test_codeccallbacks.py

from _codecs import _unregister_error as _codecs_unregister_error
import codecs
import html.entities
import itertools
import re
import sys
import unicodedata
import unittest


class PosReturn:
    # this can be used for configurable callbacks

    def __init__(self):
        self.pos = 0

    def handle(self, exc):
        oldpos = self.pos
        realpos = oldpos
        if realpos<0:
            realpos = len(exc.object) + realpos
        # if we don't advance this time, terminate on the next call
        # otherwise we'd get an endless loop
        if realpos <= exc.start:
            self.pos = len(exc.object)
        return ("<?>", oldpos)

class RepeatedPosReturn:
    def __init__(self, repl="<?>"):
        self.repl = repl
        self.pos = 0
        self.count = 0

    def handle(self, exc):
        if self.count > 0:
            self.count -= 1
            return (self.repl, self.pos)
        return (self.repl, exc.end)

# A UnicodeEncodeError object with a bad start attribute
class BadStartUnicodeEncodeError(UnicodeEncodeError):
    def __init__(self):
        UnicodeEncodeError.__init__(self, "ascii", "", 0, 1, "bad")
        self.start = []

# A UnicodeEncodeError object with a bad object attribute
class BadObjectUnicodeEncodeError(UnicodeEncodeError):
    def __init__(self):
        UnicodeEncodeError.__init__(self, "ascii", "", 0, 1, "bad")
        self.object = []

# A UnicodeDecodeError object without an end attribute
class NoEndUnicodeDecodeError(UnicodeDecodeError):
    def __init__(self):
        UnicodeDecodeError.__init__(self, "ascii", bytearray(b""), 0, 1, "bad")
        del self.end

# A UnicodeDecodeError object with a bad object attribute
class BadObjectUnicodeDecodeError(UnicodeDecodeError):
    def __init__(self):
        UnicodeDecodeError.__init__(self, "ascii", bytearray(b""), 0, 1, "bad")
        self.object = []

# A UnicodeTranslateError object without a start attribute
class NoStartUnicodeTranslateError(UnicodeTranslateError):
    def __init__(self):
        UnicodeTranslateError.__init__(self, "", 0, 1, "bad")
        del self.start

# A UnicodeTranslateError object without an end attribute
class NoEndUnicodeTranslateError(UnicodeTranslateError):
    def __init__(self):
        UnicodeTranslateError.__init__(self,  "", 0, 1, "bad")
        del self.end

# A UnicodeTranslateError object without an object attribute
class NoObjectUnicodeTranslateError(UnicodeTranslateError):
    def __init__(self):
        UnicodeTranslateError.__init__(self, "", 0, 1, "bad")
        del self.object

class CodecCallbackTest(unittest.TestCase):

    def test_xmlcharrefreplace(self):
        # replace unencodable characters which numeric character entities.
        # For ascii, latin-1 and charmaps this is completely implemented
        # in C and should be reasonably fast.
        s = "\u30b9\u30d1\u30e2 \xe4nd eggs"
        self.assertEqual(
            s.encode("ascii", "xmlcharrefreplace"),
            b"&#12473;&#12497;&#12514; &#228;nd eggs"
        )
        self.assertEqual(
            s.encode("latin-1", "xmlcharrefreplace"),
            b"&#12473;&#12497;&#12514; \xe4nd eggs"
        )

    def test_xmlcharnamereplace(self):
        # This time use a named character entity for unencodable
        # characters, if one is available.

        def xmlcharnamereplace(exc):
            if not isinstance(exc, UnicodeEncodeError):
                raise TypeError("don't know how to handle %r" % exc)
            l = []
            for c in exc.object[exc.start:exc.end]:
                try:
                    l.append("&%s;" % html.entities.codepoint2name[ord(c)])
                except KeyError:
                    l.append("&#%d;" % ord(c))
            return ("".join(l), exc.end)

        codecs.register_error(
            "test.xmlcharnamereplace", xmlcharnamereplace)

        sin = "\xab\u211c\xbb = \u2329\u1234\u20ac\u232a"
        sout = b"&laquo;&real;&raquo; = &lang;&#4660;&euro;&rang;"
        self.assertEqual(sin.encode("ascii", "test.xmlcharnamereplace"), sout)
        sout = b"\xab&real;\xbb = &lang;&#4660;&euro;&rang;"
        self.assertEqual(sin.encode("latin-1", "test.xmlcharnamereplace"), sout)
        sout = b"\xab&real;\xbb = &lang;&#4660;\xa4&rang;"
        self.assertEqual(sin.encode("iso-8859-15", "test.xmlcharnamereplace"), sout)

    def test_uninamereplace(self):
        # We're using the names from the unicode database this time,
        # and we're doing "syntax highlighting" here, i.e. we include
        # the replaced text in ANSI escape sequences. For this it is
        # useful that the error handler is not called for every single
        # unencodable character, but for a complete sequence of
        # unencodable characters, otherwise we would output many
        # unnecessary escape sequences.

        def uninamereplace(exc):
            if not isinstance(exc, UnicodeEncodeError):
                raise TypeError("don't know how to handle %r" % exc)
            l = []
            for c in exc.object[exc.start:exc.end]:
                l.append(unicodedata.name(c, "0x%x" % ord(c)))
            return ("\033[1m%s\033[0m" % ", ".join(l), exc.end)

        codecs.register_error(
            "test.uninamereplace", uninamereplace)

        sin = "\xac\u1234\u20ac\u8000"
        sout = b"\033[1mNOT SIGN, ETHIOPIC SYLLABLE SEE, EURO SIGN, CJK UNIFIED IDEOGRAPH-8000\033[0m"
        self.assertEqual(sin.encode("ascii", "test.uninamereplace"), sout)

        sout = b"\xac\033[1mETHIOPIC SYLLABLE SEE, EURO SIGN, CJK UNIFIED IDEOGRAPH-8000\033[0m"
        self.assertEqual(sin.encode("latin-1", "test.uninamereplace"), sout)

        sout = b"\xac\033[1mETHIOPIC SYLLABLE SEE\033[0m\xa4\033[1mCJK UNIFIED IDEOGRAPH-8000\033[0m"
        self.assertEqual(sin.encode("iso-8859-15", "test.uninamereplace"), sout)

    def test_backslashescape(self):
        # Does the same as the "unicode-escape" encoding, but with different
        # base encodings.
        sin = "a\xac\u1234\u20ac\u8000\U0010ffff"
        sout = b"a\\xac\\u1234\\u20ac\\u8000\\U0010ffff"
        self.assertEqual(sin.encode("ascii", "backslashreplace"), sout)

