SF patch# 1770008 by Christian Heimes (plus some extras).

Completely get rid of StringIO.py and cStringIO.c.

I had to fix a few tests and modules beyond what Christian did, and
invent a few conventions.  E.g. in elementtree, I chose to
write/return Unicode strings whe no encoding is given, but bytes when
an explicit encoding is given.  Also mimetools was made to always
assume binary files.

40 files changed, 215 insertions, 230 deletions

diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index 7bff76f..0ad1f48 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -406,7 +406,7 @@ class AbstractPickleTests(unittest.TestCase):
     # is a mystery.  cPickle also suppresses PUT for objects with a refcount
     # of 1.
     def dont_test_disassembly(self):
-        from cStringIO import StringIO
+        from io import StringIO
         from pickletools import dis
 
         for proto, expected in (0, DATA0_DIS), (1, DATA1_DIS):
@@ -951,8 +951,8 @@ class AbstractPickleModuleTests(unittest.TestCase):
         self.assertEqual(self.module.HIGHEST_PROTOCOL, 2)
 
     def test_callapi(self):
-        from cStringIO import StringIO
-        f = StringIO()
+        from io import BytesIO
+        f = BytesIO()
         # With and without keyword arguments
         self.module.dump(123, f, -1)
         self.module.dump(123, file=f, protocol=-1)
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index 28b82ad..31e4eaf 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -125,7 +125,7 @@ import getopt
 import random
 import warnings
 import re
-import StringIO
+import io
 import traceback
 
 # I see no other way to suppress these warnings;
@@ -537,7 +537,7 @@ def runtest_inner(test, generate, verbose, quiet,
     if verbose:
         cfp = None
     else:
-        cfp = StringIO.StringIO()  # XXX Should use io.StringIO()
+        cfp = io.StringIO()  # XXX Should use io.StringIO()
 
     try:
         save_stdout = sys.stdout
diff --git a/Lib/test/test_StringIO.py b/Lib/test/test_StringIO.py
index 2f4a221..4f3ce83 100644
--- a/Lib/test/test_StringIO.py
+++ b/Lib/test/test_StringIO.py
@@ -2,13 +2,13 @@
 
 import sys
 import unittest
-import StringIO
-import cStringIO
+import io
 from test import test_support
 
 
 class TestGenericStringIO:
-    # use a class variable MODULE to define which module is being tested
+    # use a class variable CLASS to define which class is being tested
+    CLASS = None
 
     # Line of data to test as string
     _line = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!'
@@ -20,7 +20,7 @@ class TestGenericStringIO:
     def setUp(self):
         self._line = self.constructor(self._line)
         self._lines = self.constructor((self._line + '\n') * 5)
-        self._fp = self.MODULE.StringIO(self._lines)
+        self._fp = self.CLASS(self._lines)
 
     def test_reads(self):
         eq = self.assertEqual
@@ -30,7 +30,7 @@ class TestGenericStringIO:
         eq(len(self._fp.readlines(60)), 2)
 
     def test_writes(self):
-        f = self.MODULE.StringIO()
+        f = self.CLASS()
         self.assertRaises(TypeError, f.seek)
         f.write(self._line[:6])
         f.seek(3)
@@ -39,7 +39,7 @@ class TestGenericStringIO:
         self.assertEqual(f.getvalue(), 'abcuvwxyz!')
 
     def test_writelines(self):
-        f = self.MODULE.StringIO()
+        f = self.CLASS()
         f.writelines([self._line[0], self._line[1], self._line[2]])
         f.seek(0)
         self.assertEqual(f.getvalue(), 'abc')
@@ -48,12 +48,12 @@ class TestGenericStringIO:
         def errorGen():
             yield 'a'
             raise KeyboardInterrupt()
-        f = self.MODULE.StringIO()
+        f = self.CLASS()
         self.assertRaises(KeyboardInterrupt, f.writelines, errorGen())
 
     def test_truncate(self):
         eq = self.assertEqual
-        f = self.MODULE.StringIO()
+        f = self.CLASS()
         f.write(self._lines)
         f.seek(10)
         f.truncate()
@@ -62,22 +62,22 @@ class TestGenericStringIO:
         eq(f.getvalue(), 'abcde')
         f.write('xyz')
         eq(f.getvalue(), 'abcdexyz')
-        self.assertRaises(IOError, f.truncate, -1)
+        self.assertRaises(ValueError, f.truncate, -1)
         f.close()
         self.assertRaises(ValueError, f.write, 'frobnitz')
 
     def test_closed_flag(self):
-        f = self.MODULE.StringIO()
+        f = self.CLASS()
         self.assertEqual(f.closed, False)
         f.close()
         self.assertEqual(f.closed, True)
-        f = self.MODULE.StringIO(self.constructor("abc"))
+        f = self.CLASS(self.constructor("abc"))
         self.assertEqual(f.closed, False)
         f.close()
         self.assertEqual(f.closed, True)
 
     def test_isatty(self):
-        f = self.MODULE.StringIO()
+        f = self.CLASS()
         self.assertRaises(TypeError, f.isatty, None)
         self.assertEqual(f.isatty(), False)
         f.close()
@@ -96,10 +96,10 @@ class TestGenericStringIO:
             i += 1
         eq(i, 5)
         self._fp.close()
-        self.assertRaises(ValueError, next, self._fp)
+        self.assertRaises(StopIteration, next, self._fp)
 
-class TestStringIO(TestGenericStringIO, unittest.TestCase):
-    MODULE = StringIO
+class TestioStringIO(TestGenericStringIO, unittest.TestCase):
+    CLASS = io.StringIO
 
     def test_unicode(self):
 
@@ -109,7 +109,7 @@ class TestStringIO(TestGenericStringIO, unittest.TestCase):
         # snippets to larger Unicode strings. This is tested by this
         # method. Note that cStringIO does not support this extension.
 
