Lib/test/test_file2k.py

import sys
import os
import unittest
import itertools
import select
import signal
import subprocess
import time
from array import array
from weakref import proxy
try:
    import threading
except ImportError:
    threading = None

from test import test_support
from test.test_support import TESTFN, run_unittest
from UserList import UserList

class AutoFileTests(unittest.TestCase):
    # file tests for which a test file is automatically set up

    def setUp(self):
        self.f = open(TESTFN, 'wb')

    def tearDown(self):
        if self.f:
            self.f.close()
        os.remove(TESTFN)

    def testWeakRefs(self):
        # verify weak references
        p = proxy(self.f)
        p.write('teststring')
        self.assertEqual(self.f.tell(), p.tell())
        self.f.close()
        self.f = None
        self.assertRaises(ReferenceError, getattr, p, 'tell')

    def testAttributes(self):
        # verify expected attributes exist
        f = self.f
        with test_support.check_py3k_warnings():
            softspace = f.softspace
        f.name     # merely shouldn't blow up
        f.mode     # ditto
        f.closed   # ditto

        with test_support.check_py3k_warnings():
            # verify softspace is writable
            f.softspace = softspace    # merely shouldn't blow up

        # verify the others aren't
        for attr in 'name', 'mode', 'closed':
            self.assertRaises((AttributeError, TypeError), setattr, f, attr, 'oops')

    def testReadinto(self):
        # verify readinto
        self.f.write('12')
        self.f.close()
        a = array('c', 'x'*10)
        self.f = open(TESTFN, 'rb')
        n = self.f.readinto(a)
        self.assertEqual('12', a.tostring()[:n])

    def testWritelinesUserList(self):
        # verify writelines with instance sequence
        l = UserList(['1', '2'])
        self.f.writelines(l)
        self.f.close()
        self.f = open(TESTFN, 'rb')
        buf = self.f.read()
        self.assertEqual(buf, '12')

    def testWritelinesIntegers(self):
        # verify writelines with integers
        self.assertRaises(TypeError, self.f.writelines, [1, 2, 3])

    def testWritelinesIntegersUserList(self):
        # verify writelines with integers in UserList
        l = UserList([1,2,3])
        self.assertRaises(TypeError, self.f.writelines, l)

    def testWritelinesNonString(self):
        # verify writelines with non-string object
        class NonString:
            pass

        self.assertRaises(TypeError, self.f.writelines,
                          [NonString(), NonString()])

    def testRepr(self):
        # verify repr works
        self.assertTrue(repr(self.f).startswith("<open file '" + TESTFN))
        # see issue #14161
        # Windows doesn't like \r\n\t" in the file name, but ' is ok
        fname = 'xx\rxx\nxx\'xx"xx' if sys.platform != "win32" else "xx'xx"
        with open(fname, 'w') as f:
            self.addCleanup(os.remove, fname)
            self.assertTrue(repr(f).startswith(
                    "<open file %r, mode 'w' at" % fname))

    def testErrors(self):
        self.f.close()
        self.f = open(TESTFN, 'rb')
        f = self.f
        self.assertEqual(f.name, TESTFN)
        self.assertTrue(not f.isatty())
        self.assertTrue(not f.closed)

        self.assertRaises(TypeError, f.readinto, "")
        f.close()
        self.assertTrue(f.closed)

    def testMethods(self):
        methods = ['fileno', 'flush', 'isatty', 'next', 'read', 'readinto',
                   'readline', 'readlines', 'seek', 'tell', 'truncate',
                   'write', '__iter__']
        deprecated_methods = ['xreadlines']
        if sys.platform.startswith('atheos'):
            methods.remove('truncate')

        # __exit__ should close the file
        self.f.__exit__(None, None, None)
        self.assertTrue(self.f.closed)

        for methodname in methods:
            method = getattr(self.f, methodname)
            # should raise on closed file
            self.assertRaises(ValueError, method)
        with test_support.check_py3k_warnings():
            for methodname in deprecated_methods:
                method = getattr(self.f, methodname)
                self.assertRaises(ValueError, method)
        self.assertRaises(ValueError, self.f.writelines, [])

        # file is closed, __exit__ shouldn't do anything
        self.assertEqual(self.f.__exit__(None, None, None), None)
        # it must also return None if an exception was given
        try:
            1 // 0
        except:
            self.assertEqual(self.f.__exit__(*sys.exc_info()), None)

    def testReadWhenWriting(self):
        self.assertRaises(IOError, self.f.read)

    def testNastyWritelinesGenerator(self):
        def nasty():
            for i in range(5):
                if i == 3:
                    self.f.close()
                yield str(i)
        self.assertRaises(ValueError, self.f.writelines, nasty())

    def testIssue5677(self):
        # Remark: Do not perform more than one test per open file,
        # since that does NOT catch the readline error on Windows.
        data = 'xxx'
        for mode in ['w', 'wb', 'a', 'ab']:
            for attr in ['read', 'readline', 'readlines']:
                self.f = open(TESTFN, mode)
                self.f.write(data)
                self.assertRaises(IOError, getattr(self.f, attr))
                self.f.close()

            self.f = open(TESTFN, mode)
            self.f.write(data)
            self.assertRaises(IOError, lambda: [line for line in self.f])
            self.f.close()

            self.f = open(TESTFN, mode)
            self.f.write(data)
            self.assertRaises(IOError, self.f.readinto, bytearray(len(data)))
            self.f.close()

        for mode in ['r', 'rb', 'U', 'Ub', 'Ur', 'rU', 'rbU', 'rUb']:
            self.f = open(TESTFN, mode)
            self.assertRaises(IOError, self.f.write, data)
            self.f.close()

            self.f = open(TESTFN, mode)
            self.assertRaises(IOError, self.f.writelines, [data, data])
            self.f.close()

            self.f = open(TESTFN, mode)
            self.assertRaises(IOError, self.f.truncate)
            self.f.close()

class OtherFileTests(unittest.TestCase):

    def testOpenDir(self):
        this_dir = os.path.dirname(__file__) or os.curdir
        for mode in (None, "w"):
            try:
                if mode:
                    f = open(this_dir, mode)
                else:
                    f = open(this_dir)
            except IOError as e:
                self.assertEqual(e.filename, this_dir)
            else:
                self.fail("opening a directory didn't raise an IOError")

    def testModeStrings(self):
        # check invalid mode strings
        for mode in ("", "aU", "wU+"):
            try:
                f = open(TESTFN, mode)
            except ValueError:
                pass
            else:
                f.close()
                self.fail('%r is an invalid file mode' % mode)

        # Some invalid modes fail on Windows, but pass on Unix
        # Issue3965: avoid a crash on Windows when filename is unicode
        for name in (TESTFN, unicode(TESTFN), unicode(TESTFN + '\t')):
            try:
                f = open(name, "rr")
            except (IOError, ValueError):
                pass
            else:
                f.close()

    def testStdin(self):
        # This causes the interpreter to exit on OSF1 v5.1.
        if sys.platform != 'osf1V5':
            self.assertRaises(IOError, sys.stdin.seek, -1)
        else:
            print >>sys.__stdout__, (
                '  Skipping sys.stdin.seek(-1), it may crash the interpreter.'
                ' Test manually.')
        self.assertRaises(IOError, sys.stdin.truncate)

    def testUnicodeOpen(self):
        # verify repr works for unicode too
        f = open(unicode(TESTFN), "w")
        self.assertTrue(repr(f).startswith("<open file u'" + TESTFN))
        f.close()
        os.unlink(TESTFN)

    def testBadModeArgument(self):
        # verify that we get a sensible error message for bad mode argument
        bad_mode = "qwerty"
        try:
            f = open(TESTFN, bad_mode)
        except ValueError, msg:
            if msg.args[0] != 0:
                s = str(msg)
                if TESTFN in s or bad_mode not in s:
                    self.fail("bad error message for invalid mode: %s" % s)
            # if msg.args[0] == 0, we're probably on Windows where there may
            # be no obvious way to discover why open() failed.
        else:
            f.close()
            self.fail("no error for invalid mode: %s" % bad_mode)

    def testSetBufferSize(self):
        # make sure that explicitly setting the buffer size doesn't cause
        # misbehaviour especially with repeated close() calls
        for s in (-1, 0, 1, 512):
            try:
                f = open(TESTFN, 'w', s)
                f.write(str(s))
                f.close()
                f.close()
                f = open(TESTFN, 'r', s)
                d = int(f.read())
                f.close()
                f.close()
            except IOError, msg:
                self.fail('error setting buffer size %d: %s' % (s, str(msg)))
            self.assertEqual(d, s)

    def testTruncateOnWindows(self):
        os.unlink(TESTFN)

        def bug801631():
            # SF bug <http://www.python.org/sf/801631>
            # "file.truncate fault on windows"
            f = open(TESTFN, 'wb')
            f.write('12345678901')   # 11 bytes
            f.close()

            f = open(TESTFN,'rb+')
            data = f.read(5)
            if data != '12345':
                self.fail("Read on file opened for update failed %r" % data)
            if f.tell() != 5:
                self.fail("File pos after read wrong %d" % f.tell())

            f.truncate()
            if f.tell() != 5:
                self.fail("File pos after ftruncate wrong %d" % f.tell())

            f.close()
            size = os.path.getsize(TESTFN)
            if size != 5:
                self.fail("File size after ftruncate wrong %d" % size)

        try:
            bug801631()
        finally:
            os.unlink(TESTFN)

    def testIteration(self):
        # Test the complex interaction when mixing file-iteration and the
        # various read* methods. Ostensibly, the mixture could just be tested
        # to work when it should work according to the Python language,
        # instead of fail when it should fail according to the current CPython
        # implementation.  People don't always program Python the way they
        # should, though, and the implemenation might change in subtle ways,
        # so we explicitly test for errors, too; the test will just have to
        # be updated when the implementation changes.
        dataoffset = 16384
        filler = "ham\n"
        assert not dataoffset % len(filler), \
            "dataoffset must be multiple of len(filler)"
        nchunks = dataoffset // len(filler)
        testlines = [
            "spam, spam and eggs\n",
            "eggs, spam, ham and spam\n",
            "saussages, spam, spam and eggs\n",
            "spam, ham, spam and eggs\n",
            "spam, spam, spam, spam, spam, ham, spam\n",
            "wonderful spaaaaaam.\n"
        ]
        methods = [("readline", ()), ("read", ()), ("readlines", ()),
                   ("readinto", (array("c", " "*100),))]

        try:
            # Prepare the testfile
            bag = open(TESTFN, "w")
            bag.write(filler * nchunks)
            bag.writelines(testlines)
            bag.close()
            # Test for appropriate errors mixing read* and iteration
            for methodname, args in methods:
                f = open(TESTFN)
                if f.next() != filler:
                    self.fail, "Broken testfile"
                meth = getattr(f, methodname)
                try:
                    meth(*args)
                except ValueError:
                    pass
                else:
                    self.fail("%s%r after next() didn't raise ValueError" %
                                     (methodname, args))
                f.close()

            # Test to see if harmless (by accident) mixing of read* and
            # iteration still works. This depends on the size of the internal
            # iteration buffer (currently 8192,) but we can test it in a
            # flexible manner.  Each line in the bag o' ham is 4 bytes
            # ("h", "a", "m", "\n"), so 4096 lines of that should get us
            # exactly on the buffer boundary for any power-of-2 buffersize
            # between 4 and 16384 (inclusive).
            f = open(TESTFN)
            for i in range(nchunks):
                f.next()
            testline = testlines.pop(0)
            try:
                line = f.readline()
            except ValueError:
                self.fail("readline() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            if line != testline:
                self.fail("readline() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))
            testline = testlines.pop(0)
            buf = array("c", "\x00" * len(testline))
            try:
                f.readinto(buf)
            except ValueError:
                self.fail("readinto() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            line = buf.tostring()
            if line != testline:
                self.fail("readinto() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))

            testline = testlines.pop(0)
            try:
                line = f.read(len(testline))
            except ValueError:
                self.fail("read() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            if line != testline:
                self.fail("read() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))
            try:
                lines = f.readlines()
            except ValueError:
                self.fail("readlines() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            if lines != testlines:
                self.fail("readlines() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))
            # Reading after iteration hit EOF shouldn't hurt either
            f = open(TESTFN)
            try:
                for line in f:
                    pass
                try:
                    f.readline()
                    f.readinto(buf)
                    f.read()
                    f.readlines()
                except ValueError:
                    self.fail("read* failed after next() consumed file")
            finally:
                f.close()
        finally:
            os.unlink(TESTFN)

    @unittest.skipUnless(os.name == 'posix', 'test requires a posix system.')
    def test_write_full(self):
        # Issue #17976
        try:
            f = open('/dev/full', 'w', 1)
        except IOError:
            self.skipTest("requires '/dev/full'")
        try:
            with self.assertRaises(IOError):
                f.write('hello')
                f.write('\n')
        finally:
            f.close()

class FileSubclassTests(unittest.TestCase):

    def testExit(self):
        # test that exiting with context calls subclass' close
        class C(file):
            def __init__(self, *args):
                self.subclass_closed = False
                file.__init__(self, *args)
            def close(self):
                self.subclass_closed = True
                file.close(self)

        with C(TESTFN, 'w') as f:
            pass
        self.assertTrue(f.subclass_closed)


@unittest.skipUnless(threading, 'Threading required for this test.')
class FileThreadingTests(unittest.TestCase):
    # These tests check the ability to call various methods of file objects
    # (including close()) concurrently without crashing the Python interpreter.
    # See #815646, #595601

    def setUp(self):
        self._threads = test_support.threading_setup()
        self.f = None
        self.filename = TESTFN
        with open(self.filename, "w") as f:
            f.write("\n".join("0123456789"))
        self._count_lock = threading.Lock()
        self.close_count = 0
        self.close_success_count = 0
        self.use_buffering = False

    def tearDown(self):
        if self.f:
            try:
                self.f.close()
            except (EnvironmentError, ValueError):
                pass
        try:
            os.remove(self.filename)
        except EnvironmentError:
            pass
        test_support.threading_cleanup(*self._threads)

    def _create_file(self):
        if self.use_buffering:
            self.f = open(self.filename, "w+", buffering=1024*16)
        else:
            self.f = open(self.filename, "w+")

    def _close_file(self):
        with self._count_lock:
            self.close_count += 1
        self.f.close()
        with self._count_lock:
            self.close_success_count += 1

    def _close_and_reopen_file(self):
        self._close_file()
        # if close raises an exception thats fine, self.f remains valid so
        # we don't need to reopen.
        self._create_file()

    def _run_workers(self, func, nb_workers, duration=0.2):
        with self._count_lock:
            self.close_count = 0
            self.close_success_count = 0
        self.do_continue = True
        threads = []
        try:
            for i in range(nb_workers):
                t = threading.Thread(target=func)
                t.start()
                threads.append(t)
            for _ in xrange(100):
                time.sleep(duration/100)
                with self._count_lock:
                    if self.close_count-self.close_success_count > nb_workers+1:
                        if test_support.verbose:
                            print 'Q',
                        break
            time.sleep(duration)
        finally:
            self.do_continue = False
            for t in threads:
                t.join()

    def _test_close_open_io(self, io_func, nb_workers=5):
        def worker():
            self._create_file()
            funcs = itertools.cycle((
                lambda: io_func(),
                lambda: self._close_and_reopen_file(),
            ))
            for f in funcs:
                if not self.do_continue:
                    break
                try:
                    f()
                except (IOError, ValueError):
                    pass
        self._run_workers(worker, nb_workers)
        if test_support.verbose:
            # Useful verbose statistics when tuning this test to take
            # less time to run but still ensuring that its still useful.
            #
            # the percent of close calls that raised an error
            percent = 100. - 100.*self.close_success_count/self.close_count
            print self.close_count, ('%.4f ' % percent),

    def test_close_open(self):
        def io_func():
            pass
        self._test_close_open_io(io_func)

    def test_close_open_flush(self):
        def io_func():
            self.f.flush()
        self._test_close_open_io(io_func)

    def test_close_open_iter(self):
        def io_func():
            list(iter(self.f))
        self._test_close_open_io(io_func)

    def test_close_open_isatty(self):
        def io_func():
            self.f.isatty()
        self._test_close_open_io(io_func)

    def test_close_open_print(self):
        def io_func():
            print >> self.f, ''
        self._test_close_open_io(io_func)

    def test_close_open_print_buffered(self):
        self.use_buffering = True
        def io_func():
            print >> self.f, ''
        self._test_close_open_io(io_func)

    def test_close_open_read(self):
        def io_func():
            self.f.read(0)
        self._test_close_open_io(io_func)

    def test_close_open_readinto(self):
        def io_func():
            a = array('c', 'xxxxx')
            self.f.readinto(a)
        self._test_close_open_io(io_func)

    def test_close_open_readline(self):
        def io_func():
            self.f.readline()
        self._test_close_open_io(io_func)

    def test_close_open_readlines(self):
        def io_func():
            self.f.readlines()
        self._test_close_open_io(io_func)

    def test_close_open_seek(self):
        def io_func():
            self.f.seek(0, 0)
        self._test_close_open_io(io_func)

    def test_close_open_tell(self):
        def io_func():
            self.f.tell()
        self._test_close_open_io(io_func)

    def test_close_open_truncate(self):
        def io_func():
            self.f.truncate()
        self._test_close_open_io(io_func)

    def test_close_open_write(self):
        def io_func():
            self.f.write('')
        self._test_close_open_io(io_func)

    def test_close_open_writelines(self):
        def io_func():
            self.f.writelines('')
        self._test_close_open_io(io_func)


@unittest.skipUnless(os.name == 'posix', 'test requires a posix system.')
class TestFileSignalEINTR(unittest.TestCase):
    def _test_reading(self, data_to_write, read_and_verify_code, method_name,
                      universal_newlines=False):
        """Generic buffered read method test harness to verify EINTR behavior.

        Also validates that Python signal handlers are run during the read.

        Args:
            data_to_write: String to write to the child process for reading
                before sending it a signal, confirming the signal was handled,
                writing a final newline char and closing the infile pipe.
            read_and_verify_code: Single "line" of code to read from a file
                object named 'infile' and validate the result.  This will be
                executed as part of a python subprocess fed data_to_write.
            method_name: The name of the read method being tested, for use in
                an error message on failure.
            universal_newlines: If True, infile will be opened in universal
                newline mode in the child process.
        """
        if universal_newlines:
            # Test the \r\n -> \n conversion while we're at it.
            data_to_write = data_to_write.replace('\n', '\r\n')
            infile_setup_code = 'infile = os.fdopen(sys.stdin.fileno(), "rU")'
        else:
            infile_setup_code = 'infile = sys.stdin'
        # Total pipe IO in this function is smaller than the minimum posix OS
        # pipe buffer size of 512 bytes.  No writer should block.
        assert len(data_to_write) < 512, 'data_to_write must fit in pipe buf.'

        child_code = (
             'import os, signal, sys ;'
             'signal.signal('
                     'signal.SIGINT, lambda s, f: sys.stderr.write("$\\n")) ;'
             + infile_setup_code + ' ;' +
             'assert isinstance(infile, file) ;'
             'sys.stderr.write("Go.\\n") ;'
             + read_and_verify_code)
        reader_process = subprocess.Popen(
                [sys.executable, '-c', child_code],
                stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                stderr=subprocess.PIPE)
        # Wait for the signal handler to be installed.
        go = reader_process.stderr.read(4)
        if go != 'Go.\n':
            reader_process.kill()
            self.fail('Error from %s process while awaiting "Go":\n%s' % (
                    method_name, go+reader_process.stderr.read()))
        reader_process.stdin.write(data_to_write)
        signals_sent = 0
        rlist = []
        # We don't know when the read_and_verify_code in our child is actually
        # executing within the read system call we want to interrupt.  This
        # loop waits for a bit before sending the first signal to increase
        # the likelihood of that.  Implementations without correct EINTR
        # and signal handling usually fail this test.
        while not rlist:
            rlist, _, _ = select.select([reader_process.stderr], (), (), 0.05)
            reader_process.send_signal(signal.SIGINT)
            # Give the subprocess time to handle it before we loop around and
            # send another one.  On OSX the second signal happening close to
            # immediately after the first was causing the subprocess to crash
            # via the OS's default SIGINT handler.
            time.sleep(0.1)
            signals_sent += 1
            if signals_sent > 200:
                reader_process.kill()
                self.fail("failed to handle signal during %s." % method_name)
        # This assumes anything unexpected that writes to stderr will also
        # write a newline.  That is true of the traceback printing code.
        signal_line = reader_process.stderr.readline()
        if signal_line != '$\n':
            reader_process.kill()
            self.fail('Error from %s process while awaiting signal:\n%s' % (
                    method_name, signal_line+reader_process.stderr.read()))
        # We append a newline to our input so that a readline call can
        # end on its own before the EOF is seen.
        stdout, stderr = reader_process.communicate(input='\n')
        if reader_process.returncode != 0:
            self.fail('%s() process exited rc=%d.\nSTDOUT:\n%s\nSTDERR:\n%s' % (
                    method_name, reader_process.returncode, stdout, stderr))

    def test_readline(self, universal_newlines=False):
        """file.readline must handle signals and not lose data."""
        self._test_reading(
                data_to_write='hello, world!',
                read_and_verify_code=(
                        'line = infile.readline() ;'
                        'expected_line = "hello, world!\\n" ;'
                        'assert line == expected_line, ('
                        '"read %r expected %r" % (line, expected_line))'
                ),
                method_name='readline',
                universal_newlines=universal_newlines)

    def test_readline_with_universal_newlines(self):
        self.test_readline(universal_newlines=True)

    def test_readlines(self, universal_newlines=False):
        """file.readlines must handle signals and not lose data."""
        self._test_reading(
                data_to_write='hello\nworld!',
                read_and_verify_code=(
                        'lines = infile.readlines() ;'
                        'expected_lines = ["hello\\n", "world!\\n"] ;'
                        'assert lines == expected_lines, ('
                        '"readlines returned wrong data.\\n" '
                        '"got lines %r\\nexpected  %r" '
                        '% (lines, expected_lines))'
                ),
                method_name='readlines',
                universal_newlines=universal_newlines)

    def test_readlines_with_universal_newlines(self):
        self.test_readlines(universal_newlines=True)

    def test_readall(self):
        """Unbounded file.read() must handle signals and not lose data."""
        self._test_reading(
                data_to_write='hello, world!abcdefghijklm',
                read_and_verify_code=(
                        'data = infile.read() ;'
                        'expected_data = "hello, world!abcdefghijklm\\n";'
                        'assert data == expected_data, ('
                        '"read %r expected %r" % (data, expected_data))'
                ),
                method_name='unbounded read')

    def test_readinto(self):
        """file.readinto must handle signals and not lose data."""
        self._test_reading(
                data_to_write='hello, world!',
                read_and_verify_code=(
                        'data = bytearray(50) ;'
                        'num_read = infile.readinto(data) ;'
                        'expected_data = "hello, world!\\n";'
                        'assert data[:num_read] == expected_data, ('
                        '"read %r expected %r" % (data, expected_data))'
                ),
                method_name='readinto')


class StdoutTests(unittest.TestCase):

    def test_move_stdout_on_write(self):
        # Issue 3242: sys.stdout can be replaced (and freed) during a
        # print statement; prevent a segfault in this case
        save_stdout = sys.stdout

        class File:
            def write(self, data):
                if '\n' in data:
                    sys.stdout = save_stdout

        try:
            sys.stdout = File()
            print "some text"
        finally:
            sys.stdout = save_stdout

    def test_del_stdout_before_print(self):
        # Issue 4597: 'print' with no argument wasn't reporting when
        # sys.stdout was deleted.
        save_stdout = sys.stdout
        del sys.stdout
        try:
            print
        except RuntimeError as e:
            self.assertEqual(str(e), "lost sys.stdout")
        else:
            self.fail("Expected RuntimeError")
        finally:
            sys.stdout = save_stdout

    def test_unicode(self):
        import subprocess

        def get_message(encoding, *code):
            code = '\n'.join(code)
            env = os.environ.copy()
            env['PYTHONIOENCODING'] = encoding
            process = subprocess.Popen([sys.executable, "-c", code],
                                       stdout=subprocess.PIPE, env=env)
            stdout, stderr = process.communicate()
            self.assertEqual(process.returncode, 0)
            return stdout

        def check_message(text, encoding, expected):
            stdout = get_message(encoding,
                "import sys",
                "sys.stdout.write(%r)" % text,
                "sys.stdout.flush()")
            self.assertEqual(stdout, expected)

        # test the encoding
        check_message(u'15\u20ac', "iso-8859-15", "15\xa4")
        check_message(u'15\u20ac', "utf-8", '15\xe2\x82\xac')
        check_message(u'15\u20ac', "utf-16-le", '1\x005\x00\xac\x20')

        # test the error handler
        check_message(u'15\u20ac', "iso-8859-1:ignore", "15")
        check_message(u'15\u20ac', "iso-8859-1:replace", "15?")
        check_message(u'15\u20ac', "iso-8859-1:backslashreplace", "15\\u20ac")

        # test the buffer API
        for objtype in ('buffer', 'bytearray'):
            stdout = get_message('ascii',
                'import sys',
                r'sys.stdout.write(%s("\xe9"))' % objtype,
                'sys.stdout.flush()')
            self.assertEqual(stdout, "\xe9")


def test_main():
    # Historically, these tests have been sloppy about removing TESTFN.
    # So get rid of it no matter what.
    try:
        run_unittest(AutoFileTests, OtherFileTests, FileSubclassTests,
            FileThreadingTests, TestFileSignalEINTR, StdoutTests)
    finally:
        if os.path.exists(TESTFN):
            os.unlink(TESTFN)

if __name__ == '__main__':
    test_main()