# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Tests for L{twisted.application} and its interaction with
L{twisted.persisted.sob}.
"""


import copy
import os
import pickle
from io import StringIO

try:
    import asyncio
except ImportError:
    asyncio = None  # type: ignore[assignment]

from unittest import skipIf

from twisted.application import app, internet, reactors, service
from twisted.application.internet import backoffPolicy
from twisted.internet import defer, interfaces, protocol, reactor
from twisted.internet.testing import MemoryReactor
from twisted.persisted import sob
from twisted.plugins import twisted_reactors
from twisted.protocols import basic, wire
from twisted.python import usage
from twisted.python.runtime import platformType
from twisted.python.test.modules_helpers import TwistedModulesMixin
from twisted.trial.unittest import SkipTest, TestCase


class Dummy:
    processName = None


class ServiceTests(TestCase):
    def testName(self):
        s = service.Service()
        s.setName("hello")
        self.assertEqual(s.name, "hello")

    def testParent(self):
        s = service.Service()
        p = service.MultiService()
        s.setServiceParent(p)
        self.assertEqual(list(p), [s])
        self.assertEqual(s.parent, p)

    def testApplicationAsParent(self):
        s = service.Service()
        p = service.Application("")
        s.setServiceParent(p)
        self.assertEqual(list(service.IServiceCollection(p)), [s])
        self.assertEqual(s.parent, service.IServiceCollection(p))

    def testNamedChild(self):
        s = service.Service()
        p = service.MultiService()
        s.setName("hello")
        s.setServiceParent(p)
        self.assertEqual(list(p), [s])
        self.assertEqual(s.parent, p)
        self.assertEqual(p.getServiceNamed("hello"), s)

    def testDoublyNamedChild(self):
        s = service.Service()
        p = service.MultiService()
        s.setName("hello")
        s.setServiceParent(p)
        self.assertRaises(RuntimeError, s.setName, "lala")

    def testDuplicateNamedChild(self):
        s = service.Service()
        p = service.MultiService()
        s.setName("hello")
        s.setServiceParent(p)
        s = service.Service()
        s.setName("hello")
        self.assertRaises(RuntimeError, s.setServiceParent, p)

    def testDisowning(self):
        s = service.Service()
        p = service.MultiService()
        s.setServiceParent(p)
        self.assertEqual(list(p), [s])
        self.assertEqual(s.parent, p)
        s.disownServiceParent()
        self.assertEqual(list(p), [])
        self.assertIsNone(s.parent)

    def testRunning(self):
        s = service.Service()
        self.assertFalse(s.running)
        s.startService()
        self.assertTrue(s.running)
        s.stopService()
        self.assertFalse(s.running)

    def testRunningChildren1(self):
        s = service.Service()
        p = service.MultiService()
        s.setServiceParent(p)
        self.assertFalse(s.running)
        self.assertFalse(p.running)
        p.startService()
        self.assertTrue(s.running)
        self.assertTrue(p.running)
        p.stopService()
        self.assertFalse(s.running)
        self.assertFalse(p.running)

    def testRunningChildren2(self):
        s = service.Service()

        def checkRunning():
            self.assertTrue(s.running)

        t = service.Service()
        t.stopService = checkRunning
        t.startService = checkRunning
        p = service.MultiService()
        s.setServiceParent(p)
        t.setServiceParent(p)
        p.startService()
        p.stopService()

    def testAddingIntoRunning(self):
        p = service.MultiService()
        p.startService()
        s = service.Service()
        self.assertFalse(s.running)
        s.setServiceParent(p)
        self.assertTrue(s.running)
        s.disownServiceParent()
        self.assertFalse(s.running)

    def testPrivileged(self):
        s = service.Service()

        def pss():
            s.privilegedStarted = 1

        s.privilegedStartService = pss
        s1 = service.Service()
        p = service.MultiService()
        s.setServiceParent(p)
        s1.setServiceParent(p)
        p.privilegedStartService()
        self.assertTrue(s.privilegedStarted)

