diff --git a/Lib/codecs.py b/Lib/codecs.py
index f6c2448..b150d64 100644
--- a/Lib/codecs.py
+++ b/Lib/codecs.py
@@ -396,6 +396,8 @@
 
 class StreamReader(Codec):
 
+    charbuffertype = str
+
     def __init__(self, stream, errors='strict'):
 
         """ Creates a StreamReader instance.
@@ -417,9 +419,8 @@
         self.stream = stream
         self.errors = errors
         self.bytebuffer = b""
-        # For str->str decoding this will stay a str
-        # For str->unicode decoding the first read will promote it to unicode
-        self.charbuffer = ""
+        self._empty_charbuffer = self.charbuffertype()
+        self.charbuffer = self._empty_charbuffer
         self.linebuffer = None
 
     def decode(self, input, errors='strict'):
@@ -455,7 +456,7 @@
         """
         # If we have lines cached, first merge them back into characters
         if self.linebuffer:
-            self.charbuffer = "".join(self.linebuffer)
+            self.charbuffer = self._empty_charbuffer.join(self.linebuffer)
             self.linebuffer = None
 
         # read until we get the required number of characters (if available)
@@ -498,7 +499,7 @@
         if chars < 0:
             # Return everything we've got
             result = self.charbuffer
-            self.charbuffer = ""
+            self.charbuffer = self._empty_charbuffer
         else:
             # Return the first chars characters
             result = self.charbuffer[:chars]
@@ -529,7 +530,7 @@
             return line
 
         readsize = size or 72
-        line = ""
+        line = self._empty_charbuffer
         # If size is given, we call read() only once
         while True:
             data = self.read(readsize, firstline=True)
@@ -537,7 +538,8 @@
                 # If we're at a "\r" read one extra character (which might
                 # be a "\n") to get a proper line ending. If the stream is
                 # temporarily exhausted we return the wrong line ending.
-                if data.endswith("\r"):
+                if (isinstance(data, str) and data.endswith("\r")) or \
+                   (isinstance(data, bytes) and data.endswith(b"\r")):
                     data += self.read(size=1, chars=1)
 
             line += data
@@ -563,7 +565,8 @@
                 line0withoutend = lines[0].splitlines(False)[0]
                 if line0withend != line0withoutend: # We really have a line end
                     # Put the rest back together and keep it until the next call
-                    self.charbuffer = "".join(lines[1:]) + self.charbuffer
+                    self.charbuffer = self._empty_charbuffer.join(lines[1:]) + \
+                                      self.charbuffer
                     if keepends:
                         line = line0withend
                     else:
@@ -574,7 +577,7 @@
                 if line and not keepends:
                     line = line.splitlines(False)[0]
                 break
-            if readsize<8000:
+            if readsize < 8000:
                 readsize *= 2
         return line
 
@@ -603,7 +606,7 @@
 
         """
         self.bytebuffer = b""
-        self.charbuffer = ""
+        self.charbuffer = self._empty_charbuffer
         self.linebuffer = None
 
     def seek(self, offset, whence=0):
diff --git a/Lib/encodings/aliases.py b/Lib/encodings/aliases.py
index 235deb5..331095b 100644
--- a/Lib/encodings/aliases.py
+++ b/Lib/encodings/aliases.py
@@ -33,9 +33,9 @@
     'us'                 : 'ascii',
     'us_ascii'           : 'ascii',
 
-    ## base64_codec codec
-    #'base64'             : 'base64_codec',
-    #'base_64'            : 'base64_codec',
+    # base64_codec codec
+    'base64'             : 'base64_codec',
+    'base_64'            : 'base64_codec',
 
     # big5 codec
     'big5_tw'            : 'big5',
@@ -45,8 +45,8 @@
     'big5_hkscs'         : 'big5hkscs',
     'hkscs'              : 'big5hkscs',
 
-    ## bz2_codec codec
-    #'bz2'                : 'bz2_codec',
+    # bz2_codec codec
+    'bz2'                : 'bz2_codec',
 
