
        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            with self.subTest(protocol=proto):
                pickled_codec_info = pickle.dumps(codec_info)
                unpickled_codec_info = pickle.loads(pickled_codec_info)
                self.assertIsNot(codec_info, unpickled_codec_info)
                self.assertEqual(codec_info, unpickled_codec_info)
                self.assertEqual(codec_info.name, unpickled_codec_info.name)
                self.assertEqual(
                     codec_info.incrementalencoder,
                     unpickled_codec_info.incrementalencoder
                )
                self.assertTrue(unpickled_codec_info._is_text_encoding)
                self.assertEqual(unpickled_codec_info._expat_decoding_table,
                                 codec_info._expat_decoding_table)

        # Test a CodecInfo with _is_text_encoding equal to false.
        codec_info = codecs.lookup('base64')
        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            with self.subTest(protocol=proto):
                pickled_codec_info = pickle.dumps(codec_info)
                unpickled_codec_info = pickle.loads(pickled_codec_info)
                self.assertIsNot(codec_info, unpickled_codec_info)
                self.assertEqual(codec_info, unpickled_codec_info)
                self.assertEqual(codec_info.name, unpickled_codec_info.name)
                self.assertEqual(
                     codec_info.incrementalencoder,
                     unpickled_codec_info.incrementalencoder
                )
                self.assertFalse(unpickled_codec_info._is_text_encoding)
                self.assertNotHasAttr(unpickled_codec_info, '_expat_decoding_table')


class StreamReaderTest(unittest.TestCase):

    def setUp(self):
        self.reader = codecs.getreader('utf-8')
        self.stream = io.BytesIO(b'\xed\x95\x9c\n\xea\xb8\x80')

    def test_readlines(self):
        f = self.reader(self.stream)
        self.assertEqual(f.readlines(), ['\ud55c\n', '\uae00'])

    def test_copy(self):
        f = self.reader(Queue(b'\xed\x95\x9c\n\xea\xb8\x80'))
        with self.assertRaisesRegex(TypeError, 'StreamReader'):
            copy.copy(f)
        with self.assertRaisesRegex(TypeError, 'StreamReader'):
            copy.deepcopy(f)

    def test_pickle(self):
        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            with self.subTest(protocol=proto):
                f = self.reader(Queue(b'\xed\x95\x9c\n\xea\xb8\x80'))
                with self.assertRaisesRegex(TypeError, 'StreamReader'):
                    pickle.dumps(f, proto)


class StreamWriterTest(unittest.TestCase):

    def setUp(self):
        self.writer = codecs.getwriter('utf-8')

    def test_copy(self):
        f = self.writer(Queue(b''))
        with self.assertRaisesRegex(TypeError, 'StreamWriter'):
            copy.copy(f)
        with self.assertRaisesRegex(TypeError, 'StreamWriter'):
            copy.deepcopy(f)

    def test_pickle(self):
        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            with self.subTest(protocol=proto):
                f = self.writer(Queue(b''))
                with self.assertRaisesRegex(TypeError, 'StreamWriter'):
                    pickle.dumps(f, proto)


class StreamReaderWriterTest(unittest.TestCase):

    def setUp(self):
        self.reader = codecs.getreader('latin1')
        self.writer = codecs.getwriter('utf-8')

    def test_copy(self):
        f = codecs.StreamReaderWriter(Queue(b''), self.reader, self.writer)
        with self.assertRaisesRegex(TypeError, 'StreamReaderWriter'):
            copy.copy(f)
        with self.assertRaisesRegex(TypeError, 'StreamReaderWriter'):
            copy.deepcopy(f)

    def test_pickle(self):
        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            with self.subTest(protocol=proto):
                f = codecs.StreamReaderWriter(Queue(b''), self.reader, self.writer)
                with self.assertRaisesRegex(TypeError, 'StreamReaderWriter'):
                    pickle.dumps(f, proto)


class EncodedFileTest(unittest.TestCase):

    def test_basic(self):
        f = io.BytesIO(b'\xed\x95\x9c\n\xea\xb8\x80')
        ef = codecs.EncodedFile(f, 'utf-16-le', 'utf-8')
        self.assertEqual(ef.read(), b'\\\xd5\n\x00\x00\xae')

        f = io.BytesIO()
        ef = codecs.EncodedFile(f, 'utf-8', 'latin-1')
        ef.write(b'\xc3\xbc')
        self.assertEqual(f.getvalue(), b'\xfc')

all_unicode_encodings = [
    "ascii",
    "big5",
    "big5hkscs",
    "charmap",
    "cp037",
    "cp1006",
    "cp1026",
    "cp1125",
    "cp1140",
    "cp1250",
    "cp1251",
    "cp1252",
    "cp1253",
    "cp1254",
    "cp1255",
    "cp1256",
    "cp1257",
    "cp1258",
    "cp424",
    "cp437",
    "cp500",
    "cp720",
    "cp737",
    "cp775",
    "cp850",
    "cp852",
    "cp855",
    "cp856",
    "cp857",
    "cp858",
    "cp860",
    "cp861",
    "cp862",
    "cp863",
    "cp864",
    "cp865",
    "cp866",
    "cp869",
    "cp874",
    "cp875",
    "cp932",
    "cp949",
    "cp950",
    "euc_jis_2004",
    "euc_jisx0213",
    "euc_jp",
    "euc_kr",
    "gb18030",
    "gb2312",
    "gbk",
    "hp_roman8",
    "hz",
    "idna",
    "iso2022_jp",
    "iso2022_jp_1",
    "iso2022_jp_2",
    "iso2022_jp_2004",
    "iso2022_jp_3",
    "iso2022_jp_ext",
    "iso2022_kr",
    "iso8859_1",
    "iso8859_10",
    "iso8859_11",
    "iso8859_13",
    "iso8859_14",
    "iso8859_15",
    "iso8859_16",
    "iso8859_2",
    "iso8859_3",
    "iso8859_4",
    "iso8859_5",
    "iso8859_6",
    "iso8859_7",
    "iso8859_8",
    "iso8859_9",
    "johab",
    "koi8_r",
    "koi8_t",
    "koi8_u",
    "kz1048",
    "latin_1",
    "mac_cyrillic",
    "mac_greek",
    "mac_iceland",
    "mac_latin2",
    "mac_roman",
    "mac_turkish",
    "palmos",
    "ptcp154",
    "punycode",
    "raw_unicode_escape",
    "shift_jis",
    "shift_jis_2004",
    "shift_jisx0213",
    "tis_620",
    "unicode_escape",
    "utf_16",
    "utf_16_be",
    "utf_16_le",
    "utf_7",
    "utf_8",
]

if hasattr(codecs, "mbcs_encode"):
    all_unicode_encodings.append("mbcs")
if hasattr(codecs, "oem_encode"):
    all_unicode_encodings.append("oem")

# The following encoding is not tested, because it's not supposed
# to work:
#    "undefined"

# The following encodings don't work in stateful mode
broken_unicode_with_stateful = [
    "punycode",
]


class BasicUnicodeTest(unittest.TestCase, MixInCheckStateHandling):
    def test_basics(self):
        s = "abc123"  # all codecs should be able to encode these
        for encoding in all_unicode_encodings:
            name = codecs.lookup(encoding).name
            if encoding.endswith("_codec"):
                name += "_codec"
            elif encoding == "latin_1":
                name = "latin_1"
            # Skip the mbcs alias on Windows
            if name != "mbcs":
                self.assertEqual(encoding.replace("_", "-"),
                                 name.replace("_", "-"))

            (b, size) = codecs.getencoder(encoding)(s)
            self.assertEqual(size, len(s), "encoding=%r" % encoding)
            (chars, size) = codecs.getdecoder(encoding)(b)
            self.assertEqual(chars, s, "encoding=%r" % encoding)

            if encoding not in broken_unicode_with_stateful:
                # check stream reader/writer
                q = Queue(b"")
                writer = codecs.getwriter(encoding)(q)
                encodedresult = b""
                for c in s:
                    writer.write(c)
                    chunk = q.read()
                    self.assertTrue(type(chunk) is bytes, type(chunk))
                    encodedresult += chunk
                q = Queue(b"")
                reader = codecs.getreader(encoding)(q)
                decodedresult = ""
                for c in encodedresult:
                    q.write(bytes([c]))
                    decodedresult += reader.read()
                self.assertEqual(decodedresult, s, "encoding=%r" % encoding)

            if encoding not in broken_unicode_with_stateful:
                # check incremental decoder/encoder and iterencode()/iterdecode()
                try:
                    encoder = codecs.getincrementalencoder(encoding)()
                except LookupError:  # no IncrementalEncoder
                    pass
                else:
                    # check incremental decoder/encoder
                    encodedresult = b""
                    for c in s:
                        encodedresult += encoder.encode(c)
                    encodedresult += encoder.encode("", True)
                    decoder = codecs.getincrementaldecoder(encoding)()
                    decodedresult = ""
                    for c in encodedresult:
                        decodedresult += decoder.decode(bytes([c]))
                    decodedresult += decoder.decode(b"", True)
                    self.assertEqual(decodedresult, s,
                                     "encoding=%r" % encoding)

                    # check iterencode()/iterdecode()
                    result = "".join(codecs.iterdecode(
                            codecs.iterencode(s, encoding), encoding))
                    self.assertEqual(result, s, "encoding=%r" % encoding)

                    # check iterencode()/iterdecode() with empty string
                    result = "".join(codecs.iterdecode(
                            codecs.iterencode("", encoding), encoding))
                    self.assertEqual(result, "")

                if encoding not in ("idna", "mbcs"):
                    # check incremental decoder/encoder with errors argument
                    try:
                        encoder = codecs.getincrementalencoder(encoding)("ignore")
                    except LookupError:  # no IncrementalEncoder
                        pass
                    else:
                        encodedresult = b"".join(encoder.encode(c) for c in s)
                        decoder = codecs.getincrementaldecoder(encoding)("ignore")
                        decodedresult = "".join(decoder.decode(bytes([c]))
                                                for c in encodedresult)
                        self.assertEqual(decodedresult, s,
                                         "encoding=%r" % encoding)

