Lib/test/test_io.py

"""Unit tests for io.py."""

import os
import sys
import time
import array
import threading
import random
import unittest
from itertools import chain, cycle
from test import support

import codecs
import io  # The module under test


class MockRawIO(io.RawIOBase):

    def __init__(self, read_stack=()):
        self._read_stack = list(read_stack)
        self._write_stack = []

    def read(self, n=None):
        try:
            return self._read_stack.pop(0)
        except:
            return b""

    def write(self, b):
        self._write_stack.append(b[:])
        return len(b)

    def writable(self):
        return True

    def fileno(self):
        return 42

    def readable(self):
        return True

    def seekable(self):
        return True

    def seek(self, pos, whence):
        pass

    def tell(self):
        return 42


class MockFileIO(io.BytesIO):

    def __init__(self, data):
        self.read_history = []
        io.BytesIO.__init__(self, data)

    def read(self, n=None):
        res = io.BytesIO.read(self, n)
        self.read_history.append(None if res is None else len(res))
        return res


class MockNonBlockWriterIO(io.RawIOBase):

    def __init__(self, blocking_script):
        self._blocking_script = list(blocking_script)
        self._write_stack = []

    def write(self, b):
        self._write_stack.append(b[:])
        n = self._blocking_script.pop(0)
        if (n < 0):
            raise io.BlockingIOError(0, "test blocking", -n)
        else:
            return n

    def writable(self):
        return True


class IOTest(unittest.TestCase):

    def setUp(self):
        support.unlink(support.TESTFN)

    def tearDown(self):
        support.unlink(support.TESTFN)

    def write_ops(self, f):
        self.assertEqual(f.write(b"blah."), 5)
        self.assertEqual(f.seek(0), 0)
        self.assertEqual(f.write(b"Hello."), 6)
        self.assertEqual(f.tell(), 6)
        self.assertEqual(f.seek(-1, 1), 5)
        self.assertEqual(f.tell(), 5)
        self.assertEqual(f.write(bytearray(b" world\n\n\n")), 9)
        self.assertEqual(f.seek(0), 0)
        self.assertEqual(f.write(b"h"), 1)
        self.assertEqual(f.seek(-1, 2), 13)
        self.assertEqual(f.tell(), 13)
        self.assertEqual(f.truncate(12), 12)
        self.assertEqual(f.tell(), 12)
        self.assertRaises(TypeError, f.seek, 0.0)

    def read_ops(self, f, buffered=False):
        data = f.read(5)
        self.assertEqual(data, b"hello")
        data = bytearray(data)
        self.assertEqual(f.readinto(data), 5)
        self.assertEqual(data, b" worl")
        self.assertEqual(f.readinto(data), 2)
        self.assertEqual(len(data), 5)
        self.assertEqual(data[:2], b"d\n")
        self.assertEqual(f.seek(0), 0)
        self.assertEqual(f.read(20), b"hello world\n")
        self.assertEqual(f.read(1), b"")
        self.assertEqual(f.readinto(bytearray(b"x")), 0)
        self.assertEqual(f.seek(-6, 2), 6)
        self.assertEqual(f.read(5), b"world")
        self.assertEqual(f.read(0), b"")
        self.assertEqual(f.readinto(bytearray()), 0)
        self.assertEqual(f.seek(-6, 1), 5)
        self.assertEqual(f.read(5), b" worl")
        self.assertEqual(f.tell(), 10)
        self.assertRaises(TypeError, f.seek, 0.0)
        if buffered:
            f.seek(0)
            self.assertEqual(f.read(), b"hello world\n")
            f.seek(6)
            self.assertEqual(f.read(), b"world\n")
            self.assertEqual(f.read(), b"")

    LARGE = 2**31

    def large_file_ops(self, f):
        assert f.readable()
        assert f.writable()
        self.assertEqual(f.seek(self.LARGE), self.LARGE)
        self.assertEqual(f.tell(), self.LARGE)
        self.assertEqual(f.write(b"xxx"), 3)
        self.assertEqual(f.tell(), self.LARGE + 3)
        self.assertEqual(f.seek(-1, 1), self.LARGE + 2)
        self.assertEqual(f.truncate(), self.LARGE + 2)
        self.assertEqual(f.tell(), self.LARGE + 2)
        self.assertEqual(f.seek(0, 2), self.LARGE + 2)
        self.assertEqual(f.truncate(self.LARGE + 1), self.LARGE + 1)
        self.assertEqual(f.tell(), self.LARGE + 1)
        self.assertEqual(f.seek(0, 2), self.LARGE + 1)
        self.assertEqual(f.seek(-1, 2), self.LARGE)
        self.assertEqual(f.read(2), b"x")

    def test_raw_file_io(self):
        f = io.open(support.TESTFN, "wb", buffering=0)
        self.assertEqual(f.readable(), False)
        self.assertEqual(f.writable(), True)
        self.assertEqual(f.seekable(), True)
        self.write_ops(f)
        f.close()
        f = io.open(support.TESTFN, "rb", buffering=0)
        self.assertEqual(f.readable(), True)
        self.assertEqual(f.writable(), False)
        self.assertEqual(f.seekable(), True)
        self.read_ops(f)
        f.close()

    def test_buffered_file_io(self):
        f = io.open(support.TESTFN, "wb")
        self.assertEqual(f.readable(), False)
        self.assertEqual(f.writable(), True)
        self.assertEqual(f.seekable(), True)
        self.write_ops(f)
        f.close()
        f = io.open(support.TESTFN, "rb")
        self.assertEqual(f.readable(), True)
        self.assertEqual(f.writable(), False)
        self.assertEqual(f.seekable(), True)
        self.read_ops(f, True)
        f.close()