     # cp037 codec
     '037'                : 'cp037',
@@ -248,8 +248,8 @@
     'cp936'              : 'gbk',
     'ms936'              : 'gbk',
 
-    ## hex_codec codec
-    #'hex'                : 'hex_codec',
+    # hex_codec codec
+    'hex'                : 'hex_codec',
 
     # hp_roman8 codec
     'roman8'             : 'hp_roman8',
@@ -450,13 +450,13 @@
     'cp154'              : 'ptcp154',
     'cyrillic_asian'     : 'ptcp154',
 
-    ## quopri_codec codec
-    #'quopri'             : 'quopri_codec',
-    #'quoted_printable'   : 'quopri_codec',
-    #'quotedprintable'    : 'quopri_codec',
+    # quopri_codec codec
+    'quopri'             : 'quopri_codec',
+    'quoted_printable'   : 'quopri_codec',
+    'quotedprintable'    : 'quopri_codec',
 
-    ## rot_13 codec
-    #'rot13'              : 'rot_13',
+    # rot_13 codec
+    'rot13'              : 'rot_13',
 
     # shift_jis codec
     'csshiftjis'         : 'shift_jis',
@@ -518,12 +518,12 @@
     'utf8_ucs2'          : 'utf_8',
     'utf8_ucs4'          : 'utf_8',
 
-    ## uu_codec codec
-    #'uu'                 : 'uu_codec',
+    # uu_codec codec
+    'uu'                 : 'uu_codec',
 
-    ## zlib_codec codec
-    #'zip'                : 'zlib_codec',
-    #'zlib'               : 'zlib_codec',
+    # zlib_codec codec
+    'zip'                : 'zlib_codec',
+    'zlib'               : 'zlib_codec',
 