-        f = self.MODULE.StringIO()
+        f = self.CLASS()
         f.write(self._line[:6])
         f.seek(3)
         f.write(str(self._line[20:26]))
@@ -118,55 +118,10 @@ class TestStringIO(TestGenericStringIO, unittest.TestCase):
         self.assertEqual(s, str('abcuvwxyz!'))
         self.assertEqual(type(s), str)
 
-class TestcStringIO(TestGenericStringIO, unittest.TestCase):
-    MODULE = cStringIO
-    constructor = str8
-
-    def test_unicode(self):
-
-        if not test_support.have_unicode: return
-
-        # The cStringIO module converts Unicode strings to character
-        # strings when writing them to cStringIO objects.
-        # Check that this works.
-
-        f = self.MODULE.StringIO()
-        f.write(str(self._line[:5]))
-        s = f.getvalue()
-        self.assertEqual(s, 'abcde')
-        self.assertEqual(type(s), str8)
-
-        f = self.MODULE.StringIO(str(self._line[:5]))
-        s = f.getvalue()
-        self.assertEqual(s, 'abcde')
-        self.assertEqual(type(s), str8)
-
-        # XXX This no longer fails -- the default encoding is always UTF-8.
-        ##self.assertRaises(UnicodeDecodeError, self.MODULE.StringIO, '\xf4')
-
-class TestBufferStringIO(TestStringIO):
-
-    def constructor(self, s):
-        return buffer(str8(s))
-
-class TestBuffercStringIO(TestcStringIO):
-
-    def constructor(self, s):
-        return buffer(str8(s))
-
 
 def test_main():
-    classes = [
-        TestStringIO,
-        TestcStringIO,
-        ]
-    if not sys.platform.startswith('java'):
-        classes.extend([
-        TestBufferStringIO,
-        TestBuffercStringIO
-        ])
-    test_support.run_unittest(*classes)
+    test_support.run_unittest(TestioStringIO)
 
 
 if __name__ == '__main__':
-    unittest.main()
+    test_main()
diff --git a/Lib/test/test___all__.py b/Lib/test/test___all__.py
index 4cf2e25..99bc330 100644
--- a/Lib/test/test___all__.py
+++ b/Lib/test/test___all__.py
@@ -36,7 +36,6 @@ class AllTest(unittest.TestCase):
         self.check_all("Queue")
         self.check_all("SimpleHTTPServer")
         self.check_all("SocketServer")
-        self.check_all("StringIO")
         self.check_all("UserString")
         self.check_all("aifc")
         self.check_all("base64")
diff --git a/Lib/test/test_atexit.py b/Lib/test/test_atexit.py
index 142e543..76a5036 100644
--- a/Lib/test/test_atexit.py
+++ b/Lib/test/test_atexit.py
@@ -1,6 +1,6 @@
 import sys
 import unittest
-import StringIO
+import io
 import atexit
 from test import test_support
 
@@ -25,7 +25,7 @@ def raise2():
 
 class TestCase(unittest.TestCase):
     def setUp(self):
-        self.stream = StringIO.StringIO()
+        self.stream = io.StringIO()
         sys.stdout = sys.stderr = self.stream
         atexit._clear()
 
diff --git a/Lib/test/test_base64.py b/Lib/test/test_base64.py
index 2f592f1..6f88695 100644
--- a/Lib/test/test_base64.py
+++ b/Lib/test/test_base64.py
@@ -36,23 +36,23 @@ class LegacyBase64TestCase(unittest.TestCase):
 
     def test_encode(self):
         eq = self.assertEqual
-        from cStringIO import StringIO
-        infp = StringIO('abcdefghijklmnopqrstuvwxyz'
-                        'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
-                        '0123456789!@#0^&*();:<>,. []{}')
-        outfp = StringIO()
+        from io import BytesIO
+        infp = BytesIO(b'abcdefghijklmnopqrstuvwxyz'
+                       b'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+                       b'0123456789!@#0^&*();:<>,. []{}')
+        outfp = BytesIO()
         base64.encode(infp, outfp)
         eq(outfp.getvalue(),
-           'YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXpBQkNE'
-           'RUZHSElKS0xNTk9QUVJTVFVWV1hZWjAxMjM0\nNT'
-           'Y3ODkhQCMwXiYqKCk7Ojw+LC4gW117fQ==\n')
+           b'YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXpBQkNE'
+           b'RUZHSElKS0xNTk9QUVJTVFVWV1hZWjAxMjM0\nNT'
+           b'Y3ODkhQCMwXiYqKCk7Ojw+LC4gW117fQ==\n')
 
     def test_decode(self):
-        from cStringIO import StringIO
-        infp = StringIO('d3d3LnB5dGhvbi5vcmc=')
-        outfp = StringIO()
+        from io import BytesIO
+        infp = BytesIO(b'd3d3LnB5dGhvbi5vcmc=')
+        outfp = BytesIO()
         base64.decode(infp, outfp)
-        self.assertEqual(outfp.getvalue(), 'www.python.org')
+        self.assertEqual(outfp.getvalue(), b'www.python.org')
 
 
 
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 7e37c29..a4ae21a 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -5,7 +5,7 @@ from test.test_support import fcmp, TESTFN, unlink,  run_unittest, \
                               run_with_locale
 from operator import neg
 
