"""
Tests for traitlets.config.application.Application
"""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
from __future__ import annotations

import contextlib
import io
import json
import logging
import os
import sys
import typing as t
from io import StringIO
from tempfile import TemporaryDirectory
from unittest import TestCase, mock

import pytest

from traitlets import (
    Bool,
    Bytes,
    Dict,
    HasTraits,
    Int,
    Integer,
    List,
    Set,
    Tuple,
    Unicode,
)
from traitlets.config.application import Application
from traitlets.config.configurable import Configurable
from traitlets.config.loader import Config, KVArgParseConfigLoader
from traitlets.tests.utils import check_help_all_output, check_help_output, get_output_error_code

pjoin = os.path.join


class Foo(Configurable):
    i = Integer(
        0,
        help="""
    The integer i.

    Details about i.
    """,
    ).tag(config=True)
    j = Integer(1, help="The integer j.").tag(config=True)
    name = Unicode("Brian", help="First name.").tag(config=True)
    la = List([]).tag(config=True)
    li = List(Integer()).tag(config=True)
    fdict = Dict().tag(config=True, multiplicity="+")


class Bar(Configurable):
    b = Integer(0, help="The integer b.").tag(config=True)
    enabled = Bool(True, help="Enable bar.").tag(config=True)
    tb = Tuple(()).tag(config=True, multiplicity="*")
    aset = Set().tag(config=True, multiplicity="+")
    bdict = Dict().tag(config=True)
    idict = Dict(value_trait=Integer()).tag(config=True)
    key_dict = Dict(per_key_traits={"i": Integer(), "b": Bytes()}).tag(config=True)


class MyApp(Application):
    name = Unicode("myapp")
    running = Bool(False, help="Is the app running?").tag(config=True)
    classes = List([Bar, Foo])  # type:ignore
    config_file = Unicode("", help="Load this config file").tag(config=True)

    warn_tpyo = Unicode(
        "yes the name is wrong on purpose",
        config=True,
        help="Should print a warning if `MyApp.warn-typo=...` command is passed",
    )

    aliases: dict[t.Any, t.Any] = {}
    aliases.update(Application.aliases)
    aliases.update(
        {
            ("fooi", "i"): "Foo.i",
            ("j", "fooj"): ("Foo.j", "`j` terse help msg"),
            "name": "Foo.name",
            "la": "Foo.la",
            "li": "Foo.li",
            "tb": "Bar.tb",
            "D": "Bar.bdict",
            "enabled": "Bar.enabled",
            "enable": "Bar.enabled",
            "log-level": "Application.log_level",
        }
    )

    flags: dict[t.Any, t.Any] = {}
    flags.update(Application.flags)
    flags.update(
        {
            ("enable", "e"): ({"Bar": {"enabled": True}}, "Set Bar.enabled to True"),
            ("d", "disable"): ({"Bar": {"enabled": False}}, "Set Bar.enabled to False"),
            "crit": ({"Application": {"log_level": logging.CRITICAL}}, "set level=CRITICAL"),
        }
    )

    def init_foo(self):
        self.foo = Foo(parent=self)

    def init_bar(self):
        self.bar = Bar(parent=self)


def class_to_names(classes):
    return [klass.__name__ for klass in classes]


class TestApplication(TestCase):
    def test_log(self):
        stream = StringIO()
        app = MyApp(log_level=logging.INFO)
        handler = logging.StreamHandler(stream)
        # trigger reconstruction of the log formatter
        app.log_format = "%(message)s"
        app.log_datefmt = "%Y-%m-%d %H:%M"
        app.log.handlers = [handler]
        app.log.info("hello")
        assert "hello" in stream.getvalue()

    def test_no_eval_cli_text(self):
        app = MyApp()
        app.initialize(["--Foo.name=1"])
        app.init_foo()
        assert app.foo.name == "1"