    def test_readline(self):
        f = io.open(support.TESTFN, "wb")
        f.write(b"abc\ndef\nxyzzy\nfoo")
        f.close()
        f = io.open(support.TESTFN, "rb")
        self.assertEqual(f.readline(), b"abc\n")
        self.assertEqual(f.readline(10), b"def\n")
        self.assertEqual(f.readline(2), b"xy")
        self.assertEqual(f.readline(4), b"zzy\n")
        self.assertEqual(f.readline(), b"foo")
        f.close()

    def test_raw_bytes_io(self):
        f = io.BytesIO()
        self.write_ops(f)
        data = f.getvalue()
        self.assertEqual(data, b"hello world\n")
        f = io.BytesIO(data)
        self.read_ops(f, True)

    def test_large_file_ops(self):
        # On Windows and Mac OSX this test comsumes large resources; It takes
        # a long time to build the >2GB file and takes >2GB of disk space
        # therefore the resource must be enabled to run this test.
        if sys.platform[:3] == 'win' or sys.platform == 'darwin':
            if not support.is_resource_enabled("largefile"):
                print("\nTesting large file ops skipped on %s." % sys.platform,
                      file=sys.stderr)
                print("It requires %d bytes and a long time." % self.LARGE,
                      file=sys.stderr)
                print("Use 'regrtest.py -u largefile test_io' to run it.",
                      file=sys.stderr)
                return
        f = io.open(support.TESTFN, "w+b", 0)
        self.large_file_ops(f)
        f.close()
        f = io.open(support.TESTFN, "w+b")
        self.large_file_ops(f)
        f.close()

    def test_with_open(self):
        for bufsize in (0, 1, 100):
            f = None
            with open(support.TESTFN, "wb", bufsize) as f:
                f.write(b"xxx")
            self.assertEqual(f.closed, True)
            f = None
            try:
                with open(support.TESTFN, "wb", bufsize) as f:
                    1/0
            except ZeroDivisionError:
                self.assertEqual(f.closed, True)
            else:
                self.fail("1/0 didn't raise an exception")

    def test_destructor(self):
        record = []
        class MyFileIO(io.FileIO):
            def __del__(self):
                record.append(1)
                io.FileIO.__del__(self)
            def close(self):
                record.append(2)
                io.FileIO.close(self)
            def flush(self):
                record.append(3)
                io.FileIO.flush(self)
        f = MyFileIO(support.TESTFN, "w")
        f.write("xxx")
        del f
        self.assertEqual(record, [1, 2, 3])

    def test_close_flushes(self):
        f = io.open(support.TESTFN, "wb")
        f.write(b"xxx")
        f.close()
        f = io.open(support.TESTFN, "rb")
        self.assertEqual(f.read(), b"xxx")
        f.close()

    def test_array_writes(self):
        a = array.array('i', range(10))
        n = len(memoryview(a))
        f = io.open(support.TESTFN, "wb", 0)
        self.assertEqual(f.write(a), n)
        f.close()
        f = io.open(support.TESTFN, "wb")
        self.assertEqual(f.write(a), n)
        f.close()

    def test_closefd(self):
        self.assertRaises(ValueError, io.open, support.TESTFN, 'w',
                          closefd=False)

class MemorySeekTestMixin:

    def testInit(self):
        buf = self.buftype("1234567890")
        bytesIo = self.ioclass(buf)

    def testRead(self):
        buf = self.buftype("1234567890")
        bytesIo = self.ioclass(buf)

        self.assertEquals(buf[:1], bytesIo.read(1))
        self.assertEquals(buf[1:5], bytesIo.read(4))
        self.assertEquals(buf[5:], bytesIo.read(900))
        self.assertEquals(self.EOF, bytesIo.read())

    def testReadNoArgs(self):
        buf = self.buftype("1234567890")
        bytesIo = self.ioclass(buf)

        self.assertEquals(buf, bytesIo.read())
        self.assertEquals(self.EOF, bytesIo.read())

    def testSeek(self):
        buf = self.buftype("1234567890")
        bytesIo = self.ioclass(buf)

        bytesIo.read(5)
        bytesIo.seek(0)
        self.assertEquals(buf, bytesIo.read())

        bytesIo.seek(3)
        self.assertEquals(buf[3:], bytesIo.read())
        self.assertRaises(TypeError, bytesIo.seek, 0.0)

    def testTell(self):
        buf = self.buftype("1234567890")
        bytesIo = self.ioclass(buf)

        self.assertEquals(0, bytesIo.tell())
        bytesIo.seek(5)
        self.assertEquals(5, bytesIo.tell())
        bytesIo.seek(10000)
        self.assertEquals(10000, bytesIo.tell())


class BytesIOTest(MemorySeekTestMixin, unittest.TestCase):
    @staticmethod
    def buftype(s):
        return s.encode("utf-8")
    ioclass = io.BytesIO
    EOF = b""


class StringIOTest(MemorySeekTestMixin, unittest.TestCase):
    buftype = str
    ioclass = io.StringIO
    EOF = ""


class BufferedReaderTest(unittest.TestCase):

    def testRead(self):
        rawio = MockRawIO((b"abc", b"d", b"efg"))
        bufio = io.BufferedReader(rawio)

        self.assertEquals(b"abcdef", bufio.read(6))

    def testBuffering(self):
        data = b"abcdefghi"
        dlen = len(data)

        tests = [
            [ 100, [ 3, 1, 4, 8 ], [ dlen, 0 ] ],
            [ 100, [ 3, 3, 3],     [ dlen ]    ],
            [   4, [ 1, 2, 4, 2 ], [ 4, 4, 1 ] ],
        ]