        sout = b"a\xac\\u1234\\u20ac\\u8000\\U0010ffff"
        self.assertEqual(sin.encode("latin-1", "backslashreplace"), sout)

        sout = b"a\xac\\u1234\xa4\\u8000\\U0010ffff"
        self.assertEqual(sin.encode("iso-8859-15", "backslashreplace"), sout)

    def test_nameescape(self):
        # Does the same as backslashescape, but prefers ``\N{...}`` escape
        # sequences.
        sin = "a\xac\u1234\u20ac\u8000\U0010ffff"
        sout = (b'a\\N{NOT SIGN}\\N{ETHIOPIC SYLLABLE SEE}\\N{EURO SIGN}'
                b'\\N{CJK UNIFIED IDEOGRAPH-8000}\\U0010ffff')
        self.assertEqual(sin.encode("ascii", "namereplace"), sout)

        sout = (b'a\xac\\N{ETHIOPIC SYLLABLE SEE}\\N{EURO SIGN}'
                b'\\N{CJK UNIFIED IDEOGRAPH-8000}\\U0010ffff')
        self.assertEqual(sin.encode("latin-1", "namereplace"), sout)

        sout = (b'a\xac\\N{ETHIOPIC SYLLABLE SEE}\xa4'
                b'\\N{CJK UNIFIED IDEOGRAPH-8000}\\U0010ffff')
        self.assertEqual(sin.encode("iso-8859-15", "namereplace"), sout)

    def test_decoding_callbacks(self):
        # This is a test for a decoding callback handler
        # that allows the decoding of the invalid sequence
        # "\xc0\x80" and returns "\x00" instead of raising an error.
        # All other illegal sequences will be handled strictly.
        def relaxedutf8(exc):
            if not isinstance(exc, UnicodeDecodeError):
                raise TypeError("don't know how to handle %r" % exc)
            if exc.object[exc.start:exc.start+2] == b"\xc0\x80":
                return ("\x00", exc.start+2) # retry after two bytes
            else:
                raise exc

        codecs.register_error("test.relaxedutf8", relaxedutf8)

        # all the "\xc0\x80" will be decoded to "\x00"
        sin = b"a\x00b\xc0\x80c\xc3\xbc\xc0\x80\xc0\x80"
        sout = "a\x00b\x00c\xfc\x00\x00"
        self.assertEqual(sin.decode("utf-8", "test.relaxedutf8"), sout)

        # "\xc0\x81" is not valid and a UnicodeDecodeError will be raised
        sin = b"\xc0\x80\xc0\x81"
        self.assertRaises(UnicodeDecodeError, sin.decode,
                          "utf-8", "test.relaxedutf8")

    def test_charmapencode(self):
        # For charmap encodings the replacement string will be
        # mapped through the encoding again. This means, that
        # to be able to use e.g. the "replace" handler, the
        # charmap has to have a mapping for "?".
        charmap = dict((ord(c), bytes(2*c.upper(), 'ascii')) for c in "abcdefgh")
        sin = "abc"
        sout = b"AABBCC"
        self.assertEqual(codecs.charmap_encode(sin, "strict", charmap)[0], sout)

        sin = "abcA"
        self.assertRaises(UnicodeError, codecs.charmap_encode, sin, "strict", charmap)

        charmap[ord("?")] = b"XYZ"
        sin = "abcDEF"
        sout = b"AABBCCXYZXYZXYZ"
        self.assertEqual(codecs.charmap_encode(sin, "replace", charmap)[0], sout)

        charmap[ord("?")] = "XYZ" # wrong type in mapping
        self.assertRaises(TypeError, codecs.charmap_encode, sin, "replace", charmap)

    def test_callbacks(self):
        def handler1(exc):
            r = range(exc.start, exc.end)
            if isinstance(exc, UnicodeEncodeError):
                l = ["<%d>" % ord(exc.object[pos]) for pos in r]
            elif isinstance(exc, UnicodeDecodeError):
                l = ["<%d>" % exc.object[pos] for pos in r]
            else:
                raise TypeError("don't know how to handle %r" % exc)
            return ("[%s]" % "".join(l), exc.end)

        codecs.register_error("test.handler1", handler1)

        def handler2(exc):
            if not isinstance(exc, UnicodeDecodeError):
                raise TypeError("don't know how to handle %r" % exc)
            l = ["<%d>" % exc.object[pos] for pos in range(exc.start, exc.end)]
            return ("[%s]" % "".join(l), exc.end+1) # skip one character

        codecs.register_error("test.handler2", handler2)

        s = b"\x00\x81\x7f\x80\xff"

        self.assertEqual(
            s.decode("ascii", "test.handler1"),
            "\x00[<129>]\x7f[<128>][<255>]"
        )
        self.assertEqual(
            s.decode("ascii", "test.handler2"),
            "\x00[<129>][<128>]"
        )

        self.assertEqual(
            b"\\u3042\\u3xxx".decode("unicode-escape", "test.handler1"),
            "\u3042[<92><117><51>]xxx"
        )

        self.assertEqual(
            b"\\u3042\\u3xx".decode("unicode-escape", "test.handler1"),
            "\u3042[<92><117><51>]xx"
        )

        self.assertEqual(
            codecs.charmap_decode(b"abc", "test.handler1", {ord("a"): "z"})[0],
            "z[<98>][<99>]"
        )

        self.assertEqual(
            "g\xfc\xdfrk".encode("ascii", "test.handler1"),
            b"g[<252><223>]rk"
        )

        self.assertEqual(
            "g\xfc\xdf".encode("ascii", "test.handler1"),
            b"g[<252><223>]"
        )

    def test_longstrings(self):
        # test long strings to check for memory overflow problems
        errors = [ "strict", "ignore", "replace", "xmlcharrefreplace",
                   "backslashreplace", "namereplace"]
        # register the handlers under different names,
        # to prevent the codec from recognizing the name
        for err in errors:
            codecs.register_error("test." + err, codecs.lookup_error(err))
        l = 1000
        errors += [ "test." + err for err in errors ]
        for uni in [ s*l for s in ("x", "\u3042", "a\xe4") ]:
            for enc in ("ascii", "latin-1", "iso-8859-1", "iso-8859-15",
                        "utf-8", "utf-7", "utf-16", "utf-32"):
                for err in errors:
                    try:
                        uni.encode(enc, err)
                    except UnicodeError:
                        pass

    def check_exceptionobjectargs(self, exctype, args, msg):
        # Test UnicodeError subclasses: construction, attribute assignment and __str__ conversion
        # check with one missing argument
        self.assertRaises(TypeError, exctype, *args[:-1])
        # check with one argument too much
        self.assertRaises(TypeError, exctype, *(args + ["too much"]))
        # check with one argument of the wrong type
        wrongargs = [ "spam", b"eggs", b"spam", 42, 1.0, None ]
        for i in range(len(args)):
            for wrongarg in wrongargs:
                if type(wrongarg) is type(args[i]):
                    continue
                # build argument array
                callargs = []
                for j in range(len(args)):
                    if i==j:
                        callargs.append(wrongarg)
                    else:
                        callargs.append(args[i])
                self.assertRaises(TypeError, exctype, *callargs)