     # temporary mac CJK aliases, will be replaced by proper codecs in 3.1
     'x_mac_japanese'      : 'shift_jis',
diff --git a/Lib/encodings/base64_codec.py b/Lib/encodings/base64_codec.py
new file mode 100644
index 0000000..e8b19ee
--- /dev/null
+++ b/Lib/encodings/base64_codec.py
@@ -0,0 +1,55 @@
+"""Python 'base64_codec' Codec - base64 content transfer encoding.
+
+This codec de/encodes from bytes to bytes and is therefore usable with
+bytes.transform() and bytes.untransform().
+
+Written by Marc-Andre Lemburg (mal@lemburg.com).
+"""
+
+import codecs
+import base64
+
+### Codec APIs
+
+def base64_encode(input, errors='strict'):
+    assert errors == 'strict'
+    return (base64.encodestring(input), len(input))
+
+def base64_decode(input, errors='strict'):
+    assert errors == 'strict'
+    return (base64.decodestring(input), len(input))
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return base64_encode(input, errors)
+    def decode(self, input, errors='strict'):
+        return base64_decode(input, errors)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def encode(self, input, final=False):
+        assert self.errors == 'strict'
+        return base64.encodestring(input)
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def decode(self, input, final=False):
+        assert self.errors == 'strict'
+        return base64.decodestring(input)
+
+class StreamWriter(Codec, codecs.StreamWriter):
+    charbuffertype = bytes
+
+class StreamReader(Codec, codecs.StreamReader):
+    charbuffertype = bytes
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='base64',
+        encode=base64_encode,
+        decode=base64_decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamwriter=StreamWriter,
+        streamreader=StreamReader,
+    )
diff --git a/Lib/encodings/bz2_codec.py b/Lib/encodings/bz2_codec.py
new file mode 100644
index 0000000..e65d226
--- /dev/null
+++ b/Lib/encodings/bz2_codec.py
@@ -0,0 +1,77 @@
+"""Python 'bz2_codec' Codec - bz2 compression encoding.
+
+This codec de/encodes from bytes to bytes and is therefore usable with
+bytes.transform() and bytes.untransform().
+
+Adapted by Raymond Hettinger from zlib_codec.py which was written
+by Marc-Andre Lemburg (mal@lemburg.com).
+"""
+
+import codecs
+import bz2 # this codec needs the optional bz2 module !
+
+### Codec APIs
+
+def bz2_encode(input, errors='strict'):
+    assert errors == 'strict'
+    return (bz2.compress(input), len(input))
+
+def bz2_decode(input, errors='strict'):
+    assert errors == 'strict'
+    return (bz2.decompress(input), len(input))
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return bz2_encode(input, errors)
+    def decode(self, input, errors='strict'):
+        return bz2_decode(input, errors)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def __init__(self, errors='strict'):
+        assert errors == 'strict'
+        self.errors = errors
+        self.compressobj = bz2.BZ2Compressor()
+
+    def encode(self, input, final=False):
+        if final:
+            c = self.compressobj.compress(input)
+            return c + self.compressobj.flush()
+        else:
+            return self.compressobj.compress(input)
+
+    def reset(self):
+        self.compressobj = bz2.BZ2Compressor()
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def __init__(self, errors='strict'):
+        assert errors == 'strict'
+        self.errors = errors
+        self.decompressobj = bz2.BZ2Decompressor()
+
+    def decode(self, input, final=False):
+        try:
+            return self.decompressobj.decompress(input)
+        except EOFError:
+            return ''
+
+    def reset(self):
+        self.decompressobj = bz2.BZ2Decompressor()
+
+class StreamWriter(Codec, codecs.StreamWriter):
+    charbuffertype = bytes
+
+class StreamReader(Codec, codecs.StreamReader):
+    charbuffertype = bytes
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name="bz2",
+        encode=bz2_encode,
+        decode=bz2_decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamwriter=StreamWriter,
+        streamreader=StreamReader,
+    )
diff --git a/Lib/encodings/hex_codec.py b/Lib/encodings/hex_codec.py
new file mode 100644
index 0000000..e003fc3
--- /dev/null
+++ b/Lib/encodings/hex_codec.py
@@ -0,0 +1,55 @@
+"""Python 'hex_codec' Codec - 2-digit hex content transfer encoding.
+
+This codec de/encodes from bytes to bytes and is therefore usable with
+bytes.transform() and bytes.untransform().
+
+Written by Marc-Andre Lemburg (mal@lemburg.com).
+"""
+
+import codecs
+import binascii
+
+### Codec APIs
+
+def hex_encode(input, errors='strict'):
+    assert errors == 'strict'
+    return (binascii.b2a_hex(input), len(input))
+
+def hex_decode(input, errors='strict'):
+    assert errors == 'strict'
+    return (binascii.a2b_hex(input), len(input))
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return hex_encode(input, errors)
+    def decode(self, input, errors='strict'):
+        return hex_decode(input, errors)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def encode(self, input, final=False):
+        assert self.errors == 'strict'
+        return binascii.b2a_hex(input)