        for bufsize, buf_read_sizes, raw_read_sizes in tests:
            rawio = MockFileIO(data)
            bufio = io.BufferedReader(rawio, buffer_size=bufsize)
            pos = 0
            for nbytes in buf_read_sizes:
                self.assertEquals(bufio.read(nbytes), data[pos:pos+nbytes])
                pos += nbytes
            self.assertEquals(rawio.read_history, raw_read_sizes)

    def testReadNonBlocking(self):
        # Inject some None's in there to simulate EWOULDBLOCK
        rawio = MockRawIO((b"abc", b"d", None, b"efg", None, None))
        bufio = io.BufferedReader(rawio)

        self.assertEquals(b"abcd", bufio.read(6))
        self.assertEquals(b"e", bufio.read(1))
        self.assertEquals(b"fg", bufio.read())
        self.assert_(None is bufio.read())
        self.assertEquals(b"", bufio.read())

    def testReadToEof(self):
        rawio = MockRawIO((b"abc", b"d", b"efg"))
        bufio = io.BufferedReader(rawio)

        self.assertEquals(b"abcdefg", bufio.read(9000))

    def testReadNoArgs(self):
        rawio = MockRawIO((b"abc", b"d", b"efg"))
        bufio = io.BufferedReader(rawio)

        self.assertEquals(b"abcdefg", bufio.read())

    def testFileno(self):
        rawio = MockRawIO((b"abc", b"d", b"efg"))
        bufio = io.BufferedReader(rawio)

        self.assertEquals(42, bufio.fileno())

    def testFilenoNoFileno(self):
        # XXX will we always have fileno() function? If so, kill
        # this test. Else, write it.
        pass

    def testThreads(self):
        try:
            # Write out many bytes with exactly the same number of 0's,
            # 1's... 255's. This will help us check that concurrent reading
            # doesn't duplicate or forget contents.
            N = 1000
            l = list(range(256)) * N
            random.shuffle(l)
            s = bytes(bytearray(l))
            with io.open(support.TESTFN, "wb") as f:
                f.write(s)
            with io.open(support.TESTFN, "rb", buffering=0) as raw:
                bufio = io.BufferedReader(raw, 8)
                errors = []
                results = []
                def f():
                    try:
                        # Intra-buffer read then buffer-flushing read
                        for n in cycle([1, 19]):
                            s = bufio.read(n)
                            if not s:
                                break
                            # list.append() is atomic
                            results.append(s)
                    except Exception as e:
                        errors.append(e)
                        raise
                threads = [threading.Thread(target=f) for x in range(20)]
                for t in threads:
                    t.start()
                time.sleep(0.02) # yield
                for t in threads:
                    t.join()
                self.assertFalse(errors,
                    "the following exceptions were caught: %r" % errors)
                s = b''.join(results)
                for i in range(256):
                    c = bytes(bytearray([i]))
                    self.assertEqual(s.count(c), N)
        finally:
            support.unlink(support.TESTFN)



class BufferedWriterTest(unittest.TestCase):

    def testWrite(self):
        # Write to the buffered IO but don't overflow the buffer.
        writer = MockRawIO()
        bufio = io.BufferedWriter(writer, 8)

        bufio.write(b"abc")

        self.assertFalse(writer._write_stack)

    def testWriteOverflow(self):
        writer = MockRawIO()
        bufio = io.BufferedWriter(writer, 8)

        bufio.write(b"abc")
        bufio.write(b"defghijkl")

        self.assertEquals(b"abcdefghijkl", writer._write_stack[0])

    def testWriteNonBlocking(self):
        raw = MockNonBlockWriterIO((9, 2, 22, -6, 10, 12, 12))
        bufio = io.BufferedWriter(raw, 8, 16)

        bufio.write(b"asdf")
        bufio.write(b"asdfa")
        self.assertEquals(b"asdfasdfa", raw._write_stack[0])

        bufio.write(b"asdfasdfasdf")
        self.assertEquals(b"asdfasdfasdf", raw._write_stack[1])
        bufio.write(b"asdfasdfasdf")
        self.assertEquals(b"dfasdfasdf", raw._write_stack[2])
        self.assertEquals(b"asdfasdfasdf", raw._write_stack[3])

        bufio.write(b"asdfasdfasdf")

        # XXX I don't like this test. It relies too heavily on how the
        # algorithm actually works, which we might change. Refactor
        # later.

    def testFileno(self):
        rawio = MockRawIO((b"abc", b"d", b"efg"))
        bufio = io.BufferedWriter(rawio)

        self.assertEquals(42, bufio.fileno())

    def testFlush(self):
        writer = MockRawIO()
        bufio = io.BufferedWriter(writer, 8)

        bufio.write(b"abc")
        bufio.flush()

        self.assertEquals(b"abc", writer._write_stack[0])

    def testThreads(self):
        # BufferedWriter should not raise exceptions or crash
        # when called from multiple threads.
        try:
            # We use a real file object because it allows us to
            # exercise situations where the GIL is released before
            # writing the buffer to the raw streams. This is in addition
            # to concurrency issues due to switching threads in the middle
            # of Python code.
            with io.open(support.TESTFN, "wb", buffering=0) as raw:
                bufio = io.BufferedWriter(raw, 8)
                errors = []
                def f():
                    try:
                        # Write enough bytes to flush the buffer
                        s = b"a" * 19
                        for i in range(50):
                            bufio.write(s)
                    except Exception as e:
                        errors.append(e)
                        raise
                threads = [threading.Thread(target=f) for x in range(20)]
                for t in threads:
                    t.start()
                time.sleep(0.02) # yield
                for t in threads:
                    t.join()
                self.assertFalse(errors,
                    "the following exceptions were caught: %r" % errors)
        finally:
            support.unlink(support.TESTFN)


class BufferedRWPairTest(unittest.TestCase):

    def testRWPair(self):
        r = MockRawIO(())
        w = MockRawIO()
        pair = io.BufferedRWPair(r, w)