        # check with the correct number and type of arguments
        exc = exctype(*args)
        self.assertEqual(str(exc), msg)

    def test_unicodeencodeerror(self):
        self.check_exceptionobjectargs(
            UnicodeEncodeError,
            ["ascii", "g\xfcrk", 1, 2, "ouch"],
            "'ascii' codec can't encode character '\\xfc' in position 1: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeEncodeError,
            ["ascii", "g\xfcrk", 1, 4, "ouch"],
            "'ascii' codec can't encode characters in position 1-3: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeEncodeError,
            ["ascii", "\xfcx", 0, 1, "ouch"],
            "'ascii' codec can't encode character '\\xfc' in position 0: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeEncodeError,
            ["ascii", "\u0100x", 0, 1, "ouch"],
            "'ascii' codec can't encode character '\\u0100' in position 0: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeEncodeError,
            ["ascii", "\uffffx", 0, 1, "ouch"],
            "'ascii' codec can't encode character '\\uffff' in position 0: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeEncodeError,
            ["ascii", "\U00010000x", 0, 1, "ouch"],
            "'ascii' codec can't encode character '\\U00010000' in position 0: ouch"
        )

    def test_unicodedecodeerror(self):
        self.check_exceptionobjectargs(
            UnicodeDecodeError,
            ["ascii", bytearray(b"g\xfcrk"), 1, 2, "ouch"],
            "'ascii' codec can't decode byte 0xfc in position 1: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeDecodeError,
            ["ascii", bytearray(b"g\xfcrk"), 1, 3, "ouch"],
            "'ascii' codec can't decode bytes in position 1-2: ouch"
        )

    def test_unicodetranslateerror(self):
        self.check_exceptionobjectargs(
            UnicodeTranslateError,
            ["g\xfcrk", 1, 2, "ouch"],
            "can't translate character '\\xfc' in position 1: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeTranslateError,
            ["g\u0100rk", 1, 2, "ouch"],
            "can't translate character '\\u0100' in position 1: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeTranslateError,
            ["g\uffffrk", 1, 2, "ouch"],
            "can't translate character '\\uffff' in position 1: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeTranslateError,
            ["g\U00010000rk", 1, 2, "ouch"],
            "can't translate character '\\U00010000' in position 1: ouch"
        )
        self.check_exceptionobjectargs(
            UnicodeTranslateError,
            ["g\xfcrk", 1, 3, "ouch"],
            "can't translate characters in position 1-2: ouch"
        )

    def test_badandgoodstrictexceptions(self):
        # "strict" complains about a non-exception passed in
        self.assertRaises(
            TypeError,
            codecs.strict_errors,
            42
        )
        # "strict" complains about the wrong exception type
        self.assertRaises(
            Exception,
            codecs.strict_errors,
            Exception("ouch")
        )

        # If the correct exception is passed in, "strict" raises it
        self.assertRaises(
            UnicodeEncodeError,
            codecs.strict_errors,
            UnicodeEncodeError("ascii", "\u3042", 0, 1, "ouch")
        )
        self.assertRaises(
            UnicodeDecodeError,
            codecs.strict_errors,
            UnicodeDecodeError("ascii", bytearray(b"\xff"), 0, 1, "ouch")
        )
        self.assertRaises(
            UnicodeTranslateError,
            codecs.strict_errors,
            UnicodeTranslateError("\u3042", 0, 1, "ouch")
        )

    def test_badandgoodignoreexceptions(self):
        # "ignore" complains about a non-exception passed in
        self.assertRaises(
           TypeError,
           codecs.ignore_errors,
           42
        )
        # "ignore" complains about the wrong exception type
        self.assertRaises(
           TypeError,
           codecs.ignore_errors,
           UnicodeError("ouch")
        )
        # If the correct exception is passed in, "ignore" returns an empty replacement
        self.assertEqual(
            codecs.ignore_errors(
                UnicodeEncodeError("ascii", "a\u3042b", 1, 2, "ouch")),
            ("", 2)
        )
        self.assertEqual(
            codecs.ignore_errors(
                UnicodeDecodeError("ascii", bytearray(b"a\xffb"), 1, 2, "ouch")),
            ("", 2)
        )
        self.assertEqual(
            codecs.ignore_errors(
                UnicodeTranslateError("a\u3042b", 1, 2, "ouch")),
            ("", 2)
        )

    def test_badandgoodreplaceexceptions(self):
        # "replace" complains about a non-exception passed in
        self.assertRaises(
           TypeError,
           codecs.replace_errors,
           42
        )
        # "replace" complains about the wrong exception type
        self.assertRaises(
           TypeError,
           codecs.replace_errors,
           UnicodeError("ouch")
        )
        self.assertRaises(
            TypeError,
            codecs.replace_errors,
            BadObjectUnicodeEncodeError()
        )
        self.assertRaises(
            TypeError,
            codecs.replace_errors,
            BadObjectUnicodeDecodeError()
        )
        # With the correct exception, "replace" returns an "?" or "\ufffd" replacement
        self.assertEqual(
            codecs.replace_errors(
                UnicodeEncodeError("ascii", "a\u3042b", 1, 2, "ouch")),
            ("?", 2)
        )
        self.assertEqual(
            codecs.replace_errors(
                UnicodeDecodeError("ascii", bytearray(b"a\xffb"), 1, 2, "ouch")),
            ("\ufffd", 2)
        )
        self.assertEqual(
            codecs.replace_errors(
                UnicodeTranslateError("a\u3042b", 1, 2, "ouch")),
            ("\ufffd", 2)
        )