-import sys, warnings, cStringIO, random, UserDict
+import sys, warnings, random, UserDict, io
 warnings.filterwarnings("ignore", "hex../oct.. of negative int",
                         FutureWarning, __name__)
 warnings.filterwarnings("ignore", "integer argument expected",
@@ -1455,11 +1455,11 @@ class BuiltinTest(unittest.TestCase):
             self.assertRaises(ValueError, input)
 
             sys.stdout = BitBucket()
-            sys.stdin = cStringIO.StringIO("NULL\0")
+            sys.stdin = io.StringIO("NULL\0")
             self.assertRaises(TypeError, input, 42, 42)
-            sys.stdin = cStringIO.StringIO("    'whitespace'")
+            sys.stdin = io.StringIO("    'whitespace'")
             self.assertEqual(input(), "    'whitespace'")
-            sys.stdin = cStringIO.StringIO()
+            sys.stdin = io.StringIO()
             self.assertRaises(EOFError, input)
 
             del sys.stdout
diff --git a/Lib/test/test_bz2.py b/Lib/test/test_bz2.py
index 06293f5..32c9cef 100644
--- a/Lib/test/test_bz2.py
+++ b/Lib/test/test_bz2.py
@@ -3,7 +3,7 @@ from test import test_support
 from test.test_support import TESTFN
 
 import unittest
-from cStringIO import StringIO
+from io import BytesIO
 import os
 import subprocess
 import sys
@@ -98,7 +98,7 @@ class BZ2FileTest(BaseTest):
         self.createTempFile()
         bz2f = BZ2File(self.filename)
         self.assertRaises(TypeError, bz2f.readline, None)
-        sio = StringIO(self.TEXT)
+        sio = BytesIO(self.TEXT)
         for line in sio.readlines():
             self.assertEqual(bz2f.readline(), line)
         bz2f.close()
@@ -108,7 +108,7 @@ class BZ2FileTest(BaseTest):
         self.createTempFile()
         bz2f = BZ2File(self.filename)
         self.assertRaises(TypeError, bz2f.readlines, None)
-        sio = StringIO(self.TEXT)
+        sio = BytesIO(self.TEXT)
         self.assertEqual(bz2f.readlines(), sio.readlines())
         bz2f.close()
 
@@ -116,7 +116,7 @@ class BZ2FileTest(BaseTest):
         # "Test iter(BZ2File)"
         self.createTempFile()
         bz2f = BZ2File(self.filename)
-        sio = StringIO(self.TEXT)
+        sio = BytesIO(self.TEXT)
         self.assertEqual(list(iter(bz2f)), sio.readlines())
         bz2f.close()
 
@@ -149,7 +149,7 @@ class BZ2FileTest(BaseTest):
         # "Test BZ2File.writelines()"
         bz2f = BZ2File(self.filename, "w")
         self.assertRaises(TypeError, bz2f.writelines)
-        sio = StringIO(self.TEXT)
+        sio = BytesIO(self.TEXT)
         bz2f.writelines(sio.readlines())
         bz2f.close()
         # patch #1535500
diff --git a/Lib/test/test_cfgparser.py b/Lib/test/test_cfgparser.py
index 076de4a..8822735 100644
--- a/Lib/test/test_cfgparser.py
+++ b/Lib/test/test_cfgparser.py
@@ -1,5 +1,5 @@
 import ConfigParser
-import StringIO
+import io
 import unittest
 import UserDict
 
@@ -30,7 +30,7 @@ class TestCaseBase(unittest.TestCase):
 
     def fromstring(self, string, defaults=None):
         cf = self.newconfig(defaults)
-        sio = StringIO.StringIO(string)
+        sio = io.StringIO(string)
         cf.readfp(sio)
         return cf
 
@@ -156,7 +156,7 @@ class TestCaseBase(unittest.TestCase):
                          "No Section!\n")
 
     def parse_error(self, exc, src):
-        sio = StringIO.StringIO(src)
+        sio = io.StringIO(src)
         self.assertRaises(exc, self.cf.readfp, sio)
 
     def test_query_errors(self):
@@ -222,7 +222,7 @@ class TestCaseBase(unittest.TestCase):
             "foo: another very\n"
             " long line"
             )
-        output = StringIO.StringIO()
+        output = io.StringIO()
         cf.write(output)
         self.assertEqual(
             output.getvalue(),
@@ -449,7 +449,7 @@ class SortedTestCase(RawConfigParserTestCase):
                         "o1=4\n"
                         "[a]\n"
                         "k=v\n")
-        output = StringIO.StringIO()
+        output = io.StringIO()
         self.cf.write(output)
         self.assertEquals(output.getvalue(),
                           "[a]\n"
diff --git a/Lib/test/test_cgi.py b/Lib/test/test_cgi.py
index 6d5bfd6..652b36e 100644
--- a/Lib/test/test_cgi.py
+++ b/Lib/test/test_cgi.py
@@ -4,7 +4,7 @@ import os
 import sys
 import tempfile
 import unittest
-from StringIO import StringIO
+from io import StringIO
 
 class HackedSysModule:
     # The regression test will have real values in sys.argv, which
@@ -15,9 +15,9 @@ class HackedSysModule:
 cgi.sys = HackedSysModule()
 
 try:
-    from cStringIO import StringIO
+    from io import StringIO
 except ImportError:
-    from StringIO import StringIO
+    from io import StringIO
 
 class ComparableException:
     def __init__(self, err):
diff --git a/Lib/test/test_codeop.py b/Lib/test/test_codeop.py
index b3fd18a..edea601 100644
--- a/Lib/test/test_codeop.py
+++ b/Lib/test/test_codeop.py
@@ -6,10 +6,10 @@ import unittest
 from test.test_support import run_unittest, is_jython
 