        # XXX need implementation


class BufferedRandomTest(unittest.TestCase):

    def testReadAndWrite(self):
        raw = MockRawIO((b"asdf", b"ghjk"))
        rw = io.BufferedRandom(raw, 8, 12)

        self.assertEqual(b"as", rw.read(2))
        rw.write(b"ddd")
        rw.write(b"eee")
        self.assertFalse(raw._write_stack) # Buffer writes
        self.assertEqual(b"ghjk", rw.read()) # This read forces write flush
        self.assertEquals(b"dddeee", raw._write_stack[0])

    def testSeekAndTell(self):
        raw = io.BytesIO(b"asdfghjkl")
        rw = io.BufferedRandom(raw)

        self.assertEquals(b"as", rw.read(2))
        self.assertEquals(2, rw.tell())
        rw.seek(0, 0)
        self.assertEquals(b"asdf", rw.read(4))

        rw.write(b"asdf")
        rw.seek(0, 0)
        self.assertEquals(b"asdfasdfl", rw.read())
        self.assertEquals(9, rw.tell())
        rw.seek(-4, 2)
        self.assertEquals(5, rw.tell())
        rw.seek(2, 1)
        self.assertEquals(7, rw.tell())
        self.assertEquals(b"fl", rw.read(11))
        self.assertRaises(TypeError, rw.seek, 0.0)

# To fully exercise seek/tell, the StatefulIncrementalDecoder has these
# properties:
#   - A single output character can correspond to many bytes of input.
#   - The number of input bytes to complete the character can be
#     undetermined until the last input byte is received.
#   - The number of input bytes can vary depending on previous input.
#   - A single input byte can correspond to many characters of output.
#   - The number of output characters can be undetermined until the
#     last input byte is received.
#   - The number of output characters can vary depending on previous input.

class StatefulIncrementalDecoder(codecs.IncrementalDecoder):
    """
    For testing seek/tell behavior with a stateful, buffering decoder.

    Input is a sequence of words.  Words may be fixed-length (length set
    by input) or variable-length (period-terminated).  In variable-length
    mode, extra periods are ignored.  Possible words are:
      - 'i' followed by a number sets the input length, I (maximum 99).
        When I is set to 0, words are space-terminated.
      - 'o' followed by a number sets the output length, O (maximum 99).
      - Any other word is converted into a word followed by a period on
        the output.  The output word consists of the input word truncated
        or padded out with hyphens to make its length equal to O.  If O
        is 0, the word is output verbatim without truncating or padding.
    I and O are initially set to 1.  When I changes, any buffered input is
    re-scanned according to the new I.  EOF also terminates the last word.
    """

    def __init__(self, errors='strict'):
        codecs.IncrementalDecoder.__init__(self, errors)
        self.reset()

    def __repr__(self):
        return '<SID %x>' % id(self)

    def reset(self):
        self.i = 1
        self.o = 1
        self.buffer = bytearray()

    def getstate(self):
        i, o = self.i ^ 1, self.o ^ 1 # so that flags = 0 after reset()
        return bytes(self.buffer), i*100 + o

    def setstate(self, state):
        buffer, io = state
        self.buffer = bytearray(buffer)
        i, o = divmod(io, 100)
        self.i, self.o = i ^ 1, o ^ 1

    def decode(self, input, final=False):
        output = ''
        for b in input:
            if self.i == 0: # variable-length, terminated with period
                if b == ord('.'):
                    if self.buffer:
                        output += self.process_word()
                else:
                    self.buffer.append(b)
            else: # fixed-length, terminate after self.i bytes
                self.buffer.append(b)
                if len(self.buffer) == self.i:
                    output += self.process_word()
        if final and self.buffer: # EOF terminates the last word
            output += self.process_word()
        return output

    def process_word(self):
        output = ''
        if self.buffer[0] == ord('i'):
            self.i = min(99, int(self.buffer[1:] or 0)) # set input length
        elif self.buffer[0] == ord('o'):
            self.o = min(99, int(self.buffer[1:] or 0)) # set output length
        else:
            output = self.buffer.decode('ascii')
            if len(output) < self.o:
                output += '-'*self.o # pad out with hyphens
            if self.o:
                output = output[:self.o] # truncate to output length
            output += '.'
        self.buffer = bytearray()
        return output

    codecEnabled = False

    @classmethod
    def lookupTestDecoder(cls, name):
        if cls.codecEnabled and name == 'test_decoder':
            return codecs.CodecInfo(
                name='test_decoder', encode=None, decode=None,
                incrementalencoder=None,
                streamreader=None, streamwriter=None,
                incrementaldecoder=cls)

# Register the previous decoder for testing.
# Disabled by default, tests will enable it.
codecs.register(StatefulIncrementalDecoder.lookupTestDecoder)


class StatefulIncrementalDecoderTest(unittest.TestCase):
    """
    Make sure the StatefulIncrementalDecoder actually works.
    """

    test_cases = [
        # I=1, O=1 (fixed-length input == fixed-length output)
        (b'abcd', False, 'a.b.c.d.'),
        # I=0, O=0 (variable-length input, variable-length output)
        (b'oiabcd', True, 'abcd.'),
        # I=0, O=0 (should ignore extra periods)
        (b'oi...abcd...', True, 'abcd.'),
        # I=0, O=6 (variable-length input, fixed-length output)
        (b'i.o6.x.xyz.toolongtofit.', False, 'x-----.xyz---.toolon.'),
        # I=2, O=6 (fixed-length input < fixed-length output)
        (b'i.i2.o6xyz', True, 'xy----.z-----.'),
        # I=6, O=3 (fixed-length input > fixed-length output)
        (b'i.o3.i6.abcdefghijklmnop', True, 'abc.ghi.mno.'),
        # I=0, then 3; O=29, then 15 (with longer output)
        (b'i.o29.a.b.cde.o15.abcdefghijabcdefghij.i3.a.b.c.d.ei00k.l.m', True,
         'a----------------------------.' +
         'b----------------------------.' +
         'cde--------------------------.' +
         'abcdefghijabcde.' +
         'a.b------------.' +
         '.c.------------.' +
         'd.e------------.' +
         'k--------------.' +
         'l--------------.' +
         'm--------------.')
    ]

    def testDecoder(self):
        # Try a few one-shot test cases.
        for input, eof, output in self.test_cases:
            d = StatefulIncrementalDecoder()
            self.assertEquals(d.decode(input, eof), output)