    @support.cpython_only
    @unittest.skipIf(_testlimitedcapi is None, 'need _testlimitedcapi module')
    def test_basics_capi(self):
        s = "abc123"  # all codecs should be able to encode these
        for encoding in all_unicode_encodings:
            if encoding not in broken_unicode_with_stateful:
                # check incremental decoder/encoder (fetched via the C API)
                try:
                    cencoder = _testlimitedcapi.codec_incrementalencoder(encoding)
                except LookupError:  # no IncrementalEncoder
                    pass
                else:
                    # check C API
                    encodedresult = b""
                    for c in s:
                        encodedresult += cencoder.encode(c)
                    encodedresult += cencoder.encode("", True)
                    cdecoder = _testlimitedcapi.codec_incrementaldecoder(encoding)
                    decodedresult = ""
                    for c in encodedresult:
                        decodedresult += cdecoder.decode(bytes([c]))
                    decodedresult += cdecoder.decode(b"", True)
                    self.assertEqual(decodedresult, s,
                                     "encoding=%r" % encoding)

                if encoding not in ("idna", "mbcs"):
                    # check incremental decoder/encoder with errors argument
                    try:
                        cencoder = _testlimitedcapi.codec_incrementalencoder(encoding, "ignore")
                    except LookupError:  # no IncrementalEncoder
                        pass
                    else:
                        encodedresult = b"".join(cencoder.encode(c) for c in s)
                        cdecoder = _testlimitedcapi.codec_incrementaldecoder(encoding, "ignore")
                        decodedresult = "".join(cdecoder.decode(bytes([c]))
                                                for c in encodedresult)
                        self.assertEqual(decodedresult, s,
                                         "encoding=%r" % encoding)

    def test_seek(self):
        # all codecs should be able to encode these
        s = "%s\n%s\n" % (100*"abc123", 100*"def456")
        for encoding in all_unicode_encodings:
            if encoding == "idna": # FIXME: See SF bug #1163178
                continue
            if encoding in broken_unicode_with_stateful:
                continue
            reader = codecs.getreader(encoding)(io.BytesIO(s.encode(encoding)))
            for t in range(5):
                # Test that calling seek resets the internal codec state and buffers
                reader.seek(0, 0)
                data = reader.read()
                self.assertEqual(s, data)

    def test_bad_decode_args(self):
        for encoding in all_unicode_encodings:
            decoder = codecs.getdecoder(encoding)
            self.assertRaises(TypeError, decoder)
            if encoding not in ("idna", "punycode"):
                self.assertRaises(TypeError, decoder, 42)

    def test_bad_encode_args(self):
        for encoding in all_unicode_encodings:
            encoder = codecs.getencoder(encoding)
            self.assertRaises(TypeError, encoder)

    def test_encoding_map_type_initialized(self):
        from encodings import cp1140
        # This used to crash, we are only verifying there's no crash.
        table_type = type(cp1140.encoding_table)
        self.assertEqual(table_type, table_type)

    def test_decoder_state(self):
        # Check that getstate() and setstate() handle the state properly
        u = "abc123"
        for encoding in all_unicode_encodings:
            if encoding not in broken_unicode_with_stateful:
                self.check_state_handling_decode(encoding, u, u.encode(encoding))
                self.check_state_handling_encode(encoding, u, u.encode(encoding))


class CharmapTest(unittest.TestCase):
    def test_decode_with_string_map(self):
        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict", "abc"),
            ("abc", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict", "\U0010FFFFbc"),
            ("\U0010FFFFbc", 3)
        )

        self.assertRaises(UnicodeDecodeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict", "ab"
        )

        self.assertRaises(UnicodeDecodeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict", "ab\ufffe"
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "replace", "ab"),
            ("ab\ufffd", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "replace", "ab\ufffe"),
            ("ab\ufffd", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "backslashreplace", "ab"),
            ("ab\\x02", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "backslashreplace", "ab\ufffe"),
            ("ab\\x02", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "ignore", "ab"),
            ("ab", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "ignore", "ab\ufffe"),
            ("ab", 3)
        )

        allbytes = bytes(range(256))
        self.assertEqual(
            codecs.charmap_decode(allbytes, "ignore", ""),
            ("", len(allbytes))
        )

    def test_decode_with_int2str_map(self):
        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict",
                                  {0: 'a', 1: 'b', 2: 'c'}),
            ("abc", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict",
                                  {0: 'Aa', 1: 'Bb', 2: 'Cc'}),
            ("AaBbCc", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict",
                                  {0: '\U0010FFFF', 1: 'b', 2: 'c'}),
            ("\U0010FFFFbc", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict",
                                  {0: 'a', 1: 'b', 2: ''}),
            ("ab", 3)
        )

        self.assertRaises(UnicodeDecodeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict",
                                   {0: 'a', 1: 'b'}
        )

        self.assertRaises(UnicodeDecodeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict",
                                   {0: 'a', 1: 'b', 2: None}
        )

        # Issue #14850
        self.assertRaises(UnicodeDecodeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict",
                                   {0: 'a', 1: 'b', 2: '\ufffe'}
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "replace",
                                  {0: 'a', 1: 'b'}),
            ("ab\ufffd", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "replace",
                                  {0: 'a', 1: 'b', 2: None}),
            ("ab\ufffd", 3)
        )

        # Issue #14850
        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "replace",
                                  {0: 'a', 1: 'b', 2: '\ufffe'}),
            ("ab\ufffd", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "backslashreplace",
                                  {0: 'a', 1: 'b'}),
            ("ab\\x02", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "backslashreplace",
                                  {0: 'a', 1: 'b', 2: None}),
            ("ab\\x02", 3)
        )

        # Issue #14850
        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "backslashreplace",
                                  {0: 'a', 1: 'b', 2: '\ufffe'}),
            ("ab\\x02", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "ignore",
                                  {0: 'a', 1: 'b'}),
            ("ab", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "ignore",
                                  {0: 'a', 1: 'b', 2: None}),
            ("ab", 3)
        )

        # Issue #14850
        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "ignore",
                                  {0: 'a', 1: 'b', 2: '\ufffe'}),
            ("ab", 3)
        )

        allbytes = bytes(range(256))
        self.assertEqual(
            codecs.charmap_decode(allbytes, "ignore", {}),
            ("", len(allbytes))
        )

        self.assertRaisesRegex(TypeError,
            "character mapping must be in range\\(0x110000\\)",
            codecs.charmap_decode,
            b"\x00\x01\x02", "strict", {0: "A", 1: 'Bb', 2: -2}
        )

        self.assertRaisesRegex(TypeError,
            "character mapping must be in range\\(0x110000\\)",
            codecs.charmap_decode,
            b"\x00\x01\x02", "strict", {0: "A", 1: 'Bb', 2: 999999999}
        )

    def test_decode_with_int2int_map(self):
        a = ord('a')
        b = ord('b')
        c = ord('c')

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict",
                                  {0: a, 1: b, 2: c}),
            ("abc", 3)
        )

        # Issue #15379
        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict",
                                  {0: 0x10FFFF, 1: b, 2: c}),
            ("\U0010FFFFbc", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "strict",
                                  {0: sys.maxunicode, 1: b, 2: c}),
            (chr(sys.maxunicode) + "bc", 3)
        )

        self.assertRaises(TypeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict",
                                   {0: sys.maxunicode + 1, 1: b, 2: c}
        )

        self.assertRaises(UnicodeDecodeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict",
                                   {0: a, 1: b},
        )

        self.assertRaises(UnicodeDecodeError,
            codecs.charmap_decode, b"\x00\x01\x02", "strict",
                                   {0: a, 1: b, 2: 0xFFFE},
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "replace",
                                  {0: a, 1: b}),
            ("ab\ufffd", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "replace",
                                  {0: a, 1: b, 2: 0xFFFE}),
            ("ab\ufffd", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "backslashreplace",
                                  {0: a, 1: b}),
            ("ab\\x02", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "backslashreplace",
                                  {0: a, 1: b, 2: 0xFFFE}),
            ("ab\\x02", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "ignore",
                                  {0: a, 1: b}),
            ("ab", 3)
        )

        self.assertEqual(
            codecs.charmap_decode(b"\x00\x01\x02", "ignore",
                                  {0: a, 1: b, 2: 0xFFFE}),
            ("ab", 3)
        )


class WithStmtTest(unittest.TestCase):
    def test_encodedfile(self):
        f = io.BytesIO(b"\xc3\xbc")
        with codecs.EncodedFile(f, "latin-1", "utf-8") as ef:
            self.assertEqual(ef.read(), b"\xfc")
        self.assertTrue(f.closed)

    def test_streamreaderwriter(self):
        f = io.BytesIO(b"\xc3\xbc")
        info = codecs.lookup("utf-8")
        with codecs.StreamReaderWriter(f, info.streamreader,
                                       info.streamwriter, 'strict') as srw:
            self.assertEqual(srw.read(), "\xfc")


class TypesTest(unittest.TestCase):
    def test_decode_unicode(self):
        # Most decoders don't accept unicode input
        decoders = [
            codecs.utf_7_decode,
            codecs.utf_8_decode,
            codecs.utf_16_le_decode,
            codecs.utf_16_be_decode,
            codecs.utf_16_ex_decode,
            codecs.utf_32_decode,
            codecs.utf_32_le_decode,
            codecs.utf_32_be_decode,
            codecs.utf_32_ex_decode,
            codecs.latin_1_decode,
            codecs.ascii_decode,
            codecs.charmap_decode,
        ]
        if hasattr(codecs, "mbcs_decode"):
            decoders.append(codecs.mbcs_decode)
        for decoder in decoders:
            self.assertRaises(TypeError, decoder, "xxx")

    def test_unicode_escape(self):
        # Escape-decoding a unicode string is supported and gives the same
        # result as decoding the equivalent ASCII bytes string.
        self.assertEqual(codecs.unicode_escape_decode(r"\u1234"), ("\u1234", 6))
        self.assertEqual(codecs.unicode_escape_decode(br"\u1234"), ("\u1234", 6))
        self.assertEqual(codecs.raw_unicode_escape_decode(r"\u1234"), ("\u1234", 6))
        self.assertEqual(codecs.raw_unicode_escape_decode(br"\u1234"), ("\u1234", 6))

        self.assertRaises(UnicodeDecodeError, codecs.unicode_escape_decode, br"\U00110000")
        self.assertEqual(codecs.unicode_escape_decode(r"\U00110000", "replace"), ("\ufffd", 10))
        self.assertEqual(codecs.unicode_escape_decode(r"\U00110000", "backslashreplace"),
                         (r"\x5c\x55\x30\x30\x31\x31\x30\x30\x30\x30", 10))