    def test_basic(self):
        app = MyApp()
        self.assertEqual(app.name, "myapp")
        self.assertEqual(app.running, False)
        self.assertEqual(app.classes, [MyApp, Bar, Foo])  # type:ignore
        self.assertEqual(app.config_file, "")

    def test_app_name_set_via_constructor(self):
        app = MyApp(name="set_via_constructor")
        assert app.name == "set_via_constructor"

    def test_mro_discovery(self):
        app = MyApp()

        self.assertSequenceEqual(
            class_to_names(app._classes_with_config_traits()),
            ["Application", "MyApp", "Bar", "Foo"],
        )
        self.assertSequenceEqual(
            class_to_names(app._classes_inc_parents()),
            [
                "Configurable",
                "LoggingConfigurable",
                "SingletonConfigurable",
                "Application",
                "MyApp",
                "Bar",
                "Foo",
            ],
        )

        self.assertSequenceEqual(
            class_to_names(app._classes_with_config_traits([Application])), ["Application"]
        )
        self.assertSequenceEqual(
            class_to_names(app._classes_inc_parents([Application])),
            ["Configurable", "LoggingConfigurable", "SingletonConfigurable", "Application"],
        )

        self.assertSequenceEqual(class_to_names(app._classes_with_config_traits([Foo])), ["Foo"])
        self.assertSequenceEqual(
            class_to_names(app._classes_inc_parents([Bar])), ["Configurable", "Bar"]
        )

        class MyApp2(Application):  # no defined `classes` attr
            pass

        self.assertSequenceEqual(class_to_names(app._classes_with_config_traits([Foo])), ["Foo"])
        self.assertSequenceEqual(
            class_to_names(app._classes_inc_parents([Bar])), ["Configurable", "Bar"]
        )

    def test_config(self):
        app = MyApp()
        app.parse_command_line(
            [
                "--i=10",
                "--Foo.j=10",
                "--enable=False",
                "--log-level=50",
            ]
        )
        config = app.config
        print(config)
        self.assertEqual(config.Foo.i, 10)
        self.assertEqual(config.Foo.j, 10)
        self.assertEqual(config.Bar.enabled, False)
        self.assertEqual(config.MyApp.log_level, 50)

    def test_config_seq_args(self):
        app = MyApp()
        app.parse_command_line(
            [
                "--li",
                "1",
                "--li",
                "3",
                "--la",
                "1",
                "--tb",
                "AB",
                "2",
                "--Foo.la=ab",
                "--Bar.aset",
                "S1",
                "--Bar.aset",
                "S2",
                "--Bar.aset",
                "S1",
            ]
        )
        assert app.extra_args == ["2"]
        config = app.config
        assert config.Foo.li == [1, 3]
        assert config.Foo.la == ["1", "ab"]
        assert config.Bar.tb == ("AB",)
        self.assertEqual(config.Bar.aset, {"S1", "S2"})
        app.init_foo()
        assert app.foo.li == [1, 3]
        assert app.foo.la == ["1", "ab"]
        app.init_bar()
        self.assertEqual(app.bar.aset, {"S1", "S2"})
        assert app.bar.tb == ("AB",)

    def test_config_dict_args(self):
        app = MyApp()
        app.parse_command_line(
            [
                "--Foo.fdict",
                "a=1",
                "--Foo.fdict",
                "b=b",
                "--Foo.fdict",
                "c=3",
                "--Bar.bdict",
                "k=1",
                "-D=a=b",
                "-D",
                "22=33",
                "--Bar.idict",
                "k=1",
                "--Bar.idict",
                "b=2",
                "--Bar.idict",
                "c=3",
            ]
        )
        fdict = {"a": "1", "b": "b", "c": "3"}
        bdict = {"k": "1", "a": "b", "22": "33"}
        idict = {"k": 1, "b": 2, "c": 3}
        config = app.config
        assert config.Bar.idict == idict
        self.assertDictEqual(config.Foo.fdict, fdict)
        self.assertDictEqual(config.Bar.bdict, bdict)
        app.init_foo()
        self.assertEqual(app.foo.fdict, fdict)
        app.init_bar()
        assert app.bar.idict == idict
        self.assertEqual(app.bar.bdict, bdict)

