Lib/test/test_subprocess.py

import unittest
from test import support
import subprocess
import sys
import signal
import os
import errno
import tempfile
import time
import re
import sysconfig
import warnings
import select
import shutil
try:
    import gc
except ImportError:
    gc = None

mswindows = (sys.platform == "win32")

#
# Depends on the following external programs: Python
#

if mswindows:
    SETBINARY = ('import msvcrt; msvcrt.setmode(sys.stdout.fileno(), '
                                                'os.O_BINARY);')
else:
    SETBINARY = ''


try:
    mkstemp = tempfile.mkstemp
except AttributeError:
    # tempfile.mkstemp is not available
    def mkstemp():
        """Replacement for mkstemp, calling mktemp."""
        fname = tempfile.mktemp()
        return os.open(fname, os.O_RDWR|os.O_CREAT), fname


class BaseTestCase(unittest.TestCase):
    def setUp(self):
        # Try to minimize the number of children we have so this test
        # doesn't crash on some buildbots (Alphas in particular).
        support.reap_children()

    def tearDown(self):
        for inst in subprocess._active:
            inst.wait()
        subprocess._cleanup()
        self.assertFalse(subprocess._active, "subprocess._active not empty")

    def assertStderrEqual(self, stderr, expected, msg=None):
        # In a debug build, stuff like "[6580 refs]" is printed to stderr at
        # shutdown time.  That frustrates tests trying to check stderr produced
        # from a spawned Python process.
        actual = support.strip_python_stderr(stderr)
        # strip_python_stderr also strips whitespace, so we do too.
        expected = expected.strip()
        self.assertEqual(actual, expected, msg)


class ProcessTestCase(BaseTestCase):

    def test_call_seq(self):
        # call() function with sequence argument
        rc = subprocess.call([sys.executable, "-c",
                              "import sys; sys.exit(47)"])
        self.assertEqual(rc, 47)

    def test_call_timeout(self):
        # call() function with timeout argument; we want to test that the child
        # process gets killed when the timeout expires.  If the child isn't
        # killed, this call will deadlock since subprocess.call waits for the
        # child.
        self.assertRaises(subprocess.TimeoutExpired, subprocess.call,
                          [sys.executable, "-c", "while True: pass"],
                          timeout=0.1)

    def test_check_call_zero(self):
        # check_call() function with zero return code
        rc = subprocess.check_call([sys.executable, "-c",
                                    "import sys; sys.exit(0)"])
        self.assertEqual(rc, 0)

    def test_check_call_nonzero(self):
        # check_call() function with non-zero return code
        with self.assertRaises(subprocess.CalledProcessError) as c:
            subprocess.check_call([sys.executable, "-c",
                                   "import sys; sys.exit(47)"])
        self.assertEqual(c.exception.returncode, 47)

    def test_check_output(self):
        # check_output() function with zero return code
        output = subprocess.check_output(
                [sys.executable, "-c", "print('BDFL')"])
        self.assertIn(b'BDFL', output)

    def test_check_output_nonzero(self):
        # check_call() function with non-zero return code
        with self.assertRaises(subprocess.CalledProcessError) as c:
            subprocess.check_output(
                    [sys.executable, "-c", "import sys; sys.exit(5)"])
        self.assertEqual(c.exception.returncode, 5)

    def test_check_output_stderr(self):
        # check_output() function stderr redirected to stdout
        output = subprocess.check_output(
                [sys.executable, "-c", "import sys; sys.stderr.write('BDFL')"],
                stderr=subprocess.STDOUT)
        self.assertIn(b'BDFL', output)

    def test_check_output_stdout_arg(self):
        # check_output() function stderr redirected to stdout
        with self.assertRaises(ValueError) as c:
            output = subprocess.check_output(
                    [sys.executable, "-c", "print('will not be run')"],
                    stdout=sys.stdout)
            self.fail("Expected ValueError when stdout arg supplied.")
        self.assertIn('stdout', c.exception.args[0])

    def test_check_output_timeout(self):
        # check_output() function with timeout arg
        with self.assertRaises(subprocess.TimeoutExpired) as c:
            output = subprocess.check_output(
                    [sys.executable, "-c",
                     "import sys; sys.stdout.write('BDFL')\n"
                     "sys.stdout.flush()\n"
                     "while True: pass"],
                    timeout=1.5)
            self.fail("Expected TimeoutExpired.")
        self.assertEqual(c.exception.output, b'BDFL')

    def test_call_kwargs(self):
        # call() function with keyword args
        newenv = os.environ.copy()
        newenv["FRUIT"] = "banana"
        rc = subprocess.call([sys.executable, "-c",
                              'import sys, os;'
                              'sys.exit(os.getenv("FRUIT")=="banana")'],
                             env=newenv)
        self.assertEqual(rc, 1)

    def test_stdin_none(self):
        # .stdin is None when not redirected
        p = subprocess.Popen([sys.executable, "-c", 'print("banana")'],
                         stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        p.wait()
        self.assertEqual(p.stdin, None)

    def test_stdout_none(self):
        # .stdout is None when not redirected
        p = subprocess.Popen([sys.executable, "-c",
                             'print("    this bit of output is from a '
                             'test of stdout in a different '
                             'process ...")'],
                             stdin=subprocess.PIPE, stderr=subprocess.PIPE)
        self.addCleanup(p.stdin.close)
        self.addCleanup(p.stderr.close)
        p.wait()
        self.assertEqual(p.stdout, None)

    def test_stderr_none(self):
        # .stderr is None when not redirected
        p = subprocess.Popen([sys.executable, "-c", 'print("banana")'],
                         stdin=subprocess.PIPE, stdout=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stdin.close)
        p.wait()
        self.assertEqual(p.stderr, None)

    def test_executable_with_cwd(self):
        python_dir = os.path.dirname(os.path.realpath(sys.executable))
        p = subprocess.Popen(["somethingyoudonthave", "-c",
                              "import sys; sys.exit(47)"],
                             executable=sys.executable, cwd=python_dir)
        p.wait()
        self.assertEqual(p.returncode, 47)

    @unittest.skipIf(sysconfig.is_python_build(),
                     "need an installed Python. See #7774")
    def test_executable_without_cwd(self):
        # For a normal installation, it should work without 'cwd'
        # argument.  For test runs in the build directory, see #7774.
        p = subprocess.Popen(["somethingyoudonthave", "-c",
                              "import sys; sys.exit(47)"],
                             executable=sys.executable)
        p.wait()
        self.assertEqual(p.returncode, 47)

    def test_stdin_pipe(self):
        # stdin redirection
        p = subprocess.Popen([sys.executable, "-c",
                         'import sys; sys.exit(sys.stdin.read() == "pear")'],
                        stdin=subprocess.PIPE)
        p.stdin.write(b"pear")
        p.stdin.close()
        p.wait()
        self.assertEqual(p.returncode, 1)

    def test_stdin_filedes(self):
        # stdin is set to open file descriptor
        tf = tempfile.TemporaryFile()
        self.addCleanup(tf.close)
        d = tf.fileno()
        os.write(d, b"pear")
        os.lseek(d, 0, 0)
        p = subprocess.Popen([sys.executable, "-c",
                         'import sys; sys.exit(sys.stdin.read() == "pear")'],
                         stdin=d)
        p.wait()
        self.assertEqual(p.returncode, 1)

    def test_stdin_fileobj(self):
        # stdin is set to open file object
        tf = tempfile.TemporaryFile()
        self.addCleanup(tf.close)
        tf.write(b"pear")
        tf.seek(0)
        p = subprocess.Popen([sys.executable, "-c",
                         'import sys; sys.exit(sys.stdin.read() == "pear")'],
                         stdin=tf)
        p.wait()
        self.assertEqual(p.returncode, 1)

    def test_stdout_pipe(self):
        # stdout redirection
        p = subprocess.Popen([sys.executable, "-c",
                          'import sys; sys.stdout.write("orange")'],
                         stdout=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.assertEqual(p.stdout.read(), b"orange")

    def test_stdout_filedes(self):
        # stdout is set to open file descriptor
        tf = tempfile.TemporaryFile()
        self.addCleanup(tf.close)
        d = tf.fileno()
        p = subprocess.Popen([sys.executable, "-c",
                          'import sys; sys.stdout.write("orange")'],
                         stdout=d)
        p.wait()
        os.lseek(d, 0, 0)
        self.assertEqual(os.read(d, 1024), b"orange")

    def test_stdout_fileobj(self):
        # stdout is set to open file object
        tf = tempfile.TemporaryFile()
        self.addCleanup(tf.close)
        p = subprocess.Popen([sys.executable, "-c",
                          'import sys; sys.stdout.write("orange")'],
                         stdout=tf)
        p.wait()
        tf.seek(0)
        self.assertEqual(tf.read(), b"orange")

    def test_stderr_pipe(self):
        # stderr redirection
        p = subprocess.Popen([sys.executable, "-c",
                          'import sys; sys.stderr.write("strawberry")'],
                         stderr=subprocess.PIPE)
        self.addCleanup(p.stderr.close)
        self.assertStderrEqual(p.stderr.read(), b"strawberry")

    def test_stderr_filedes(self):
        # stderr is set to open file descriptor
        tf = tempfile.TemporaryFile()
        self.addCleanup(tf.close)
        d = tf.fileno()
        p = subprocess.Popen([sys.executable, "-c",
                          'import sys; sys.stderr.write("strawberry")'],
                         stderr=d)
        p.wait()
        os.lseek(d, 0, 0)
        self.assertStderrEqual(os.read(d, 1024), b"strawberry")

    def test_stderr_fileobj(self):
        # stderr is set to open file object
        tf = tempfile.TemporaryFile()
        self.addCleanup(tf.close)
        p = subprocess.Popen([sys.executable, "-c",
                          'import sys; sys.stderr.write("strawberry")'],
                         stderr=tf)
        p.wait()
        tf.seek(0)
        self.assertStderrEqual(tf.read(), b"strawberry")

    def test_stdout_stderr_pipe(self):
        # capture stdout and stderr to the same pipe
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys;'
                              'sys.stdout.write("apple");'
                              'sys.stdout.flush();'
                              'sys.stderr.write("orange")'],
                             stdout=subprocess.PIPE,
                             stderr=subprocess.STDOUT)
        self.addCleanup(p.stdout.close)
        self.assertStderrEqual(p.stdout.read(), b"appleorange")

    def test_stdout_stderr_file(self):
        # capture stdout and stderr to the same open file
        tf = tempfile.TemporaryFile()
        self.addCleanup(tf.close)
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys;'
                              'sys.stdout.write("apple");'
                              'sys.stdout.flush();'
                              'sys.stderr.write("orange")'],
                             stdout=tf,
                             stderr=tf)
        p.wait()
        tf.seek(0)
        self.assertStderrEqual(tf.read(), b"appleorange")

    def test_stdout_filedes_of_stdout(self):
        # stdout is set to 1 (#1531862).
        cmd = r"import sys, os; sys.exit(os.write(sys.stdout.fileno(), b'.\n'))"
        rc = subprocess.call([sys.executable, "-c", cmd], stdout=1)
        self.assertEqual(rc, 2)

    def test_cwd(self):
        tmpdir = tempfile.gettempdir()
        # We cannot use os.path.realpath to canonicalize the path,
        # since it doesn't expand Tru64 {memb} strings. See bug 1063571.
        cwd = os.getcwd()
        os.chdir(tmpdir)
        tmpdir = os.getcwd()
        os.chdir(cwd)
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(os.getcwd())'],
                             stdout=subprocess.PIPE,
                             cwd=tmpdir)
        self.addCleanup(p.stdout.close)
        normcase = os.path.normcase
        self.assertEqual(normcase(p.stdout.read().decode("utf-8")),
                         normcase(tmpdir))

    def test_env(self):
        newenv = os.environ.copy()
        newenv["FRUIT"] = "orange"
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(os.getenv("FRUIT"))'],
                             stdout=subprocess.PIPE,
                             env=newenv)
        self.addCleanup(p.stdout.close)
        self.assertEqual(p.stdout.read(), b"orange")

    def test_communicate_stdin(self):
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys;'
                              'sys.exit(sys.stdin.read() == "pear")'],
                             stdin=subprocess.PIPE)
        p.communicate(b"pear")
        self.assertEqual(p.returncode, 1)

    def test_communicate_stdout(self):
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys; sys.stdout.write("pineapple")'],
                             stdout=subprocess.PIPE)
        (stdout, stderr) = p.communicate()
        self.assertEqual(stdout, b"pineapple")
        self.assertEqual(stderr, None)

    def test_communicate_stderr(self):
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys; sys.stderr.write("pineapple")'],
                             stderr=subprocess.PIPE)
        (stdout, stderr) = p.communicate()
        self.assertEqual(stdout, None)
        self.assertStderrEqual(stderr, b"pineapple")

    def test_communicate(self):
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stderr.write("pineapple");'
                              'sys.stdout.write(sys.stdin.read())'],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        self.addCleanup(p.stdin.close)
        (stdout, stderr) = p.communicate(b"banana")
        self.assertEqual(stdout, b"banana")
        self.assertStderrEqual(stderr, b"pineapple")

    def test_communicate_timeout(self):
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os,time;'
                              'sys.stderr.write("pineapple\\n");'
                              'time.sleep(1);'
                              'sys.stderr.write("pear\\n");'
                              'sys.stdout.write(sys.stdin.read())'],
                             universal_newlines=True,
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.assertRaises(subprocess.TimeoutExpired, p.communicate, "banana",
                          timeout=0.3)
        # Make sure we can keep waiting for it, and that we get the whole output
        # after it completes.
        (stdout, stderr) = p.communicate()
        self.assertEqual(stdout, "banana")
        self.assertStderrEqual(stderr.encode(), b"pineapple\npear\n")

    def test_communicate_timeout_large_ouput(self):
        # Test a expring timeout while the child is outputting lots of data.
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os,time;'
                              'sys.stdout.write("a" * (64 * 1024));'
                              'time.sleep(0.2);'
                              'sys.stdout.write("a" * (64 * 1024));'
                              'time.sleep(0.2);'
                              'sys.stdout.write("a" * (64 * 1024));'
                              'time.sleep(0.2);'
                              'sys.stdout.write("a" * (64 * 1024));'],
                             stdout=subprocess.PIPE)
        self.assertRaises(subprocess.TimeoutExpired, p.communicate, timeout=0.4)
        (stdout, _) = p.communicate()
        self.assertEqual(len(stdout), 4 * 64 * 1024)

    # Test for the fd leak reported in http://bugs.python.org/issue2791.
    def test_communicate_pipe_fd_leak(self):
        for stdin_pipe in (False, True):
            for stdout_pipe in (False, True):
                for stderr_pipe in (False, True):
                    options = {}
                    if stdin_pipe:
                        options['stdin'] = subprocess.PIPE
                    if stdout_pipe:
                        options['stdout'] = subprocess.PIPE
                    if stderr_pipe:
                        options['stderr'] = subprocess.PIPE
                    if not options:
                        continue
                    p = subprocess.Popen((sys.executable, "-c", "pass"), **options)
                    p.communicate()
                    if p.stdin is not None:
                        self.assertTrue(p.stdin.closed)
                    if p.stdout is not None:
                        self.assertTrue(p.stdout.closed)
                    if p.stderr is not None:
                        self.assertTrue(p.stderr.closed)

    def test_communicate_returns(self):
        # communicate() should return None if no redirection is active
        p = subprocess.Popen([sys.executable, "-c",
                              "import sys; sys.exit(47)"])
        (stdout, stderr) = p.communicate()
        self.assertEqual(stdout, None)
        self.assertEqual(stderr, None)

    def test_communicate_pipe_buf(self):
        # communicate() with writes larger than pipe_buf
        # This test will probably deadlock rather than fail, if
        # communicate() does not work properly.
        x, y = os.pipe()
        if mswindows:
            pipe_buf = 512
        else:
            pipe_buf = os.fpathconf(x, "PC_PIPE_BUF")
        os.close(x)
        os.close(y)
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(sys.stdin.read(47));'
                              'sys.stderr.write("xyz"*%d);'
                              'sys.stdout.write(sys.stdin.read())' % pipe_buf],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        self.addCleanup(p.stdin.close)
        string_to_write = b"abc"*pipe_buf
        (stdout, stderr) = p.communicate(string_to_write)
        self.assertEqual(stdout, string_to_write)

    def test_writes_before_communicate(self):
        # stdin.write before communicate()
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(sys.stdin.read())'],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        self.addCleanup(p.stdin.close)
        p.stdin.write(b"banana")
        (stdout, stderr) = p.communicate(b"split")
        self.assertEqual(stdout, b"bananasplit")
        self.assertStderrEqual(stderr, b"")

    def test_universal_newlines(self):
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;' + SETBINARY +
                              'sys.stdout.write("line1\\n");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("line2\\n");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("line3\\r\\n");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("line4\\r");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("\\nline5");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("\\nline6");'],
                             stdout=subprocess.PIPE,
                             universal_newlines=1)
        self.addCleanup(p.stdout.close)
        stdout = p.stdout.read()
        self.assertEqual(stdout, "line1\nline2\nline3\nline4\nline5\nline6")

    def test_universal_newlines_communicate(self):
        # universal newlines through communicate()
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;' + SETBINARY +
                              'sys.stdout.write("line1\\n");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("line2\\n");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("line3\\r\\n");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("line4\\r");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("\\nline5");'
                              'sys.stdout.flush();'
                              'sys.stdout.write("\\nline6");'],
                             stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                             universal_newlines=1)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        (stdout, stderr) = p.communicate()
        self.assertEqual(stdout, "line1\nline2\nline3\nline4\nline5\nline6")

    def test_no_leaking(self):
        # Make sure we leak no resources
        if not mswindows:
            max_handles = 1026 # too much for most UNIX systems
        else:
            max_handles = 2050 # too much for (at least some) Windows setups
        handles = []
        tmpdir = tempfile.mkdtemp()
        try:
            for i in range(max_handles):
                try:
                    tmpfile = os.path.join(tmpdir, support.TESTFN)
                    handles.append(os.open(tmpfile, os.O_WRONLY|os.O_CREAT))
                except OSError as e:
                    if e.errno != errno.EMFILE:
                        raise
                    break
            else:
                self.skipTest("failed to reach the file descriptor limit "
                    "(tried %d)" % max_handles)
            # Close a couple of them (should be enough for a subprocess)
            for i in range(10):
                os.close(handles.pop())
            # Loop creating some subprocesses. If one of them leaks some fds,
            # the next loop iteration will fail by reaching the max fd limit.
            for i in range(15):
                p = subprocess.Popen([sys.executable, "-c",
                                      "import sys;"
                                      "sys.stdout.write(sys.stdin.read())"],
                                     stdin=subprocess.PIPE,
                                     stdout=subprocess.PIPE,
                                     stderr=subprocess.PIPE)
                data = p.communicate(b"lime")[0]
                self.assertEqual(data, b"lime")
        finally:
            for h in handles:
                os.close(h)
            shutil.rmtree(tmpdir)

    def test_list2cmdline(self):
        self.assertEqual(subprocess.list2cmdline(['a b c', 'd', 'e']),
                         '"a b c" d e')
        self.assertEqual(subprocess.list2cmdline(['ab"c', '\\', 'd']),
                         'ab\\"c \\ d')
        self.assertEqual(subprocess.list2cmdline(['ab"c', ' \\', 'd']),
                         'ab\\"c " \\\\" d')
        self.assertEqual(subprocess.list2cmdline(['a\\\\\\b', 'de fg', 'h']),
                         'a\\\\\\b "de fg" h')
        self.assertEqual(subprocess.list2cmdline(['a\\"b', 'c', 'd']),
                         'a\\\\\\"b c d')
        self.assertEqual(subprocess.list2cmdline(['a\\\\b c', 'd', 'e']),
                         '"a\\\\b c" d e')
        self.assertEqual(subprocess.list2cmdline(['a\\\\b\\ c', 'd', 'e']),
                         '"a\\\\b\\ c" d e')
        self.assertEqual(subprocess.list2cmdline(['ab', '']),
                         'ab ""')


    def test_poll(self):
        p = subprocess.Popen([sys.executable,
                          "-c", "import time; time.sleep(1)"])
        count = 0
        while p.poll() is None:
            time.sleep(0.1)
            count += 1
        # We expect that the poll loop probably went around about 10 times,
        # but, based on system scheduling we can't control, it's possible
        # poll() never returned None.  It "should be" very rare that it
        # didn't go around at least twice.
        self.assertGreaterEqual(count, 2)
        # Subsequent invocations should just return the returncode
        self.assertEqual(p.poll(), 0)


    def test_wait(self):
        p = subprocess.Popen([sys.executable,
                          "-c", "import time; time.sleep(2)"])
        self.assertEqual(p.wait(), 0)
        # Subsequent invocations should just return the returncode
        self.assertEqual(p.wait(), 0)


    def test_wait_timeout(self):
        p = subprocess.Popen([sys.executable,
                              "-c", "import time; time.sleep(0.1)"])
        self.assertRaises(subprocess.TimeoutExpired, p.wait, timeout=0.01)
        self.assertEqual(p.wait(timeout=2), 0)


    def test_invalid_bufsize(self):
        # an invalid type of the bufsize argument should raise
        # TypeError.
        with self.assertRaises(TypeError):
            subprocess.Popen([sys.executable, "-c", "pass"], "orange")

    def test_bufsize_is_none(self):
        # bufsize=None should be the same as bufsize=0.
        p = subprocess.Popen([sys.executable, "-c", "pass"], None)
        self.assertEqual(p.wait(), 0)
        # Again with keyword arg
        p = subprocess.Popen([sys.executable, "-c", "pass"], bufsize=None)
        self.assertEqual(p.wait(), 0)

    def test_leaking_fds_on_error(self):
        # see bug #5179: Popen leaks file descriptors to PIPEs if
        # the child fails to execute; this will eventually exhaust
        # the maximum number of open fds. 1024 seems a very common
        # value for that limit, but Windows has 2048, so we loop
        # 1024 times (each call leaked two fds).
        for i in range(1024):
            # Windows raises IOError.  Others raise OSError.
            with self.assertRaises(EnvironmentError) as c:
                subprocess.Popen(['nonexisting_i_hope'],
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.PIPE)
            # ignore errors that indicate the command was not found
            if c.exception.errno not in (errno.ENOENT, errno.EACCES):
                raise c.exception

    def test_issue8780(self):
        # Ensure that stdout is inherited from the parent
        # if stdout=PIPE is not used
        code = ';'.join((
            'import subprocess, sys',
            'retcode = subprocess.call('
                "[sys.executable, '-c', 'print(\"Hello World!\")'])",
            'assert retcode == 0'))
        output = subprocess.check_output([sys.executable, '-c', code])
        self.assertTrue(output.startswith(b'Hello World!'), ascii(output))

    def test_handles_closed_on_exception(self):
        # If CreateProcess exits with an error, ensure the
        # duplicate output handles are released
        ifhandle, ifname = mkstemp()
        ofhandle, ofname = mkstemp()
        efhandle, efname = mkstemp()
        try:
            subprocess.Popen (["*"], stdin=ifhandle, stdout=ofhandle,
              stderr=efhandle)
        except OSError:
            os.close(ifhandle)
            os.remove(ifname)
            os.close(ofhandle)
            os.remove(ofname)
            os.close(efhandle)
            os.remove(efname)
        self.assertFalse(os.path.exists(ifname))
        self.assertFalse(os.path.exists(ofname))
        self.assertFalse(os.path.exists(efname))


# context manager
class _SuppressCoreFiles(object):
    """Try to prevent core files from being created."""
    old_limit = None

    def __enter__(self):
        """Try to save previous ulimit, then set it to (0, 0)."""
        try:
            import resource
            self.old_limit = resource.getrlimit(resource.RLIMIT_CORE)
            resource.setrlimit(resource.RLIMIT_CORE, (0, 0))
        except (ImportError, ValueError, resource.error):
            pass

        if sys.platform == 'darwin':
            # Check if the 'Crash Reporter' on OSX was configured
            # in 'Developer' mode and warn that it will get triggered
            # when it is.
            #
            # This assumes that this context manager is used in tests
            # that might trigger the next manager.
            value = subprocess.Popen(['/usr/bin/defaults', 'read',
                    'com.apple.CrashReporter', 'DialogType'],
                    stdout=subprocess.PIPE).communicate()[0]
            if value.strip() == b'developer':
                print("this tests triggers the Crash Reporter, "
                      "that is intentional", end='')
                sys.stdout.flush()

    def __exit__(self, *args):
        """Return core file behavior to default."""
        if self.old_limit is None:
            return
        try:
            import resource
            resource.setrlimit(resource.RLIMIT_CORE, self.old_limit)
        except (ImportError, ValueError, resource.error):
            pass


@unittest.skipIf(mswindows, "POSIX specific tests")
class POSIXProcessTestCase(BaseTestCase):

    def test_exceptions(self):
        nonexistent_dir = "/_this/pa.th/does/not/exist"
        try:
            os.chdir(nonexistent_dir)
        except OSError as e:
            # This avoids hard coding the errno value or the OS perror()
            # string and instead capture the exception that we want to see
            # below for comparison.
            desired_exception = e
            desired_exception.strerror += ': ' + repr(sys.executable)
        else:
            self.fail("chdir to nonexistant directory %s succeeded." %
                      nonexistent_dir)

        # Error in the child re-raised in the parent.
        try:
            p = subprocess.Popen([sys.executable, "-c", ""],
                                 cwd=nonexistent_dir)
        except OSError as e:
            # Test that the child process chdir failure actually makes
            # it up to the parent process as the correct exception.
            self.assertEqual(desired_exception.errno, e.errno)
            self.assertEqual(desired_exception.strerror, e.strerror)
        else:
            self.fail("Expected OSError: %s" % desired_exception)

    def test_restore_signals(self):
        # Code coverage for both values of restore_signals to make sure it
        # at least does not blow up.
        # A test for behavior would be complex.  Contributions welcome.
        subprocess.call([sys.executable, "-c", ""], restore_signals=True)
        subprocess.call([sys.executable, "-c", ""], restore_signals=False)

    def test_start_new_session(self):
        # For code coverage of calling setsid().  We don't care if we get an
        # EPERM error from it depending on the test execution environment, that
        # still indicates that it was called.
        try:
            output = subprocess.check_output(
                    [sys.executable, "-c",
                     "import os; print(os.getpgid(os.getpid()))"],
                    start_new_session=True)
        except OSError as e:
            if e.errno != errno.EPERM:
                raise
        else:
            parent_pgid = os.getpgid(os.getpid())
            child_pgid = int(output)
            self.assertNotEqual(parent_pgid, child_pgid)

    def test_run_abort(self):
        # returncode handles signal termination
        with _SuppressCoreFiles():
            p = subprocess.Popen([sys.executable, "-c",
                                  'import os; os.abort()'])
            p.wait()
        self.assertEqual(-p.returncode, signal.SIGABRT)

    def test_preexec(self):
        # DISCLAIMER: Setting environment variables is *not* a good use
        # of a preexec_fn.  This is merely a test.
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(os.getenv("FRUIT"))'],
                             stdout=subprocess.PIPE,
                             preexec_fn=lambda: os.putenv("FRUIT", "apple"))
        self.addCleanup(p.stdout.close)
        self.assertEqual(p.stdout.read(), b"apple")

    def test_preexec_exception(self):
        def raise_it():
            raise ValueError("What if two swallows carried a coconut?")
        try:
            p = subprocess.Popen([sys.executable, "-c", ""],
                                 preexec_fn=raise_it)
        except RuntimeError as e:
            self.assertTrue(
                    subprocess._posixsubprocess,
                    "Expected a ValueError from the preexec_fn")
        except ValueError as e:
            self.assertIn("coconut", e.args[0])
        else:
            self.fail("Exception raised by preexec_fn did not make it "
                      "to the parent process.")

    @unittest.skipUnless(gc, "Requires a gc module.")
    def test_preexec_gc_module_failure(self):
        # This tests the code that disables garbage collection if the child
        # process will execute any Python.
        def raise_runtime_error():
            raise RuntimeError("this shouldn't escape")
        enabled = gc.isenabled()
        orig_gc_disable = gc.disable
        orig_gc_isenabled = gc.isenabled
        try:
            gc.disable()
            self.assertFalse(gc.isenabled())
            subprocess.call([sys.executable, '-c', ''],
                            preexec_fn=lambda: None)
            self.assertFalse(gc.isenabled(),
                             "Popen enabled gc when it shouldn't.")

            gc.enable()
            self.assertTrue(gc.isenabled())
            subprocess.call([sys.executable, '-c', ''],
                            preexec_fn=lambda: None)
            self.assertTrue(gc.isenabled(), "Popen left gc disabled.")

            gc.disable = raise_runtime_error
            self.assertRaises(RuntimeError, subprocess.Popen,
                              [sys.executable, '-c', ''],
                              preexec_fn=lambda: None)

            del gc.isenabled  # force an AttributeError
            self.assertRaises(AttributeError, subprocess.Popen,
                              [sys.executable, '-c', ''],
                              preexec_fn=lambda: None)
        finally:
            gc.disable = orig_gc_disable
            gc.isenabled = orig_gc_isenabled
            if not enabled:
                gc.disable()

    def test_args_string(self):
        # args is a string
        fd, fname = mkstemp()
        # reopen in text mode
        with open(fd, "w", errors="surrogateescape") as fobj:
            fobj.write("#!/bin/sh\n")
            fobj.write("exec '%s' -c 'import sys; sys.exit(47)'\n" %
                       sys.executable)
        os.chmod(fname, 0o700)
        p = subprocess.Popen(fname)
        p.wait()
        os.remove(fname)
        self.assertEqual(p.returncode, 47)

    def test_invalid_args(self):
        # invalid arguments should raise ValueError
        self.assertRaises(ValueError, subprocess.call,
                          [sys.executable, "-c",
                           "import sys; sys.exit(47)"],
                          startupinfo=47)
        self.assertRaises(ValueError, subprocess.call,
                          [sys.executable, "-c",
                           "import sys; sys.exit(47)"],
                          creationflags=47)

    def test_shell_sequence(self):
        # Run command through the shell (sequence)
        newenv = os.environ.copy()
        newenv["FRUIT"] = "apple"
        p = subprocess.Popen(["echo $FRUIT"], shell=1,
                             stdout=subprocess.PIPE,
                             env=newenv)
        self.addCleanup(p.stdout.close)
        self.assertEqual(p.stdout.read().strip(b" \t\r\n\f"), b"apple")

    def test_shell_string(self):
        # Run command through the shell (string)
        newenv = os.environ.copy()
        newenv["FRUIT"] = "apple"
        p = subprocess.Popen("echo $FRUIT", shell=1,
                             stdout=subprocess.PIPE,
                             env=newenv)
        self.addCleanup(p.stdout.close)
        self.assertEqual(p.stdout.read().strip(b" \t\r\n\f"), b"apple")

    def test_call_string(self):
        # call() function with string argument on UNIX
        fd, fname = mkstemp()
        # reopen in text mode
        with open(fd, "w", errors="surrogateescape") as fobj:
            fobj.write("#!/bin/sh\n")
            fobj.write("exec '%s' -c 'import sys; sys.exit(47)'\n" %
                       sys.executable)
        os.chmod(fname, 0o700)
        rc = subprocess.call(fname)
        os.remove(fname)
        self.assertEqual(rc, 47)

    def test_specific_shell(self):
        # Issue #9265: Incorrect name passed as arg[0].
        shells = []
        for prefix in ['/bin', '/usr/bin/', '/usr/local/bin']:
            for name in ['bash', 'ksh']:
                sh = os.path.join(prefix, name)
                if os.path.isfile(sh):
                    shells.append(sh)
        if not shells: # Will probably work for any shell but csh.
            self.skipTest("bash or ksh required for this test")
        sh = '/bin/sh'
        if os.path.isfile(sh) and not os.path.islink(sh):
            # Test will fail if /bin/sh is a symlink to csh.
            shells.append(sh)
        for sh in shells:
            p = subprocess.Popen("echo $0", executable=sh, shell=True,
                                 stdout=subprocess.PIPE)
            self.addCleanup(p.stdout.close)
            self.assertEqual(p.stdout.read().strip(), bytes(sh, 'ascii'))

    def _kill_process(self, method, *args):
        # Do not inherit file handles from the parent.
        # It should fix failures on some platforms.
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                             import sys, time
                             sys.stdout.write('x\\n')
                             sys.stdout.flush()
                             time.sleep(30)
                             """],
                             close_fds=True,
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        # Wait for the interpreter to be completely initialized before
        # sending any signal.
        p.stdout.read(1)
        getattr(p, method)(*args)
        return p

    def test_send_signal(self):
        p = self._kill_process('send_signal', signal.SIGINT)
        _, stderr = p.communicate()
        self.assertIn(b'KeyboardInterrupt', stderr)
        self.assertNotEqual(p.wait(), 0)

    def test_kill(self):
        p = self._kill_process('kill')
        _, stderr = p.communicate()
        self.assertStderrEqual(stderr, b'')
        self.assertEqual(p.wait(), -signal.SIGKILL)

    def test_terminate(self):
        p = self._kill_process('terminate')
        _, stderr = p.communicate()
        self.assertStderrEqual(stderr, b'')
        self.assertEqual(p.wait(), -signal.SIGTERM)

    def check_close_std_fds(self, fds):
        # Issue #9905: test that subprocess pipes still work properly with
        # some standard fds closed
        stdin = 0
        newfds = []
        for a in fds:
            b = os.dup(a)
            newfds.append(b)
            if a == 0:
                stdin = b
        try:
            for fd in fds:
                os.close(fd)
            out, err = subprocess.Popen([sys.executable, "-c",
                              'import sys;'
                              'sys.stdout.write("apple");'
                              'sys.stdout.flush();'
                              'sys.stderr.write("orange")'],
                       stdin=stdin,
                       stdout=subprocess.PIPE,
                       stderr=subprocess.PIPE).communicate()
            err = support.strip_python_stderr(err)
            self.assertEqual((out, err), (b'apple', b'orange'))
        finally:
            for b, a in zip(newfds, fds):
                os.dup2(b, a)
            for b in newfds:
                os.close(b)

    def test_close_fd_0(self):
        self.check_close_std_fds([0])

    def test_close_fd_1(self):
        self.check_close_std_fds([1])

    def test_close_fd_2(self):
        self.check_close_std_fds([2])

    def test_close_fds_0_1(self):
        self.check_close_std_fds([0, 1])

    def test_close_fds_0_2(self):
        self.check_close_std_fds([0, 2])

    def test_close_fds_1_2(self):
        self.check_close_std_fds([1, 2])

    def test_close_fds_0_1_2(self):
        # Issue #10806: test that subprocess pipes still work properly with
        # all standard fds closed.
        self.check_close_std_fds([0, 1, 2])

    def test_remapping_std_fds(self):
        # open up some temporary files
        temps = [mkstemp() for i in range(3)]
        try:
            temp_fds = [fd for fd, fname in temps]

            # unlink the files -- we won't need to reopen them
            for fd, fname in temps:
                os.unlink(fname)

            # write some data to what will become stdin, and rewind
            os.write(temp_fds[1], b"STDIN")
            os.lseek(temp_fds[1], 0, 0)

            # move the standard file descriptors out of the way
            saved_fds = [os.dup(fd) for fd in range(3)]
            try:
                # duplicate the file objects over the standard fd's
                for fd, temp_fd in enumerate(temp_fds):
                    os.dup2(temp_fd, fd)

                # now use those files in the "wrong" order, so that subprocess
                # has to rearrange them in the child
                p = subprocess.Popen([sys.executable, "-c",
                    'import sys; got = sys.stdin.read();'
                    'sys.stdout.write("got %s"%got); sys.stderr.write("err")'],
                    stdin=temp_fds[1],
                    stdout=temp_fds[2],
                    stderr=temp_fds[0])
                p.wait()
            finally:
                # restore the original fd's underneath sys.stdin, etc.
                for std, saved in enumerate(saved_fds):
                    os.dup2(saved, std)
                    os.close(saved)

            for fd in temp_fds:
                os.lseek(fd, 0, 0)

            out = os.read(temp_fds[2], 1024)
            err = support.strip_python_stderr(os.read(temp_fds[0], 1024))
            self.assertEqual(out, b"got STDIN")
            self.assertEqual(err, b"err")

        finally:
            for fd in temp_fds:
                os.close(fd)

    def test_surrogates_error_message(self):
        def prepare():
            raise ValueError("surrogate:\uDCff")

        try:
            subprocess.call(
                [sys.executable, "-c", "pass"],
                preexec_fn=prepare)
        except ValueError as err:
            # Pure Python implementations keeps the message
            self.assertIsNone(subprocess._posixsubprocess)
            self.assertEqual(str(err), "surrogate:\uDCff")
        except RuntimeError as err:
            # _posixsubprocess uses a default message
            self.assertIsNotNone(subprocess._posixsubprocess)
            self.assertEqual(str(err), "Exception occurred in preexec_fn.")
        else:
            self.fail("Expected ValueError or RuntimeError")

    def test_undecodable_env(self):
        for key, value in (('test', 'abc\uDCFF'), ('test\uDCFF', '42')):
            # test str with surrogates
            script = "import os; print(ascii(os.getenv(%s)))" % repr(key)
            env = os.environ.copy()
            env[key] = value
            # Use C locale to get ascii for the locale encoding to force
            # surrogate-escaping of \xFF in the child process; otherwise it can
            # be decoded as-is if the default locale is latin-1.
            env['LC_ALL'] = 'C'
            stdout = subprocess.check_output(
                [sys.executable, "-c", script],
                env=env)
            stdout = stdout.rstrip(b'\n\r')
            self.assertEqual(stdout.decode('ascii'), ascii(value))

            # test bytes
            key = key.encode("ascii", "surrogateescape")
            value = value.encode("ascii", "surrogateescape")
            script = "import os; print(ascii(os.getenvb(%s)))" % repr(key)
            env = os.environ.copy()
            env[key] = value
            stdout = subprocess.check_output(
                [sys.executable, "-c", script],
                env=env)
            stdout = stdout.rstrip(b'\n\r')
            self.assertEqual(stdout.decode('ascii'), ascii(value))

    def test_bytes_program(self):
        abs_program = os.fsencode(sys.executable)
        path, program = os.path.split(sys.executable)
        program = os.fsencode(program)

        # absolute bytes path
        exitcode = subprocess.call([abs_program, "-c", "pass"])
        self.assertEqual(exitcode, 0)

        # absolute bytes path as a string
        cmd = b"'" + abs_program + b"' -c pass"
        exitcode = subprocess.call(cmd, shell=True)
        self.assertEqual(exitcode, 0)

        # bytes program, unicode PATH
        env = os.environ.copy()
        env["PATH"] = path
        exitcode = subprocess.call([program, "-c", "pass"], env=env)
        self.assertEqual(exitcode, 0)

        # bytes program, bytes PATH
        envb = os.environb.copy()
        envb[b"PATH"] = os.fsencode(path)
        exitcode = subprocess.call([program, "-c", "pass"], env=envb)
        self.assertEqual(exitcode, 0)

    def test_pipe_cloexec(self):
        sleeper = support.findfile("input_reader.py", subdir="subprocessdata")
        fd_status = support.findfile("fd_status.py", subdir="subprocessdata")

        p1 = subprocess.Popen([sys.executable, sleeper],
                              stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE, close_fds=False)

        self.addCleanup(p1.communicate, b'')

        p2 = subprocess.Popen([sys.executable, fd_status],
                              stdout=subprocess.PIPE, close_fds=False)

        output, error = p2.communicate()
        result_fds = set(map(int, output.split(b',')))
        unwanted_fds = set([p1.stdin.fileno(), p1.stdout.fileno(),
                            p1.stderr.fileno()])

        self.assertFalse(result_fds & unwanted_fds,
                         "Expected no fds from %r to be open in child, "
                         "found %r" %
                              (unwanted_fds, result_fds & unwanted_fds))

    def test_pipe_cloexec_real_tools(self):
        qcat = support.findfile("qcat.py", subdir="subprocessdata")
        qgrep = support.findfile("qgrep.py", subdir="subprocessdata")

        subdata = b'zxcvbn'
        data = subdata * 4 + b'\n'

        p1 = subprocess.Popen([sys.executable, qcat],
                              stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                              close_fds=False)

        p2 = subprocess.Popen([sys.executable, qgrep, subdata],
                              stdin=p1.stdout, stdout=subprocess.PIPE,
                              close_fds=False)

        self.addCleanup(p1.wait)
        self.addCleanup(p2.wait)
        self.addCleanup(p1.terminate)
        self.addCleanup(p2.terminate)

        p1.stdin.write(data)
        p1.stdin.close()

        readfiles, ignored1, ignored2 = select.select([p2.stdout], [], [], 10)

        self.assertTrue(readfiles, "The child hung")
        self.assertEqual(p2.stdout.read(), data)

        p1.stdout.close()
        p2.stdout.close()

    def test_close_fds(self):
        fd_status = support.findfile("fd_status.py", subdir="subprocessdata")

        fds = os.pipe()
        self.addCleanup(os.close, fds[0])
        self.addCleanup(os.close, fds[1])

        open_fds = set(fds)

        p = subprocess.Popen([sys.executable, fd_status],
                             stdout=subprocess.PIPE, close_fds=False)
        output, ignored = p.communicate()
        remaining_fds = set(map(int, output.split(b',')))

        self.assertEqual(remaining_fds & open_fds, open_fds,
                         "Some fds were closed")

        p = subprocess.Popen([sys.executable, fd_status],
                             stdout=subprocess.PIPE, close_fds=True)
        output, ignored = p.communicate()
        remaining_fds = set(map(int, output.split(b',')))

        self.assertFalse(remaining_fds & open_fds,
                         "Some fds were left open")
        self.assertIn(1, remaining_fds, "Subprocess failed")

    def test_pass_fds(self):
        fd_status = support.findfile("fd_status.py", subdir="subprocessdata")

        open_fds = set()

        for x in range(5):
            fds = os.pipe()
            self.addCleanup(os.close, fds[0])
            self.addCleanup(os.close, fds[1])
            open_fds.update(fds)

        for fd in open_fds:
            p = subprocess.Popen([sys.executable, fd_status],
                                 stdout=subprocess.PIPE, close_fds=True,
                                 pass_fds=(fd, ))
            output, ignored = p.communicate()

            remaining_fds = set(map(int, output.split(b',')))
            to_be_closed = open_fds - {fd}

            self.assertIn(fd, remaining_fds, "fd to be passed not passed")
            self.assertFalse(remaining_fds & to_be_closed,
                             "fd to be closed passed")

            # pass_fds overrides close_fds with a warning.
            with self.assertWarns(RuntimeWarning) as context:
                self.assertFalse(subprocess.call(
                        [sys.executable, "-c", "import sys; sys.exit(0)"],
                        close_fds=False, pass_fds=(fd, )))
            self.assertIn('overriding close_fds', str(context.warning))

    def test_wait_when_sigchild_ignored(self):
        # NOTE: sigchild_ignore.py may not be an effective test on all OSes.
        sigchild_ignore = support.findfile("sigchild_ignore.py",
                                           subdir="subprocessdata")
        p = subprocess.Popen([sys.executable, sigchild_ignore],
                             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        stdout, stderr = p.communicate()
        self.assertEqual(0, p.returncode, "sigchild_ignore.py exited"
                         " non-zero with this error:\n%s" %
                         stderr.decode('utf-8'))


@unittest.skipUnless(mswindows, "Windows specific tests")
class Win32ProcessTestCase(BaseTestCase):

    def test_startupinfo(self):
        # startupinfo argument
        # We uses hardcoded constants, because we do not want to
        # depend on win32all.
        STARTF_USESHOWWINDOW = 1
        SW_MAXIMIZE = 3
        startupinfo = subprocess.STARTUPINFO()
        startupinfo.dwFlags = STARTF_USESHOWWINDOW
        startupinfo.wShowWindow = SW_MAXIMIZE
        # Since Python is a console process, it won't be affected
        # by wShowWindow, but the argument should be silently
        # ignored
        subprocess.call([sys.executable, "-c", "import sys; sys.exit(0)"],
                        startupinfo=startupinfo)

    def test_creationflags(self):
        # creationflags argument
        CREATE_NEW_CONSOLE = 16
        sys.stderr.write("    a DOS box should flash briefly ...\n")
        subprocess.call(sys.executable +
                        ' -c "import time; time.sleep(0.25)"',
                        creationflags=CREATE_NEW_CONSOLE)

    def test_invalid_args(self):
        # invalid arguments should raise ValueError
        self.assertRaises(ValueError, subprocess.call,
                          [sys.executable, "-c",
                           "import sys; sys.exit(47)"],
                          preexec_fn=lambda: 1)
        self.assertRaises(ValueError, subprocess.call,
                          [sys.executable, "-c",
                           "import sys; sys.exit(47)"],
                          stdout=subprocess.PIPE,
                          close_fds=True)

    def test_close_fds(self):
        # close file descriptors
        rc = subprocess.call([sys.executable, "-c",
                              "import sys; sys.exit(47)"],
                              close_fds=True)
        self.assertEqual(rc, 47)

    def test_shell_sequence(self):
        # Run command through the shell (sequence)
        newenv = os.environ.copy()
        newenv["FRUIT"] = "physalis"
        p = subprocess.Popen(["set"], shell=1,
                             stdout=subprocess.PIPE,
                             env=newenv)
        self.addCleanup(p.stdout.close)
        self.assertIn(b"physalis", p.stdout.read())

    def test_shell_string(self):
        # Run command through the shell (string)
        newenv = os.environ.copy()
        newenv["FRUIT"] = "physalis"
        p = subprocess.Popen("set", shell=1,
                             stdout=subprocess.PIPE,
                             env=newenv)
        self.addCleanup(p.stdout.close)
        self.assertIn(b"physalis", p.stdout.read())

    def test_call_string(self):
        # call() function with string argument on Windows
        rc = subprocess.call(sys.executable +
                             ' -c "import sys; sys.exit(47)"')
        self.assertEqual(rc, 47)

    def _kill_process(self, method, *args):
        # Some win32 buildbot raises EOFError if stdin is inherited
        p = subprocess.Popen([sys.executable, "-c", """if 1:
                             import sys, time
                             sys.stdout.write('x\\n')
                             sys.stdout.flush()
                             time.sleep(30)
                             """],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        self.addCleanup(p.stdin.close)
        # Wait for the interpreter to be completely initialized before
        # sending any signal.
        p.stdout.read(1)
        getattr(p, method)(*args)
        _, stderr = p.communicate()
        self.assertStderrEqual(stderr, b'')
        returncode = p.wait()
        self.assertNotEqual(returncode, 0)

    def test_send_signal(self):
        self._kill_process('send_signal', signal.SIGTERM)

    def test_kill(self):
        self._kill_process('kill')

    def test_terminate(self):
        self._kill_process('terminate')


# The module says:
#   "NB This only works (and is only relevant) for UNIX."
#
# Actually, getoutput should work on any platform with an os.popen, but
# I'll take the comment as given, and skip this suite.
@unittest.skipUnless(os.name == 'posix', "only relevant for UNIX")
class CommandTests(unittest.TestCase):
    def test_getoutput(self):
        self.assertEqual(subprocess.getoutput('echo xyzzy'), 'xyzzy')
        self.assertEqual(subprocess.getstatusoutput('echo xyzzy'),
                         (0, 'xyzzy'))

        # we use mkdtemp in the next line to create an empty directory
        # under our exclusive control; from that, we can invent a pathname
        # that we _know_ won't exist.  This is guaranteed to fail.
        dir = None
        try:
            dir = tempfile.mkdtemp()
            name = os.path.join(dir, "foo")

            status, output = subprocess.getstatusoutput('cat ' + name)
            self.assertNotEqual(status, 0)
        finally:
            if dir is not None:
                os.rmdir(dir)


@unittest.skipUnless(getattr(subprocess, '_has_poll', False),
                     "poll system call not supported")
class ProcessTestCaseNoPoll(ProcessTestCase):
    def setUp(self):
        subprocess._has_poll = False
        ProcessTestCase.setUp(self)

    def tearDown(self):
        subprocess._has_poll = True
        ProcessTestCase.tearDown(self)


@unittest.skipUnless(getattr(subprocess, '_posixsubprocess', False),
                     "_posixsubprocess extension module not found.")
class ProcessTestCasePOSIXPurePython(ProcessTestCase, POSIXProcessTestCase):
    def setUp(self):
        subprocess._posixsubprocess = None
        ProcessTestCase.setUp(self)
        POSIXProcessTestCase.setUp(self)

    def tearDown(self):
        subprocess._posixsubprocess = sys.modules['_posixsubprocess']
        POSIXProcessTestCase.tearDown(self)
        ProcessTestCase.tearDown(self)


class HelperFunctionTests(unittest.TestCase):
    @unittest.skipIf(mswindows, "errno and EINTR make no sense on windows")
    def test_eintr_retry_call(self):
        record_calls = []
        def fake_os_func(*args):
            record_calls.append(args)
            if len(record_calls) == 2:
                raise OSError(errno.EINTR, "fake interrupted system call")
            return tuple(reversed(args))

        self.assertEqual((999, 256),
                         subprocess._eintr_retry_call(fake_os_func, 256, 999))
        self.assertEqual([(256, 999)], record_calls)
        # This time there will be an EINTR so it will loop once.
        self.assertEqual((666,),
                         subprocess._eintr_retry_call(fake_os_func, 666))
        self.assertEqual([(256, 999), (666,), (666,)], record_calls)


@unittest.skipUnless(mswindows, "Windows-specific tests")
class CommandsWithSpaces (BaseTestCase):

    def setUp(self):
        super().setUp()
        f, fname = mkstemp(".py", "te st")
        self.fname = fname.lower ()
        os.write(f, b"import sys;"
                    b"sys.stdout.write('%d %s' % (len(sys.argv), [a.lower () for a in sys.argv]))"
        )
        os.close(f)

    def tearDown(self):
        os.remove(self.fname)
        super().tearDown()

    def with_spaces(self, *args, **kwargs):
        kwargs['stdout'] = subprocess.PIPE
        p = subprocess.Popen(*args, **kwargs)
        self.addCleanup(p.stdout.close)
        self.assertEqual(
          p.stdout.read ().decode("mbcs"),
          "2 [%r, 'ab cd']" % self.fname
        )

    def test_shell_string_with_spaces(self):
        # call() function with string argument with spaces on Windows
        self.with_spaces('"%s" "%s" "%s"' % (sys.executable, self.fname,
                                             "ab cd"), shell=1)

    def test_shell_sequence_with_spaces(self):
        # call() function with sequence argument with spaces on Windows
        self.with_spaces([sys.executable, self.fname, "ab cd"], shell=1)

    def test_noshell_string_with_spaces(self):
        # call() function with string argument with spaces on Windows
        self.with_spaces('"%s" "%s" "%s"' % (sys.executable, self.fname,
                             "ab cd"))

    def test_noshell_sequence_with_spaces(self):
        # call() function with sequence argument with spaces on Windows
        self.with_spaces([sys.executable, self.fname, "ab cd"])


class ContextManagerTests(ProcessTestCase):

    def test_pipe(self):
        with subprocess.Popen([sys.executable, "-c",
                               "import sys;"
                               "sys.stdout.write('stdout');"
                               "sys.stderr.write('stderr');"],
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE) as proc:
            self.assertEqual(proc.stdout.read(), b"stdout")
            self.assertStderrEqual(proc.stderr.read(), b"stderr")

        self.assertTrue(proc.stdout.closed)
        self.assertTrue(proc.stderr.closed)

    def test_returncode(self):
        with subprocess.Popen([sys.executable, "-c",
                               "import sys; sys.exit(100)"]) as proc:
            proc.wait()
        self.assertEqual(proc.returncode, 100)

    def test_communicate_stdin(self):
        with subprocess.Popen([sys.executable, "-c",
                              "import sys;"
                              "sys.exit(sys.stdin.read() == 'context')"],
                             stdin=subprocess.PIPE) as proc:
            proc.communicate(b"context")
            self.assertEqual(proc.returncode, 1)

    def test_invalid_args(self):
        with self.assertRaises(EnvironmentError) as c:
            with subprocess.Popen(['nonexisting_i_hope'],
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE) as proc:
                pass

            if c.exception.errno != errno.ENOENT:  # ignore "no such file"
                raise c.exception


def test_main():
    unit_tests = (ProcessTestCase,
                  POSIXProcessTestCase,
                  Win32ProcessTestCase,
                  ProcessTestCasePOSIXPurePython,
                  CommandTests,
                  ProcessTestCaseNoPoll,
                  HelperFunctionTests,
                  CommandsWithSpaces,
                  ContextManagerTests)

    support.run_unittest(*unit_tests)
    support.reap_children()

if __name__ == "__main__":
    test_main()