    def testCopying(self):
        s = service.Service()
        s.startService()
        s1 = copy.copy(s)
        self.assertFalse(s1.running)
        self.assertTrue(s.running)


if hasattr(os, "getuid"):
    curuid = os.getuid()
    curgid = os.getgid()
else:
    curuid = curgid = 0


class ProcessTests(TestCase):
    def testID(self):
        p = service.Process(5, 6)
        self.assertEqual(p.uid, 5)
        self.assertEqual(p.gid, 6)

    def testDefaults(self):
        p = service.Process(5)
        self.assertEqual(p.uid, 5)
        self.assertIsNone(p.gid)
        p = service.Process(gid=5)
        self.assertIsNone(p.uid)
        self.assertEqual(p.gid, 5)
        p = service.Process()
        self.assertIsNone(p.uid)
        self.assertIsNone(p.gid)

    def testProcessName(self):
        p = service.Process()
        self.assertIsNone(p.processName)
        p.processName = "hello"
        self.assertEqual(p.processName, "hello")


class InterfacesTests(TestCase):
    def testService(self):
        self.assertTrue(service.IService.providedBy(service.Service()))

    def testMultiService(self):
        self.assertTrue(service.IService.providedBy(service.MultiService()))
        self.assertTrue(service.IServiceCollection.providedBy(service.MultiService()))

    def testProcess(self):
        self.assertTrue(service.IProcess.providedBy(service.Process()))


class ApplicationTests(TestCase):
    def testConstructor(self):
        service.Application("hello")
        service.Application("hello", 5)
        service.Application("hello", 5, 6)

    def testProcessComponent(self):
        a = service.Application("hello")
        self.assertIsNone(service.IProcess(a).uid)
        self.assertIsNone(service.IProcess(a).gid)
        a = service.Application("hello", 5)
        self.assertEqual(service.IProcess(a).uid, 5)
        self.assertIsNone(service.IProcess(a).gid)
        a = service.Application("hello", 5, 6)
        self.assertEqual(service.IProcess(a).uid, 5)
        self.assertEqual(service.IProcess(a).gid, 6)

    def testServiceComponent(self):
        a = service.Application("hello")
        self.assertIs(service.IService(a), service.IServiceCollection(a))
        self.assertEqual(service.IService(a).name, "hello")
        self.assertIsNone(service.IService(a).parent)

    def testPersistableComponent(self):
        a = service.Application("hello")
        p = sob.IPersistable(a)
        self.assertEqual(p.style, "pickle")
        self.assertEqual(p.name, "hello")
        self.assertIs(p.original, a)


class LoadingTests(TestCase):
    def test_simpleStoreAndLoad(self):
        a = service.Application("hello")
        p = sob.IPersistable(a)
        for style in "source pickle".split():
            p.setStyle(style)
            p.save()
            a1 = service.loadApplication("hello.ta" + style[0], style)
            self.assertEqual(service.IService(a1).name, "hello")
        with open("hello.tac", "w") as f:
            f.writelines(
                [
                    "from twisted.application import service\n",
                    "application = service.Application('hello')\n",
                ]
            )
        a1 = service.loadApplication("hello.tac", "python")
        self.assertEqual(service.IService(a1).name, "hello")


class AppSupportTests(TestCase):
    def testPassphrase(self):
        self.assertIsNone(app.getPassphrase(0))

    def testLoadApplication(self):
        """
        Test loading an application file in different dump format.
        """
        a = service.Application("hello")
        baseconfig = {"file": None, "source": None, "python": None}
        for style in "source pickle".split():
            config = baseconfig.copy()
            config[{"pickle": "file"}.get(style, style)] = "helloapplication"
            sob.IPersistable(a).setStyle(style)
            sob.IPersistable(a).save(filename="helloapplication")
            a1 = app.getApplication(config, None)
            self.assertEqual(service.IService(a1).name, "hello")
        config = baseconfig.copy()
        config["python"] = "helloapplication"
        with open("helloapplication", "w") as f:
            f.writelines(
                [
                    "from twisted.application import service\n",
                    "application = service.Application('hello')\n",
                ]
            )
        a1 = app.getApplication(config, None)
        self.assertEqual(service.IService(a1).name, "hello")