    def test_config_propagation(self):
        app = MyApp()
        app.parse_command_line(["--i=10", "--Foo.j=10", "--enable=False", "--log-level=50"])
        app.init_foo()
        app.init_bar()
        self.assertEqual(app.foo.i, 10)
        self.assertEqual(app.foo.j, 10)
        self.assertEqual(app.bar.enabled, False)

    def test_cli_priority(self):
        """Test that loading config files does not override CLI options"""
        name = "config.py"

        class TestApp(Application):
            value = Unicode().tag(config=True)
            config_file_loaded = Bool().tag(config=True)
            aliases = {"v": "TestApp.value"}

        app = TestApp()
        with TemporaryDirectory() as td:
            config_file = pjoin(td, name)
            with open(config_file, "w") as f:
                f.writelines(
                    ["c.TestApp.value = 'config file'\n", "c.TestApp.config_file_loaded = True\n"]
                )

            app.parse_command_line(["--v=cli"])
            assert "value" in app.config.TestApp
            assert app.config.TestApp.value == "cli"
            assert app.value == "cli"

            app.load_config_file(name, path=[td])
            assert app.config_file_loaded
            assert app.config.TestApp.value == "cli"
            assert app.value == "cli"

    def test_ipython_cli_priority(self):
        # this test is almost entirely redundant with above,
        # but we can keep it around in case of subtle issues creeping into
        # the exact sequence IPython follows.
        name = "config.py"

        class TestApp(Application):
            value = Unicode().tag(config=True)
            config_file_loaded = Bool().tag(config=True)
            aliases = {"v": ("TestApp.value", "some help")}

        app = TestApp()
        with TemporaryDirectory() as td:
            config_file = pjoin(td, name)
            with open(config_file, "w") as f:
                f.writelines(
                    ["c.TestApp.value = 'config file'\n", "c.TestApp.config_file_loaded = True\n"]
                )
            # follow IPython's config-loading sequence to ensure CLI priority is preserved
            app.parse_command_line(["--v=cli"])
            # this is where IPython makes a mistake:
            # it assumes app.config will not be modified,
            # and storing a reference is storing a copy
            cli_config = app.config
            assert "value" in app.config.TestApp
            assert app.config.TestApp.value == "cli"
            assert app.value == "cli"
            app.load_config_file(name, path=[td])
            assert app.config_file_loaded
            # enforce cl-opts override config file opts:
            # this is where IPython makes a mistake: it assumes
            # that cl_config is a different object, but it isn't.
            app.update_config(cli_config)
            assert app.config.TestApp.value == "cli"
            assert app.value == "cli"

    def test_cli_allow_none(self):
        class App(Application):
            aliases = {"opt": "App.opt"}
            opt = Unicode(allow_none=True, config=True)

        app = App()
        app.parse_command_line(["--opt=None"])
        assert app.opt is None

    def test_flags(self):
        app = MyApp()
        app.parse_command_line(["--disable"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, False)

        app = MyApp()
        app.parse_command_line(["-d"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, False)

        app = MyApp()
        app.parse_command_line(["--enable"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, True)

        app = MyApp()
        app.parse_command_line(["-e"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, True)

    def test_flags_help_msg(self):
        app = MyApp()
        stdout = io.StringIO()
        with contextlib.redirect_stdout(stdout):
            app.print_flag_help()
        hmsg = stdout.getvalue()
        self.assertRegex(hmsg, "(?<!-)-e, --enable\\b")
        self.assertRegex(hmsg, "(?<!-)-d, --disable\\b")
        self.assertIn("Equivalent to: [--Bar.enabled=True]", hmsg)
        self.assertIn("Equivalent to: [--Bar.enabled=False]", hmsg)