    def test_badandgoodxmlcharrefreplaceexceptions(self):
        # "xmlcharrefreplace" complains about a non-exception passed in
        self.assertRaises(
           TypeError,
           codecs.xmlcharrefreplace_errors,
           42
        )
        # "xmlcharrefreplace" complains about the wrong exception types
        self.assertRaises(
           TypeError,
           codecs.xmlcharrefreplace_errors,
           UnicodeError("ouch")
        )
        # "xmlcharrefreplace" can only be used for encoding
        self.assertRaises(
            TypeError,
            codecs.xmlcharrefreplace_errors,
            UnicodeDecodeError("ascii", bytearray(b"\xff"), 0, 1, "ouch")
        )
        self.assertRaises(
            TypeError,
            codecs.xmlcharrefreplace_errors,
            UnicodeTranslateError("\u3042", 0, 1, "ouch")
        )
        # Use the correct exception
        cs = (0, 1, 9, 10, 99, 100, 999, 1000, 9999, 10000, 99999, 100000,
              999999, 1000000)
        cs += (0xd800, 0xdfff)
        s = "".join(chr(c) for c in cs)
        self.assertEqual(
            codecs.xmlcharrefreplace_errors(
                UnicodeEncodeError("ascii", "a" + s + "b",
                                   1, 1 + len(s), "ouch")
            ),
            ("".join("&#%d;" % c for c in cs), 1 + len(s))
        )

    def test_badandgoodbackslashreplaceexceptions(self):
        # "backslashreplace" complains about a non-exception passed in
        self.assertRaises(
           TypeError,
           codecs.backslashreplace_errors,
           42
        )
        # "backslashreplace" complains about the wrong exception types
        self.assertRaises(
           TypeError,
           codecs.backslashreplace_errors,
           UnicodeError("ouch")
        )
        # Use the correct exception
        tests = [
            ("\u3042", "\\u3042"),
            ("\n", "\\x0a"),
            ("a", "\\x61"),
            ("\x00", "\\x00"),
            ("\xff", "\\xff"),
            ("\u0100", "\\u0100"),
            ("\uffff", "\\uffff"),
            ("\U00010000", "\\U00010000"),
            ("\U0010ffff", "\\U0010ffff"),
            # Lone surrogates
            ("\ud800", "\\ud800"),
            ("\udfff", "\\udfff"),
            ("\ud800\udfff", "\\ud800\\udfff"),
        ]
        for s, r in tests:
            with self.subTest(str=s):
                self.assertEqual(
                    codecs.backslashreplace_errors(
                        UnicodeEncodeError("ascii", "a" + s + "b",
                                           1, 1 + len(s), "ouch")),
                    (r, 1 + len(s))
                )
                self.assertEqual(
                    codecs.backslashreplace_errors(
                        UnicodeTranslateError("a" + s + "b",
                                              1, 1 + len(s), "ouch")),
                    (r, 1 + len(s))
                )
        tests = [
            (b"a", "\\x61"),
            (b"\n", "\\x0a"),
            (b"\x00", "\\x00"),
            (b"\xff", "\\xff"),
        ]
        for b, r in tests:
            with self.subTest(bytes=b):
                self.assertEqual(
                    codecs.backslashreplace_errors(
                        UnicodeDecodeError("ascii", bytearray(b"a" + b + b"b"),
                                           1, 2, "ouch")),
                    (r, 2)
                )

    def test_badandgoodnamereplaceexceptions(self):
        # "namereplace" complains about a non-exception passed in
        self.assertRaises(
           TypeError,
           codecs.namereplace_errors,
           42
        )
        # "namereplace" complains about the wrong exception types
        self.assertRaises(
           TypeError,
           codecs.namereplace_errors,
           UnicodeError("ouch")
        )
        # "namereplace" can only be used for encoding
        self.assertRaises(
            TypeError,
            codecs.namereplace_errors,
            UnicodeDecodeError("ascii", bytearray(b"\xff"), 0, 1, "ouch")
        )
        self.assertRaises(
            TypeError,
            codecs.namereplace_errors,
            UnicodeTranslateError("\u3042", 0, 1, "ouch")
        )
        # Use the correct exception
        tests = [
            ("\u3042", "\\N{HIRAGANA LETTER A}"),
            ("\x00", "\\x00"),
            ("\ufbf9", "\\N{ARABIC LIGATURE UIGHUR KIRGHIZ YEH WITH "
                       "HAMZA ABOVE WITH ALEF MAKSURA ISOLATED FORM}"),
            ("\U000e007f", "\\N{CANCEL TAG}"),
            ("\U0010ffff", "\\U0010ffff"),
            # Lone surrogates
            ("\ud800", "\\ud800"),
            ("\udfff", "\\udfff"),
            ("\ud800\udfff", "\\ud800\\udfff"),
        ]
        for s, r in tests:
            with self.subTest(str=s):
                self.assertEqual(
                    codecs.namereplace_errors(
                        UnicodeEncodeError("ascii", "a" + s + "b",
                                           1, 1 + len(s), "ouch")),
                    (r, 1 + len(s))
                )

    def test_badandgoodsurrogateescapeexceptions(self):
        surrogateescape_errors = codecs.lookup_error('surrogateescape')
        # "surrogateescape" complains about a non-exception passed in
        self.assertRaises(
           TypeError,
           surrogateescape_errors,
           42
        )
        # "surrogateescape" complains about the wrong exception types
        self.assertRaises(
           TypeError,
           surrogateescape_errors,
           UnicodeError("ouch")
        )
        # "surrogateescape" can not be used for translating
        self.assertRaises(
            TypeError,
            surrogateescape_errors,
            UnicodeTranslateError("\udc80", 0, 1, "ouch")
        )
        # Use the correct exception
        for s in ("a", "\udc7f", "\udd00"):
            with self.subTest(str=s):
                self.assertRaises(
                    UnicodeEncodeError,
                    surrogateescape_errors,
                    UnicodeEncodeError("ascii", s, 0, 1, "ouch")
                )
        self.assertEqual(
            surrogateescape_errors(
                UnicodeEncodeError("ascii", "a\udc80b", 1, 2, "ouch")),
            (b"\x80", 2)
        )
        self.assertRaises(
            UnicodeDecodeError,
            surrogateescape_errors,
            UnicodeDecodeError("ascii", bytearray(b"a"), 0, 1, "ouch")
        )
        self.assertEqual(
            surrogateescape_errors(
                UnicodeDecodeError("ascii", bytearray(b"a\x80b"), 1, 2, "ouch")),
            ("\udc80", 2)
        )