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def decode(self, input, final=False):
+        assert self.errors == 'strict'
+        return binascii.a2b_hex(input)
+
+class StreamWriter(Codec, codecs.StreamWriter):
+    charbuffertype = bytes
+
+class StreamReader(Codec, codecs.StreamReader):
+    charbuffertype = bytes
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='hex',
+        encode=hex_encode,
+        decode=hex_decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamwriter=StreamWriter,
+        streamreader=StreamReader,
+    )
diff --git a/Lib/encodings/quopri_codec.py b/Lib/encodings/quopri_codec.py
new file mode 100644
index 0000000..9243fc4
--- /dev/null
+++ b/Lib/encodings/quopri_codec.py
@@ -0,0 +1,56 @@
+"""Codec for quoted-printable encoding.
+
+This codec de/encodes from bytes to bytes and is therefore usable with
+bytes.transform() and bytes.untransform().
+"""
+
+import codecs
+import quopri
+from io import BytesIO
+
+def quopri_encode(input, errors='strict'):
+    assert errors == 'strict'
+    f = BytesIO(input)
+    g = BytesIO()
+    quopri.encode(f, g, 1)
+    return (g.getvalue(), len(input))
+
+def quopri_decode(input, errors='strict'):
+    assert errors == 'strict'
+    f = BytesIO(input)
+    g = BytesIO()
+    quopri.decode(f, g)
+    return (g.getvalue(), len(input))
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return quopri_encode(input, errors)
+    def decode(self, input, errors='strict'):
+        return quopri_decode(input, errors)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def encode(self, input, final=False):
+        return quopri_encode(input, self.errors)[0]
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def decode(self, input, final=False):
+        return quopri_decode(input, self.errors)[0]
+
+class StreamWriter(Codec, codecs.StreamWriter):
+    charbuffertype = bytes
+
+class StreamReader(Codec, codecs.StreamReader):
+    charbuffertype = bytes
+
+# encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='quopri',
+        encode=quopri_encode,
+        decode=quopri_decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamwriter=StreamWriter,
+        streamreader=StreamReader,
+    )
diff --git a/Lib/encodings/rot_13.py b/Lib/encodings/rot_13.py
new file mode 100755
index 0000000..3140c14
--- /dev/null
+++ b/Lib/encodings/rot_13.py
@@ -0,0 +1,113 @@
+#!/usr/bin/env python
+""" Python Character Mapping Codec for ROT13.
+
+This codec de/encodes from str to str and is therefore usable with
+str.transform() and str.untransform().
+
+Written by Marc-Andre Lemburg (mal@lemburg.com).
+"""
+
+import codecs
+
+### Codec APIs
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return (input.translate(rot13_map), len(input))
+
+    def decode(self, input, errors='strict'):
+        return (input.translate(rot13_map), len(input))
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def encode(self, input, final=False):
+        return input.translate(rot13_map)
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def decode(self, input, final=False):
+        return input.translate(rot13_map)
+
+class StreamWriter(Codec,codecs.StreamWriter):
+    pass
+
+class StreamReader(Codec,codecs.StreamReader):
+    pass
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='rot-13',
+        encode=Codec().encode,
+        decode=Codec().decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamwriter=StreamWriter,
+        streamreader=StreamReader,
+    )
+
+### Map
+
+rot13_map = codecs.make_identity_dict(range(256))
+rot13_map.update({
+   0x0041: 0x004e,
+   0x0042: 0x004f,
+   0x0043: 0x0050,
+   0x0044: 0x0051,
+   0x0045: 0x0052,
+   0x0046: 0x0053,
+   0x0047: 0x0054,
+   0x0048: 0x0055,
+   0x0049: 0x0056,
+   0x004a: 0x0057,
+   0x004b: 0x0058,
+   0x004c: 0x0059,
+   0x004d: 0x005a,
+   0x004e: 0x0041,
+   0x004f: 0x0042,
+   0x0050: 0x0043,
+   0x0051: 0x0044,
+   0x0052: 0x0045,
+   0x0053: 0x0046,
+   0x0054: 0x0047,
+   0x0055: 0x0048,
+   0x0056: 0x0049,
+   0x0057: 0x004a,
+   0x0058: 0x004b,
+   0x0059: 0x004c,
+   0x005a: 0x004d,
+   0x0061: 0x006e,
+   0x0062: 0x006f,
+   0x0063: 0x0070,
+   0x0064: 0x0071,
+   0x0065: 0x0072,
+   0x0066: 0x0073,
+   0x0067: 0x0074,
+   0x0068: 0x0075,
+   0x0069: 0x0076,
+   0x006a: 0x0077,
+   0x006b: 0x0078,
+   0x006c: 0x0079,
+   0x006d: 0x007a,
+   0x006e: 0x0061,
+   0x006f: 0x0062,
+   0x0070: 0x0063,
+   0x0071: 0x0064,
+   0x0072: 0x0065,
+   0x0073: 0x0066,
+   0x0074: 0x0067,
+   0x0075: 0x0068,
+   0x0076: 0x0069,
+   0x0077: 0x006a,
+   0x0078: 0x006b,
+   0x0079: 0x006c,
+   0x007a: 0x006d,
+})
+
+### Filter API
+
+def rot13(infile, outfile):
+    outfile.write(infile.read().encode('rot-13'))
+
+if __name__ == '__main__':
+    import sys
+    rot13(sys.stdin, sys.stdout)
diff --git a/Lib/encodings/uu_codec.py b/Lib/encodings/uu_codec.py
new file mode 100644
index 0000000..69c6f17
--- /dev/null
+++ b/Lib/encodings/uu_codec.py
@@ -0,0 +1,99 @@
+"""Python 'uu_codec' Codec - UU content transfer encoding.
+
+This codec de/encodes from bytes to bytes and is therefore usable with
+bytes.transform() and bytes.untransform().