 from codeop import compile_command, PyCF_DONT_IMPLY_DEDENT
+import io
 
 if is_jython:
     import sys
-    import cStringIO
 
     def unify_callables(d):
         for n,v in d.items():
@@ -27,7 +27,7 @@ class CodeopTests(unittest.TestCase):
             if symbol == "single":
                 d,r = {},{}
                 saved_stdout = sys.stdout
-                sys.stdout = cStringIO.StringIO()
+                sys.stdout = io.StringIO()
                 try:
                     exec(code, d)
                     exec(compile(str,"<input>","single"), r)
diff --git a/Lib/test/test_cookielib.py b/Lib/test/test_cookielib.py
index d72a3a8..87f118d 100644
--- a/Lib/test/test_cookielib.py
+++ b/Lib/test/test_cookielib.py
@@ -153,8 +153,8 @@ class HeaderTests(TestCase):
             try:
                 result = split_header_words([arg])
             except:
-                import traceback, StringIO
-                f = StringIO.StringIO()
+                import traceback, io
+                f = io.StringIO()
                 traceback.print_exc(None, f)
                 result = "(error -- traceback follows)\n\n%s" % f.getvalue()
             self.assertEquals(result,  expect, """
@@ -204,8 +204,8 @@ class FakeResponse:
         """
         headers: list of RFC822-style 'Key: value' strings
         """
-        import mimetools, StringIO
-        f = StringIO.StringIO("\n".join(headers))
+        import mimetools, io
+        f = io.StringIO("\n".join(headers))
         self._headers = mimetools.Message(f)
         self._url = url
     def info(self): return self._headers
diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
index 6098285..21cc408 100644
--- a/Lib/test/test_csv.py
+++ b/Lib/test/test_csv.py
@@ -5,7 +5,7 @@
 import sys
 import os
 import unittest
-from StringIO import StringIO
+from io import StringIO
 from tempfile import TemporaryFile
 import csv
 import gc
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 63391af..d51a865 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -4,7 +4,7 @@ from test import test_support, seq_tests
 from weakref import proxy
 import copy
 import pickle
-from cStringIO import StringIO
+from io import StringIO
 import random
 import os
 
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index d98c607..c016681 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -1,7 +1,7 @@
 import unittest
 from test import test_support
 
-import sys, UserDict, cStringIO
+import sys, UserDict
 
 
 class DictTest(unittest.TestCase):
diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
index f1bd3e7..f135780 100644
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -4,7 +4,7 @@ from test.test_support import verbose, run_unittest
 import unittest
 import sys
 import dis
-import StringIO
+import io
 
 
 def _f(a):
@@ -103,7 +103,7 @@ Disassembly of g:
 
 class DisTests(unittest.TestCase):
     def do_disassembly_test(self, func, expected):
-        s = StringIO.StringIO()
+        s = io.StringIO()
         save_stdout = sys.stdout
         sys.stdout = s
         dis.dis(func)
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 5307395..dea03d3 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -2405,7 +2405,7 @@ def test_main():
     from test import test_doctest
     test_support.run_doctest(test_doctest, verbosity=True)
 
-import trace, sys, re, StringIO
+import trace, sys, re, io
 def test_coverage(coverdir):
     tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix,],
                          trace=0, count=1)
diff --git a/Lib/test/test_fileinput.py b/Lib/test/test_fileinput.py
index e0b5818..a9d2fa6 100644
--- a/Lib/test/test_fileinput.py
+++ b/Lib/test/test_fileinput.py
@@ -7,7 +7,7 @@ import unittest
 from test.test_support import verbose, TESTFN, run_unittest
 from test.test_support import unlink as safe_unlink
 import sys, os, re
-from StringIO import StringIO
+from io import StringIO
 from fileinput import FileInput, hook_encoded
 
 # The fileinput module has 2 interfaces: the FileInput class which does
diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
index a1ab0f1..4710c8c 100644
--- a/Lib/test/test_generators.py
+++ b/Lib/test/test_generators.py
@@ -1685,8 +1685,8 @@ RuntimeError: generator ignored GeneratorExit
 
 Our ill-behaved code should be invoked during GC:
 
->>> import sys, StringIO
->>> old, sys.stderr = sys.stderr, StringIO.StringIO()
+>>> import sys, io
+>>> old, sys.stderr = sys.stderr, io.StringIO()
 >>> g = f()
 >>> next(g)
 >>> del g
@@ -1796,10 +1796,10 @@ explicitly, without generators. We do have to redirect stderr to avoid
 printing warnings and to doublecheck that we actually tested what we wanted
 to test.
 
->>> import sys, StringIO
+>>> import sys, io
 >>> old = sys.stderr
 >>> try:
-...     sys.stderr = StringIO.StringIO()
+...     sys.stderr = io.StringIO()
 ...     class Leaker:
 ...         def __del__(self):
 ...             raise RuntimeError
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index 953acad..1073cdd 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -25,7 +25,7 @@ Copyright (C) 2001-2002 Vinay Sajip. All Rights Reserved.
 """
 
 import select
-import os, sys, struct, pickle, cStringIO
+import os, sys, struct, pickle, io
 import socket, tempfile, threading, time
 import logging, logging.handlers, logging.config
 from test.test_support import run_with_locale
@@ -606,7 +606,7 @@ def test_main_inner():
     #Configure the logger for logrecv so events do not propagate beyond it.
     #The sockLogger output is buffered in memory until the end of the test,
     #and printed at the end.
-    sockOut = cStringIO.StringIO()
+    sockOut = io.StringIO()
     sockLogger = logging.getLogger("logrecv")
     sockLogger.setLevel(logging.DEBUG)
     sockhdlr = logging.StreamHandler(sockOut)
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index 4761aa7..59def94 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -7,7 +7,7 @@ import email
 import email.message
 import rfc822
 import re
-import StringIO
+import io
 from test import test_support
 import unittest
 import mailbox
@@ -69,7 +69,7 @@ class TestMailbox(TestBase):
         self.assertEqual(len(self._box), 2)
         keys.append(self._box.add(email.message_from_string(_sample_message)))
         self.assertEqual(len(self._box), 3)
-        keys.append(self._box.add(StringIO.StringIO(_sample_message)))
+        keys.append(self._box.add(io.StringIO(_sample_message)))
         self.assertEqual(len(self._box), 4)
         keys.append(self._box.add(_sample_message))
         self.assertEqual(len(self._box), 5)
@@ -400,12 +400,12 @@ class TestMailbox(TestBase):
     def test_dump_message(self):
         # Write message representations to disk
         for input in (email.message_from_string(_sample_message),
-                      _sample_message, StringIO.StringIO(_sample_message)):
-            output = StringIO.StringIO()
+                      _sample_message, io.StringIO(_sample_message)):
+            output = io.StringIO()
             self._box._dump_message(input, output)
             self.assert_(output.getvalue() ==
                          _sample_message.replace('\n', os.linesep))
-        output = StringIO.StringIO()
+        output = io.StringIO()
         self.assertRaises(TypeError,
                           lambda: self._box._dump_message(None, output))
 
diff --git a/Lib/test/test_mhlib.py b/Lib/test/test_mhlib.py
index 1b1af6a..ad66ede 100644
--- a/Lib/test/test_mhlib.py
+++ b/Lib/test/test_mhlib.py
@@ -8,7 +8,8 @@
 
 import unittest
 from test.test_support import run_unittest, TESTFN, TestSkipped
-import os, StringIO
+import os
+import io
 import sys
 import mhlib
 