    def test_convertStyle(self):
        appl = service.Application("lala")
        for instyle in "source pickle".split():
            for outstyle in "source pickle".split():
                sob.IPersistable(appl).setStyle(instyle)
                sob.IPersistable(appl).save(filename="converttest")
                app.convertStyle(
                    "converttest", instyle, None, "converttest.out", outstyle, 0
                )
                appl2 = service.loadApplication("converttest.out", outstyle)
                self.assertEqual(service.IService(appl2).name, "lala")

    def test_startApplication(self):
        appl = service.Application("lala")
        app.startApplication(appl, 0)
        self.assertTrue(service.IService(appl).running)


class Foo(basic.LineReceiver):
    def connectionMade(self):
        self.transport.write(b"lalala\r\n")

    def lineReceived(self, line):
        self.factory.line = line
        self.transport.loseConnection()

    def connectionLost(self, reason):
        self.factory.d.callback(self.factory.line)


class DummyApp:
    processName = None

    def addService(self, service):
        self.services[service.name] = service

    def removeService(self, service):
        del self.services[service.name]


class TimerTarget:
    def __init__(self):
        self.l = []

    def append(self, what):
        self.l.append(what)


class TestEcho(wire.Echo):
    def connectionLost(self, reason):
        self.d.callback(True)


class InternetTests(TestCase):
    def testTCP(self):
        s = service.MultiService()
        s.startService()
        factory = protocol.ServerFactory()
        factory.protocol = TestEcho
        TestEcho.d = defer.Deferred()
        t = internet.TCPServer(0, factory)
        t.setServiceParent(s)
        num = t._port.getHost().port
        factory = protocol.ClientFactory()
        factory.d = defer.Deferred()
        factory.protocol = Foo
        factory.line = None
        internet.TCPClient("127.0.0.1", num, factory).setServiceParent(s)
        factory.d.addCallback(self.assertEqual, b"lalala")
        factory.d.addCallback(lambda x: s.stopService())
        factory.d.addCallback(lambda x: TestEcho.d)
        return factory.d

    def test_UDP(self):
        """
        Test L{internet.UDPServer} with a random port: starting the service
        should give it valid port, and stopService should free it so that we
        can start a server on the same port again.
        """
        if not interfaces.IReactorUDP(reactor, None):
            raise SkipTest("This reactor does not support UDP sockets")
        p = protocol.DatagramProtocol()
        t = internet.UDPServer(0, p)
        t.startService()
        num = t._port.getHost().port
        self.assertNotEqual(num, 0)

        def onStop(ignored):
            t = internet.UDPServer(num, p)
            t.startService()
            return t.stopService()

        return defer.maybeDeferred(t.stopService).addCallback(onStop)

    def testPrivileged(self):
        factory = protocol.ServerFactory()
        factory.protocol = TestEcho
        TestEcho.d = defer.Deferred()
        t = internet.TCPServer(0, factory)
        t.privileged = 1
        t.privilegedStartService()
        num = t._port.getHost().port
        factory = protocol.ClientFactory()
        factory.d = defer.Deferred()
        factory.protocol = Foo
        factory.line = None
        c = internet.TCPClient("127.0.0.1", num, factory)
        c.startService()
        factory.d.addCallback(self.assertEqual, b"lalala")
        factory.d.addCallback(lambda x: c.stopService())
        factory.d.addCallback(lambda x: t.stopService())
        factory.d.addCallback(lambda x: TestEcho.d)
        return factory.d

    def testConnectionGettingRefused(self):
        factory = protocol.ServerFactory()
        factory.protocol = wire.Echo
        t = internet.TCPServer(0, factory)
        t.startService()
        num = t._port.getHost().port
        t.stopService()
        d = defer.Deferred()
        factory = protocol.ClientFactory()
        factory.clientConnectionFailed = lambda *args: d.callback(None)
        c = internet.TCPClient("127.0.0.1", num, factory)
        c.startService()
        return d