+
+Written by Marc-Andre Lemburg (mal@lemburg.com). Some details were
+adapted from uu.py which was written by Lance Ellinghouse and
+modified by Jack Jansen and Fredrik Lundh.
+"""
+
+import codecs
+import binascii
+from io import BytesIO
+
+### Codec APIs
+
+def uu_encode(input, errors='strict', filename='<data>', mode=0o666):
+    assert errors == 'strict'
+    infile = BytesIO(input)
+    outfile = BytesIO()
+    read = infile.read
+    write = outfile.write
+
+    # Encode
+    write(('begin %o %s\n' % (mode & 0o777, filename)).encode('ascii'))
+    chunk = read(45)
+    while chunk:
+        write(binascii.b2a_uu(chunk))
+        chunk = read(45)
+    write(b' \nend\n')
+
+    return (outfile.getvalue(), len(input))
+
+def uu_decode(input, errors='strict'):
+    assert errors == 'strict'
+    infile = BytesIO(input)
+    outfile = BytesIO()
+    readline = infile.readline
+    write = outfile.write
+
+    # Find start of encoded data
+    while 1:
+        s = readline()
+        if not s:
+            raise ValueError('Missing "begin" line in input data')
+        if s[:5] == b'begin':
+            break
+
+    # Decode
+    while True:
+        s = readline()
+        if not s or s == b'end\n':
+            break
+        try:
+            data = binascii.a2b_uu(s)
+        except binascii.Error as v:
+            # Workaround for broken uuencoders by /Fredrik Lundh
+            nbytes = (((ord(s[0])-32) & 63) * 4 + 5) / 3
+            data = binascii.a2b_uu(s[:nbytes])
+            #sys.stderr.write("Warning: %s\n" % str(v))
+        write(data)
+    if not s:
+        raise ValueError('Truncated input data')
+
+    return (outfile.getvalue(), len(input))
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return uu_encode(input, errors)
+
+    def decode(self, input, errors='strict'):
+        return uu_decode(input, errors)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def encode(self, input, final=False):
+        return uu_encode(input, self.errors)[0]
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def decode(self, input, final=False):
+        return uu_decode(input, self.errors)[0]
+
+class StreamWriter(Codec, codecs.StreamWriter):
+    charbuffertype = bytes
+
+class StreamReader(Codec, codecs.StreamReader):
+    charbuffertype = bytes
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='uu',
+        encode=uu_encode,
+        decode=uu_decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamreader=StreamReader,
+        streamwriter=StreamWriter,
+    )
diff --git a/Lib/encodings/zlib_codec.py b/Lib/encodings/zlib_codec.py
new file mode 100644
index 0000000..e0b9cda
--- /dev/null
+++ b/Lib/encodings/zlib_codec.py
@@ -0,0 +1,77 @@
+"""Python 'zlib_codec' Codec - zlib compression encoding.
+
+This codec de/encodes from bytes to bytes and is therefore usable with
+bytes.transform() and bytes.untransform().
+
+Written by Marc-Andre Lemburg (mal@lemburg.com).
+"""
+
+import codecs
+import zlib # this codec needs the optional zlib module !
+
+### Codec APIs
+
+def zlib_encode(input, errors='strict'):
+    assert errors == 'strict'
+    return (zlib.compress(input), len(input))
+
+def zlib_decode(input, errors='strict'):
+    assert errors == 'strict'
+    return (zlib.decompress(input), len(input))
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return zlib_encode(input, errors)
+    def decode(self, input, errors='strict'):
+        return zlib_decode(input, errors)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def __init__(self, errors='strict'):
+        assert errors == 'strict'
+        self.errors = errors
+        self.compressobj = zlib.compressobj()
+
+    def encode(self, input, final=False):
+        if final:
+            c = self.compressobj.compress(input)
+            return c + self.compressobj.flush()
+        else:
+            return self.compressobj.compress(input)
+
+    def reset(self):
+        self.compressobj = zlib.compressobj()
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def __init__(self, errors='strict'):
+        assert errors == 'strict'
+        self.errors = errors
+        self.decompressobj = zlib.decompressobj()
+
+    def decode(self, input, final=False):
+        if final:
+            c = self.decompressobj.decompress(input)
+            return c + self.decompressobj.flush()
+        else:
+            return self.decompressobj.decompress(input)
+
+    def reset(self):
+        self.decompressobj = zlib.decompressobj()
+
+class StreamWriter(Codec, codecs.StreamWriter):
+    charbuffertype = bytes
+
+class StreamReader(Codec, codecs.StreamReader):
+    charbuffertype = bytes
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='zlib',
+        encode=zlib_encode,
+        decode=zlib_decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamreader=StreamReader,
+        streamwriter=StreamWriter,
+    )
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 24ee487..49b50f2 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -207,6 +207,11 @@
         self.assertEqual(b.decode(errors="ignore", encoding="utf8"),
                          "Hello world\n")
 