        # Also test an unfinished decode, followed by forcing EOF.
        d = StatefulIncrementalDecoder()
        self.assertEquals(d.decode(b'oiabcd'), '')
        self.assertEquals(d.decode(b'', 1), 'abcd.')

class TextIOWrapperTest(unittest.TestCase):

    def setUp(self):
        self.testdata = b"AAA\r\nBBB\rCCC\r\nDDD\nEEE\r\n"
        self.normalized = b"AAA\nBBB\nCCC\nDDD\nEEE\n".decode("ascii")
        support.unlink(support.TESTFN)

    def tearDown(self):
        support.unlink(support.TESTFN)

    def testLineBuffering(self):
        r = io.BytesIO()
        b = io.BufferedWriter(r, 1000)
        t = io.TextIOWrapper(b, newline="\n", line_buffering=True)
        t.write("X")
        self.assertEquals(r.getvalue(), b"")  # No flush happened
        t.write("Y\nZ")
        self.assertEquals(r.getvalue(), b"XY\nZ")  # All got flushed
        t.write("A\rB")
        self.assertEquals(r.getvalue(), b"XY\nZA\rB")

    def testEncodingErrorsReading(self):
        # (1) default
        b = io.BytesIO(b"abc\n\xff\n")
        t = io.TextIOWrapper(b, encoding="ascii")
        self.assertRaises(UnicodeError, t.read)
        # (2) explicit strict
        b = io.BytesIO(b"abc\n\xff\n")
        t = io.TextIOWrapper(b, encoding="ascii", errors="strict")
        self.assertRaises(UnicodeError, t.read)
        # (3) ignore
        b = io.BytesIO(b"abc\n\xff\n")
        t = io.TextIOWrapper(b, encoding="ascii", errors="ignore")
        self.assertEquals(t.read(), "abc\n\n")
        # (4) replace
        b = io.BytesIO(b"abc\n\xff\n")
        t = io.TextIOWrapper(b, encoding="ascii", errors="replace")
        self.assertEquals(t.read(), "abc\n\ufffd\n")

    def testEncodingErrorsWriting(self):
        # (1) default
        b = io.BytesIO()
        t = io.TextIOWrapper(b, encoding="ascii")
        self.assertRaises(UnicodeError, t.write, "\xff")
        # (2) explicit strict
        b = io.BytesIO()
        t = io.TextIOWrapper(b, encoding="ascii", errors="strict")
        self.assertRaises(UnicodeError, t.write, "\xff")
        # (3) ignore
        b = io.BytesIO()
        t = io.TextIOWrapper(b, encoding="ascii", errors="ignore",
                             newline="\n")
        t.write("abc\xffdef\n")
        t.flush()
        self.assertEquals(b.getvalue(), b"abcdef\n")
        # (4) replace
        b = io.BytesIO()
        t = io.TextIOWrapper(b, encoding="ascii", errors="replace",
                             newline="\n")
        t.write("abc\xffdef\n")
        t.flush()
        self.assertEquals(b.getvalue(), b"abc?def\n")

    def testNewlinesInput(self):
        testdata = b"AAA\nBBB\nCCC\rDDD\rEEE\r\nFFF\r\nGGG"
        normalized = testdata.replace(b"\r\n", b"\n").replace(b"\r", b"\n")
        for newline, expected in [
            (None, normalized.decode("ascii").splitlines(True)),
            ("", testdata.decode("ascii").splitlines(True)),
            ("\n", ["AAA\n", "BBB\n", "CCC\rDDD\rEEE\r\n", "FFF\r\n", "GGG"]),
            ("\r\n", ["AAA\nBBB\nCCC\rDDD\rEEE\r\n", "FFF\r\n", "GGG"]),
            ("\r",  ["AAA\nBBB\nCCC\r", "DDD\r", "EEE\r", "\nFFF\r", "\nGGG"]),
            ]:
            buf = io.BytesIO(testdata)
            txt = io.TextIOWrapper(buf, encoding="ascii", newline=newline)
            self.assertEquals(txt.readlines(), expected)
            txt.seek(0)
            self.assertEquals(txt.read(), "".join(expected))

    def testNewlinesOutput(self):
        testdict = {
            "": b"AAA\nBBB\nCCC\nX\rY\r\nZ",
            "\n": b"AAA\nBBB\nCCC\nX\rY\r\nZ",
            "\r": b"AAA\rBBB\rCCC\rX\rY\r\rZ",
            "\r\n": b"AAA\r\nBBB\r\nCCC\r\nX\rY\r\r\nZ",
            }
        tests = [(None, testdict[os.linesep])] + sorted(testdict.items())
        for newline, expected in tests:
            buf = io.BytesIO()
            txt = io.TextIOWrapper(buf, encoding="ascii", newline=newline)
            txt.write("AAA\nB")
            txt.write("BB\nCCC\n")
            txt.write("X\rY\r\nZ")
            txt.flush()
            self.assertEquals(buf.closed, False)
            self.assertEquals(buf.getvalue(), expected)

    def testNewlines(self):
        input_lines = [ "unix\n", "windows\r\n", "os9\r", "last\n", "nonl" ]

        tests = [
            [ None, [ 'unix\n', 'windows\n', 'os9\n', 'last\n', 'nonl' ] ],
            [ '', input_lines ],
            [ '\n', [ "unix\n", "windows\r\n", "os9\rlast\n", "nonl" ] ],
            [ '\r\n', [ "unix\nwindows\r\n", "os9\rlast\nnonl" ] ],
            [ '\r', [ "unix\nwindows\r", "\nos9\r", "last\nnonl" ] ],
        ]

        encodings = ('utf-8', 'latin-1')