    def test_badandgoodsurrogatepassexceptions(self):
        surrogatepass_errors = codecs.lookup_error('surrogatepass')
        # "surrogatepass" complains about a non-exception passed in
        self.assertRaises(
           TypeError,
           surrogatepass_errors,
           42
        )
        # "surrogatepass" complains about the wrong exception types
        self.assertRaises(
           TypeError,
           surrogatepass_errors,
           UnicodeError("ouch")
        )
        # "surrogatepass" can not be used for translating
        self.assertRaises(
            TypeError,
            surrogatepass_errors,
            UnicodeTranslateError("\ud800", 0, 1, "ouch")
        )
        # Use the correct exception
        for enc in ("utf-8", "utf-16le", "utf-16be", "utf-32le", "utf-32be"):
            with self.subTest(encoding=enc):
                self.assertRaises(
                    UnicodeEncodeError,
                    surrogatepass_errors,
                    UnicodeEncodeError(enc, "a", 0, 1, "ouch")
                )
                self.assertRaises(
                    UnicodeDecodeError,
                    surrogatepass_errors,
                    UnicodeDecodeError(enc, "a".encode(enc), 0, 1, "ouch")
                )
        for s in ("\ud800", "\udfff", "\ud800\udfff"):
            with self.subTest(str=s):
                self.assertRaises(
                    UnicodeEncodeError,
                    surrogatepass_errors,
                    UnicodeEncodeError("ascii", s, 0, len(s), "ouch")
                )
        tests = [
            ("utf-8", "\ud800", b'\xed\xa0\x80', 3),
            ("utf-16le", "\ud800", b'\x00\xd8', 2),
            ("utf-16be", "\ud800", b'\xd8\x00', 2),
            ("utf-32le", "\ud800", b'\x00\xd8\x00\x00', 4),
            ("utf-32be", "\ud800", b'\x00\x00\xd8\x00', 4),
            ("utf-8", "\udfff", b'\xed\xbf\xbf', 3),
            ("utf-16le", "\udfff", b'\xff\xdf', 2),
            ("utf-16be", "\udfff", b'\xdf\xff', 2),
            ("utf-32le", "\udfff", b'\xff\xdf\x00\x00', 4),
            ("utf-32be", "\udfff", b'\x00\x00\xdf\xff', 4),
            ("utf-8", "\ud800\udfff", b'\xed\xa0\x80\xed\xbf\xbf', 3),
            ("utf-16le", "\ud800\udfff", b'\x00\xd8\xff\xdf', 2),
            ("utf-16be", "\ud800\udfff", b'\xd8\x00\xdf\xff', 2),
            ("utf-32le", "\ud800\udfff", b'\x00\xd8\x00\x00\xff\xdf\x00\x00', 4),
            ("utf-32be", "\ud800\udfff", b'\x00\x00\xd8\x00\x00\x00\xdf\xff', 4),
        ]
        for enc, s, b, n in tests:
            with self.subTest(encoding=enc, str=s, bytes=b):
                self.assertEqual(
                    surrogatepass_errors(
                        UnicodeEncodeError(enc, "a" + s + "b",
                                           1, 1 + len(s), "ouch")),
                    (b, 1 + len(s))
                )
                self.assertEqual(
                    surrogatepass_errors(
                        UnicodeDecodeError(enc, bytearray(b"a" + b[:n] + b"b"),
                                           1, 1 + n, "ouch")),
                    (s[:1], 1 + n)
                )

    def test_badhandlerresults(self):
        results = ( 42, "foo", (1,2,3), ("foo", 1, 3), ("foo", None), ("foo",), ("foo", 1, 3), ("foo", None), ("foo",) )
        encs = ("ascii", "latin-1", "iso-8859-1", "iso-8859-15")

        for res in results:
            codecs.register_error("test.badhandler", lambda x: res)
            for enc in encs:
                self.assertRaises(
                    TypeError,
                    "\u3042".encode,
                    enc,
                    "test.badhandler"
                )
            for (enc, bytes) in (
                ("ascii", b"\xff"),
                ("utf-8", b"\xff"),
                ("utf-7", b"+x-"),
            ):
                self.assertRaises(
                    TypeError,
                    bytes.decode,
                    enc,
                    "test.badhandler"
                )

    def test_lookup(self):
        self.assertEqual(codecs.strict_errors, codecs.lookup_error("strict"))
        self.assertEqual(codecs.ignore_errors, codecs.lookup_error("ignore"))
        self.assertEqual(codecs.strict_errors, codecs.lookup_error("strict"))
        self.assertEqual(
            codecs.xmlcharrefreplace_errors,
            codecs.lookup_error("xmlcharrefreplace")
        )
        self.assertEqual(
            codecs.backslashreplace_errors,
            codecs.lookup_error("backslashreplace")
        )
        self.assertEqual(
            codecs.namereplace_errors,
            codecs.lookup_error("namereplace")
        )

    def test_encode_nonascii_replacement(self):
        def handle(exc):
            if isinstance(exc, UnicodeEncodeError):
                return (repl, exc.end)
            raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error("test.replacing", handle)

        for enc, input, repl in (
                ("ascii", "[¤]", "abc"),
                ("iso-8859-1", "[€]", "½¾"),
                ("iso-8859-15", "[¤]", "œŸ"),
        ):
            res = input.encode(enc, "test.replacing")
            self.assertEqual(res, ("[" + repl + "]").encode(enc))

        for enc, input, repl in (
                ("utf-8", "[\udc80]", "\U0001f40d"),
                ("utf-16", "[\udc80]", "\U0001f40d"),
                ("utf-32", "[\udc80]", "\U0001f40d"),
        ):
            with self.subTest(encoding=enc):
                with self.assertRaises(UnicodeEncodeError) as cm:
                    input.encode(enc, "test.replacing")
                exc = cm.exception
                self.assertEqual(exc.start, 1)
                self.assertEqual(exc.end, 2)
                self.assertEqual(exc.object, input)

    def test_encode_unencodable_replacement(self):
        def unencrepl(exc):
            if isinstance(exc, UnicodeEncodeError):
                return (repl, exc.end)
            else:
                raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error("test.unencreplhandler", unencrepl)

        for enc, input, repl in (
                ("ascii", "[¤]", "½"),
                ("iso-8859-1", "[€]", "œ"),
                ("iso-8859-15", "[¤]", "½"),
                ("utf-8", "[\udc80]", "\udcff"),
                ("utf-16", "[\udc80]", "\udcff"),
                ("utf-32", "[\udc80]", "\udcff"),
        ):
            with self.subTest(encoding=enc):
                with self.assertRaises(UnicodeEncodeError) as cm:
                    input.encode(enc, "test.unencreplhandler")
                exc = cm.exception
                self.assertEqual(exc.start, 1)
                self.assertEqual(exc.end, 2)
                self.assertEqual(exc.object, input)

    def test_encode_bytes_replacement(self):
        def handle(exc):
            if isinstance(exc, UnicodeEncodeError):
                return (repl, exc.end)
            raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error("test.replacing", handle)