    @skipIf(
        not interfaces.IReactorUNIX(reactor, None),
        "This reactor does not support UNIX domain sockets",
    )
    def testUNIX(self):
        # FIXME: This test is far too dense.  It needs comments.
        #  -- spiv, 2004-11-07
        s = service.MultiService()
        s.startService()
        factory = protocol.ServerFactory()
        factory.protocol = TestEcho
        TestEcho.d = defer.Deferred()
        t = internet.UNIXServer("echo.skt", factory)
        t.setServiceParent(s)
        factory = protocol.ClientFactory()
        factory.protocol = Foo
        factory.d = defer.Deferred()
        factory.line = None
        internet.UNIXClient("echo.skt", factory).setServiceParent(s)
        factory.d.addCallback(self.assertEqual, b"lalala")
        factory.d.addCallback(lambda x: s.stopService())
        factory.d.addCallback(lambda x: TestEcho.d)
        factory.d.addCallback(self._cbTestUnix, factory, s)
        return factory.d

    def _cbTestUnix(self, ignored, factory, s):
        TestEcho.d = defer.Deferred()
        factory.line = None
        factory.d = defer.Deferred()
        s.startService()
        factory.d.addCallback(self.assertEqual, b"lalala")
        factory.d.addCallback(lambda x: s.stopService())
        factory.d.addCallback(lambda x: TestEcho.d)
        return factory.d

    @skipIf(
        not interfaces.IReactorUNIX(reactor, None),
        "This reactor does not support UNIX domain sockets",
    )
    def testVolatile(self):
        factory = protocol.ServerFactory()
        factory.protocol = wire.Echo
        t = internet.UNIXServer("echo.skt", factory)
        t.startService()
        self.failIfIdentical(t._port, None)
        t1 = copy.copy(t)
        self.assertIsNone(t1._port)
        t.stopService()
        self.assertIsNone(t._port)
        self.assertFalse(t.running)

        factory = protocol.ClientFactory()
        factory.protocol = wire.Echo
        t = internet.UNIXClient("echo.skt", factory)
        t.startService()
        self.failIfIdentical(t._connection, None)
        t1 = copy.copy(t)
        self.assertIsNone(t1._connection)
        t.stopService()
        self.assertIsNone(t._connection)
        self.assertFalse(t.running)

    @skipIf(
        not interfaces.IReactorUNIX(reactor, None),
        "This reactor does not support UNIX domain sockets",
    )
    def testStoppingServer(self):
        factory = protocol.ServerFactory()
        factory.protocol = wire.Echo
        t = internet.UNIXServer("echo.skt", factory)
        t.startService()
        t.stopService()
        self.assertFalse(t.running)
        factory = protocol.ClientFactory()
        d = defer.Deferred()
        factory.clientConnectionFailed = lambda *args: d.callback(None)
        reactor.connectUNIX("echo.skt", factory)
        return d

    def testPickledTimer(self):
        target = TimerTarget()
        t0 = internet.TimerService(1, target.append, "hello")
        t0.startService()
        s = pickle.dumps(t0)
        t0.stopService()

        t = pickle.loads(s)
        self.assertFalse(t.running)

    def testBrokenTimer(self):
        d = defer.Deferred()
        t = internet.TimerService(1, lambda: 1 // 0)
        oldFailed = t._failed

        def _failed(why):
            oldFailed(why)
            d.callback(None)

        t._failed = _failed
        t.startService()
        d.addCallback(lambda x: t.stopService)
        d.addCallback(
            lambda x: self.assertEqual(
                [ZeroDivisionError],
                [o.value.__class__ for o in self.flushLoggedErrors(ZeroDivisionError)],
            )
        )
        return d