+    def test_transform(self):
+        b1 = self.type2test(range(256))
+        b2 = b1.transform("base64").untransform("base64")
+        self.assertEqual(b2, b1)
+
     def test_from_int(self):
         b = self.type2test(0)
         self.assertEqual(b, self.type2test())
diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index f989a55..bc29e06 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -1659,6 +1659,67 @@
                 self.assertEqual(f.read(), data * 2)
 
 
+bytes_transform_encodings = [
+    "base64_codec",
+    "uu_codec",
+    "quopri_codec",
+    "hex_codec",
+]
+try:
+    import zlib
+except ImportError:
+    pass
+else:
+    bytes_transform_encodings.append("zlib_codec")
+try:
+    import bz2
+except ImportError:
+    pass
+else:
+    bytes_transform_encodings.append("bz2_codec")
+
+class TransformCodecTest(unittest.TestCase):
+    def test_basics(self):
+        binput = bytes(range(256))
+        ainput = bytearray(binput)
+        for encoding in bytes_transform_encodings:
+            # 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)
+
+            # transform interface
+            boutput = binput.transform(encoding)
+            aoutput = ainput.transform(encoding)
+            self.assertEqual(boutput, aoutput)
+            self.assertIsInstance(boutput, bytes)
+            self.assertIsInstance(aoutput, bytearray)
+            bback = boutput.untransform(encoding)
+            aback = aoutput.untransform(encoding)
+            self.assertEqual(bback, aback)
+            self.assertEqual(bback, binput)
+            self.assertIsInstance(bback, bytes)
+            self.assertIsInstance(aback, bytearray)
+
+    def test_read(self):
+        for encoding in bytes_transform_encodings:
+            sin = b"\x80".transform(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:
+            if encoding in ['uu_codec', 'zlib_codec']:
+                continue
+            sin = b"\x80".transform(encoding)
+            reader = codecs.getreader(encoding)(io.BytesIO(sin))
+            sout = reader.readline()
+            self.assertEqual(sout, b"\x80")
+
+
 def test_main():
     support.run_unittest(
         UTF32Test,
@@ -1686,6 +1747,7 @@
         TypesTest,
         SurrogateEscapeTest,
         BomTest,
+        TransformCodecTest,
     )