        # It works even if the bytes sequence is not decodable.
        for enc, input, repl in (
                ("ascii", "[¤]", b"\xbd\xbe"),
                ("iso-8859-1", "[€]", b"\xbd\xbe"),
                ("iso-8859-15", "[¤]", b"\xbd\xbe"),
                ("utf-8", "[\udc80]", b"\xbd\xbe"),
                ("utf-16le", "[\udc80]", b"\xbd\xbe"),
                ("utf-16be", "[\udc80]", b"\xbd\xbe"),
                ("utf-32le", "[\udc80]", b"\xbc\xbd\xbe\xbf"),
                ("utf-32be", "[\udc80]", b"\xbc\xbd\xbe\xbf"),
        ):
            with self.subTest(encoding=enc):
                res = input.encode(enc, "test.replacing")
                self.assertEqual(res, "[".encode(enc) + repl + "]".encode(enc))

    def test_encode_odd_bytes_replacement(self):
        def handle(exc):
            if isinstance(exc, UnicodeEncodeError):
                return (repl, exc.end)
            raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error("test.replacing", handle)

        input = "[\udc80]"
        # Tests in which the replacement bytestring contains not whole number
        # of code units.
        for enc, repl in (
            *itertools.product(("utf-16le", "utf-16be"),
                               [b"a", b"abc"]),
            *itertools.product(("utf-32le", "utf-32be"),
                               [b"a", b"ab", b"abc", b"abcde"]),
        ):
            with self.subTest(encoding=enc, repl=repl):
                with self.assertRaises(UnicodeEncodeError) as cm:
                    input.encode(enc, "test.replacing")
                exc = cm.exception
                self.assertEqual(exc.start, 1)
                self.assertEqual(exc.end, 2)
                self.assertEqual(exc.object, input)
                self.assertEqual(exc.reason, "surrogates not allowed")

    def test_badregistercall(self):
        # enhance coverage of:
        # Modules/_codecsmodule.c::register_error()
        # Python/codecs.c::PyCodec_RegisterError()
        self.assertRaises(TypeError, codecs.register_error, 42)
        self.assertRaises(TypeError, codecs.register_error, "test.dummy", 42)

    def test_badlookupcall(self):
        # enhance coverage of:
        # Modules/_codecsmodule.c::lookup_error()
        self.assertRaises(TypeError, codecs.lookup_error)

    def test_unknownhandler(self):
        # enhance coverage of:
        # Modules/_codecsmodule.c::lookup_error()
        self.assertRaises(LookupError, codecs.lookup_error, "test.unknown")

    def test_xmlcharrefvalues(self):
        # enhance coverage of:
        # Python/codecs.c::PyCodec_XMLCharRefReplaceErrors()
        # and inline implementations
        v = (1, 5, 10, 50, 100, 500, 1000, 5000, 10000, 50000, 100000,
             500000, 1000000)
        s = "".join([chr(x) for x in v])
        codecs.register_error("test.xmlcharrefreplace", codecs.xmlcharrefreplace_errors)
        for enc in ("ascii", "iso-8859-15"):
            for err in ("xmlcharrefreplace", "test.xmlcharrefreplace"):
                s.encode(enc, err)

    def test_decodehelper(self):
        # enhance coverage of:
        # Objects/unicodeobject.c::unicode_decode_call_errorhandler()
        # and callers
        self.assertRaises(LookupError, b"\xff".decode, "ascii", "test.unknown")

        def baddecodereturn1(exc):
            return 42
        codecs.register_error("test.baddecodereturn1", baddecodereturn1)
        self.assertRaises(TypeError, b"\xff".decode, "ascii", "test.baddecodereturn1")
        self.assertRaises(TypeError, b"\\".decode, "unicode-escape", "test.baddecodereturn1")
        self.assertRaises(TypeError, b"\\x0".decode, "unicode-escape", "test.baddecodereturn1")
        self.assertRaises(TypeError, b"\\x0y".decode, "unicode-escape", "test.baddecodereturn1")
        self.assertRaises(TypeError, b"\\Uffffeeee".decode, "unicode-escape", "test.baddecodereturn1")
        self.assertRaises(TypeError, b"\\uyyyy".decode, "raw-unicode-escape", "test.baddecodereturn1")

        def baddecodereturn2(exc):
            return ("?", None)
        codecs.register_error("test.baddecodereturn2", baddecodereturn2)
        self.assertRaises(TypeError, b"\xff".decode, "ascii", "test.baddecodereturn2")

        handler = PosReturn()
        codecs.register_error("test.posreturn", handler.handle)

        # Valid negative position
        handler.pos = -1
        self.assertEqual(b"\xff0".decode("ascii", "test.posreturn"), "<?>0")

        # Valid negative position
        handler.pos = -2
        self.assertEqual(b"\xff0".decode("ascii", "test.posreturn"), "<?><?>")

        # Negative position out of bounds
        handler.pos = -3
        self.assertRaises(IndexError, b"\xff0".decode, "ascii", "test.posreturn")

        # Valid positive position
        handler.pos = 1
        self.assertEqual(b"\xff0".decode("ascii", "test.posreturn"), "<?>0")

        # Largest valid positive position (one beyond end of input)
        handler.pos = 2
        self.assertEqual(b"\xff0".decode("ascii", "test.posreturn"), "<?>")

        # Invalid positive position
        handler.pos = 3
        self.assertRaises(IndexError, b"\xff0".decode, "ascii", "test.posreturn")