@@ -262,7 +263,7 @@ class MhlibTests(unittest.TestCase):
         f = mh.openfolder('dummy1')
         def create(n):
             msg = "From: foo\nSubject: %s\n\nDummy Message %s\n" % (n,n)
-            f.createmessage(n, StringIO.StringIO(msg))
+            f.createmessage(n, io.StringIO(msg))
 
         create(7)
         create(8)
diff --git a/Lib/test/test_mimetools.py b/Lib/test/test_mimetools.py
index ad24776..cf0e191 100644
--- a/Lib/test/test_mimetools.py
+++ b/Lib/test/test_mimetools.py
@@ -1,28 +1,54 @@
 import unittest
 from test import test_support
 
-import string, StringIO, mimetools
+import string, mimetools
+import io
 
-msgtext1 = mimetools.Message(StringIO.StringIO(
+msgtext1 = mimetools.Message(io.StringIO(
 """Content-Type: text/plain; charset=iso-8859-1; format=flowed
 Content-Transfer-Encoding: 8bit
 
 Foo!
 """))
 
+sample = bytes(string.ascii_letters + "=" + string.digits + "\n", "ASCII")
+
 class MimeToolsTest(unittest.TestCase):
 
-    def test_decodeencode(self):
-        start = string.ascii_letters + "=" + string.digits + "\n"
-        for enc in ['7bit','8bit','base64','quoted-printable',
-                    'uuencode', 'x-uuencode', 'uue', 'x-uue']:
-            i = StringIO.StringIO(start)
-            o = StringIO.StringIO()
-            mimetools.encode(i, o, enc)
-            i = StringIO.StringIO(o.getvalue())
-            o = StringIO.StringIO()
-            mimetools.decode(i, o, enc)
-            self.assertEqual(o.getvalue(), start)
+    def decode_encode_test(self, enc):
+        i = io.BytesIO(sample)
+        o = io.BytesIO()
+        mimetools.encode(i, o, enc)
+        i = io.BytesIO(o.getvalue())
+        o = io.BytesIO()
+        mimetools.decode(i, o, enc)
+        self.assertEqual(o.getvalue(), sample)
+
+    # Separate tests for better diagnostics
+
+    def test_7bit(self):
+        self.decode_encode_test('7bit')
+
+    def test_8bit(self):
+        self.decode_encode_test('8bit')
+
+    def test_base64(self):
+        self.decode_encode_test('base64')
+
+    def test_quoted_printable(self):
+        self.decode_encode_test('quoted-printable')
+
+    def test_uuencode(self):
+        self.decode_encode_test('uuencode')
+
+    def test_x_uuencode(self):
+        self.decode_encode_test('x-uuencode')
+
+    def test_uue(self):
+        self.decode_encode_test('uue')
+
+    def test_x_uue(self):
+        self.decode_encode_test('x-uue')
 
     def test_boundary(self):
         s = set([""])
@@ -32,7 +58,7 @@ class MimeToolsTest(unittest.TestCase):
             s.add(nb)
 
     def test_message(self):
-        msg = mimetools.Message(StringIO.StringIO(msgtext1))
+        msg = mimetools.Message(io.StringIO(msgtext1))
         self.assertEqual(msg.gettype(), "text/plain")
         self.assertEqual(msg.getmaintype(), "text")
         self.assertEqual(msg.getsubtype(), "plain")
diff --git a/Lib/test/test_mimetypes.py b/Lib/test/test_mimetypes.py
index 0190c2f..53de072 100644
--- a/Lib/test/test_mimetypes.py
+++ b/Lib/test/test_mimetypes.py
@@ -1,5 +1,5 @@
 import mimetypes
-import StringIO
+import io
 import unittest
 
 from test import test_support
@@ -30,7 +30,7 @@ class MimeTypesTestCase(unittest.TestCase):
 
     def test_file_parsing(self):
         eq = self.assertEqual
-        sio = StringIO.StringIO("x-application/x-unittest pyunit\n")
+        sio = io.StringIO("x-application/x-unittest pyunit\n")
         self.db.readfp(sio)
         eq(self.db.guess_type("foo.pyunit"),
            ("x-application/x-unittest", None))
diff --git a/Lib/test/test_minidom.py b/Lib/test/test_minidom.py
index cc637d0..fb3b098 100644
--- a/Lib/test/test_minidom.py
+++ b/Lib/test/test_minidom.py
@@ -4,7 +4,7 @@ import os
 import sys
 import pickle
 import traceback
-from StringIO import StringIO
+from io import StringIO
 from test.test_support import verbose, run_unittest, TestSkipped
 import unittest
 
diff --git a/Lib/test/test_multifile.py b/Lib/test/test_multifile.py
index 437c394..b29137c 100644
--- a/Lib/test/test_multifile.py
+++ b/Lib/test/test_multifile.py
@@ -1,6 +1,6 @@
 import mimetools
 import multifile
-import cStringIO
+import io
 
 msg = """Mime-Version: 1.0
 Content-Type: multipart/mixed;
@@ -57,7 +57,7 @@ def test_main():
     global boundaries, linecount
     boundaries = 0
     linecount = 0
-    f = cStringIO.StringIO(msg)
+    f = io.StringIO(msg)
     getMIMEMsg(multifile.MultiFile(f))
     assert boundaries == 2
     assert linecount == 9
diff --git a/Lib/test/test_optparse.py b/Lib/test/test_optparse.py
index 2bae0a6..1cfdd50 100644
--- a/Lib/test/test_optparse.py
+++ b/Lib/test/test_optparse.py
@@ -14,7 +14,7 @@ import re
 import copy
 import unittest
 