        self.assertRaises(UnicodeDecodeError, codecs.raw_unicode_escape_decode, br"\U00110000")
        self.assertEqual(codecs.raw_unicode_escape_decode(r"\U00110000", "replace"), ("\ufffd", 10))
        self.assertEqual(codecs.raw_unicode_escape_decode(r"\U00110000", "backslashreplace"),
                         (r"\x5c\x55\x30\x30\x31\x31\x30\x30\x30\x30", 10))


class UnicodeEscapeTest(ReadTest, unittest.TestCase):
    encoding = "unicode-escape"

    test_lone_surrogates = None

    def test_empty(self):
        self.assertEqual(codecs.unicode_escape_encode(""), (b"", 0))
        self.assertEqual(codecs.unicode_escape_decode(b""), ("", 0))

    def test_raw_encode(self):
        encode = codecs.unicode_escape_encode
        for b in range(32, 127):
            if b != b'\\'[0]:
                self.assertEqual(encode(chr(b)), (bytes([b]), 1))

    def test_raw_decode(self):
        decode = codecs.unicode_escape_decode
        for b in range(256):
            if b != b'\\'[0]:
                self.assertEqual(decode(bytes([b]) + b'0'), (chr(b) + '0', 2))

    def test_escape_encode(self):
        encode = codecs.unicode_escape_encode
        check = coding_checker(self, encode)
        check('\t', br'\t')
        check('\n', br'\n')
        check('\r', br'\r')
        check('\\', br'\\')
        for b in range(32):
            if chr(b) not in '\t\n\r':
                check(chr(b), ('\\x%02x' % b).encode())
        for b in range(127, 256):
            check(chr(b), ('\\x%02x' % b).encode())
        check('\u20ac', br'\u20ac')
        check('\U0001d120', br'\U0001d120')

    def test_escape_decode(self):
        decode = codecs.unicode_escape_decode
        check = coding_checker(self, decode)
        check(b"[\\\n]", "[]")
        check(br'[\"]', '["]')
        check(br"[\']", "[']")
        check(br"[\\]", r"[\]")
        check(br"[\a]", "[\x07]")
        check(br"[\b]", "[\x08]")
        check(br"[\t]", "[\x09]")
        check(br"[\n]", "[\x0a]")
        check(br"[\v]", "[\x0b]")
        check(br"[\f]", "[\x0c]")
        check(br"[\r]", "[\x0d]")
        check(br"[\7]", "[\x07]")
        check(br"[\78]", "[\x078]")
        check(br"[\41]", "[!]")
        check(br"[\418]", "[!8]")
        check(br"[\101]", "[A]")
        check(br"[\1010]", "[A0]")
        check(br"[\x41]", "[A]")
        check(br"[\x410]", "[A0]")
        check(br"\u20ac", "\u20ac")
        check(br"\U0001d120", "\U0001d120")

    def test_decode_warnings(self):
        decode = codecs.unicode_escape_decode
        check = coding_checker(self, decode)
        for i in range(97, 123):
            b = bytes([i])
            if b not in b'abfnrtuvx':
                with self.assertWarnsRegex(DeprecationWarning,
                        r'"\\%c" is an invalid escape sequence' % i):
                    check(b"\\" + b, "\\" + chr(i))
            if b.upper() not in b'UN':
                with self.assertWarnsRegex(DeprecationWarning,
                        r'"\\%c" is an invalid escape sequence' % (i-32)):
                    check(b"\\" + b.upper(), "\\" + chr(i-32))
        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\8" is an invalid escape sequence'):
            check(br"\8", "\\8")
        with self.assertWarns(DeprecationWarning):
            check(br"\9", "\\9")
        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\\xfa" is an invalid escape sequence') as cm:
            check(b"\\\xfa", "\\\xfa")
        for i in range(0o400, 0o1000):
            with self.assertWarnsRegex(DeprecationWarning,
                    r'"\\%o" is an invalid octal escape sequence' % i):
                check(rb'\%o' % i, chr(i))

        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\z" is an invalid escape sequence'):
            self.assertEqual(decode(br'\x\z', 'ignore'), ('\\z', 4))
        with self.assertWarnsRegex(DeprecationWarning,
                r'"\\501" is an invalid octal escape sequence'):
            self.assertEqual(decode(br'\x\501', 'ignore'), ('\u0141', 6))

    def test_decode_errors(self):
        decode = codecs.unicode_escape_decode
        for c, d in (b'x', 2), (b'u', 4), (b'U', 4):
            for i in range(d):
                self.assertRaises(UnicodeDecodeError, decode,
                                  b"\\" + c + b"0"*i)
                self.assertRaises(UnicodeDecodeError, decode,
                                  b"[\\" + c + b"0"*i + b"]")
                data = b"[\\" + c + b"0"*i + b"]\\" + c + b"0"*i
                self.assertEqual(decode(data, "ignore"), ("[]", len(data)))
                self.assertEqual(decode(data, "replace"),
                                 ("[\ufffd]\ufffd", len(data)))
        self.assertRaises(UnicodeDecodeError, decode, br"\U00110000")
        self.assertEqual(decode(br"\U00110000", "ignore"), ("", 10))
        self.assertEqual(decode(br"\U00110000", "replace"), ("\ufffd", 10))

    def test_partial(self):
        self.check_partial(
            "\x00\t\n\r\\\xff\uffff\U00010000",
            [
                '',
                '',
                '',
                '\x00',
                '\x00',
                '\x00\t',
                '\x00\t',
                '\x00\t\n',
                '\x00\t\n',
                '\x00\t\n\r',
                '\x00\t\n\r',
                '\x00\t\n\r\\',
                '\x00\t\n\r\\',
                '\x00\t\n\r\\',
                '\x00\t\n\r\\',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff\U00010000',
            ]
        )

class RawUnicodeEscapeTest(ReadTest, unittest.TestCase):
    encoding = "raw-unicode-escape"

    test_lone_surrogates = None

    def test_empty(self):
        self.assertEqual(codecs.raw_unicode_escape_encode(""), (b"", 0))
        self.assertEqual(codecs.raw_unicode_escape_decode(b""), ("", 0))

    def test_raw_encode(self):
        encode = codecs.raw_unicode_escape_encode
        for b in range(256):
            self.assertEqual(encode(chr(b)), (bytes([b]), 1))

    def test_raw_decode(self):
        decode = codecs.raw_unicode_escape_decode
        for b in range(256):
            self.assertEqual(decode(bytes([b]) + b'0'), (chr(b) + '0', 2))

    def test_escape_encode(self):
        encode = codecs.raw_unicode_escape_encode
        check = coding_checker(self, encode)
        for b in range(256):
            if b not in b'uU':
                check('\\' + chr(b), b'\\' + bytes([b]))
        check('\u20ac', br'\u20ac')
        check('\U0001d120', br'\U0001d120')

    def test_escape_decode(self):
        decode = codecs.raw_unicode_escape_decode
        check = coding_checker(self, decode)
        for b in range(256):
            if b not in b'uU':
                check(b'\\' + bytes([b]), '\\' + chr(b))
        check(br"\u20ac", "\u20ac")
        check(br"\U0001d120", "\U0001d120")

    def test_decode_errors(self):
        decode = codecs.raw_unicode_escape_decode
        for c, d in (b'u', 4), (b'U', 4):
            for i in range(d):
                self.assertRaises(UnicodeDecodeError, decode,
                                  b"\\" + c + b"0"*i)
                self.assertRaises(UnicodeDecodeError, decode,
                                  b"[\\" + c + b"0"*i + b"]")
                data = b"[\\" + c + b"0"*i + b"]\\" + c + b"0"*i
                self.assertEqual(decode(data, "ignore"), ("[]", len(data)))
                self.assertEqual(decode(data, "replace"),
                                 ("[\ufffd]\ufffd", len(data)))
        self.assertRaises(UnicodeDecodeError, decode, br"\U00110000")
        self.assertEqual(decode(br"\U00110000", "ignore"), ("", 10))
        self.assertEqual(decode(br"\U00110000", "replace"), ("\ufffd", 10))

    def test_partial(self):
        self.check_partial(
            "\x00\t\n\r\\\xff\uffff\U00010000",
            [
                '\x00',
                '\x00\t',
                '\x00\t\n',
                '\x00\t\n\r',
                '\x00\t\n\r',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff',
                '\x00\t\n\r\\\xff\uffff\U00010000',
            ]
        )


class EscapeEncodeTest(unittest.TestCase):

    def test_escape_encode(self):
        tests = [
            (b'', (b'', 0)),
            (b'foobar', (b'foobar', 6)),
            (b'spam\0eggs', (b'spam\\x00eggs', 9)),
            (b'a\'b', (b"a\\'b", 3)),
            (b'b\\c', (b'b\\\\c', 3)),
            (b'c\nd', (b'c\\nd', 3)),
            (b'd\re', (b'd\\re', 3)),
            (b'f\x7fg', (b'f\\x7fg', 3)),
        ]
        for data, output in tests:
            with self.subTest(data=data):
                self.assertEqual(codecs.escape_encode(data), output)
        self.assertRaises(TypeError, codecs.escape_encode, 'spam')
        self.assertRaises(TypeError, codecs.escape_encode, bytearray(b'spam'))


class SurrogateEscapeTest(unittest.TestCase):

    def test_utf8(self):
        # Bad byte
        self.assertEqual(b"foo\x80bar".decode("utf-8", "surrogateescape"),
                         "foo\udc80bar")
        self.assertEqual("foo\udc80bar".encode("utf-8", "surrogateescape"),
                         b"foo\x80bar")
        # bad-utf-8 encoded surrogate
        self.assertEqual(b"\xed\xb0\x80".decode("utf-8", "surrogateescape"),
                         "\udced\udcb0\udc80")
        self.assertEqual("\udced\udcb0\udc80".encode("utf-8", "surrogateescape"),
                         b"\xed\xb0\x80")

    def test_ascii(self):
        # bad byte
        self.assertEqual(b"foo\x80bar".decode("ascii", "surrogateescape"),
                         "foo\udc80bar")
        self.assertEqual("foo\udc80bar".encode("ascii", "surrogateescape"),
                         b"foo\x80bar")

    def test_charmap(self):
        # bad byte: \xa5 is unmapped in iso-8859-3
        self.assertEqual(b"foo\xa5bar".decode("iso-8859-3", "surrogateescape"),
                         "foo\udca5bar")
        self.assertEqual("foo\udca5bar".encode("iso-8859-3", "surrogateescape"),
                         b"foo\xa5bar")

    def test_latin1(self):
        # Issue6373
        self.assertEqual("\udce4\udceb\udcef\udcf6\udcfc".encode("latin-1", "surrogateescape"),
                         b"\xe4\xeb\xef\xf6\xfc")


class BomTest(unittest.TestCase):
    def test_seek0(self):
        data = "1234567890"
        tests = ("utf-16",
                 "utf-16-le",
                 "utf-16-be",
                 "utf-32",
                 "utf-32-le",
                 "utf-32-be")
        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
        for encoding in tests:
            # Check if the BOM is written only once
            with codecs_open_no_warn(os_helper.TESTFN, 'w+', encoding=encoding) as f:
                f.write(data)
                f.write(data)
                f.seek(0)
                self.assertEqual(f.read(), data * 2)
                f.seek(0)
                self.assertEqual(f.read(), data * 2)