        # Restart at the "0"
        handler.pos = 6
        self.assertEqual(b"\\uyyyy0".decode("raw-unicode-escape", "test.posreturn"), "<?>0")

        class D(dict):
            def __getitem__(self, key):
                raise ValueError
        self.assertRaises(UnicodeError, codecs.charmap_decode, b"\xff", "strict", {0xff: None})
        self.assertRaises(ValueError, codecs.charmap_decode, b"\xff", "strict", D())
        self.assertRaises(TypeError, codecs.charmap_decode, b"\xff", "strict", {0xff: sys.maxunicode+1})

    def test_encodehelper(self):
        # enhance coverage of:
        # Objects/unicodeobject.c::unicode_encode_call_errorhandler()
        # and callers
        self.assertRaises(LookupError, "\xff".encode, "ascii", "test.unknown")

        def badencodereturn1(exc):
            return 42
        codecs.register_error("test.badencodereturn1", badencodereturn1)
        self.assertRaises(TypeError, "\xff".encode, "ascii", "test.badencodereturn1")

        def badencodereturn2(exc):
            return ("?", None)
        codecs.register_error("test.badencodereturn2", badencodereturn2)
        self.assertRaises(TypeError, "\xff".encode, "ascii", "test.badencodereturn2")

        handler = PosReturn()
        codecs.register_error("test.posreturn", handler.handle)

        # Valid negative position
        handler.pos = -1
        self.assertEqual("\xff0".encode("ascii", "test.posreturn"), b"<?>0")

        # Valid negative position
        handler.pos = -2
        self.assertEqual("\xff0".encode("ascii", "test.posreturn"), b"<?><?>")

        # Negative position out of bounds
        handler.pos = -3
        self.assertRaises(IndexError, "\xff0".encode, "ascii", "test.posreturn")

        # Valid positive position
        handler.pos = 1
        self.assertEqual("\xff0".encode("ascii", "test.posreturn"), b"<?>0")

        # Largest valid positive position (one beyond end of input
        handler.pos = 2
        self.assertEqual("\xff0".encode("ascii", "test.posreturn"), b"<?>")

        # Invalid positive position
        handler.pos = 3
        self.assertRaises(IndexError, "\xff0".encode, "ascii", "test.posreturn")

        handler.pos = 0

        class D(dict):
            def __getitem__(self, key):
                raise ValueError
        for err in ("strict", "replace", "xmlcharrefreplace",
                    "backslashreplace", "namereplace", "test.posreturn"):
            self.assertRaises(UnicodeError, codecs.charmap_encode, "\xff", err, {0xff: None})
            self.assertRaises(ValueError, codecs.charmap_encode, "\xff", err, D())
            self.assertRaises(TypeError, codecs.charmap_encode, "\xff", err, {0xff: 300})

    def test_decodehelper_bug36819(self):
        handler = RepeatedPosReturn("x")
        codecs.register_error("test.bug36819", handler.handle)

        testcases = [
            ("ascii", b"\xff"),
            ("utf-8", b"\xff"),
            ("utf-16be", b'\xdc\x80'),
            ("utf-32be", b'\x00\x00\xdc\x80'),
            ("iso-8859-6", b"\xff"),
        ]
        for enc, bad in testcases:
            input = "abcd".encode(enc) + bad
            with self.subTest(encoding=enc):
                handler.count = 50
                decoded = input.decode(enc, "test.bug36819")
                self.assertEqual(decoded, 'abcdx' * 51)

    def test_encodehelper_bug36819(self):
        handler = RepeatedPosReturn()
        codecs.register_error("test.bug36819", handler.handle)

        input = "abcd\udc80"
        encodings = ["ascii", "latin1", "utf-8", "utf-16", "utf-32"]  # built-in
        encodings += ["iso-8859-15"]  # charmap codec
        if sys.platform == 'win32':
            encodings = ["mbcs", "oem"]  # code page codecs

        handler.repl = "\udcff"
        for enc in encodings:
            with self.subTest(encoding=enc):
                handler.count = 50
                with self.assertRaises(UnicodeEncodeError) as cm:
                    input.encode(enc, "test.bug36819")
                exc = cm.exception
                self.assertEqual(exc.start, 4)
                self.assertEqual(exc.end, 5)
                self.assertEqual(exc.object, input)
        if sys.platform == "win32":
            handler.count = 50
            with self.assertRaises(UnicodeEncodeError) as cm:
                codecs.code_page_encode(437, input, "test.bug36819")
            exc = cm.exception
            self.assertEqual(exc.start, 4)
            self.assertEqual(exc.end, 5)
            self.assertEqual(exc.object, input)

        handler.repl = "x"
        for enc in encodings:
            with self.subTest(encoding=enc):
                # The interpreter should segfault after a handful of attempts.
                # 50 was chosen to try to ensure a segfault without a fix,
                # but not OOM a machine with one.
                handler.count = 50
                encoded = input.encode(enc, "test.bug36819")
                self.assertEqual(encoded.decode(enc), "abcdx" * 51)
        if sys.platform == "win32":
            handler.count = 50
            encoded = codecs.code_page_encode(437, input, "test.bug36819")
            self.assertEqual(encoded[0].decode(), "abcdx" * 51)
            self.assertEqual(encoded[1], len(input))

    def test_translatehelper(self):
        # enhance coverage of:
        # Objects/unicodeobject.c::unicode_encode_call_errorhandler()
        # and callers
        # (Unfortunately the errors argument is not directly accessible
        # from Python, so we can't test that much)
        class D(dict):
            def __getitem__(self, key):
                raise ValueError
        #self.assertRaises(ValueError, "\xff".translate, D())
        self.assertRaises(ValueError, "\xff".translate, {0xff: sys.maxunicode+1})
        self.assertRaises(TypeError, "\xff".translate, {0xff: ()})

    def test_bug828737(self):
        charmap = {
            ord("&"): "&amp;",
            ord("<"): "&lt;",
            ord(">"): "&gt;",
            ord('"'): "&quot;",
        }

        for n in (1, 10, 100, 1000):
            text = 'abc<def>ghi'*n
            text.translate(charmap)

    def test_mutating_decode_handler(self):
        baddata = [
            ("ascii", b"\xff"),
            ("utf-7", b"++"),
            ("utf-8",  b"\xff"),
            ("utf-16", b"\xff"),
            ("utf-32", b"\xff"),
            ("unicode-escape", b"\\u123g"),
            ("raw-unicode-escape", b"\\u123g"),
        ]

        def replacing(exc):
            if isinstance(exc, UnicodeDecodeError):
                exc.object = 42
                return ("\u4242", 0)
            else:
                raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error("test.replacing", replacing)

        for (encoding, data) in baddata:
            with self.assertRaises(TypeError):
                data.decode(encoding, "test.replacing")

        def mutating(exc):
            if isinstance(exc, UnicodeDecodeError):
                exc.object = b""
                return ("\u4242", 0)
            else:
                raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error("test.mutating", mutating)
        # If the decoder doesn't pick up the modified input the following
        # will lead to an endless loop
        for (encoding, data) in baddata:
            self.assertEqual(data.decode(encoding, "test.mutating"), "\u4242")