-from StringIO import StringIO
+from io import StringIO
 from pprint import pprint
 from test import test_support
 
@@ -157,12 +157,9 @@ and kwargs %(kwargs)r
                      expected_error=None):
         """Assert the parser prints the expected output on stdout."""
         save_stdout = sys.stdout
-        encoding = getattr(save_stdout, 'encoding', None)
         try:
             try:
                 sys.stdout = StringIO()
-                if encoding:
-                    sys.stdout.encoding = encoding
                 self.parser.parse_args(cmdline_args)
             finally:
                 output = sys.stdout.getvalue()
diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index 28ad055..faa5523 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -1,6 +1,6 @@
 import dis
 import sys
-from cStringIO import StringIO
+from io import StringIO
 import unittest
 
 def disassemble(func):
diff --git a/Lib/test/test_rfc822.py b/Lib/test/test_rfc822.py
index c355950..b563c9c 100644
--- a/Lib/test/test_rfc822.py
+++ b/Lib/test/test_rfc822.py
@@ -4,9 +4,9 @@ import unittest
 from test import test_support
 
 try:
-    from cStringIO import StringIO
+    from io import StringIO
 except ImportError:
-    from StringIO import StringIO
+    from io import StringIO
 
 
 class MessageTestCase(unittest.TestCase):
diff --git a/Lib/test/test_robotparser.py b/Lib/test/test_robotparser.py
index 666d00a..e1e8055 100644
--- a/Lib/test/test_robotparser.py
+++ b/Lib/test/test_robotparser.py
@@ -1,4 +1,5 @@
-import unittest, StringIO, robotparser
+import unittest, robotparser
+import io
 from test import test_support
 
 class RobotTestCase(unittest.TestCase):
@@ -32,7 +33,7 @@ tests = unittest.TestSuite()
 def RobotTest(index, robots_txt, good_urls, bad_urls,
               agent="test_robotparser"):
 
-    lines = StringIO.StringIO(robots_txt).readlines()
+    lines = io.StringIO(robots_txt).readlines()
     parser = robotparser.RobotFileParser()
     parser.parse(lines)
     for url in good_urls:
diff --git a/Lib/test/test_sax.py b/Lib/test/test_sax.py
index 0d76cbb..e2639fa 100644
--- a/Lib/test/test_sax.py
+++ b/Lib/test/test_sax.py
@@ -12,7 +12,7 @@ from xml.sax.saxutils import XMLGenerator, escape, unescape, quoteattr, \
                              XMLFilterBase
 from xml.sax.expatreader import create_parser
 from xml.sax.xmlreader import InputSource, AttributesImpl, AttributesNSImpl
-from cStringIO import StringIO
+from io import StringIO
 from test.test_support import findfile, run_unittest
 import unittest
 import os
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 7d7a09b..d9adf02 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1,13 +1,13 @@
 # -*- coding: iso-8859-1 -*-
 import unittest, test.test_support
-import sys, cStringIO
+import sys, io
 
 class SysModuleTest(unittest.TestCase):
 
     def test_original_displayhook(self):
         import __builtin__
         savestdout = sys.stdout
-        out = cStringIO.StringIO()
+        out = io.StringIO()
         sys.stdout = out
 
         dh = sys.__displayhook__
@@ -46,7 +46,7 @@ class SysModuleTest(unittest.TestCase):
 
     def test_original_excepthook(self):
         savestderr = sys.stderr
-        err = cStringIO.StringIO()
+        err = io.StringIO()
         sys.stderr = err
 
         eh = sys.__excepthook__
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index ea32ef5..0585131 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -3,7 +3,7 @@ import os
 import io
 import shutil
 import tempfile
-import StringIO
+import io
 from hashlib import md5
 import errno
 
@@ -897,15 +897,15 @@ class AppendTest(unittest.TestCase):
         self._test()
 
     def test_empty_fileobj(self):
-        fobj = StringIO.StringIO()
+        fobj = io.BytesIO()
         self._add_testfile(fobj)
         fobj.seek(0)
         self._test(fileobj=fobj)
 
     def test_fileobj(self):
         self._create_testtar()
-        data = open(self.tarname).read()
-        fobj = StringIO.StringIO(data)
+        data = open(self.tarname, "rb").read()
+        fobj = io.BytesIO(data)
         self._add_testfile(fobj)
         fobj.seek(0)
         self._test(names=["foo", "bar"], fileobj=fobj)
diff --git a/Lib/test/test_threadedtempfile.py b/Lib/test/test_threadedtempfile.py
index 753f388..cde15b4 100644
--- a/Lib/test/test_threadedtempfile.py
+++ b/Lib/test/test_threadedtempfile.py
@@ -22,7 +22,7 @@ import tempfile
 
 from test.test_support import threading_setup, threading_cleanup, run_unittest
 import unittest
-import StringIO
+import io
 from traceback import print_exc
 
 startEvent = threading.Event()
@@ -32,7 +32,7 @@ class TempFileGreedy(threading.Thread):
     ok_count = 0
 
     def run(self):
-        self.errors = StringIO.StringIO()
+        self.errors = io.StringIO()
         startEvent.wait()
         for i in range(FILES_PER_THREAD):
             try:
diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py
index e3e6de2..91d6ba7 100644
--- a/Lib/test/test_urllib2.py
+++ b/Lib/test/test_urllib2.py
@@ -2,7 +2,7 @@ import unittest
 from test import test_support
 
 import os, socket
-import StringIO
+import io
 
 import urllib2
 from urllib2 import Request, OpenerDirector
@@ -236,9 +236,9 @@ class MockHeaders(dict):
     def getheaders(self, name):
         return list(self.values())
 