        # Try a range of buffer sizes to test the case where \r is the last
        # character in TextIOWrapper._pending_line.
        for encoding in encodings:
            # XXX: str.encode() should return bytes
            data = bytes(''.join(input_lines).encode(encoding))
            for do_reads in (False, True):
                for bufsize in range(1, 10):
                    for newline, exp_lines in tests:
                        bufio = io.BufferedReader(io.BytesIO(data), bufsize)
                        textio = io.TextIOWrapper(bufio, newline=newline,
                                                  encoding=encoding)
                        if do_reads:
                            got_lines = []
                            while True:
                                c2 = textio.read(2)
                                if c2 == '':
                                    break
                                self.assertEquals(len(c2), 2)
                                got_lines.append(c2 + textio.readline())
                        else:
                            got_lines = list(textio)

                        for got_line, exp_line in zip(got_lines, exp_lines):
                            self.assertEquals(got_line, exp_line)
                        self.assertEquals(len(got_lines), len(exp_lines))

    def testNewlinesInput(self):
        testdata = b"AAA\nBBB\nCCC\rDDD\rEEE\r\nFFF\r\nGGG"
        normalized = testdata.replace(b"\r\n", b"\n").replace(b"\r", b"\n")
        for newline, expected in [
            (None, normalized.decode("ascii").splitlines(True)),
            ("", testdata.decode("ascii").splitlines(True)),
            ("\n", ["AAA\n", "BBB\n", "CCC\rDDD\rEEE\r\n", "FFF\r\n", "GGG"]),
            ("\r\n", ["AAA\nBBB\nCCC\rDDD\rEEE\r\n", "FFF\r\n", "GGG"]),
            ("\r",  ["AAA\nBBB\nCCC\r", "DDD\r", "EEE\r", "\nFFF\r", "\nGGG"]),
            ]:
            buf = io.BytesIO(testdata)
            txt = io.TextIOWrapper(buf, encoding="ascii", newline=newline)
            self.assertEquals(txt.readlines(), expected)
            txt.seek(0)
            self.assertEquals(txt.read(), "".join(expected))

    def testNewlinesOutput(self):
        data = "AAA\nBBB\rCCC\n"
        data_lf = b"AAA\nBBB\rCCC\n"
        data_cr = b"AAA\rBBB\rCCC\r"
        data_crlf = b"AAA\r\nBBB\rCCC\r\n"
        save_linesep = os.linesep
        try:
            for os.linesep, newline, expected in [
                ("\n", None, data_lf),
                ("\r\n", None, data_crlf),
                ("\n", "", data_lf),
                ("\r\n", "", data_lf),
                ("\n", "\n", data_lf),
                ("\r\n", "\n", data_lf),
                ("\n", "\r", data_cr),
                ("\r\n", "\r", data_cr),
                ("\n", "\r\n", data_crlf),
                ("\r\n", "\r\n", data_crlf),
                ]:
                buf = io.BytesIO()
                txt = io.TextIOWrapper(buf, encoding="ascii", newline=newline)
                txt.write(data)
                txt.close()
                self.assertEquals(buf.closed, True)
                self.assertRaises(ValueError, buf.getvalue)
        finally:
            os.linesep = save_linesep

    # Systematic tests of the text I/O API

    def testBasicIO(self):
        for chunksize in (1, 2, 3, 4, 5, 15, 16, 17, 31, 32, 33, 63, 64, 65):
            for enc in "ascii", "latin1", "utf8" :# , "utf-16-be", "utf-16-le":
                f = io.open(support.TESTFN, "w+", encoding=enc)
                f._CHUNK_SIZE = chunksize
                self.assertEquals(f.write("abc"), 3)
                f.close()
                f = io.open(support.TESTFN, "r+", encoding=enc)
                f._CHUNK_SIZE = chunksize
                self.assertEquals(f.tell(), 0)
                self.assertEquals(f.read(), "abc")
                cookie = f.tell()
                self.assertEquals(f.seek(0), 0)
                self.assertEquals(f.read(2), "ab")
                self.assertEquals(f.read(1), "c")
                self.assertEquals(f.read(1), "")
                self.assertEquals(f.read(), "")
                self.assertEquals(f.tell(), cookie)
                self.assertEquals(f.seek(0), 0)
                self.assertEquals(f.seek(0, 2), cookie)
                self.assertEquals(f.write("def"), 3)
                self.assertEquals(f.seek(cookie), cookie)
                self.assertEquals(f.read(), "def")
                if enc.startswith("utf"):
                    self.multi_line_test(f, enc)
                f.close()

    def multi_line_test(self, f, enc):
        f.seek(0)
        f.truncate()
        sample = "s\xff\u0fff\uffff"
        wlines = []
        for size in (0, 1, 2, 3, 4, 5, 30, 31, 32, 33, 62, 63, 64, 65, 1000):
            chars = []
            for i in range(size):
                chars.append(sample[i % len(sample)])
            line = "".join(chars) + "\n"
            wlines.append((f.tell(), line))
            f.write(line)
        f.seek(0)
        rlines = []
        while True:
            pos = f.tell()
            line = f.readline()
            if not line:
                break
            rlines.append((pos, line))
        self.assertEquals(rlines, wlines)