    def test_everythingThere(self):
        """
        L{twisted.application.internet} dynamically defines a set of
        L{service.Service} subclasses that in general have corresponding
        reactor.listenXXX or reactor.connectXXX calls.
        """
        trans = ["TCP", "UNIX", "SSL", "UDP", "UNIXDatagram", "Multicast"]
        for tran in trans[:]:
            if not getattr(interfaces, "IReactor" + tran)(reactor, None):
                trans.remove(tran)
        for tran in trans:
            for side in ["Server", "Client"]:
                if tran == "Multicast" and side == "Client":
                    continue
                if tran == "UDP" and side == "Client":
                    continue
                self.assertTrue(hasattr(internet, tran + side))
                method = getattr(internet, tran + side).method
                prefix = {"Server": "listen", "Client": "connect"}[side]
                self.assertTrue(
                    hasattr(reactor, prefix + method)
                    or (prefix == "connect" and method == "UDP")
                )
                o = getattr(internet, tran + side)()
                self.assertEqual(service.IService(o), o)

    def test_importAll(self):
        """
        L{twisted.application.internet} dynamically defines L{service.Service}
        subclasses. This test ensures that the subclasses exposed by C{__all__}
        are valid attributes of the module.
        """
        for cls in internet.__all__:
            self.assertTrue(
                hasattr(internet, cls),
                f"{cls} not importable from twisted.application.internet",
            )

    def test_reactorParametrizationInServer(self):
        """
        L{internet._AbstractServer} supports a C{reactor} keyword argument
        that can be used to parametrize the reactor used to listen for
        connections.
        """
        reactor = MemoryReactor()

        factory = object()
        t = internet.TCPServer(1234, factory, reactor=reactor)
        t.startService()
        self.assertEqual(reactor.tcpServers.pop()[:2], (1234, factory))

    def test_reactorParametrizationInClient(self):
        """
        L{internet._AbstractClient} supports a C{reactor} keyword arguments
        that can be used to parametrize the reactor used to create new client
        connections.
        """
        reactor = MemoryReactor()

        factory = protocol.ClientFactory()
        t = internet.TCPClient("127.0.0.1", 1234, factory, reactor=reactor)
        t.startService()
        self.assertEqual(reactor.tcpClients.pop()[:3], ("127.0.0.1", 1234, factory))

    def test_reactorParametrizationInServerMultipleStart(self):
        """
        Like L{test_reactorParametrizationInServer}, but stop and restart the
        service and check that the given reactor is still used.
        """
        reactor = MemoryReactor()

        factory = protocol.Factory()
        t = internet.TCPServer(1234, factory, reactor=reactor)
        t.startService()
        self.assertEqual(reactor.tcpServers.pop()[:2], (1234, factory))
        t.stopService()
        t.startService()
        self.assertEqual(reactor.tcpServers.pop()[:2], (1234, factory))

    def test_reactorParametrizationInClientMultipleStart(self):
        """
        Like L{test_reactorParametrizationInClient}, but stop and restart the
        service and check that the given reactor is still used.
        """
        reactor = MemoryReactor()

        factory = protocol.ClientFactory()
        t = internet.TCPClient("127.0.0.1", 1234, factory, reactor=reactor)
        t.startService()
        self.assertEqual(reactor.tcpClients.pop()[:3], ("127.0.0.1", 1234, factory))
        t.stopService()
        t.startService()
        self.assertEqual(reactor.tcpClients.pop()[:3], ("127.0.0.1", 1234, factory))


class TimerBasicTests(TestCase):
    def testTimerRuns(self):
        d = defer.Deferred()
        self.t = internet.TimerService(1, d.callback, "hello")
        self.t.startService()
        d.addCallback(self.assertEqual, "hello")
        d.addCallback(lambda x: self.t.stopService())
        d.addCallback(lambda x: self.assertFalse(self.t.running))
        return d

    def tearDown(self):
        return self.t.stopService()