-class MockResponse(StringIO.StringIO):
+class MockResponse(io.StringIO):
     def __init__(self, code, msg, headers, data, url=None):
-        StringIO.StringIO.__init__(self, data)
+        io.StringIO.__init__(self, data)
         self.code, self.msg, self.headers, self.url = code, msg, headers, url
     def info(self):
         return self.headers
@@ -353,7 +353,7 @@ class MockHTTPHandler(urllib2.BaseHandler):
         self.requests = []
     def http_open(self, req):
         import mimetools, httplib, copy
-        from StringIO import StringIO
+        from io import StringIO
         self.requests.append(copy.deepcopy(req))
         if self._count == 0:
             self._count = self._count + 1
@@ -546,7 +546,7 @@ class HandlerTests(unittest.TestCase):
             def __init__(self, data): self.data = data
             def retrfile(self, filename, filetype):
                 self.filename, self.filetype = filename, filetype
-                return StringIO.StringIO(self.data), len(self.data)
+                return io.StringIO(self.data), len(self.data)
 
         class NullFTPHandler(urllib2.FTPHandler):
             def __init__(self, data): self.data = data
diff --git a/Lib/test/test_uu.py b/Lib/test/test_uu.py
index 181e361..4723174 100644
--- a/Lib/test/test_uu.py
+++ b/Lib/test/test_uu.py
@@ -6,47 +6,50 @@ Nick Mathewson
 import unittest
 from test import test_support
 
-import sys, os, uu, cStringIO
+import sys, os
 import uu
-from StringIO import StringIO
+from io import BytesIO
+import io
 
-plaintext = "The smooth-scaled python crept over the sleeping dog\n"
+plaintext = b"The smooth-scaled python crept over the sleeping dog\n"
 
-encodedtext = """\
+encodedtext = b"""\
 M5&AE('-M;V]T:\"US8V%L960@<'ET:&]N(&-R97!T(&]V97(@=&AE('-L965P
 (:6YG(&1O9PH """
 
-encodedtextwrapped = "begin %03o %s\n" + encodedtext.replace("%", "%%") + "\n \nend\n"
+def encodedtextwrapped(mode, filename):
+    return (bytes("begin %03o %s\n" % (mode, filename), "ascii") +
+            encodedtext + b"\n \nend\n")
 
 class UUTest(unittest.TestCase):
 
     def test_encode(self):
-        inp = cStringIO.StringIO(plaintext)
-        out = cStringIO.StringIO()
+        inp = io.BytesIO(plaintext)
+        out = io.BytesIO()
         uu.encode(inp, out, "t1")
-        self.assertEqual(out.getvalue(), encodedtextwrapped % (0o666, "t1"))
-        inp = cStringIO.StringIO(plaintext)
-        out = cStringIO.StringIO()
+        self.assertEqual(out.getvalue(), encodedtextwrapped(0o666, "t1"))
+        inp = io.BytesIO(plaintext)
+        out = io.BytesIO()
         uu.encode(inp, out, "t1", 0o644)
-        self.assertEqual(out.getvalue(), encodedtextwrapped % (0o644, "t1"))
+        self.assertEqual(out.getvalue(), encodedtextwrapped(0o644, "t1"))
 
     def test_decode(self):
-        inp = cStringIO.StringIO(encodedtextwrapped % (0o666, "t1"))
-        out = cStringIO.StringIO()
+        inp = io.BytesIO(encodedtextwrapped(0o666, "t1"))
+        out = io.BytesIO()
         uu.decode(inp, out)
         self.assertEqual(out.getvalue(), plaintext)
-        inp = cStringIO.StringIO(
-            "UUencoded files may contain many lines,\n" +
-            "even some that have 'begin' in them.\n" +
-            encodedtextwrapped % (0o666, "t1")
+        inp = io.BytesIO(
+            b"UUencoded files may contain many lines,\n" +
+            b"even some that have 'begin' in them.\n" +
+            encodedtextwrapped(0o666, "t1")
         )
-        out = cStringIO.StringIO()
+        out = io.BytesIO()
         uu.decode(inp, out)
         self.assertEqual(out.getvalue(), plaintext)
 
     def test_truncatedinput(self):
-        inp = cStringIO.StringIO("begin 644 t1\n" + encodedtext)
-        out = cStringIO.StringIO()
+        inp = io.BytesIO(b"begin 644 t1\n" + encodedtext)
+        out = io.BytesIO()
         try:
             uu.decode(inp, out)
             self.fail("No exception thrown")
@@ -54,8 +57,8 @@ class UUTest(unittest.TestCase):
             self.assertEqual(str(e), "Truncated input file")
 
     def test_missingbegin(self):
-        inp = cStringIO.StringIO("")
-        out = cStringIO.StringIO()
+        inp = io.BytesIO(b"")
+        out = io.BytesIO()
         try:
             uu.decode(inp, out)
             self.fail("No exception thrown")
@@ -73,24 +76,27 @@ class UUStdIOTest(unittest.TestCase):
         sys.stdout = self.stdout
 
     def test_encode(self):
-        sys.stdin = cStringIO.StringIO(plaintext)
-        sys.stdout = cStringIO.StringIO()
+        sys.stdin = io.StringIO(plaintext.decode("ascii"))
+        sys.stdout = io.StringIO()
         uu.encode("-", "-", "t1", 0o666)
-        self.assertEqual(
-            sys.stdout.getvalue(),
-            encodedtextwrapped % (0o666, "t1")
-        )
+        self.assertEqual(sys.stdout.getvalue(),
+                         encodedtextwrapped(0o666, "t1").decode("ascii"))
 
     def test_decode(self):
-        sys.stdin = cStringIO.StringIO(encodedtextwrapped % (0o666, "t1"))
-        sys.stdout = cStringIO.StringIO()
+        sys.stdin = io.StringIO(encodedtextwrapped(0o666, "t1").decode("ascii"))
+        sys.stdout = io.StringIO()
         uu.decode("-", "-")
-        self.assertEqual(sys.stdout.getvalue(), plaintext)
+        stdout = sys.stdout
+        sys.stdout = self.stdout
+        sys.stdin = self.stdin
+        self.assertEqual(stdout.getvalue(), plaintext.decode("ascii"))
 
 class UUFileTest(unittest.TestCase):
 
     def _kill(self, f):
         # close and remove file
+        if f is None:
+            return
         try:
             f.close()
         except (SystemExit, KeyboardInterrupt):
@@ -113,44 +119,46 @@ class UUFileTest(unittest.TestCase):
         del self.tmpout
 
     def test_encode(self):
+        fin = fout = None
         try:
             fin = open(self.tmpin, 'wb')
             fin.write(plaintext)
             fin.close()
 
             fin = open(self.tmpin, 'rb')
-            fout = open(self.tmpout, 'w')
+            fout = open(self.tmpout, 'wb')
             uu.encode(fin, fout, self.tmpin, mode=0o644)
             fin.close()
             fout.close()
 