            # Check that the BOM is written after a seek(0)
            with codecs_open_no_warn(os_helper.TESTFN, 'w+', encoding=encoding) as f:
                f.write(data[0])
                self.assertNotEqual(f.tell(), 0)
                f.seek(0)
                f.write(data)
                f.seek(0)
                self.assertEqual(f.read(), data)

            # (StreamWriter) Check that the BOM is written after a seek(0)
            with codecs_open_no_warn(os_helper.TESTFN, 'w+', encoding=encoding) as f:
                f.writer.write(data[0])
                self.assertNotEqual(f.writer.tell(), 0)
                f.writer.seek(0)
                f.writer.write(data)
                f.seek(0)
                self.assertEqual(f.read(), data)

            # Check that the BOM is not written after a seek() at a position
            # different than the start
            with codecs_open_no_warn(os_helper.TESTFN, 'w+', encoding=encoding) as f:
                f.write(data)
                f.seek(f.tell())
                f.write(data)
                f.seek(0)
                self.assertEqual(f.read(), data * 2)

            # (StreamWriter) Check that the BOM is not written after a seek()
            # at a position different than the start
            with codecs_open_no_warn(os_helper.TESTFN, 'w+', encoding=encoding) as f:
                f.writer.write(data)
                f.writer.seek(f.writer.tell())
                f.writer.write(data)
                f.seek(0)
                self.assertEqual(f.read(), data * 2)


bytes_transform_encodings = [
    "base64_codec",
    "uu_codec",
    "quopri_codec",
    "hex_codec",
]

transform_aliases = {
    "base64_codec": ["base64", "base_64"],
    "uu_codec": ["uu"],
    "quopri_codec": ["quopri", "quoted_printable", "quotedprintable"],
    "hex_codec": ["hex"],
    "rot_13": ["rot13"],
}

try:
    import zlib
except ImportError:
    zlib = None
else:
    bytes_transform_encodings.append("zlib_codec")
    transform_aliases["zlib_codec"] = ["zip", "zlib"]
try:
    import bz2  # noqa: F401
except ImportError:
    pass
else:
    bytes_transform_encodings.append("bz2_codec")
    transform_aliases["bz2_codec"] = ["bz2"]


class TransformCodecTest(unittest.TestCase):

    def test_basics(self):
        binput = bytes(range(256))
        for encoding in bytes_transform_encodings:
            with self.subTest(encoding=encoding):
                # generic codecs interface
                (o, size) = codecs.getencoder(encoding)(binput)
                self.assertEqual(size, len(binput))
                (i, size) = codecs.getdecoder(encoding)(o)
                self.assertEqual(size, len(o))
                self.assertEqual(i, binput)

    def test_read(self):
        for encoding in bytes_transform_encodings:
            with self.subTest(encoding=encoding):
                sin = codecs.encode(b"\x80", encoding)
                reader = codecs.getreader(encoding)(io.BytesIO(sin))
                sout = reader.read()
                self.assertEqual(sout, b"\x80")

    def test_readline(self):
        for encoding in bytes_transform_encodings:
            with self.subTest(encoding=encoding):
                sin = codecs.encode(b"\x80", encoding)
                reader = codecs.getreader(encoding)(io.BytesIO(sin))
                sout = reader.readline()
                self.assertEqual(sout, b"\x80")

    def test_buffer_api_usage(self):
        # We check all the transform codecs accept memoryview input
        # for encoding and decoding
        # and also that they roundtrip correctly
        original = b"12345\x80"
        for encoding in bytes_transform_encodings:
            with self.subTest(encoding=encoding):
                data = original
                view = memoryview(data)
                data = codecs.encode(data, encoding)
                view_encoded = codecs.encode(view, encoding)
                self.assertEqual(view_encoded, data)
                view = memoryview(data)
                data = codecs.decode(data, encoding)
                self.assertEqual(data, original)
                view_decoded = codecs.decode(view, encoding)
                self.assertEqual(view_decoded, data)

    def test_text_to_binary_denylists_binary_transforms(self):
        # Check binary -> binary codecs give a good error for str input
        bad_input = "bad input type"
        for encoding in bytes_transform_encodings:
            with self.subTest(encoding=encoding):
                fmt = (r"{!r} is not a text encoding; "
                       r"use codecs.encode\(\) to handle arbitrary codecs")
                msg = fmt.format(encoding)
                with self.assertRaisesRegex(LookupError, msg) as failure:
                    bad_input.encode(encoding)
                self.assertIsNone(failure.exception.__cause__)

    def test_text_to_binary_denylists_text_transforms(self):
        # Check str.encode gives a good error message for str -> str codecs
        msg = (r"^'rot_13' is not a text encoding; "
               r"use codecs.encode\(\) to handle arbitrary codecs")
        with self.assertRaisesRegex(LookupError, msg):
            "just an example message".encode("rot_13")

    def test_binary_to_text_denylists_binary_transforms(self):
        # Check bytes.decode and bytearray.decode give a good error
        # message for binary -> binary codecs
        data = b"encode first to ensure we meet any format restrictions"
        for encoding in bytes_transform_encodings:
            with self.subTest(encoding=encoding):
                encoded_data = codecs.encode(data, encoding)
                fmt = (r"{!r} is not a text encoding; "
                       r"use codecs.decode\(\) to handle arbitrary codecs")
                msg = fmt.format(encoding)
                with self.assertRaisesRegex(LookupError, msg):
                    encoded_data.decode(encoding)
                with self.assertRaisesRegex(LookupError, msg):
                    bytearray(encoded_data).decode(encoding)

    def test_binary_to_text_denylists_text_transforms(self):
        # Check str -> str codec gives a good error for binary input
        for bad_input in (b"immutable", bytearray(b"mutable")):
            with self.subTest(bad_input=bad_input):
                msg = (r"^'rot_13' is not a text encoding; "
                       r"use codecs.decode\(\) to handle arbitrary codecs")
                with self.assertRaisesRegex(LookupError, msg) as failure:
                    bad_input.decode("rot_13")
                self.assertIsNone(failure.exception.__cause__)

    @unittest.skipUnless(zlib, "Requires zlib support")
    def test_custom_zlib_error_is_noted(self):
        # Check zlib codec gives a good error for malformed input
        msg = "decoding with 'zlib_codec' codec failed"
        with self.assertRaises(zlib.error) as failure:
            codecs.decode(b"hello", "zlib_codec")
        self.assertEqual(msg, failure.exception.__notes__[0])

    def test_custom_hex_error_is_noted(self):
        # Check hex codec gives a good error for malformed input
        import binascii
        msg = "decoding with 'hex_codec' codec failed"
        with self.assertRaises(binascii.Error) as failure:
            codecs.decode(b"hello", "hex_codec")
        self.assertEqual(msg, failure.exception.__notes__[0])

    # Ensure codec aliases from http://bugs.python.org/issue7475 work
    def test_aliases(self):
        for codec_name, aliases in transform_aliases.items():
            expected_name = codecs.lookup(codec_name).name
            for alias in aliases:
                with self.subTest(alias=alias):
                    info = codecs.lookup(alias)
                    self.assertEqual(info.name, expected_name)

    def test_alias_modules_exist(self):
        encodings_dir = os.path.dirname(encodings.__file__)
        for value in encodings.aliases.aliases.values():
            codec_mod = f"encodings.{value}"
            self.assertIsNotNone(importlib.util.find_spec(codec_mod),
                                 f"Codec module not found: {codec_mod}")

    def test_quopri_stateless(self):
        # Should encode with quotetabs=True
        encoded = codecs.encode(b"space tab\teol \n", "quopri-codec")
        self.assertEqual(encoded, b"space=20tab=09eol=20\n")
        # But should still support unescaped tabs and spaces
        unescaped = b"space tab eol\n"
        self.assertEqual(codecs.decode(unescaped, "quopri-codec"), unescaped)

    def test_uu_invalid(self):
        # Missing "begin" line
        self.assertRaises(ValueError, codecs.decode, b"", "uu-codec")


# The codec system tries to add notes to exceptions in order to ensure
# the error mentions the operation being performed and the codec involved.

# Use a local codec registry to avoid appearing to leak objects when
# registering multiple search functions
_TEST_CODECS = {}

def _get_test_codec(codec_name):
    return _TEST_CODECS.get(codec_name)


class ExceptionNotesTest(unittest.TestCase):

    def setUp(self):
        self.codec_name = 'exception_notes_test'
        codecs.register(_get_test_codec)
        self.addCleanup(codecs.unregister, _get_test_codec)

        # We store the object to raise on the instance because of a bad
        # interaction between the codec caching (which means we can't
        # recreate the codec entry) and regrtest refleak hunting (which
        # runs the same test instance multiple times). This means we
        # need to ensure the codecs call back in to the instance to find
        # out which exception to raise rather than binding them in a
        # closure to an object that may change on the next run
        self.obj_to_raise = RuntimeError

    def tearDown(self):
        _TEST_CODECS.pop(self.codec_name, None)
        # Issue #22166: Also pop from caches to avoid appearance of ref leaks
        encodings._cache.pop(self.codec_name, None)

    def set_codec(self, encode, decode):
        codec_info = codecs.CodecInfo(encode, decode,
                                      name=self.codec_name)
        _TEST_CODECS[self.codec_name] = codec_info

    @contextlib.contextmanager
    def assertNoted(self, operation, exc_type, msg):
        full_msg = r"{} with {!r} codec failed".format(
                  operation, self.codec_name)
        with self.assertRaises(exc_type) as caught:
            yield caught
        self.assertIn(full_msg, caught.exception.__notes__[0])
        caught.exception.__notes__.clear()

    def raise_obj(self, *args, **kwds):
        # Helper to dynamically change the object raised by a test codec
        raise self.obj_to_raise

    def check_note(self, obj_to_raise, msg, exc_type=RuntimeError):
        self.obj_to_raise = obj_to_raise
        self.set_codec(self.raise_obj, self.raise_obj)
        with self.assertNoted("encoding", exc_type, msg):
            "str_input".encode(self.codec_name)
        with self.assertNoted("encoding", exc_type, msg):
            codecs.encode("str_input", self.codec_name)
        with self.assertNoted("decoding", exc_type, msg):
            b"bytes input".decode(self.codec_name)
        with self.assertNoted("decoding", exc_type, msg):
            codecs.decode(b"bytes input", self.codec_name)

    def test_raise_by_type(self):
        self.check_note(RuntimeError, "")

    def test_raise_by_value(self):
        msg = "This should be noted"
        self.check_note(RuntimeError(msg), msg)

    def test_raise_grandchild_subclass_exact_size(self):
        msg = "This should be noted"
        class MyRuntimeError(RuntimeError):
            __slots__ = ()
        self.check_note(MyRuntimeError(msg), msg, MyRuntimeError)

    def test_raise_subclass_with_weakref_support(self):
        msg = "This should be noted"
        class MyRuntimeError(RuntimeError):
            pass
        self.check_note(MyRuntimeError(msg), msg, MyRuntimeError)

    def test_init_override(self):
        class CustomInit(RuntimeError):
            def __init__(self):
                pass
        self.check_note(CustomInit, "")

    def test_new_override(self):
        class CustomNew(RuntimeError):
            def __new__(cls):
                return super().__new__(cls)
        self.check_note(CustomNew, "")

    def test_instance_attribute(self):
        msg = "This should be noted"
        exc = RuntimeError(msg)
        exc.attr = 1
        self.check_note(exc, "^{}$".format(msg))

    def test_non_str_arg(self):
        self.check_note(RuntimeError(1), "1")

    def test_multiple_args(self):
        msg_re = r"^\('a', 'b', 'c'\)$"
        self.check_note(RuntimeError('a', 'b', 'c'), msg_re)

    # http://bugs.python.org/issue19609
    def test_codec_lookup_failure(self):
        msg = "^unknown encoding: {}$".format(self.codec_name)
        with self.assertRaisesRegex(LookupError, msg):
            "str input".encode(self.codec_name)
        with self.assertRaisesRegex(LookupError, msg):
            codecs.encode("str input", self.codec_name)
        with self.assertRaisesRegex(LookupError, msg):
            b"bytes input".decode(self.codec_name)
        with self.assertRaisesRegex(LookupError, msg):
            codecs.decode(b"bytes input", self.codec_name)

    def test_unflagged_non_text_codec_handling(self):
        # The stdlib non-text codecs are now marked so they're
        # pre-emptively skipped by the text model related methods
        # However, third party codecs won't be flagged, so we still make
        # sure the case where an inappropriate output type is produced is
        # handled appropriately
        def encode_to_str(*args, **kwds):
            return "not bytes!", 0
        def decode_to_bytes(*args, **kwds):
            return b"not str!", 0
        self.set_codec(encode_to_str, decode_to_bytes)
        # No input or output type checks on the codecs module functions
        encoded = codecs.encode(None, self.codec_name)
        self.assertEqual(encoded, "not bytes!")
        decoded = codecs.decode(None, self.codec_name)
        self.assertEqual(decoded, b"not str!")
        # Text model methods should complain
        fmt = (r"^{!r} encoder returned 'str' instead of 'bytes'; "
               r"use codecs.encode\(\) to encode to arbitrary types$")
        msg = fmt.format(self.codec_name)
        with self.assertRaisesRegex(TypeError, msg):
            "str_input".encode(self.codec_name)
        fmt = (r"^{!r} decoder returned 'bytes' instead of 'str'; "
               r"use codecs.decode\(\) to decode to arbitrary types$")
        msg = fmt.format(self.codec_name)
        with self.assertRaisesRegex(TypeError, msg):
            b"bytes input".decode(self.codec_name)


@unittest.skipUnless(sys.platform == 'win32',
                     'code pages are specific to Windows')
class CodePageTest(unittest.TestCase):
    CP_UTF8 = 65001

    def test_invalid_code_page(self):
        self.assertRaises(ValueError, codecs.code_page_encode, -1, 'a')
        self.assertRaises(ValueError, codecs.code_page_decode, -1, b'a')
        self.assertRaises(OSError, codecs.code_page_encode, 123, 'a')
        self.assertRaises(OSError, codecs.code_page_decode, 123, b'a')

    def test_code_page_name(self):
        self.assertRaisesRegex(UnicodeEncodeError, 'cp932',
            codecs.code_page_encode, 932, '\xff')
        self.assertRaisesRegex(UnicodeDecodeError, 'cp932',
            codecs.code_page_decode, 932, b'\x81\x00', 'strict', True)
        self.assertRaisesRegex(UnicodeDecodeError, 'cp65001',
            codecs.code_page_decode, self.CP_UTF8, b'\xff', 'strict', True)

    def check_decode(self, cp, tests):
        for raw, errors, expected, *rest in tests:
            if rest:
                altexpected, = rest
            else:
                altexpected = expected
            if expected is not None:
                try:
                    decoded = codecs.code_page_decode(cp, raw, errors, True)
                except UnicodeDecodeError as err:
                    self.fail('Unable to decode %a from "cp%s" with '
                              'errors=%r: %s' % (raw, cp, errors, err))
                self.assertEqual(decoded[0], expected,
                    '%a.decode("cp%s", %r)=%a != %a'
                    % (raw, cp, errors, decoded[0], expected))
                # assert 0 <= decoded[1] <= len(raw)
                self.assertGreaterEqual(decoded[1], 0)
                self.assertLessEqual(decoded[1], len(raw))
            else:
                self.assertRaises(UnicodeDecodeError,
                    codecs.code_page_decode, cp, raw, errors, True)

            if altexpected is not None:
                decoded = raw.decode(f'cp{cp}', errors)
                self.assertEqual(decoded, altexpected,
                    '%a.decode("cp%s", %r)=%a != %a'
                    % (raw, cp, errors, decoded, altexpected))
            else:
                self.assertRaises(UnicodeDecodeError,
                    raw.decode, f'cp{cp}', errors)

    def check_encode(self, cp, tests):
        for text, errors, expected, *rest in tests:
            if rest:
                altexpected, = rest
            else:
                altexpected = expected
            if expected is not None:
                try:
                    encoded = codecs.code_page_encode(cp, text, errors)
                except UnicodeEncodeError as err:
                    self.fail('Unable to encode %a to "cp%s" with '
                              'errors=%r: %s' % (text, cp, errors, err))
                self.assertEqual(encoded[0], expected,
                    '%a.encode("cp%s", %r)=%a != %a'
                    % (text, cp, errors, encoded[0], expected))
                self.assertEqual(encoded[1], len(text))

                encoded = text.encode(f'cp{cp}', errors)
                self.assertEqual(encoded, altexpected,
                    '%a.encode("cp%s", %r)=%a != %a'
                    % (text, cp, errors, encoded, altexpected))
            else:
                self.assertRaises(UnicodeEncodeError,
                    codecs.code_page_encode, cp, text, errors)
                self.assertRaises(UnicodeEncodeError,
                    text.encode, f'cp{cp}', errors)

    def test_cp932(self):
        self.check_encode(932, (
            ('abc', 'strict', b'abc'),
            ('\uff44\u9a3e', 'strict', b'\x82\x84\xe9\x80'),
            ('\uf8f3', 'strict', b'\xff'),
            # test error handlers
            ('\xff', 'strict', None),
            ('[\xff]', 'ignore', b'[]'),
            ('[\xff]', 'replace', b'[y]', b'[?]'),
            ('[\u20ac]', 'replace', b'[?]'),
            ('[\xff]', 'backslashreplace', b'[\\xff]'),
            ('[\xff]', 'namereplace',
             b'[\\N{LATIN SMALL LETTER Y WITH DIAERESIS}]'),
            ('[\xff]', 'xmlcharrefreplace', b'[&#255;]'),
            ('\udcff', 'strict', None),
            ('[\udcff]', 'surrogateescape', b'[\xff]'),
            ('[\udcff]', 'surrogatepass', None),
        ))
        self.check_decode(932, (
            (b'abc', 'strict', 'abc'),
            (b'\x82\x84\xe9\x80', 'strict', '\uff44\u9a3e'),
            # invalid bytes
            (b'[\xff]', 'strict', None, '[\uf8f3]'),
            (b'[\xff]', 'ignore', '[]', '[\uf8f3]'),
            (b'[\xff]', 'replace', '[\ufffd]', '[\uf8f3]'),
            (b'[\xff]', 'backslashreplace', '[\\xff]', '[\uf8f3]'),
            (b'[\xff]', 'surrogateescape', '[\udcff]', '[\uf8f3]'),
            (b'[\xff]', 'surrogatepass', None, '[\uf8f3]'),
            (b'\x81\x00abc', 'strict', None),
            (b'\x81\x00abc', 'ignore', '\x00abc'),
            (b'\x81\x00abc', 'replace', '\ufffd\x00abc'),
            (b'\x81\x00abc', 'backslashreplace', '\\x81\x00abc'),
        ))

    def test_cp1252(self):
        self.check_encode(1252, (
            ('abc', 'strict', b'abc'),
            ('\xe9\u20ac', 'strict',  b'\xe9\x80'),
            ('\xff', 'strict', b'\xff'),
            # test error handlers
            ('\u0141', 'strict', None),
            ('\u0141', 'ignore', b''),
            ('\u0141', 'replace', b'L', b'?'),
            ('\udc98', 'surrogateescape', b'\x98'),
            ('\udc98', 'surrogatepass', None),
        ))
        self.check_decode(1252, (
            (b'abc', 'strict', 'abc'),
            (b'\xe9\x80', 'strict', '\xe9\u20ac'),
            (b'\xff', 'strict', '\xff'),
        ))

    def test_cp708(self):
        self.check_encode(708, (
            ('abc2%', 'strict', b'abc2%'),
            ('\u060c\u0621\u064a', 'strict',  b'\xac\xc1\xea'),
            ('\u2562\xe7\xa0', 'strict',  b'\x86\x87\xff'),
            ('\x9a\x9f', 'strict', b'\x9a\x9f'),
            ('\u256b', 'strict', b'\xc0'),
            # test error handlers
            ('[\u0662]', 'strict',  None),
            ('[\u0662]', 'ignore',  b'[]'),
            ('[\u0662]', 'replace',  b'[?]'),
            ('\udca0', 'surrogateescape', b'\xa0'),
            ('\udca0', 'surrogatepass', None),
        ))
        self.check_decode(708, (
            (b'abc2%', 'strict', 'abc2%'),
            (b'\xac\xc1\xea', 'strict', '\u060c\u0621\u064a'),
            (b'\x86\x87\xff', 'strict', '\u2562\xe7\xa0'),
            (b'\x9a\x9f', 'strict', '\x9a\x9f'),
            (b'\xc0', 'strict', '\u256b'),
            # test error handlers
            (b'\xa0', 'strict', None),
            (b'[\xa0]', 'ignore', '[]'),
            (b'[\xa0]', 'replace', '[\ufffd]'),
            (b'[\xa0]', 'backslashreplace', '[\\xa0]'),
            (b'[\xa0]', 'surrogateescape', '[\udca0]'),
            (b'[\xa0]', 'surrogatepass', None),
        ))

    def test_cp20106(self):
        self.check_encode(20106, (
            ('abc', 'strict', b'abc'),
            ('\xa7\xc4\xdf', 'strict',  b'@[~'),
            # test error handlers
            ('@', 'strict', None),
            ('@', 'ignore', b''),
            ('@', 'replace', b'?'),
            ('\udcbf', 'surrogateescape', b'\xbf'),
            ('\udcbf', 'surrogatepass', None),
        ))
        self.check_decode(20106, (
            (b'abc', 'strict', 'abc'),
            (b'@[~', 'strict', '\xa7\xc4\xdf'),
            (b'\xe1\xfe', 'strict', 'a\xdf'),
            # test error handlers
            (b'(\xbf)', 'strict', None),
            (b'(\xbf)', 'ignore', '()'),
            (b'(\xbf)', 'replace', '(\ufffd)'),
            (b'(\xbf)', 'backslashreplace', '(\\xbf)'),
            (b'(\xbf)', 'surrogateescape', '(\udcbf)'),
            (b'(\xbf)', 'surrogatepass', None),
        ))

    def test_cp_utf7(self):
        cp = 65000
        self.check_encode(cp, (
            ('abc', 'strict', b'abc'),
            ('\xe9\u20ac', 'strict',  b'+AOkgrA-'),
            ('\U0010ffff', 'strict',  b'+2//f/w-'),
            ('\udc80', 'strict', b'+3IA-'),
            ('\ufffd', 'strict', b'+//0-'),
        ))
        self.check_decode(cp, (
            (b'abc', 'strict', 'abc'),
            (b'+AOkgrA-', 'strict', '\xe9\u20ac'),
            (b'+2//f/w-', 'strict', '\U0010ffff'),
            (b'+3IA-', 'strict', '\udc80'),
            (b'+//0-', 'strict', '\ufffd'),
            # invalid bytes
            (b'[+/]', 'strict', '[]'),
            (b'[\xff]', 'strict', '[\xff]'),
        ))

    def test_multibyte_encoding(self):
        self.check_decode(932, (
            (b'\x84\xe9\x80', 'ignore', '\u9a3e'),
            (b'\x84\xe9\x80', 'replace', '\ufffd\u9a3e'),
        ))
        self.check_decode(self.CP_UTF8, (
            (b'\xff\xf4\x8f\xbf\xbf', 'ignore', '\U0010ffff'),
            (b'\xff\xf4\x8f\xbf\xbf', 'replace', '\ufffd\U0010ffff'),
        ))
        self.check_encode(self.CP_UTF8, (
            ('[\U0010ffff\uDC80]', 'ignore', b'[\xf4\x8f\xbf\xbf]'),
            ('[\U0010ffff\uDC80]', 'replace', b'[\xf4\x8f\xbf\xbf?]'),
        ))

    def test_code_page_decode_flags(self):
        # Issue #36312: For some code pages (e.g. UTF-7) flags for
        # MultiByteToWideChar() must be set to 0.
        if support.verbose:
            sys.stdout.write('\n')
        for cp in (50220, 50221, 50222, 50225, 50227, 50229,
                   *range(57002, 57011+1), 65000):
            # On small versions of Windows like Windows IoT
            # not all codepages are present.
            # A missing codepage causes an OSError exception
            # so check for the codepage before decoding
            if is_code_page_present(cp):
                self.assertEqual(codecs.code_page_decode(cp, b'abc'), ('abc', 3), f'cp{cp}')
            else:
                if support.verbose:
                    print(f"  skipping cp={cp}")
        self.assertEqual(codecs.code_page_decode(42, b'abc'),
                         ('\uf061\uf062\uf063', 3))

    def test_incremental(self):
        decoded = codecs.code_page_decode(932, b'\x82', 'strict', False)
        self.assertEqual(decoded, ('', 0))

        decoded = codecs.code_page_decode(932,
                                          b'\xe9\x80\xe9', 'strict',
                                          False)
        self.assertEqual(decoded, ('\u9a3e', 2))

        decoded = codecs.code_page_decode(932,
                                          b'\xe9\x80\xe9\x80', 'strict',
                                          False)
        self.assertEqual(decoded, ('\u9a3e\u9a3e', 4))

        decoded = codecs.code_page_decode(932,
                                          b'abc', 'strict',
                                          False)
        self.assertEqual(decoded, ('abc', 3))

    def test_mbcs_code_page(self):
        # Check that codec for the current Windows (ANSII) code page is
        # always available.
        try:
            from _winapi import GetACP
        except ImportError:
            self.skipTest('requires _winapi.GetACP')
        cp = GetACP()
        codecs.lookup(f'cp{cp}')

    @support.bigmemtest(size=2**31, memuse=7, dry_run=False)
    def test_large_input(self, size):
        # Test input longer than INT_MAX.
        # Input should contain undecodable bytes before and after
        # the INT_MAX limit.
        encoded = (b'01234567' * ((size//8)-1) +
                   b'\x85\x86\xea\xeb\xec\xef\xfc\xfd\xfe\xff')
        self.assertEqual(len(encoded), size+2)
        decoded = codecs.code_page_decode(932, encoded, 'surrogateescape', True)
        self.assertEqual(decoded[1], len(encoded))
        del encoded
        self.assertEqual(len(decoded[0]), decoded[1])
        self.assertEqual(decoded[0][:10], '0123456701')
        self.assertEqual(decoded[0][-20:],
                         '6701234567'
                         '\udc85\udc86\udcea\udceb\udcec'
                         '\udcef\udcfc\udcfd\udcfe\udcff')

    @support.bigmemtest(size=2**31, memuse=6, dry_run=False)
    def test_large_utf8_input(self, size):
        # Test input longer than INT_MAX.
        # Input should contain a decodable multi-byte character
        # surrounding INT_MAX
        encoded = (b'0123456\xed\x84\x80' * (size//8))
        self.assertEqual(len(encoded), size // 8 * 10)
        decoded = codecs.code_page_decode(65001, encoded, 'ignore', True)
        self.assertEqual(decoded[1], len(encoded))
        del encoded
        self.assertEqual(len(decoded[0]), size)
        self.assertEqual(decoded[0][:10], '0123456\ud10001')
        self.assertEqual(decoded[0][-11:], '56\ud1000123456\ud100')


def iconv_encoding_available(name):
    # The encodings iconv provides are platform-dependent, so tests must probe
    # availability rather than assume it.
    try:
        codecs.iconv_encode(name, '')
    except (LookupError, OSError):
        return False
    return True


# Candidate encodings with sample text; tests probe several and skip only when a
# whole category is unavailable.
_ICONV_SINGLE_BYTE = [
    ('KOI8-U', 'Привіт, світ!'),
    ('ISO-8859-7', 'Καλημέρα'),
    ('ISO-8859-2', 'Zażółć gęślą jaźń'),
    ('ISO-8859-1', 'Grüße'),
]
_ICONV_MULTIBYTE = ['EUC-JP', 'SHIFT_JIS', 'GBK', 'GB18030', 'BIG5']
# Encodings iconv may provide but for which CPython has no built-in codec
# (cp1047 is EBCDIC, i.e. not ASCII-compatible).
_ICONV_ONLY = ['cp1047', 'cp1133', 'GEORGIAN-PS', 'ARMSCII-8']
# Encodings that leave a shift state pending, so encoding ends with a flush.
_ICONV_SHIFT_STATE = [('ISO-2022-CN-EXT', 'ABC\u4e2dDEF'),
                      ('ISO-2022-CN', 'ABC\u4e2dDEF'),
                      ('ISO-2022-JP', 'ABC\u65e5DEF')]


@unittest.skipUnless(hasattr(codecs, 'iconv_encode'),
                     'the iconv codec is not available')
class IconvTest(unittest.TestCase):

    def require(self, *names):
        for name in names:
            if iconv_encoding_available(name):
                return name
        self.skipTest('no suitable iconv encoding is available')

    def require_single_byte(self):
        for enc, text in _ICONV_SINGLE_BYTE:
            if iconv_encoding_available(enc):
                return enc, text
        self.skipTest('no single-byte iconv encoding is available')

    def test_unknown_encoding(self):
        self.assertRaises(LookupError, codecs.iconv_encode, 'no-such-enc-42', 'a')
        self.assertRaises(LookupError, codecs.iconv_decode, 'no-such-enc-42', b'a')
        self.assertRaises(LookupError, codecs.lookup, 'iconv:no-such-enc-42')

    def test_roundtrip(self):
        cases = _ICONV_SINGLE_BYTE + [(enc, '日本語') for enc in _ICONV_MULTIBYTE]
        tested = False
        for enc, text in cases:
            if not iconv_encoding_available(enc):
                continue
            tested = True
            with self.subTest(encoding=enc):
                data = codecs.iconv_encode(enc, text)[0]
                decoded, consumed = codecs.iconv_decode(enc, data, 'strict', True)
                self.assertEqual(decoded, text)
                self.assertEqual(consumed, len(data))
        if not tested:
            self.skipTest('none of the test encodings are available')

    def test_encode_errors(self):
        # A non-ASCII character is not representable in ASCII.
        enc = self.require('ASCII')
        with self.assertRaises(UnicodeEncodeError) as cm:
            codecs.iconv_encode(enc, 'a€b')
        self.assertEqual((cm.exception.encoding, cm.exception.start,
                          cm.exception.end), (enc, 1, 2))
        self.assertEqual(codecs.iconv_encode(enc, 'a€b', 'replace')[0], b'a?b')
        self.assertEqual(codecs.iconv_encode(enc, 'a€b', 'ignore')[0], b'ab')
        self.assertEqual(codecs.iconv_encode(enc, 'a€b', 'backslashreplace')[0],
                         b'a\\u20acb')
        self.assertEqual(codecs.iconv_encode(enc, 'a€b', 'xmlcharrefreplace')[0],
                         b'a&#8364;b')