    def test_mutating_decode_handler_unicode_escape(self):
        decode = codecs.unicode_escape_decode
        def mutating(exc):
            if isinstance(exc, UnicodeDecodeError):
                r = data.get(exc.object[:exc.end])
                if r is not None:
                    exc.object = r[0] + exc.object[exc.end:]
                    return ('\u0404', r[1])
            raise AssertionError("don't know how to handle %r" % exc)

        codecs.register_error('test.mutating2', mutating)
        data = {
            br'\x0': (b'\\', 0),
            br'\x3': (b'xxx\\', 3),
            br'\x5': (b'x\\', 1),
        }
        def check(input, expected, msg):
            with self.assertWarns(DeprecationWarning) as cm:
                self.assertEqual(decode(input, 'test.mutating2'), (expected, len(input)))
            self.assertIn(msg, str(cm.warning))

        check(br'\x0n\z', '\u0404\n\\z', r'"\z" is an invalid escape sequence')
        check(br'\x0n\501', '\u0404\n\u0141', r'"\501" is an invalid octal escape sequence')
        check(br'\x0z', '\u0404\\z', r'"\z" is an invalid escape sequence')

        check(br'\x3n\zr', '\u0404\n\\zr', r'"\z" is an invalid escape sequence')
        check(br'\x3zr', '\u0404\\zr', r'"\z" is an invalid escape sequence')
        check(br'\x3z5', '\u0404\\z5', r'"\z" is an invalid escape sequence')
        check(memoryview(br'\x3z5x')[:-1], '\u0404\\z5', r'"\z" is an invalid escape sequence')
        check(memoryview(br'\x3z5xy')[:-2], '\u0404\\z5', r'"\z" is an invalid escape sequence')

        check(br'\x5n\z', '\u0404\n\\z', r'"\z" is an invalid escape sequence')
        check(br'\x5n\501', '\u0404\n\u0141', r'"\501" is an invalid octal escape sequence')
        check(br'\x5z', '\u0404\\z', r'"\z" is an invalid escape sequence')
        check(memoryview(br'\x5zy')[:-1], '\u0404\\z', r'"\z" is an invalid escape sequence')

    # issue32583
    def test_crashing_decode_handler(self):
        # better generating one more character to fill the extra space slot
        # so in debug build it can steadily fail
        def forward_shorter_than_end(exc):
            if isinstance(exc, UnicodeDecodeError):
                # size one character, 0 < forward < exc.end
                return ('\ufffd', exc.start+1)
            else:
                raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error(
            "test.forward_shorter_than_end", forward_shorter_than_end)

        self.assertEqual(
            b'\xd8\xd8\xd8\xd8\xd8\x00\x00\x00'.decode(
                'utf-16-le', 'test.forward_shorter_than_end'),
            '\ufffd\ufffd\ufffd\ufffd\xd8\x00'
        )
        self.assertEqual(
            b'\xd8\xd8\xd8\xd8\x00\xd8\x00\x00'.decode(
                'utf-16-be', 'test.forward_shorter_than_end'),
            '\ufffd\ufffd\ufffd\ufffd\xd8\x00'
        )
        self.assertEqual(
            b'\x11\x11\x11\x11\x11\x00\x00\x00\x00\x00\x00'.decode(
                'utf-32-le', 'test.forward_shorter_than_end'),
            '\ufffd\ufffd\ufffd\u1111\x00'
        )
        self.assertEqual(
            b'\x11\x11\x11\x00\x00\x11\x11\x00\x00\x00\x00'.decode(
                'utf-32-be', 'test.forward_shorter_than_end'),
            '\ufffd\ufffd\ufffd\u1111\x00'
        )

        def replace_with_long(exc):
            if isinstance(exc, UnicodeDecodeError):
                exc.object = b"\x00" * 8
                return ('\ufffd', exc.start)
            else:
                raise TypeError("don't know how to handle %r" % exc)
        codecs.register_error("test.replace_with_long", replace_with_long)

        self.assertEqual(
            b'\x00'.decode('utf-16', 'test.replace_with_long'),
            '\ufffd\x00\x00\x00\x00'
        )
        self.assertEqual(
            b'\x00'.decode('utf-32', 'test.replace_with_long'),
            '\ufffd\x00\x00'
        )

    def test_fake_error_class(self):
        handlers = [
            codecs.strict_errors,
            codecs.ignore_errors,
            codecs.replace_errors,
            codecs.backslashreplace_errors,
            codecs.namereplace_errors,
            codecs.xmlcharrefreplace_errors,
            codecs.lookup_error('surrogateescape'),
            codecs.lookup_error('surrogatepass'),
        ]
        for cls in UnicodeEncodeError, UnicodeDecodeError, UnicodeTranslateError:
            class FakeUnicodeError(str):
                __class__ = cls
            for handler in handlers:
                with self.subTest(handler=handler, error_class=cls):
                    self.assertRaises(TypeError, handler, FakeUnicodeError())
            class FakeUnicodeError(Exception):
                __class__ = cls
            for handler in handlers:
                with self.subTest(handler=handler, error_class=cls):
                    with self.assertRaises((TypeError, FakeUnicodeError)):
                        handler(FakeUnicodeError())

    def test_reject_unregister_builtin_error_handler(self):
        for name in [
            'strict', 'ignore', 'replace', 'backslashreplace', 'namereplace',
            'xmlcharrefreplace', 'surrogateescape', 'surrogatepass',
        ]:
            with self.subTest(name):
                self.assertRaises(ValueError, _codecs_unregister_error, name)

    def test_unregister_custom_error_handler(self):
        def custom_handler(exc):
            raise exc

        custom_name = 'test.test_unregister_custom_error_handler'
        self.assertRaises(LookupError, codecs.lookup_error, custom_name)
        codecs.register_error(custom_name, custom_handler)
        self.assertIs(codecs.lookup_error(custom_name), custom_handler)
        self.assertTrue(_codecs_unregister_error(custom_name))
        self.assertRaises(LookupError, codecs.lookup_error, custom_name)

    def test_unregister_custom_unknown_error_handler(self):
        unknown_name = 'test.test_unregister_custom_unknown_error_handler'
        self.assertRaises(LookupError, codecs.lookup_error, unknown_name)
        self.assertFalse(_codecs_unregister_error(unknown_name))
        self.assertRaises(LookupError, codecs.lookup_error, unknown_name)


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