    def testTelling(self):
        f = io.open(support.TESTFN, "w+", encoding="utf8")
        p0 = f.tell()
        f.write("\xff\n")
        p1 = f.tell()
        f.write("\xff\n")
        p2 = f.tell()
        f.seek(0)
        self.assertEquals(f.tell(), p0)
        self.assertEquals(f.readline(), "\xff\n")
        self.assertEquals(f.tell(), p1)
        self.assertEquals(f.readline(), "\xff\n")
        self.assertEquals(f.tell(), p2)
        f.seek(0)
        for line in f:
            self.assertEquals(line, "\xff\n")
            self.assertRaises(IOError, f.tell)
        self.assertEquals(f.tell(), p2)
        f.close()

    def testSeeking(self):
        chunk_size = io.TextIOWrapper._CHUNK_SIZE
        prefix_size = chunk_size - 2
        u_prefix = "a" * prefix_size
        prefix = bytes(u_prefix.encode("utf-8"))
        self.assertEquals(len(u_prefix), len(prefix))
        u_suffix = "\u8888\n"
        suffix = bytes(u_suffix.encode("utf-8"))
        line = prefix + suffix
        f = io.open(support.TESTFN, "wb")
        f.write(line*2)
        f.close()
        f = io.open(support.TESTFN, "r", encoding="utf-8")
        s = f.read(prefix_size)
        self.assertEquals(s, str(prefix, "ascii"))
        self.assertEquals(f.tell(), prefix_size)
        self.assertEquals(f.readline(), u_suffix)

    def testSeekingToo(self):
        # Regression test for a specific bug
        data = b'\xe0\xbf\xbf\n'
        f = io.open(support.TESTFN, "wb")
        f.write(data)
        f.close()
        f = io.open(support.TESTFN, "r", encoding="utf-8")
        f._CHUNK_SIZE  # Just test that it exists
        f._CHUNK_SIZE = 2
        f.readline()
        f.tell()

    def testSeekAndTell(self):
        """Test seek/tell using the StatefulIncrementalDecoder."""

        def testSeekAndTellWithData(data, min_pos=0):
            """Tell/seek to various points within a data stream and ensure
            that the decoded data returned by read() is consistent."""
            f = io.open(support.TESTFN, 'wb')
            f.write(data)
            f.close()
            f = io.open(support.TESTFN, encoding='test_decoder')
            decoded = f.read()
            f.close()

            for i in range(min_pos, len(decoded) + 1): # seek positions
                for j in [1, 5, len(decoded) - i]: # read lengths
                    f = io.open(support.TESTFN, encoding='test_decoder')
                    self.assertEquals(f.read(i), decoded[:i])
                    cookie = f.tell()
                    self.assertEquals(f.read(j), decoded[i:i + j])
                    f.seek(cookie)
                    self.assertEquals(f.read(), decoded[i:])
                    f.close()

        # Enable the test decoder.
        StatefulIncrementalDecoder.codecEnabled = 1

        # Run the tests.
        try:
            # Try each test case.
            for input, _, _ in StatefulIncrementalDecoderTest.test_cases:
                testSeekAndTellWithData(input)

            # Position each test case so that it crosses a chunk boundary.
            CHUNK_SIZE = io.TextIOWrapper._CHUNK_SIZE
            for input, _, _ in StatefulIncrementalDecoderTest.test_cases:
                offset = CHUNK_SIZE - len(input)//2
                prefix = b'.'*offset
                # Don't bother seeking into the prefix (takes too long).
                min_pos = offset*2
                testSeekAndTellWithData(prefix + input, min_pos)

        # Ensure our test decoder won't interfere with subsequent tests.
        finally:
            StatefulIncrementalDecoder.codecEnabled = 0

    def testEncodedWrites(self):
        data = "1234567890"
        tests = ("utf-16",
                 "utf-16-le",
                 "utf-16-be",
                 "utf-32",
                 "utf-32-le",
                 "utf-32-be")
        for encoding in tests:
            buf = io.BytesIO()
            f = io.TextIOWrapper(buf, encoding=encoding)
            # Check if the BOM is written only once (see issue1753).
            f.write(data)
            f.write(data)
            f.seek(0)
            self.assertEquals(f.read(), data * 2)
            self.assertEquals(buf.getvalue(), (data * 2).encode(encoding))

    def timingTest(self):
        timer = time.time
        enc = "utf8"
        line = "\0\x0f\xff\u0fff\uffff\U000fffff\U0010ffff"*3 + "\n"
        nlines = 10000
        nchars = len(line)
        nbytes = len(line.encode(enc))
        for chunk_size in (32, 64, 128, 256):
            f = io.open(support.TESTFN, "w+", encoding=enc)
            f._CHUNK_SIZE = chunk_size
            t0 = timer()
            for i in range(nlines):
                f.write(line)
            f.flush()
            t1 = timer()
            f.seek(0)
            for line in f:
                pass
            t2 = timer()
            f.seek(0)
            while f.readline():
                pass
            t3 = timer()
            f.seek(0)
            while f.readline():
                f.tell()
            t4 = timer()
            f.close()
            if support.verbose:
                print("\nTiming test: %d lines of %d characters (%d bytes)" %
                      (nlines, nchars, nbytes))
                print("File chunk size:          %6s" % f._CHUNK_SIZE)
                print("Writing:                  %6.3f seconds" % (t1-t0))
                print("Reading using iteration:  %6.3f seconds" % (t2-t1))
                print("Reading using readline(): %6.3f seconds" % (t3-t2))
                print("Using readline()+tell():  %6.3f seconds" % (t4-t3))

    def testReadOneByOne(self):
        txt = io.TextIOWrapper(io.BytesIO(b"AA\r\nBB"))
        reads = ""
        while True:
            c = txt.read(1)
            if not c:
                break
            reads += c
        self.assertEquals(reads, "AA\nBB")

    # read in amounts equal to TextIOWrapper._CHUNK_SIZE which is 128.
    def testReadByChunk(self):
        # make sure "\r\n" straddles 128 char boundary.
        txt = io.TextIOWrapper(io.BytesIO(b"A" * 127 + b"\r\nB"))
        reads = ""
        while True:
            c = txt.read(128)
            if not c:
                break
            reads += c
        self.assertEquals(reads, "A"*127+"\nB")

    def test_issue1395_1(self):
        txt = io.TextIOWrapper(io.BytesIO(self.testdata), encoding="ascii")

        # read one char at a time
        reads = ""
        while True:
            c = txt.read(1)
            if not c:
                break
            reads += c
        self.assertEquals(reads, self.normalized)

    def test_issue1395_2(self):
        txt = io.TextIOWrapper(io.BytesIO(self.testdata), encoding="ascii")
        txt._CHUNK_SIZE = 4

        reads = ""
        while True:
            c = txt.read(4)
            if not c:
                break
            reads += c
        self.assertEquals(reads, self.normalized)

    def test_issue1395_3(self):
        txt = io.TextIOWrapper(io.BytesIO(self.testdata), encoding="ascii")
        txt._CHUNK_SIZE = 4

        reads = txt.read(4)
        reads += txt.read(4)
        reads += txt.readline()
        reads += txt.readline()
        reads += txt.readline()
        self.assertEquals(reads, self.normalized)

    def test_issue1395_4(self):
        txt = io.TextIOWrapper(io.BytesIO(self.testdata), encoding="ascii")
        txt._CHUNK_SIZE = 4

        reads = txt.read(4)
        reads += txt.read()
        self.assertEquals(reads, self.normalized)

    def test_issue1395_5(self):
        txt = io.TextIOWrapper(io.BytesIO(self.testdata), encoding="ascii")
        txt._CHUNK_SIZE = 4

        reads = txt.read(4)
        pos = txt.tell()
        txt.seek(0)
        txt.seek(pos)
        self.assertEquals(txt.read(4), "BBB\n")

    def test_issue2282(self):
        buffer = io.BytesIO(self.testdata)
        txt = io.TextIOWrapper(buffer, encoding="ascii")

        self.assertEqual(buffer.seekable(), txt.seekable())

    def test_newline_decoder(self):
        import codecs
        decoder = codecs.getincrementaldecoder("utf-8")()
        decoder = io.IncrementalNewlineDecoder(decoder, translate=True)

        self.assertEquals(decoder.decode(b'\xe8\xa2\x88'), "\u8888")

        self.assertEquals(decoder.decode(b'\xe8'), "")
        self.assertEquals(decoder.decode(b'\xa2'), "")
        self.assertEquals(decoder.decode(b'\x88'), "\u8888")

        self.assertEquals(decoder.decode(b'\xe8'), "")
        self.assertRaises(UnicodeDecodeError, decoder.decode, b'', final=True)

        decoder.setstate((b'', 0))
        self.assertEquals(decoder.decode(b'\n'), "\n")
        self.assertEquals(decoder.decode(b'\r'), "")
        self.assertEquals(decoder.decode(b'', final=True), "\n")
        self.assertEquals(decoder.decode(b'\r', final=True), "\n")

        self.assertEquals(decoder.decode(b'\r'), "")
        self.assertEquals(decoder.decode(b'a'), "\na")

        self.assertEquals(decoder.decode(b'\r\r\n'), "\n\n")
        self.assertEquals(decoder.decode(b'\r'), "")
        self.assertEquals(decoder.decode(b'\r'), "\n")
        self.assertEquals(decoder.decode(b'\na'), "\na")

        self.assertEquals(decoder.decode(b'\xe8\xa2\x88\r\n'), "\u8888\n")
        self.assertEquals(decoder.decode(b'\xe8\xa2\x88'), "\u8888")
        self.assertEquals(decoder.decode(b'\n'), "\n")
        self.assertEquals(decoder.decode(b'\xe8\xa2\x88\r'), "\u8888")
        self.assertEquals(decoder.decode(b'\n'), "\n")

        decoder = codecs.getincrementaldecoder("utf-8")()
        decoder = io.IncrementalNewlineDecoder(decoder, translate=True)
        self.assertEquals(decoder.newlines, None)
        decoder.decode(b"abc\n\r")
        self.assertEquals(decoder.newlines, '\n')
        decoder.decode(b"\nabc")
        self.assertEquals(decoder.newlines, ('\n', '\r\n'))
        decoder.decode(b"abc\r")
        self.assertEquals(decoder.newlines, ('\n', '\r\n'))
        decoder.decode(b"abc")
        self.assertEquals(decoder.newlines, ('\r', '\n', '\r\n'))
        decoder.decode(b"abc\r")
        decoder.reset()
        self.assertEquals(decoder.decode(b"abc"), "abc")
        self.assertEquals(decoder.newlines, None)

# XXX Tests for open()

class MiscIOTest(unittest.TestCase):

    def testImport__all__(self):
        for name in io.__all__:
            obj = getattr(io, name, None)
            self.assert_(obj is not None, name)
            if name == "open":
                continue
            elif "error" in name.lower():
                self.assert_(issubclass(obj, Exception), name)
            else:
                self.assert_(issubclass(obj, io.IOBase))


def test_main():
    support.run_unittest(IOTest, BytesIOTest, StringIOTest,
                              BufferedReaderTest, BufferedWriterTest,
                              BufferedRWPairTest, BufferedRandomTest,
                              StatefulIncrementalDecoderTest,
                              TextIOWrapperTest, MiscIOTest)

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