-            fout = open(self.tmpout, 'r')
+            fout = open(self.tmpout, 'rb')
             s = fout.read()
             fout.close()
-            self.assertEqual(s, encodedtextwrapped % (0o644, self.tmpin))
+            self.assertEqual(s, encodedtextwrapped(0o644, self.tmpin))
 
             # in_file and out_file as filenames
             uu.encode(self.tmpin, self.tmpout, self.tmpin, mode=0o644)
-            fout = open(self.tmpout, 'r')
+            fout = open(self.tmpout, 'rb')
             s = fout.read()
             fout.close()
-            self.assertEqual(s, encodedtextwrapped % (0o644, self.tmpin))
+            self.assertEqual(s, encodedtextwrapped(0o644, self.tmpin))
 
         finally:
             self._kill(fin)
             self._kill(fout)
 
     def test_decode(self):
+        f = None
         try:
-            f = open(self.tmpin, 'w')
-            f.write(encodedtextwrapped % (0o644, self.tmpout))
+            f = open(self.tmpin, 'wb')
+            f.write(encodedtextwrapped(0o644, self.tmpout))
             f.close()
 
-            f = open(self.tmpin, 'r')
+            f = open(self.tmpin, 'rb')
             uu.decode(f)
             f.close()
 
-            f = open(self.tmpout, 'r')
+            f = open(self.tmpout, 'rb')
             s = f.read()
             f.close()
             self.assertEqual(s, plaintext)
@@ -160,21 +168,25 @@ class UUFileTest(unittest.TestCase):
 
     def test_decodetwice(self):
         # Verify that decode() will refuse to overwrite an existing file
+        f = None
         try:
-            f = cStringIO.StringIO(encodedtextwrapped % (0o644, self.tmpout))
+            f = io.BytesIO(encodedtextwrapped(0o644, self.tmpout))
 
-            f = open(self.tmpin, 'r')
+            f = open(self.tmpin, 'rb')
             uu.decode(f)
             f.close()
 
-            f = open(self.tmpin, 'r')
+            f = open(self.tmpin, 'rb')
             self.assertRaises(uu.Error, uu.decode, f)
             f.close()
         finally:
             self._kill(f)
 
 def test_main():
-    test_support.run_unittest(UUTest, UUStdIOTest, UUFileTest)
+    test_support.run_unittest(UUTest,
+                              UUStdIOTest,
+                              UUFileTest,
+                              )
 
 if __name__=="__main__":
     test_main()
diff --git a/Lib/test/test_xml_etree.py b/Lib/test/test_xml_etree.py
index 1c5edd0..c8dd344 100644
--- a/Lib/test/test_xml_etree.py
+++ b/Lib/test/test_xml_etree.py
@@ -39,14 +39,11 @@ def check_method(method):
     if not hasattr(method, '__call__'):
         print(method, "not callable")
 
-def serialize(ET, elem, encoding=None):
-    import StringIO
-    file = StringIO.StringIO()
+def serialize(ET, elem):
+    import io
     tree = ET.ElementTree(elem)
-    if encoding:
-        tree.write(file, encoding)
-    else:
-        tree.write(file)
+    file = io.StringIO()
+    tree.write(file)
     return file.getvalue()
 
 def summarize(elem):
diff --git a/Lib/test/test_xml_etree_c.py b/Lib/test/test_xml_etree_c.py
index 49cdfde..22d2662 100644
--- a/Lib/test/test_xml_etree_c.py
+++ b/Lib/test/test_xml_etree_c.py
@@ -37,14 +37,11 @@ def check_method(method):
     if not hasattr(method, '__call__'):
         print(method, "not callable")
 
-def serialize(ET, elem, encoding=None):
-    import StringIO
-    file = StringIO.StringIO()
+def serialize(ET, elem):
+    import io
+    file = io.StringIO()
     tree = ET.ElementTree(elem)
-    if encoding:
-        tree.write(file, encoding)
-    else:
-        tree.write(file)
+    tree.write(file)
     return file.getvalue()
 
 def summarize(elem):
diff --git a/Lib/test/test_zipfile64.py b/Lib/test/test_zipfile64.py
index dedce4a..a008fd0 100644
--- a/Lib/test/test_zipfile64.py
+++ b/Lib/test/test_zipfile64.py
@@ -20,7 +20,7 @@ import zipfile, os, unittest
 import time
 import sys
 
-from StringIO import StringIO
+from io import StringIO
 from tempfile import TemporaryFile
 
 from test.test_support import TESTFN, run_unittest
diff --git a/Lib/test/test_zipimport.py b/Lib/test/test_zipimport.py
index bae2172..f36cbf4 100644
--- a/Lib/test/test_zipimport.py
+++ b/Lib/test/test_zipimport.py
@@ -15,7 +15,7 @@ import zipimport
 import linecache
 import doctest
 import inspect
-import StringIO
+import io
 from traceback import extract_tb, extract_stack, print_tb
 raise_src = 'def do_raise(): raise TypeError\n'
 
@@ -314,7 +314,7 @@ class UncompressedZipImportTestCase(ImportHooksBaseTestCase):
             f,lno,n,line = extract_stack(tb.tb_frame, 1)[0]
             self.assertEqual(line, raise_src.strip())
 
-            s = StringIO.StringIO()
+            s = io.StringIO()
             print_tb(tb, 1, s)
             self.failUnless(s.getvalue().endswith(raise_src))
         else: