cpython/Lib/test/test_asyncio/test_unix_events.py

"""Tests for unix_events.py."""

import collections
import gc
import errno
import io
import os
import pprint
import signal
import socket
import stat
import sys
import tempfile
import threading
import unittest
from unittest import mock

if sys.platform == 'win32':
    raise unittest.SkipTest('UNIX only')


import asyncio
from asyncio import log
from asyncio import test_utils
from asyncio import unix_events


MOCK_ANY = mock.ANY


@unittest.skipUnless(signal, 'Signals are not supported')
class SelectorEventLoopSignalTests(test_utils.TestCase):

    def setUp(self):
        self.loop = asyncio.SelectorEventLoop()
        self.set_event_loop(self.loop)

    def test_check_signal(self):
        self.assertRaises(
            TypeError, self.loop._check_signal, '1')
        self.assertRaises(
            ValueError, self.loop._check_signal, signal.NSIG + 1)

    def test_handle_signal_no_handler(self):
        self.loop._handle_signal(signal.NSIG + 1, ())

    def test_handle_signal_cancelled_handler(self):
        h = asyncio.Handle(mock.Mock(), (),
                           loop=mock.Mock())
        h.cancel()
        self.loop._signal_handlers[signal.NSIG + 1] = h
        self.loop.remove_signal_handler = mock.Mock()
        self.loop._handle_signal(signal.NSIG + 1, ())
        self.loop.remove_signal_handler.assert_called_with(signal.NSIG + 1)

    @mock.patch('asyncio.unix_events.signal')
    def test_add_signal_handler_setup_error(self, m_signal):
        m_signal.NSIG = signal.NSIG
        m_signal.set_wakeup_fd.side_effect = ValueError

        self.assertRaises(
            RuntimeError,
            self.loop.add_signal_handler,
            signal.SIGINT, lambda: True)

    @mock.patch('asyncio.unix_events.signal')
    def test_add_signal_handler(self, m_signal):
        m_signal.NSIG = signal.NSIG

        cb = lambda: True
        self.loop.add_signal_handler(signal.SIGHUP, cb)
        h = self.loop._signal_handlers.get(signal.SIGHUP)
        self.assertIsInstance(h, asyncio.Handle)
        self.assertEqual(h._callback, cb)

    @mock.patch('asyncio.unix_events.signal')
    def test_add_signal_handler_install_error(self, m_signal):
        m_signal.NSIG = signal.NSIG

        def set_wakeup_fd(fd):
            if fd == -1:
                raise ValueError()
        m_signal.set_wakeup_fd = set_wakeup_fd

        class Err(OSError):
            errno = errno.EFAULT
        m_signal.signal.side_effect = Err

        self.assertRaises(
            Err,
            self.loop.add_signal_handler,
            signal.SIGINT, lambda: True)

    @mock.patch('asyncio.unix_events.signal')
    @mock.patch('asyncio.base_events.logger')
    def test_add_signal_handler_install_error2(self, m_logging, m_signal):
        m_signal.NSIG = signal.NSIG

        class Err(OSError):
            errno = errno.EINVAL
        m_signal.signal.side_effect = Err

        self.loop._signal_handlers[signal.SIGHUP] = lambda: True
        self.assertRaises(
            RuntimeError,
            self.loop.add_signal_handler,
            signal.SIGINT, lambda: True)
        self.assertFalse(m_logging.info.called)
        self.assertEqual(1, m_signal.set_wakeup_fd.call_count)

    @mock.patch('asyncio.unix_events.signal')
    @mock.patch('asyncio.base_events.logger')
    def test_add_signal_handler_install_error3(self, m_logging, m_signal):
        class Err(OSError):
            errno = errno.EINVAL
        m_signal.signal.side_effect = Err
        m_signal.NSIG = signal.NSIG

        self.assertRaises(
            RuntimeError,
            self.loop.add_signal_handler,
            signal.SIGINT, lambda: True)
        self.assertFalse(m_logging.info.called)
        self.assertEqual(2, m_signal.set_wakeup_fd.call_count)

    @mock.patch('asyncio.unix_events.signal')
    def test_remove_signal_handler(self, m_signal):
        m_signal.NSIG = signal.NSIG

        self.loop.add_signal_handler(signal.SIGHUP, lambda: True)

        self.assertTrue(
            self.loop.remove_signal_handler(signal.SIGHUP))
        self.assertTrue(m_signal.set_wakeup_fd.called)
        self.assertTrue(m_signal.signal.called)
        self.assertEqual(
            (signal.SIGHUP, m_signal.SIG_DFL), m_signal.signal.call_args[0])

    @mock.patch('asyncio.unix_events.signal')
    def test_remove_signal_handler_2(self, m_signal):
        m_signal.NSIG = signal.NSIG
        m_signal.SIGINT = signal.SIGINT

        self.loop.add_signal_handler(signal.SIGINT, lambda: True)
        self.loop._signal_handlers[signal.SIGHUP] = object()
        m_signal.set_wakeup_fd.reset_mock()

        self.assertTrue(
            self.loop.remove_signal_handler(signal.SIGINT))
        self.assertFalse(m_signal.set_wakeup_fd.called)
        self.assertTrue(m_signal.signal.called)
        self.assertEqual(
            (signal.SIGINT, m_signal.default_int_handler),
            m_signal.signal.call_args[0])

    @mock.patch('asyncio.unix_events.signal')
    @mock.patch('asyncio.base_events.logger')
    def test_remove_signal_handler_cleanup_error(self, m_logging, m_signal):
        m_signal.NSIG = signal.NSIG
        self.loop.add_signal_handler(signal.SIGHUP, lambda: True)

        m_signal.set_wakeup_fd.side_effect = ValueError

        self.loop.remove_signal_handler(signal.SIGHUP)
        self.assertTrue(m_logging.info)

    @mock.patch('asyncio.unix_events.signal')
    def test_remove_signal_handler_error(self, m_signal):
        m_signal.NSIG = signal.NSIG
        self.loop.add_signal_handler(signal.SIGHUP, lambda: True)

        m_signal.signal.side_effect = OSError

        self.assertRaises(
            OSError, self.loop.remove_signal_handler, signal.SIGHUP)

    @mock.patch('asyncio.unix_events.signal')
    def test_remove_signal_handler_error2(self, m_signal):
        m_signal.NSIG = signal.NSIG
        self.loop.add_signal_handler(signal.SIGHUP, lambda: True)

        class Err(OSError):
            errno = errno.EINVAL
        m_signal.signal.side_effect = Err

        self.assertRaises(
            RuntimeError, self.loop.remove_signal_handler, signal.SIGHUP)

    @mock.patch('asyncio.unix_events.signal')
    def test_close(self, m_signal):
        m_signal.NSIG = signal.NSIG

        self.loop.add_signal_handler(signal.SIGHUP, lambda: True)
        self.loop.add_signal_handler(signal.SIGCHLD, lambda: True)

        self.assertEqual(len(self.loop._signal_handlers), 2)

        m_signal.set_wakeup_fd.reset_mock()

        self.loop.close()

        self.assertEqual(len(self.loop._signal_handlers), 0)
        m_signal.set_wakeup_fd.assert_called_once_with(-1)


@unittest.skipUnless(hasattr(socket, 'AF_UNIX'),
                     'UNIX Sockets are not supported')
class SelectorEventLoopUnixSocketTests(test_utils.TestCase):

    def setUp(self):
        self.loop = asyncio.SelectorEventLoop()
        self.set_event_loop(self.loop)

    def test_create_unix_server_existing_path_sock(self):
        with test_utils.unix_socket_path() as path:
            sock = socket.socket(socket.AF_UNIX)
            sock.bind(path)
            with sock:
                coro = self.loop.create_unix_server(lambda: None, path)
                with self.assertRaisesRegex(OSError,
                                            'Address.*is already in use'):
                    self.loop.run_until_complete(coro)

    def test_create_unix_server_existing_path_nonsock(self):
        with tempfile.NamedTemporaryFile() as file:
            coro = self.loop.create_unix_server(lambda: None, file.name)
            with self.assertRaisesRegex(OSError,
                                        'Address.*is already in use'):
                self.loop.run_until_complete(coro)

    def test_create_unix_server_ssl_bool(self):
        coro = self.loop.create_unix_server(lambda: None, path='spam',
                                            ssl=True)
        with self.assertRaisesRegex(TypeError,
                                    'ssl argument must be an SSLContext'):
            self.loop.run_until_complete(coro)

    def test_create_unix_server_nopath_nosock(self):
        coro = self.loop.create_unix_server(lambda: None, path=None)
        with self.assertRaisesRegex(ValueError,
                                    'path was not specified, and no sock'):
            self.loop.run_until_complete(coro)

    def test_create_unix_server_path_inetsock(self):
        sock = socket.socket()
        with sock:
            coro = self.loop.create_unix_server(lambda: None, path=None,
                                                sock=sock)
            with self.assertRaisesRegex(ValueError,
                                        'A UNIX Domain Socket was expected'):
                self.loop.run_until_complete(coro)

    @mock.patch('asyncio.unix_events.socket')
    def test_create_unix_server_bind_error(self, m_socket):
        # Ensure that the socket is closed on any bind error
        sock = mock.Mock()
        m_socket.socket.return_value = sock

        sock.bind.side_effect = OSError
        coro = self.loop.create_unix_server(lambda: None, path="/test")
        with self.assertRaises(OSError):
            self.loop.run_until_complete(coro)
        self.assertTrue(sock.close.called)

        sock.bind.side_effect = MemoryError
        coro = self.loop.create_unix_server(lambda: None, path="/test")
        with self.assertRaises(MemoryError):
            self.loop.run_until_complete(coro)
        self.assertTrue(sock.close.called)

    def test_create_unix_connection_path_sock(self):
        coro = self.loop.create_unix_connection(
            lambda: None, '/dev/null', sock=object())
        with self.assertRaisesRegex(ValueError, 'path and sock can not be'):
            self.loop.run_until_complete(coro)

    def test_create_unix_connection_nopath_nosock(self):
        coro = self.loop.create_unix_connection(
            lambda: None, None)
        with self.assertRaisesRegex(ValueError,
                                    'no path and sock were specified'):
            self.loop.run_until_complete(coro)

    def test_create_unix_connection_nossl_serverhost(self):
        coro = self.loop.create_unix_connection(
            lambda: None, '/dev/null', server_hostname='spam')
        with self.assertRaisesRegex(ValueError,
                                    'server_hostname is only meaningful'):
            self.loop.run_until_complete(coro)

    def test_create_unix_connection_ssl_noserverhost(self):
        coro = self.loop.create_unix_connection(
            lambda: None, '/dev/null', ssl=True)

        with self.assertRaisesRegex(
            ValueError, 'you have to pass server_hostname when using ssl'):

            self.loop.run_until_complete(coro)


class UnixReadPipeTransportTests(test_utils.TestCase):

    def setUp(self):
        self.loop = self.new_test_loop()
        self.protocol = test_utils.make_test_protocol(asyncio.Protocol)
        self.pipe = mock.Mock(spec_set=io.RawIOBase)
        self.pipe.fileno.return_value = 5

        fcntl_patcher = mock.patch('fcntl.fcntl')
        fcntl_patcher.start()
        self.addCleanup(fcntl_patcher.stop)

        fstat_patcher = mock.patch('os.fstat')
        m_fstat = fstat_patcher.start()
        st = mock.Mock()
        st.st_mode = stat.S_IFIFO
        m_fstat.return_value = st
        self.addCleanup(fstat_patcher.stop)

    def test_ctor(self):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)
        self.loop.assert_reader(5, tr._read_ready)
        test_utils.run_briefly(self.loop)
        self.protocol.connection_made.assert_called_with(tr)

    def test_ctor_with_waiter(self):
        fut = asyncio.Future(loop=self.loop)
        unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol, fut)
        test_utils.run_briefly(self.loop)
        self.assertIsNone(fut.result())

    @mock.patch('os.read')
    def test__read_ready(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)
        m_read.return_value = b'data'
        tr._read_ready()

        m_read.assert_called_with(5, tr.max_size)
        self.protocol.data_received.assert_called_with(b'data')

    @mock.patch('os.read')
    def test__read_ready_eof(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)
        m_read.return_value = b''
        tr._read_ready()

        m_read.assert_called_with(5, tr.max_size)
        self.assertFalse(self.loop.readers)
        test_utils.run_briefly(self.loop)
        self.protocol.eof_received.assert_called_with()
        self.protocol.connection_lost.assert_called_with(None)

    @mock.patch('os.read')
    def test__read_ready_blocked(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)
        m_read.side_effect = BlockingIOError
        tr._read_ready()

        m_read.assert_called_with(5, tr.max_size)
        test_utils.run_briefly(self.loop)
        self.assertFalse(self.protocol.data_received.called)

    @mock.patch('asyncio.log.logger.error')
    @mock.patch('os.read')
    def test__read_ready_error(self, m_read, m_logexc):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)
        err = OSError()
        m_read.side_effect = err
        tr._close = mock.Mock()
        tr._read_ready()

        m_read.assert_called_with(5, tr.max_size)
        tr._close.assert_called_with(err)
        m_logexc.assert_called_with(
            test_utils.MockPattern(
                'Fatal read error on pipe transport'
                '\nprotocol:.*\ntransport:.*'),
            exc_info=(OSError, MOCK_ANY, MOCK_ANY))

    @mock.patch('os.read')
    def test_pause_reading(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)

        m = mock.Mock()
        self.loop.add_reader(5, m)
        tr.pause_reading()
        self.assertFalse(self.loop.readers)

    @mock.patch('os.read')
    def test_resume_reading(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)

        tr.resume_reading()
        self.loop.assert_reader(5, tr._read_ready)

    @mock.patch('os.read')
    def test_close(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)

        tr._close = mock.Mock()
        tr.close()
        tr._close.assert_called_with(None)

    @mock.patch('os.read')
    def test_close_already_closing(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)

        tr._closing = True
        tr._close = mock.Mock()
        tr.close()
        self.assertFalse(tr._close.called)

    @mock.patch('os.read')
    def test__close(self, m_read):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)

        err = object()
        tr._close(err)
        self.assertTrue(tr._closing)
        self.assertFalse(self.loop.readers)
        test_utils.run_briefly(self.loop)
        self.protocol.connection_lost.assert_called_with(err)

    def test__call_connection_lost(self):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)

        err = None
        tr._call_connection_lost(err)
        self.protocol.connection_lost.assert_called_with(err)
        self.pipe.close.assert_called_with()

        self.assertIsNone(tr._protocol)
        self.assertEqual(2, sys.getrefcount(self.protocol),
                         pprint.pformat(gc.get_referrers(self.protocol)))
        self.assertIsNone(tr._loop)

    def test__call_connection_lost_with_err(self):
        tr = unix_events._UnixReadPipeTransport(
            self.loop, self.pipe, self.protocol)

        err = OSError()
        tr._call_connection_lost(err)
        self.protocol.connection_lost.assert_called_with(err)
        self.pipe.close.assert_called_with()

        self.assertIsNone(tr._protocol)

        self.assertEqual(2, sys.getrefcount(self.protocol),
                         pprint.pformat(gc.get_referrers(self.protocol)))
        self.assertIsNone(tr._loop)


class UnixWritePipeTransportTests(test_utils.TestCase):

    def setUp(self):
        self.loop = self.new_test_loop()
        self.protocol = test_utils.make_test_protocol(asyncio.BaseProtocol)
        self.pipe = mock.Mock(spec_set=io.RawIOBase)
        self.pipe.fileno.return_value = 5

        fcntl_patcher = mock.patch('fcntl.fcntl')
        fcntl_patcher.start()
        self.addCleanup(fcntl_patcher.stop)

        fstat_patcher = mock.patch('os.fstat')
        m_fstat = fstat_patcher.start()
        st = mock.Mock()
        st.st_mode = stat.S_IFSOCK
        m_fstat.return_value = st
        self.addCleanup(fstat_patcher.stop)

    def test_ctor(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)
        self.loop.assert_reader(5, tr._read_ready)
        test_utils.run_briefly(self.loop)
        self.protocol.connection_made.assert_called_with(tr)

    def test_ctor_with_waiter(self):
        fut = asyncio.Future(loop=self.loop)
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol, fut)
        self.loop.assert_reader(5, tr._read_ready)
        test_utils.run_briefly(self.loop)
        self.assertEqual(None, fut.result())

    def test_can_write_eof(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)
        self.assertTrue(tr.can_write_eof())

    @mock.patch('os.write')
    def test_write(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        m_write.return_value = 4
        tr.write(b'data')
        m_write.assert_called_with(5, b'data')
        self.assertFalse(self.loop.writers)
        self.assertEqual([], tr._buffer)

    @mock.patch('os.write')
    def test_write_no_data(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        tr.write(b'')
        self.assertFalse(m_write.called)
        self.assertFalse(self.loop.writers)
        self.assertEqual([], tr._buffer)

    @mock.patch('os.write')
    def test_write_partial(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        m_write.return_value = 2
        tr.write(b'data')
        m_write.assert_called_with(5, b'data')
        self.loop.assert_writer(5, tr._write_ready)
        self.assertEqual([b'ta'], tr._buffer)

    @mock.patch('os.write')
    def test_write_buffer(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        self.loop.add_writer(5, tr._write_ready)
        tr._buffer = [b'previous']
        tr.write(b'data')
        self.assertFalse(m_write.called)
        self.loop.assert_writer(5, tr._write_ready)
        self.assertEqual([b'previous', b'data'], tr._buffer)

    @mock.patch('os.write')
    def test_write_again(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        m_write.side_effect = BlockingIOError()
        tr.write(b'data')
        m_write.assert_called_with(5, b'data')
        self.loop.assert_writer(5, tr._write_ready)
        self.assertEqual([b'data'], tr._buffer)

    @mock.patch('asyncio.unix_events.logger')
    @mock.patch('os.write')
    def test_write_err(self, m_write, m_log):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        err = OSError()
        m_write.side_effect = err
        tr._fatal_error = mock.Mock()
        tr.write(b'data')
        m_write.assert_called_with(5, b'data')
        self.assertFalse(self.loop.writers)
        self.assertEqual([], tr._buffer)
        tr._fatal_error.assert_called_with(
                            err,
                            'Fatal write error on pipe transport')
        self.assertEqual(1, tr._conn_lost)

        tr.write(b'data')
        self.assertEqual(2, tr._conn_lost)
        tr.write(b'data')
        tr.write(b'data')
        tr.write(b'data')
        tr.write(b'data')
        # This is a bit overspecified. :-(
        m_log.warning.assert_called_with(
            'pipe closed by peer or os.write(pipe, data) raised exception.')

    @mock.patch('os.write')
    def test_write_close(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)
        tr._read_ready()  # pipe was closed by peer

        tr.write(b'data')
        self.assertEqual(tr._conn_lost, 1)
        tr.write(b'data')
        self.assertEqual(tr._conn_lost, 2)

    def test__read_ready(self):
        tr = unix_events._UnixWritePipeTransport(self.loop, self.pipe,
                                                 self.protocol)
        tr._read_ready()
        self.assertFalse(self.loop.readers)
        self.assertFalse(self.loop.writers)
        self.assertTrue(tr._closing)
        test_utils.run_briefly(self.loop)
        self.protocol.connection_lost.assert_called_with(None)

    @mock.patch('os.write')
    def test__write_ready(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)
        self.loop.add_writer(5, tr._write_ready)
        tr._buffer = [b'da', b'ta']
        m_write.return_value = 4
        tr._write_ready()
        m_write.assert_called_with(5, b'data')
        self.assertFalse(self.loop.writers)
        self.assertEqual([], tr._buffer)

    @mock.patch('os.write')
    def test__write_ready_partial(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        self.loop.add_writer(5, tr._write_ready)
        tr._buffer = [b'da', b'ta']
        m_write.return_value = 3
        tr._write_ready()
        m_write.assert_called_with(5, b'data')
        self.loop.assert_writer(5, tr._write_ready)
        self.assertEqual([b'a'], tr._buffer)

    @mock.patch('os.write')
    def test__write_ready_again(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        self.loop.add_writer(5, tr._write_ready)
        tr._buffer = [b'da', b'ta']
        m_write.side_effect = BlockingIOError()
        tr._write_ready()
        m_write.assert_called_with(5, b'data')
        self.loop.assert_writer(5, tr._write_ready)
        self.assertEqual([b'data'], tr._buffer)

    @mock.patch('os.write')
    def test__write_ready_empty(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        self.loop.add_writer(5, tr._write_ready)
        tr._buffer = [b'da', b'ta']
        m_write.return_value = 0
        tr._write_ready()
        m_write.assert_called_with(5, b'data')
        self.loop.assert_writer(5, tr._write_ready)
        self.assertEqual([b'data'], tr._buffer)

    @mock.patch('asyncio.log.logger.error')
    @mock.patch('os.write')
    def test__write_ready_err(self, m_write, m_logexc):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        self.loop.add_writer(5, tr._write_ready)
        tr._buffer = [b'da', b'ta']
        m_write.side_effect = err = OSError()
        tr._write_ready()
        m_write.assert_called_with(5, b'data')
        self.assertFalse(self.loop.writers)
        self.assertFalse(self.loop.readers)
        self.assertEqual([], tr._buffer)
        self.assertTrue(tr._closing)
        m_logexc.assert_called_with(
            test_utils.MockPattern(
                'Fatal write error on pipe transport'
                '\nprotocol:.*\ntransport:.*'),
            exc_info=(OSError, MOCK_ANY, MOCK_ANY))
        self.assertEqual(1, tr._conn_lost)
        test_utils.run_briefly(self.loop)
        self.protocol.connection_lost.assert_called_with(err)

    @mock.patch('os.write')
    def test__write_ready_closing(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        self.loop.add_writer(5, tr._write_ready)
        tr._closing = True
        tr._buffer = [b'da', b'ta']
        m_write.return_value = 4
        tr._write_ready()
        m_write.assert_called_with(5, b'data')
        self.assertFalse(self.loop.writers)
        self.assertFalse(self.loop.readers)
        self.assertEqual([], tr._buffer)
        self.protocol.connection_lost.assert_called_with(None)
        self.pipe.close.assert_called_with()

    @mock.patch('os.write')
    def test_abort(self, m_write):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        self.loop.add_writer(5, tr._write_ready)
        self.loop.add_reader(5, tr._read_ready)
        tr._buffer = [b'da', b'ta']
        tr.abort()
        self.assertFalse(m_write.called)
        self.assertFalse(self.loop.readers)
        self.assertFalse(self.loop.writers)
        self.assertEqual([], tr._buffer)
        self.assertTrue(tr._closing)
        test_utils.run_briefly(self.loop)
        self.protocol.connection_lost.assert_called_with(None)

    def test__call_connection_lost(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        err = None
        tr._call_connection_lost(err)
        self.protocol.connection_lost.assert_called_with(err)
        self.pipe.close.assert_called_with()

        self.assertIsNone(tr._protocol)
        self.assertEqual(2, sys.getrefcount(self.protocol),
                         pprint.pformat(gc.get_referrers(self.protocol)))
        self.assertIsNone(tr._loop)

    def test__call_connection_lost_with_err(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        err = OSError()
        tr._call_connection_lost(err)
        self.protocol.connection_lost.assert_called_with(err)
        self.pipe.close.assert_called_with()

        self.assertIsNone(tr._protocol)
        self.assertEqual(2, sys.getrefcount(self.protocol),
                         pprint.pformat(gc.get_referrers(self.protocol)))
        self.assertIsNone(tr._loop)

    def test_close(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        tr.write_eof = mock.Mock()
        tr.close()
        tr.write_eof.assert_called_with()

    def test_close_closing(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        tr.write_eof = mock.Mock()
        tr._closing = True
        tr.close()
        self.assertFalse(tr.write_eof.called)

    def test_write_eof(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)

        tr.write_eof()
        self.assertTrue(tr._closing)
        self.assertFalse(self.loop.readers)
        test_utils.run_briefly(self.loop)
        self.protocol.connection_lost.assert_called_with(None)

    def test_write_eof_pending(self):
        tr = unix_events._UnixWritePipeTransport(
            self.loop, self.pipe, self.protocol)
        tr._buffer = [b'data']
        tr.write_eof()
        self.assertTrue(tr._closing)
        self.assertFalse(self.protocol.connection_lost.called)


class AbstractChildWatcherTests(unittest.TestCase):

    def test_not_implemented(self):
        f = mock.Mock()
        watcher = asyncio.AbstractChildWatcher()
        self.assertRaises(
            NotImplementedError, watcher.add_child_handler, f, f)
        self.assertRaises(
            NotImplementedError, watcher.remove_child_handler, f)
        self.assertRaises(
            NotImplementedError, watcher.attach_loop, f)
        self.assertRaises(
            NotImplementedError, watcher.close)
        self.assertRaises(
            NotImplementedError, watcher.__enter__)
        self.assertRaises(
            NotImplementedError, watcher.__exit__, f, f, f)


class BaseChildWatcherTests(unittest.TestCase):

    def test_not_implemented(self):
        f = mock.Mock()
        watcher = unix_events.BaseChildWatcher()
        self.assertRaises(
            NotImplementedError, watcher._do_waitpid, f)


WaitPidMocks = collections.namedtuple("WaitPidMocks",
                                      ("waitpid",
                                       "WIFEXITED",
                                       "WIFSIGNALED",
                                       "WEXITSTATUS",
                                       "WTERMSIG",
                                       ))


class ChildWatcherTestsMixin:

    ignore_warnings = mock.patch.object(log.logger, "warning")

    def setUp(self):
        self.loop = self.new_test_loop()
        self.running = False
        self.zombies = {}

        with mock.patch.object(
                self.loop, "add_signal_handler") as self.m_add_signal_handler:
            self.watcher = self.create_watcher()
            self.watcher.attach_loop(self.loop)

    def waitpid(self, pid, flags):
        if isinstance(self.watcher, asyncio.SafeChildWatcher) or pid != -1:
            self.assertGreater(pid, 0)
        try:
            if pid < 0:
                return self.zombies.popitem()
            else:
                return pid, self.zombies.pop(pid)
        except KeyError:
            pass
        if self.running:
            return 0, 0
        else:
            raise ChildProcessError()

    def add_zombie(self, pid, returncode):
        self.zombies[pid] = returncode + 32768

    def WIFEXITED(self, status):
        return status >= 32768

    def WIFSIGNALED(self, status):
        return 32700 < status < 32768

    def WEXITSTATUS(self, status):
        self.assertTrue(self.WIFEXITED(status))
        return status - 32768

    def WTERMSIG(self, status):
        self.assertTrue(self.WIFSIGNALED(status))
        return 32768 - status

    def test_create_watcher(self):
        self.m_add_signal_handler.assert_called_once_with(
            signal.SIGCHLD, self.watcher._sig_chld)

    def waitpid_mocks(func):
        def wrapped_func(self):
            def patch(target, wrapper):
                return mock.patch(target, wraps=wrapper,
                                  new_callable=mock.Mock)

            with patch('os.WTERMSIG', self.WTERMSIG) as m_WTERMSIG, \
                 patch('os.WEXITSTATUS', self.WEXITSTATUS) as m_WEXITSTATUS, \
                 patch('os.WIFSIGNALED', self.WIFSIGNALED) as m_WIFSIGNALED, \
                 patch('os.WIFEXITED', self.WIFEXITED) as m_WIFEXITED, \
                 patch('os.waitpid', self.waitpid) as m_waitpid:
                func(self, WaitPidMocks(m_waitpid,
                                        m_WIFEXITED, m_WIFSIGNALED,
                                        m_WEXITSTATUS, m_WTERMSIG,
                                        ))
        return wrapped_func

    @waitpid_mocks
    def test_sigchld(self, m):
        # register a child
        callback = mock.Mock()

        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(42, callback, 9, 10, 14)

        self.assertFalse(callback.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child is running
        self.watcher._sig_chld()

        self.assertFalse(callback.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child terminates (returncode 12)
        self.running = False
        self.add_zombie(42, 12)
        self.watcher._sig_chld()

        self.assertTrue(m.WIFEXITED.called)
        self.assertTrue(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)
        callback.assert_called_once_with(42, 12, 9, 10, 14)

        m.WIFSIGNALED.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WEXITSTATUS.reset_mock()
        callback.reset_mock()

        # ensure that the child is effectively reaped
        self.add_zombie(42, 13)
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback.called)
        self.assertFalse(m.WTERMSIG.called)

        m.WIFSIGNALED.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WEXITSTATUS.reset_mock()

        # sigchld called again
        self.zombies.clear()
        self.watcher._sig_chld()

        self.assertFalse(callback.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

    @waitpid_mocks
    def test_sigchld_two_children(self, m):
        callback1 = mock.Mock()
        callback2 = mock.Mock()

        # register child 1
        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(43, callback1, 7, 8)

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # register child 2
        with self.watcher:
            self.watcher.add_child_handler(44, callback2, 147, 18)

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # children are running
        self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child 1 terminates (signal 3)
        self.add_zombie(43, -3)
        self.watcher._sig_chld()

        callback1.assert_called_once_with(43, -3, 7, 8)
        self.assertFalse(callback2.called)
        self.assertTrue(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertTrue(m.WTERMSIG.called)

        m.WIFSIGNALED.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WTERMSIG.reset_mock()
        callback1.reset_mock()

        # child 2 still running
        self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child 2 terminates (code 108)
        self.add_zombie(44, 108)
        self.running = False
        self.watcher._sig_chld()

        callback2.assert_called_once_with(44, 108, 147, 18)
        self.assertFalse(callback1.called)
        self.assertTrue(m.WIFEXITED.called)
        self.assertTrue(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        m.WIFSIGNALED.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WEXITSTATUS.reset_mock()
        callback2.reset_mock()

        # ensure that the children are effectively reaped
        self.add_zombie(43, 14)
        self.add_zombie(44, 15)
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WTERMSIG.called)

        m.WIFSIGNALED.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WEXITSTATUS.reset_mock()

        # sigchld called again
        self.zombies.clear()
        self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

    @waitpid_mocks
    def test_sigchld_two_children_terminating_together(self, m):
        callback1 = mock.Mock()
        callback2 = mock.Mock()

        # register child 1
        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(45, callback1, 17, 8)

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # register child 2
        with self.watcher:
            self.watcher.add_child_handler(46, callback2, 1147, 18)

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # children are running
        self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child 1 terminates (code 78)
        # child 2 terminates (signal 5)
        self.add_zombie(45, 78)
        self.add_zombie(46, -5)
        self.running = False
        self.watcher._sig_chld()

        callback1.assert_called_once_with(45, 78, 17, 8)
        callback2.assert_called_once_with(46, -5, 1147, 18)
        self.assertTrue(m.WIFSIGNALED.called)
        self.assertTrue(m.WIFEXITED.called)
        self.assertTrue(m.WEXITSTATUS.called)
        self.assertTrue(m.WTERMSIG.called)

        m.WIFSIGNALED.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WTERMSIG.reset_mock()
        m.WEXITSTATUS.reset_mock()
        callback1.reset_mock()
        callback2.reset_mock()

        # ensure that the children are effectively reaped
        self.add_zombie(45, 14)
        self.add_zombie(46, 15)
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WTERMSIG.called)

    @waitpid_mocks
    def test_sigchld_race_condition(self, m):
        # register a child
        callback = mock.Mock()

        with self.watcher:
            # child terminates before being registered
            self.add_zombie(50, 4)
            self.watcher._sig_chld()

            self.watcher.add_child_handler(50, callback, 1, 12)

        callback.assert_called_once_with(50, 4, 1, 12)
        callback.reset_mock()

        # ensure that the child is effectively reaped
        self.add_zombie(50, -1)
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback.called)

    @waitpid_mocks
    def test_sigchld_replace_handler(self, m):
        callback1 = mock.Mock()
        callback2 = mock.Mock()

        # register a child
        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(51, callback1, 19)

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # register the same child again
        with self.watcher:
            self.watcher.add_child_handler(51, callback2, 21)

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child terminates (signal 8)
        self.running = False
        self.add_zombie(51, -8)
        self.watcher._sig_chld()

        callback2.assert_called_once_with(51, -8, 21)
        self.assertFalse(callback1.called)
        self.assertTrue(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertTrue(m.WTERMSIG.called)

        m.WIFSIGNALED.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WTERMSIG.reset_mock()
        callback2.reset_mock()

        # ensure that the child is effectively reaped
        self.add_zombie(51, 13)
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(m.WTERMSIG.called)

    @waitpid_mocks
    def test_sigchld_remove_handler(self, m):
        callback = mock.Mock()

        # register a child
        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(52, callback, 1984)

        self.assertFalse(callback.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # unregister the child
        self.watcher.remove_child_handler(52)

        self.assertFalse(callback.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child terminates (code 99)
        self.running = False
        self.add_zombie(52, 99)
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback.called)

    @waitpid_mocks
    def test_sigchld_unknown_status(self, m):
        callback = mock.Mock()

        # register a child
        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(53, callback, -19)

        self.assertFalse(callback.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # terminate with unknown status
        self.zombies[53] = 1178
        self.running = False
        self.watcher._sig_chld()

        callback.assert_called_once_with(53, 1178, -19)
        self.assertTrue(m.WIFEXITED.called)
        self.assertTrue(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        callback.reset_mock()
        m.WIFEXITED.reset_mock()
        m.WIFSIGNALED.reset_mock()

        # ensure that the child is effectively reaped
        self.add_zombie(53, 101)
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback.called)

    @waitpid_mocks
    def test_remove_child_handler(self, m):
        callback1 = mock.Mock()
        callback2 = mock.Mock()
        callback3 = mock.Mock()

        # register children
        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(54, callback1, 1)
            self.watcher.add_child_handler(55, callback2, 2)
            self.watcher.add_child_handler(56, callback3, 3)

        # remove child handler 1
        self.assertTrue(self.watcher.remove_child_handler(54))

        # remove child handler 2 multiple times
        self.assertTrue(self.watcher.remove_child_handler(55))
        self.assertFalse(self.watcher.remove_child_handler(55))
        self.assertFalse(self.watcher.remove_child_handler(55))

        # all children terminate
        self.add_zombie(54, 0)
        self.add_zombie(55, 1)
        self.add_zombie(56, 2)
        self.running = False
        with self.ignore_warnings:
            self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        callback3.assert_called_once_with(56, 2, 3)

    @waitpid_mocks
    def test_sigchld_unhandled_exception(self, m):
        callback = mock.Mock()

        # register a child
        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(57, callback)

        # raise an exception
        m.waitpid.side_effect = ValueError

        with mock.patch.object(log.logger,
                               'error') as m_error:

            self.assertEqual(self.watcher._sig_chld(), None)
            self.assertTrue(m_error.called)

    @waitpid_mocks
    def test_sigchld_child_reaped_elsewhere(self, m):
        # register a child
        callback = mock.Mock()

        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(58, callback)

        self.assertFalse(callback.called)
        self.assertFalse(m.WIFEXITED.called)
        self.assertFalse(m.WIFSIGNALED.called)
        self.assertFalse(m.WEXITSTATUS.called)
        self.assertFalse(m.WTERMSIG.called)

        # child terminates
        self.running = False
        self.add_zombie(58, 4)

        # waitpid is called elsewhere
        os.waitpid(58, os.WNOHANG)

        m.waitpid.reset_mock()

        # sigchld
        with self.ignore_warnings:
            self.watcher._sig_chld()

        if isinstance(self.watcher, asyncio.FastChildWatcher):
            # here the FastChildWatche enters a deadlock
            # (there is no way to prevent it)
            self.assertFalse(callback.called)
        else:
            callback.assert_called_once_with(58, 255)

    @waitpid_mocks
    def test_sigchld_unknown_pid_during_registration(self, m):
        # register two children
        callback1 = mock.Mock()
        callback2 = mock.Mock()

        with self.ignore_warnings, self.watcher:
            self.running = True
            # child 1 terminates
            self.add_zombie(591, 7)
            # an unknown child terminates
            self.add_zombie(593, 17)

            self.watcher._sig_chld()

            self.watcher.add_child_handler(591, callback1)
            self.watcher.add_child_handler(592, callback2)

        callback1.assert_called_once_with(591, 7)
        self.assertFalse(callback2.called)

    @waitpid_mocks
    def test_set_loop(self, m):
        # register a child
        callback = mock.Mock()

        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(60, callback)

        # attach a new loop
        old_loop = self.loop
        self.loop = self.new_test_loop()
        patch = mock.patch.object

        with patch(old_loop, "remove_signal_handler") as m_old_remove, \
             patch(self.loop, "add_signal_handler") as m_new_add:

            self.watcher.attach_loop(self.loop)

            m_old_remove.assert_called_once_with(
                signal.SIGCHLD)
            m_new_add.assert_called_once_with(
                signal.SIGCHLD, self.watcher._sig_chld)

        # child terminates
        self.running = False
        self.add_zombie(60, 9)
        self.watcher._sig_chld()

        callback.assert_called_once_with(60, 9)

    @waitpid_mocks
    def test_set_loop_race_condition(self, m):
        # register 3 children
        callback1 = mock.Mock()
        callback2 = mock.Mock()
        callback3 = mock.Mock()

        with self.watcher:
            self.running = True
            self.watcher.add_child_handler(61, callback1)
            self.watcher.add_child_handler(62, callback2)
            self.watcher.add_child_handler(622, callback3)

        # detach the loop
        old_loop = self.loop
        self.loop = None

        with mock.patch.object(
                old_loop, "remove_signal_handler") as m_remove_signal_handler:

            self.watcher.attach_loop(None)

            m_remove_signal_handler.assert_called_once_with(
                signal.SIGCHLD)

        # child 1 & 2 terminate
        self.add_zombie(61, 11)
        self.add_zombie(62, -5)

        # SIGCHLD was not caught
        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        self.assertFalse(callback3.called)

        # attach a new loop
        self.loop = self.new_test_loop()

        with mock.patch.object(
                self.loop, "add_signal_handler") as m_add_signal_handler:

            self.watcher.attach_loop(self.loop)

            m_add_signal_handler.assert_called_once_with(
                signal.SIGCHLD, self.watcher._sig_chld)
            callback1.assert_called_once_with(61, 11)  # race condition!
            callback2.assert_called_once_with(62, -5)  # race condition!
            self.assertFalse(callback3.called)

        callback1.reset_mock()
        callback2.reset_mock()

        # child 3 terminates
        self.running = False
        self.add_zombie(622, 19)
        self.watcher._sig_chld()

        self.assertFalse(callback1.called)
        self.assertFalse(callback2.called)
        callback3.assert_called_once_with(622, 19)

    @waitpid_mocks
    def test_close(self, m):
        # register two children
        callback1 = mock.Mock()

        with self.watcher:
            self.running = True
            # child 1 terminates
            self.add_zombie(63, 9)
            # other child terminates
            self.add_zombie(65, 18)
            self.watcher._sig_chld()

            self.watcher.add_child_handler(63, callback1)
            self.watcher.add_child_handler(64, callback1)

            self.assertEqual(len(self.watcher._callbacks), 1)
            if isinstance(self.watcher, asyncio.FastChildWatcher):
                self.assertEqual(len(self.watcher._zombies), 1)

            with mock.patch.object(
                    self.loop,
                    "remove_signal_handler") as m_remove_signal_handler:

                self.watcher.close()

                m_remove_signal_handler.assert_called_once_with(
                    signal.SIGCHLD)
                self.assertFalse(self.watcher._callbacks)
                if isinstance(self.watcher, asyncio.FastChildWatcher):
                    self.assertFalse(self.watcher._zombies)


class SafeChildWatcherTests (ChildWatcherTestsMixin, test_utils.TestCase):
    def create_watcher(self):
        return asyncio.SafeChildWatcher()


class FastChildWatcherTests (ChildWatcherTestsMixin, test_utils.TestCase):
    def create_watcher(self):
        return asyncio.FastChildWatcher()


class PolicyTests(unittest.TestCase):

    def create_policy(self):
        return asyncio.DefaultEventLoopPolicy()

    def test_get_child_watcher(self):
        policy = self.create_policy()
        self.assertIsNone(policy._watcher)

        watcher = policy.get_child_watcher()
        self.assertIsInstance(watcher, asyncio.SafeChildWatcher)

        self.assertIs(policy._watcher, watcher)

        self.assertIs(watcher, policy.get_child_watcher())
        self.assertIsNone(watcher._loop)

    def test_get_child_watcher_after_set(self):
        policy = self.create_policy()
        watcher = asyncio.FastChildWatcher()

        policy.set_child_watcher(watcher)
        self.assertIs(policy._watcher, watcher)
        self.assertIs(watcher, policy.get_child_watcher())

    def test_get_child_watcher_with_mainloop_existing(self):
        policy = self.create_policy()
        loop = policy.get_event_loop()

        self.assertIsNone(policy._watcher)
        watcher = policy.get_child_watcher()

        self.assertIsInstance(watcher, asyncio.SafeChildWatcher)
        self.assertIs(watcher._loop, loop)

        loop.close()

    def test_get_child_watcher_thread(self):

        def f():
            policy.set_event_loop(policy.new_event_loop())

            self.assertIsInstance(policy.get_event_loop(),
                                  asyncio.AbstractEventLoop)
            watcher = policy.get_child_watcher()

            self.assertIsInstance(watcher, asyncio.SafeChildWatcher)
            self.assertIsNone(watcher._loop)

            policy.get_event_loop().close()

        policy = self.create_policy()

        th = threading.Thread(target=f)
        th.start()
        th.join()

    def test_child_watcher_replace_mainloop_existing(self):
        policy = self.create_policy()
        loop = policy.get_event_loop()

        watcher = policy.get_child_watcher()

        self.assertIs(watcher._loop, loop)

        new_loop = policy.new_event_loop()
        policy.set_event_loop(new_loop)

        self.assertIs(watcher._loop, new_loop)

        policy.set_event_loop(None)

        self.assertIs(watcher._loop, None)

        loop.close()
        new_loop.close()


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