    def test_encode_errors_unencodable_replacement(self):
        # Encoding the replacement must not call the error handler again.
        enc = self.require('ASCII')
        codecs.register_error('test.iconv', lambda exc: ('€', exc.end))
        self.addCleanup(_codecs._unregister_error, 'test.iconv')
        with self.assertRaises(UnicodeEncodeError) as cm:
            codecs.iconv_encode(enc, 'a€b', 'test.iconv')
        self.assertEqual((cm.exception.start, cm.exception.end), (1, 2))
        self.assertEqual(cm.exception.reason,
                         'unable to encode error handler result')

    def test_decode_errors(self):
        enc = self.require('ASCII')
        bad = b'a\xffb'
        with self.assertRaises(UnicodeDecodeError) as cm:
            codecs.iconv_decode(enc, bad, 'strict', True)
        self.assertEqual((cm.exception.encoding, cm.exception.start), (enc, 1))
        self.assertEqual(codecs.iconv_decode(enc, bad, 'replace', True)[0],
                         'a\ufffdb')
        self.assertEqual(codecs.iconv_decode(enc, bad, 'ignore', True)[0], 'ab')
        self.assertEqual(codecs.iconv_decode(enc, bad, 'backslashreplace', True)[0],
                         'a\\xffb')

    def test_stateful_decode(self):
        enc = self.require(*_ICONV_MULTIBYTE)
        full = codecs.iconv_encode(enc, '日本')[0]
        # A trailing incomplete multibyte sequence is deferred when final is
        # false, and reported through *consumed*.
        text, consumed = codecs.iconv_decode(enc, full[:-1], 'strict', False)
        self.assertEqual(text, '日')
        self.assertEqual(consumed, len(full) - 2)
        # With final=True the same input is an error.
        self.assertRaises(UnicodeDecodeError,
                          codecs.iconv_decode, enc, full[:-1], 'strict', True)

    def test_empty(self):
        enc = self.require('ASCII')
        self.assertEqual(codecs.iconv_encode(enc, ''), (b'', 0))
        self.assertEqual(codecs.iconv_decode(enc, b'', 'strict', True), ('', 0))

    def test_lookup_bare_name(self):
        # An encoding that iconv knows but Python has no built-in codec for.
        for name in _ICONV_ONLY:
            if (iconv_encoding_available(name)
                    and encodings.search_function(name) is None):
                break
        else:
            self.skipTest('no iconv-only encoding is available')
        info = codecs.lookup(name)
        self.assertEqual(info.name, name.lower())
        # The encoding need not be ASCII-compatible (e.g. EBCDIC), so just
        # check that it round-trips.
        self.assertEqual('abc'.encode(name).decode(name), 'abc')

    def test_lookup_does_not_shadow_builtin(self):
        # Built-in codecs must win over the iconv fallback.
        self.assertEqual(codecs.lookup('utf-8').name, 'utf-8')
        self.assertEqual(codecs.lookup('ascii').name, 'ascii')

    def test_iconv_prefix_forces_engine(self):
        # These candidates all have a built-in codec to compare against.
        enc, text = self.require_single_byte()
        info = codecs.lookup('iconv:' + enc)
        # The registry lower-cases the requested name.
        self.assertEqual(info.name, ('iconv:' + enc).lower())
        self.assertEqual(text.encode('iconv:' + enc), text.encode(enc))
        self.assertEqual(text.encode('iconv:' + enc).decode('iconv:' + enc), text)

    def test_incremental_decode(self):
        enc = self.require(*_ICONV_MULTIBYTE)
        text = '日本語'
        data = codecs.encode(text, 'iconv:' + enc)
        dec = codecs.getincrementaldecoder('iconv:' + enc)()
        out = ''.join(dec.decode(data[i:i+1]) for i in range(len(data)))
        out += dec.decode(b'', True)
        self.assertEqual(out, text)

    def test_stream(self):
        enc = self.require(*_ICONV_MULTIBYTE)
        text = '日本語'
        raw = codecs.encode(text, 'iconv:' + enc)
        reader = codecs.getreader('iconv:' + enc)(io.BytesIO(raw))
        self.assertEqual(reader.read(), text)

    def test_encode_kinds(self):
        # The string's own buffer is fed to iconv per storage kind; check each
        # of the 1-, 2- and 4-byte kinds against the built-in codec.
        enc = self.require('UTF-8')
        for text in ('Gr\xfc\xdfe', 'ĀāĂ', 'A\U0001f389B'):
            with self.subTest(text=text):
                self.assertEqual(text.encode('iconv:' + enc), text.encode(enc))

    def test_encode_shift_state_flush(self):
        # Encoding ends with a flush that emits the pending shift sequence.  Its
        # return value counts nonreversible conversions, and some iconv
        # implementations make it positive for the flush itself (glibc does for
        # ISO-2022-CN-EXT).  That must not be read as a substituted character:
        # doing so discarded the whole output, ASCII included.
        #
        # Only the ASCII around the character is checked, in the encoded bytes:
        # it is written there as is.  An iconv that cannot represent the
        # character rejects it or substitutes for it silently.
        tested = False
        for enc, text in _ICONV_SHIFT_STATE:
            if not iconv_encoding_available(enc):
                continue
            with self.subTest(encoding=enc):
                try:
                    data = codecs.iconv_encode(enc, text)[0]
                except UnicodeEncodeError:
                    continue
                tested = True
                # XXX macOS 15 encodes 'ABC\u4e2dDEF' to b'?DEF': the
                # fallback character overwrites the ASCII before it.
                #self.assertIn(b'ABC', data)
                self.assertIn(b'DEF', data)
                # Something was written for the character itself.
                self.assertNotEqual(data, codecs.iconv_encode(enc, 'ABCDEF')[0])
        if not tested:
            self.skipTest('no shift-state iconv encoding is available')

    def test_encode_surrogateescape(self):
        # A lone surrogate lives in the 2-byte kind and round-trips.
        enc = self.require('ASCII')
        data = b'ab\xff'
        s = data.decode(enc, 'surrogateescape')
        self.assertEqual(s.encode('iconv:' + enc, 'surrogateescape'), data)

    def test_encode_surrogate_pair(self):
        # A surrogate pair must stay two code points, never combined into an
        # astral character (as UTF-16 would): backslashreplace escapes each
        # surrogate separately, not the escape of a single combined character.
        pair = '\ud83c\udf89'
        latin1 = self.require('ISO-8859-1', 'ASCII')
        self.assertEqual(pair.encode('iconv:' + latin1, 'backslashreplace'),
                         rb'\ud83c\udf89')


class ASCIITest(unittest.TestCase):
    def test_encode(self):
        self.assertEqual('abc123'.encode('ascii'), b'abc123')

    def test_encode_error(self):
        for data, error_handler, expected in (
            ('[\x80\xff\u20ac]', 'ignore', b'[]'),
            ('[\x80\xff\u20ac]', 'replace', b'[???]'),
            ('[\x80\xff\u20ac]', 'xmlcharrefreplace', b'[&#128;&#255;&#8364;]'),
            ('[\x80\xff\u20ac\U000abcde]', 'backslashreplace',
             b'[\\x80\\xff\\u20ac\\U000abcde]'),
            ('[\udc80\udcff]', 'surrogateescape', b'[\x80\xff]'),
        ):
            with self.subTest(data=data, error_handler=error_handler,
                              expected=expected):
                self.assertEqual(data.encode('ascii', error_handler),
                                 expected)

    def test_encode_surrogateescape_error(self):
        with self.assertRaises(UnicodeEncodeError):
            # the first character can be decoded, but not the second
            '\udc80\xff'.encode('ascii', 'surrogateescape')

    def test_decode(self):
        self.assertEqual(b'abc'.decode('ascii'), 'abc')

    def test_decode_error(self):
        for data, error_handler, expected in (
            (b'[\x80\xff]', 'ignore', '[]'),
            (b'[\x80\xff]', 'replace', '[\ufffd\ufffd]'),
            (b'[\x80\xff]', 'surrogateescape', '[\udc80\udcff]'),
            (b'[\x80\xff]', 'backslashreplace', '[\\x80\\xff]'),
        ):
            with self.subTest(data=data, error_handler=error_handler,
                              expected=expected):
                self.assertEqual(data.decode('ascii', error_handler),
                                 expected)


class Latin1Test(unittest.TestCase):
    def test_encode(self):
        for data, expected in (
            ('abc', b'abc'),
            ('\x80\xe9\xff', b'\x80\xe9\xff'),
        ):
            with self.subTest(data=data, expected=expected):
                self.assertEqual(data.encode('latin1'), expected)

    def test_encode_errors(self):
        for data, error_handler, expected in (
            ('[\u20ac\udc80]', 'ignore', b'[]'),
            ('[\u20ac\udc80]', 'replace', b'[??]'),
            ('[\u20ac\U000abcde]', 'backslashreplace',
             b'[\\u20ac\\U000abcde]'),
            ('[\u20ac\udc80]', 'xmlcharrefreplace', b'[&#8364;&#56448;]'),
            ('[\udc80\udcff]', 'surrogateescape', b'[\x80\xff]'),
        ):
            with self.subTest(data=data, error_handler=error_handler,
                              expected=expected):
                self.assertEqual(data.encode('latin1', error_handler),
                                 expected)

    def test_encode_surrogateescape_error(self):
        with self.assertRaises(UnicodeEncodeError):
            # the first character can be decoded, but not the second
            '\udc80\u20ac'.encode('latin1', 'surrogateescape')

    def test_decode(self):
        for data, expected in (
            (b'abc', 'abc'),
            (b'[\x80\xff]', '[\x80\xff]'),
        ):
            with self.subTest(data=data, expected=expected):
                self.assertEqual(data.decode('latin1'), expected)


class StreamRecoderTest(unittest.TestCase):
    def test_writelines(self):
        bio = io.BytesIO()
        codec = codecs.lookup('ascii')
        sr = codecs.StreamRecoder(bio, codec.encode, codec.decode,
                                  encodings.ascii.StreamReader, encodings.ascii.StreamWriter)
        sr.writelines([b'a', b'b'])
        self.assertEqual(bio.getvalue(), b'ab')

    def test_write(self):
        bio = io.BytesIO()
        codec = codecs.lookup('latin1')
        # Recode from Latin-1 to utf-8.
        sr = codecs.StreamRecoder(bio, codec.encode, codec.decode,
                                  encodings.utf_8.StreamReader, encodings.utf_8.StreamWriter)

        text = 'àñé'
        sr.write(text.encode('latin1'))
        self.assertEqual(bio.getvalue(), text.encode('utf-8'))

    def test_seeking_read(self):
        bio = io.BytesIO('line1\nline2\nline3\n'.encode('utf-16-le'))
        sr = codecs.EncodedFile(bio, 'utf-8', 'utf-16-le')

        self.assertEqual(sr.readline(), b'line1\n')
        sr.seek(0)
        self.assertEqual(sr.readline(), b'line1\n')
        self.assertEqual(sr.readline(), b'line2\n')
        self.assertEqual(sr.readline(), b'line3\n')
        self.assertEqual(sr.readline(), b'')

    def test_seeking_write(self):
        bio = io.BytesIO('123456789\n'.encode('utf-16-le'))
        sr = codecs.EncodedFile(bio, 'utf-8', 'utf-16-le')

        # Test that seek() only resets its internal buffer when offset
        # and whence are zero.
        sr.seek(2)
        sr.write(b'\nabc\n')
        self.assertEqual(sr.readline(), b'789\n')
        sr.seek(0)
        self.assertEqual(sr.readline(), b'1\n')
        self.assertEqual(sr.readline(), b'abc\n')
        self.assertEqual(sr.readline(), b'789\n')

    def test_copy(self):
        bio = io.BytesIO()
        codec = codecs.lookup('ascii')
        sr = codecs.StreamRecoder(bio, codec.encode, codec.decode,
                                  encodings.ascii.StreamReader, encodings.ascii.StreamWriter)

        with self.assertRaisesRegex(TypeError, 'StreamRecoder'):
            copy.copy(sr)
        with self.assertRaisesRegex(TypeError, 'StreamRecoder'):
            copy.deepcopy(sr)

    def test_pickle(self):
        q = Queue(b'')
        codec = codecs.lookup('ascii')
        sr = codecs.StreamRecoder(q, codec.encode, codec.decode,
                                  encodings.ascii.StreamReader, encodings.ascii.StreamWriter)

        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            with self.subTest(protocol=proto):
                with self.assertRaisesRegex(TypeError, 'StreamRecoder'):
                    pickle.dumps(sr, proto)


@unittest.skipIf(_testinternalcapi is None, 'need _testinternalcapi module')
class LocaleCodecTest(unittest.TestCase):
    """
    Test indirectly _Py_DecodeUTF8Ex() and _Py_EncodeUTF8Ex().
    """
    ENCODING = sys.getfilesystemencoding()
    STRINGS = ("ascii", "ulatin1:\xa7\xe9",
               "u255:\xff",
               "UCS:\xe9\u20ac\U0010ffff",
               "surrogates:\uDC80\uDCFF")
    BYTES_STRINGS = (b"blatin1:\xa7\xe9", b"b255:\xff")
    SURROGATES = "\uDC80\uDCFF"

    def encode(self, text, errors="strict"):
        return _testinternalcapi.EncodeLocaleEx(text, 0, errors)

    def check_encode_strings(self, errors):
        for text in self.STRINGS:
            with self.subTest(text=text):
                try:
                    expected = text.encode(self.ENCODING, errors)
                except UnicodeEncodeError:
                    with self.assertRaises(RuntimeError) as cm:
                        self.encode(text, errors)
                    errmsg = str(cm.exception)
                    self.assertRegex(errmsg, r"encode error: pos=[0-9]+, reason=")
                else:
                    encoded = self.encode(text, errors)
                    self.assertEqual(encoded, expected)

    def test_encode_strict(self):
        self.check_encode_strings("strict")

    def test_encode_surrogateescape(self):
        self.check_encode_strings("surrogateescape")

    def test_encode_surrogatepass(self):
        try:
            self.encode('', 'surrogatepass')
        except ValueError as exc:
            if str(exc) == 'unsupported error handler':
                self.skipTest(f"{self.ENCODING!r} encoder doesn't support "
                              f"surrogatepass error handler")
            else:
                raise

        self.check_encode_strings("surrogatepass")

    def test_encode_unsupported_error_handler(self):
        with self.assertRaises(ValueError) as cm:
            self.encode('', 'backslashreplace')
        self.assertEqual(str(cm.exception), 'unsupported error handler')

    def decode(self, encoded, errors="strict"):
        return _testinternalcapi.DecodeLocaleEx(encoded, 0, errors)

    def check_decode_strings(self, errors):
        is_utf8 = (self.ENCODING == "utf-8")
        if is_utf8:
            encode_errors = 'surrogateescape'
        else:
            encode_errors = 'strict'

        strings = list(self.BYTES_STRINGS)
        for text in self.STRINGS:
            try:
                encoded = text.encode(self.ENCODING, encode_errors)
                if encoded not in strings:
                    strings.append(encoded)
            except UnicodeEncodeError:
                encoded = None

            if is_utf8:
                encoded2 = text.encode(self.ENCODING, 'surrogatepass')
                if encoded2 != encoded:
                    strings.append(encoded2)

        for encoded in strings:
            with self.subTest(encoded=encoded):
                try:
                    expected = encoded.decode(self.ENCODING, errors)
                except UnicodeDecodeError:
                    with self.assertRaises(RuntimeError) as cm:
                        self.decode(encoded, errors)
                    errmsg = str(cm.exception)
                    self.assertStartsWith(errmsg, "decode error: ")
                else:
                    decoded = self.decode(encoded, errors)
                    self.assertEqual(decoded, expected)

    def test_decode_strict(self):
        self.check_decode_strings("strict")

    def test_decode_surrogateescape(self):
        self.check_decode_strings("surrogateescape")

    def test_decode_surrogatepass(self):
        try:
            self.decode(b'', 'surrogatepass')
        except ValueError as exc:
            if str(exc) == 'unsupported error handler':
                self.skipTest(f"{self.ENCODING!r} decoder doesn't support "
                              f"surrogatepass error handler")
            else:
                raise

        self.check_decode_strings("surrogatepass")

    def test_decode_unsupported_error_handler(self):
        with self.assertRaises(ValueError) as cm:
            self.decode(b'', 'backslashreplace')
        self.assertEqual(str(cm.exception), 'unsupported error handler')


class Rot13Test(unittest.TestCase):
    """Test the educational ROT-13 codec."""
    def test_encode(self):
        ciphertext = codecs.encode("Caesar liked ciphers", 'rot-13')
        self.assertEqual(ciphertext, 'Pnrfne yvxrq pvcuref')

    def test_decode(self):
        plaintext = codecs.decode('Rg gh, Oehgr?', 'rot-13')
        self.assertEqual(plaintext, 'Et tu, Brute?')

    def test_incremental_encode(self):
        encoder = codecs.getincrementalencoder('rot-13')()
        ciphertext = encoder.encode('ABBA nag Cheryl Baker')
        self.assertEqual(ciphertext, 'NOON ant Purely Onxre')

    def test_incremental_decode(self):
        decoder = codecs.getincrementaldecoder('rot-13')()
        plaintext = decoder.decode('terra Ares envy tha')
        self.assertEqual(plaintext, 'green Nerf rail gun')


class Rot13UtilTest(unittest.TestCase):
    """Test the ROT-13 codec via rot13 function,
    i.e. the user has done something like:
    $ echo "Hello World" | python -m encodings.rot_13
    """
    def test_rot13_func(self):
        from encodings.rot_13 import rot13
        infile = io.StringIO('Gb or, be abg gb or, gung vf gur dhrfgvba')
        outfile = io.StringIO()
        rot13(infile, outfile)
        outfile.seek(0)
        plain_text = outfile.read()
        self.assertEqual(
            plain_text,
            'To be, or not to be, that is the question')


class CodecNameNormalizationTest(unittest.TestCase):
    """Test codec name normalization"""
    def test_codecs_lookup(self):
        def search_function(encoding):
            if encoding.startswith("test."):
                return (encoding, 2, 3, 4)
            else:
                return None

        codecs.register(search_function)
        self.addCleanup(codecs.unregister, search_function)
        self.assertEqual(codecs.lookup('test.aaa_8'), ('test.aaa_8', 2, 3, 4))
        self.assertEqual(codecs.lookup('TEST.AAA-8'), ('test.aaa-8', 2, 3, 4))
        self.assertEqual(codecs.lookup('TEST.AAA 8'), ('test.aaa-8', 2, 3, 4))
        self.assertEqual(codecs.lookup('TEST.AAA---8'), ('test.aaa---8', 2, 3, 4))
        self.assertEqual(codecs.lookup('TEST.AAA   8'), ('test.aaa---8', 2, 3, 4))
        self.assertEqual(codecs.lookup('TEST.AAA.8'), ('test.aaa.8', 2, 3, 4))
        self.assertEqual(codecs.lookup('TEST.AAA...8'), ('test.aaa...8', 2, 3, 4))
        with self.assertWarns(DeprecationWarning):
            self.assertEqual(codecs.lookup('TEST.AAA\xe9\u20ac-8'), ('test.aaa\xe9\u20ac-8', 2, 3, 4))

    def test_encodings_normalize_encoding(self):
        normalize = encodings.normalize_encoding
        self.assertEqual(normalize('utf_8'), 'utf_8')
        self.assertEqual(normalize('utf   8'), 'utf_8')
        # encodings.normalize_encoding() doesn't convert
        # characters to lower case.
        self.assertEqual(normalize('UTF 8'), 'UTF_8')
        self.assertEqual(normalize('utf.8'), 'utf.8')
        self.assertEqual(normalize('utf...8'), 'utf...8')

        # Non-ASCII *encoding* is deprecated.
        msg = "Support for non-ascii encoding names will be removed in 3.17"
        with warnings_helper.check_warnings((msg, DeprecationWarning)):
            self.assertEqual(normalize('utf\xE9\u20AC\U0010ffff-8'), 'utf_8')


class CodecCacheTest(unittest.TestCase):
    def test_cache_bounded(self):
        for i in range(encodings._MAXCACHE + 1000):
            try:
                b'x'.decode(f'nonexist_{i}')
            except LookupError:
                pass

        self.assertLessEqual(len(encodings._cache), encodings._MAXCACHE)


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