    def testTimerRestart(self):
        # restart the same TimerService
        d1 = defer.Deferred()
        d2 = defer.Deferred()
        work = [(d2, "bar"), (d1, "foo")]

        def trigger():
            d, arg = work.pop()
            d.callback(arg)

        self.t = internet.TimerService(1, trigger)
        self.t.startService()

        def onFirstResult(result):
            self.assertEqual(result, "foo")
            return self.t.stopService()

        def onFirstStop(ignored):
            self.assertFalse(self.t.running)
            self.t.startService()
            return d2

        def onSecondResult(result):
            self.assertEqual(result, "bar")
            self.t.stopService()

        d1.addCallback(onFirstResult)
        d1.addCallback(onFirstStop)
        d1.addCallback(onSecondResult)
        return d1

    def testTimerLoops(self):
        l = []

        def trigger(data, number, d):
            l.append(data)
            if len(l) == number:
                d.callback(l)

        d = defer.Deferred()
        self.t = internet.TimerService(0.01, trigger, "hello", 10, d)
        self.t.startService()
        d.addCallback(self.assertEqual, ["hello"] * 10)
        d.addCallback(lambda x: self.t.stopService())
        return d


class FakeReactor(reactors.Reactor):
    """
    A fake reactor with a hooked install method.
    """

    def __init__(self, install, *args, **kwargs):
        """
        @param install: any callable that will be used as install method.
        @type install: C{callable}
        """
        reactors.Reactor.__init__(self, *args, **kwargs)
        self.install = install


class PluggableReactorTests(TwistedModulesMixin, TestCase):
    """
    Tests for the reactor discovery/inspection APIs.
    """

    def setUp(self):
        """
        Override the L{reactors.getPlugins} function, normally bound to
        L{twisted.plugin.getPlugins}, in order to control which
        L{IReactorInstaller} plugins are seen as available.

        C{self.pluginResults} can be customized and will be used as the
        result of calls to C{reactors.getPlugins}.
        """
        self.pluginCalls = []
        self.pluginResults = []
        self.originalFunction = reactors.getPlugins
        reactors.getPlugins = self._getPlugins

    def tearDown(self):
        """
        Restore the original L{reactors.getPlugins}.
        """
        reactors.getPlugins = self.originalFunction

    def _getPlugins(self, interface, package=None):
        """
        Stand-in for the real getPlugins method which records its arguments
        and returns a fixed result.
        """
        self.pluginCalls.append((interface, package))
        return list(self.pluginResults)

    def test_getPluginReactorTypes(self):
        """
        Test that reactor plugins are returned from L{getReactorTypes}
        """
        name = "fakereactortest"
        package = __name__ + ".fakereactor"
        description = "description"
        self.pluginResults = [reactors.Reactor(name, package, description)]
        reactorTypes = reactors.getReactorTypes()

        self.assertEqual(self.pluginCalls, [(reactors.IReactorInstaller, None)])

        for r in reactorTypes:
            if r.shortName == name:
                self.assertEqual(r.description, description)
                break
        else:
            self.fail("Reactor plugin not present in getReactorTypes() result")

    def test_reactorInstallation(self):
        """
        Test that L{reactors.Reactor.install} loads the correct module and
        calls its install attribute.
        """
        installed = []

        def install():
            installed.append(True)

        fakeReactor = FakeReactor(install, "fakereactortest", __name__, "described")
        modules = {"fakereactortest": fakeReactor}
        self.replaceSysModules(modules)
        installer = reactors.Reactor("fakereactor", "fakereactortest", "described")
        installer.install()
        self.assertEqual(installed, [True])

    def test_installReactor(self):
        """
        Test that the L{reactors.installReactor} function correctly installs
        the specified reactor.
        """
        installed = []

        def install():
            installed.append(True)

        name = "fakereactortest"
        package = __name__
        description = "description"
        self.pluginResults = [FakeReactor(install, name, package, description)]
        reactors.installReactor(name)
        self.assertEqual(installed, [True])

    def test_installReactorReturnsReactor(self):
        """
        Test that the L{reactors.installReactor} function correctly returns
        the installed reactor.
        """
        reactor = object()

        def install():
            from twisted import internet

            self.patch(internet, "reactor", reactor)

        name = "fakereactortest"
        package = __name__
        description = "description"
        self.pluginResults = [FakeReactor(install, name, package, description)]
        installed = reactors.installReactor(name)
        self.assertIs(installed, reactor)

    def test_installReactorMultiplePlugins(self):
        """
        Test that the L{reactors.installReactor} function correctly installs
        the specified reactor when there are multiple reactor plugins.
        """
        installed = []

        def install():
            installed.append(True)

        name = "fakereactortest"
        package = __name__
        description = "description"
        fakeReactor = FakeReactor(install, name, package, description)
        otherReactor = FakeReactor(lambda: None, "otherreactor", package, description)
        self.pluginResults = [otherReactor, fakeReactor]
        reactors.installReactor(name)
        self.assertEqual(installed, [True])

    def test_installNonExistentReactor(self):
        """
        Test that L{reactors.installReactor} raises L{reactors.NoSuchReactor}
        when asked to install a reactor which it cannot find.
        """
        self.pluginResults = []
        self.assertRaises(
            reactors.NoSuchReactor, reactors.installReactor, "somereactor"
        )

    def test_installNotAvailableReactor(self):
        """
        Test that L{reactors.installReactor} raises an exception when asked to
        install a reactor which doesn't work in this environment.
        """

        def install():
            raise ImportError("Missing foo bar")

        name = "fakereactortest"
        package = __name__
        description = "description"
        self.pluginResults = [FakeReactor(install, name, package, description)]
        self.assertRaises(ImportError, reactors.installReactor, name)

    def test_reactorSelectionMixin(self):
        """
        Test that the reactor selected is installed as soon as possible, ie
        when the option is parsed.
        """
        executed = []
        INSTALL_EVENT = "reactor installed"
        SUBCOMMAND_EVENT = "subcommands loaded"

        class ReactorSelectionOptions(usage.Options, app.ReactorSelectionMixin):
            @property
            def subCommands(self):
                executed.append(SUBCOMMAND_EVENT)
                return [("subcommand", None, lambda: self, "test subcommand")]

        def install():
            executed.append(INSTALL_EVENT)

        self.pluginResults = [
            FakeReactor(install, "fakereactortest", __name__, "described")
        ]

        options = ReactorSelectionOptions()
        options.parseOptions(["--reactor", "fakereactortest", "subcommand"])
        self.assertEqual(executed[0], INSTALL_EVENT)
        self.assertEqual(executed.count(INSTALL_EVENT), 1)
        self.assertEqual(options["reactor"], "fakereactortest")

    def test_reactorSelectionMixinNonExistent(self):
        """
        Test that the usage mixin exits when trying to use a non existent
        reactor (the name not matching to any reactor), giving an error
        message.
        """

        class ReactorSelectionOptions(usage.Options, app.ReactorSelectionMixin):
            pass

        self.pluginResults = []

        options = ReactorSelectionOptions()
        options.messageOutput = StringIO()
        e = self.assertRaises(
            usage.UsageError,
            options.parseOptions,
            ["--reactor", "fakereactortest", "subcommand"],
        )
        self.assertIn("fakereactortest", e.args[0])
        self.assertIn("help-reactors", e.args[0])

    def test_reactorSelectionMixinNotAvailable(self):
        """
        Test that the usage mixin exits when trying to use a reactor not
        available (the reactor raises an error at installation), giving an
        error message.
        """

        class ReactorSelectionOptions(usage.Options, app.ReactorSelectionMixin):
            pass

        message = "Missing foo bar"

        def install():
            raise ImportError(message)

        name = "fakereactortest"
        package = __name__
        description = "description"
        self.pluginResults = [FakeReactor(install, name, package, description)]

        options = ReactorSelectionOptions()
        options.messageOutput = StringIO()
        e = self.assertRaises(
            usage.UsageError,
            options.parseOptions,
            ["--reactor", "fakereactortest", "subcommand"],
        )
        self.assertIn(message, e.args[0])
        self.assertIn("help-reactors", e.args[0])


class HelpReactorsTests(TestCase):
    """
    --help-reactors lists the available reactors
    """

    def setUp(self):
        """
        Get the text from --help-reactors
        """
        self.options = app.ReactorSelectionMixin()
        self.options.messageOutput = StringIO()
        self.assertRaises(SystemExit, self.options.opt_help_reactors)
        self.message = self.options.messageOutput.getvalue()

    @skipIf(asyncio, "Not applicable, asyncio is available")
    def test_lacksAsyncIO(self):
        """
        --help-reactors should NOT display the asyncio reactor on Python < 3.4
        """
        self.assertIn(twisted_reactors.asyncio.description, self.message)
        self.assertIn("!" + twisted_reactors.asyncio.shortName, self.message)

    @skipIf(not asyncio, "asyncio library not available")
    def test_hasAsyncIO(self):
        """
        --help-reactors should display the asyncio reactor on Python >= 3.4
        """
        self.assertIn(twisted_reactors.asyncio.description, self.message)
        self.assertNotIn("!" + twisted_reactors.asyncio.shortName, self.message)

    @skipIf(platformType != "win32", "Test only applicable on Windows")
    def test_iocpWin32(self):
        """
        --help-reactors should display the iocp reactor on Windows
        """
        self.assertIn(twisted_reactors.iocp.description, self.message)
        self.assertNotIn("!" + twisted_reactors.iocp.shortName, self.message)

    @skipIf(platformType == "win32", "Test not applicable on Windows")
    def test_iocpNotWin32(self):
        """
        --help-reactors should NOT display the iocp reactor on Windows
        """
        self.assertIn(twisted_reactors.iocp.description, self.message)
        self.assertIn("!" + twisted_reactors.iocp.shortName, self.message)

    def test_onlySupportedReactors(self):
        """
        --help-reactors with only supported reactors
        """

        def getReactorTypes():
            yield twisted_reactors.default

        options = app.ReactorSelectionMixin()
        options._getReactorTypes = getReactorTypes
        options.messageOutput = StringIO()
        self.assertRaises(SystemExit, options.opt_help_reactors)
        message = options.messageOutput.getvalue()
        self.assertNotIn("reactors not available", message)


class BackoffPolicyTests(TestCase):
    """
    Tests of L{twisted.application.internet.backoffPolicy}
    """

    def test_calculates_correct_values(self):
        """
        Test that L{backoffPolicy()} calculates expected values
        """
        pol = backoffPolicy(1.0, 60.0, 1.5, jitter=lambda: 1)
        self.assertAlmostEqual(pol(0), 2)
        self.assertAlmostEqual(pol(1), 2.5)
        self.assertAlmostEqual(pol(10), 58.6650390625)
        self.assertEqual(pol(20), 61)
        self.assertEqual(pol(100), 61)

    def test_does_not_overflow_on_high_attempts(self):
        """
        L{backoffPolicy()} does not fail for large values of the attempt
        parameter. In previous versions, this test failed when attempt was
        larger than 1750.

        See https://twistedmatrix.com/trac/ticket/9476
        """
        pol = backoffPolicy(1.0, 60.0, 1.5, jitter=lambda: 1)
        self.assertEqual(pol(1751), 61)
        self.assertEqual(pol(1000000), 61)

    def test_does_not_overflow_with_large_factor_value(self):
        """
        Even with unusual parameters, any L{OverflowError} within
        L{backoffPolicy()} will be caught and L{maxDelay} will be returned
        instead
        """
        pol = backoffPolicy(1.0, 60.0, 1e10, jitter=lambda: 1)
        self.assertEqual(pol(1751), 61)