    def test_aliases(self):
        app = MyApp()
        app.parse_command_line(["--i=5", "--j=10"])
        app.init_foo()
        self.assertEqual(app.foo.i, 5)
        app.init_foo()
        self.assertEqual(app.foo.j, 10)

        app = MyApp()
        app.parse_command_line(["-i=5", "-j=10"])
        app.init_foo()
        self.assertEqual(app.foo.i, 5)
        app.init_foo()
        self.assertEqual(app.foo.j, 10)

        app = MyApp()
        app.parse_command_line(["--fooi=5", "--fooj=10"])
        app.init_foo()
        self.assertEqual(app.foo.i, 5)
        app.init_foo()
        self.assertEqual(app.foo.j, 10)

    def test_aliases_multiple(self):
        # Test multiple > 2 aliases for the same argument
        class TestMultiAliasApp(Application):
            foo = Integer(config=True)
            aliases = {("f", "bar", "qux"): "TestMultiAliasApp.foo"}

        app = TestMultiAliasApp()
        app.parse_command_line(["-f", "3"])
        self.assertEqual(app.foo, 3)

        app = TestMultiAliasApp()
        app.parse_command_line(["--bar", "4"])
        self.assertEqual(app.foo, 4)

        app = TestMultiAliasApp()
        app.parse_command_line(["--qux", "5"])
        self.assertEqual(app.foo, 5)

    def test_aliases_help_msg(self):
        app = MyApp()
        stdout = io.StringIO()
        with contextlib.redirect_stdout(stdout):
            app.print_alias_help()
        hmsg = stdout.getvalue()
        self.assertRegex(hmsg, "(?<!-)-i, --fooi\\b")
        self.assertRegex(hmsg, "(?<!-)-j, --fooj\\b")
        self.assertIn("Equivalent to: [--Foo.i]", hmsg)
        self.assertIn("Equivalent to: [--Foo.j]", hmsg)
        self.assertIn("Equivalent to: [--Foo.name]", hmsg)

    def test_alias_unrecognized(self):
        """Check ability to override handling for unrecognized aliases"""

        class StrictLoader(KVArgParseConfigLoader):
            def _handle_unrecognized_alias(self, arg):
                self.parser.error(f"Unrecognized alias: {arg}")

        class StrictApplication(Application):
            def _create_loader(self, argv, aliases, flags, classes):
                return StrictLoader(argv, aliases, flags, classes=classes, log=self.log)

        app = StrictApplication()
        app.initialize(["--log-level=20"])  # recognized alias
        assert app.log_level == 20

        app = StrictApplication()
        with pytest.raises(SystemExit, match="2"):
            app.initialize(["--unrecognized=20"])

        # Ideally we would use pytest capsys fixture, but fixtures are incompatible
        # with unittest.TestCase-style classes :(
        # stderr = capsys.readouterr().err
        # assert "Unrecognized alias: unrecognized" in stderr

    def test_flag_clobber(self):
        """test that setting flags doesn't clobber existing settings"""
        app = MyApp()
        app.parse_command_line(["--Bar.b=5", "--disable"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, False)
        self.assertEqual(app.bar.b, 5)
        app.parse_command_line(["--enable", "--Bar.b=10"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, True)
        self.assertEqual(app.bar.b, 10)

    def test_warn_autocorrect(self):
        stream = StringIO()
        app = MyApp(log_level=logging.INFO)
        app.log.handlers = [logging.StreamHandler(stream)]

        cfg = Config()
        cfg.MyApp.warn_typo = "WOOOO"
        app.config = cfg

        self.assertIn("warn_typo", stream.getvalue())
        self.assertIn("warn_tpyo", stream.getvalue())

    def test_flatten_flags(self):
        cfg = Config()
        cfg.MyApp.log_level = logging.WARN
        app = MyApp()
        app.update_config(cfg)
        self.assertEqual(app.log_level, logging.WARN)
        self.assertEqual(app.config.MyApp.log_level, logging.WARN)
        app.initialize(["--crit"])
        self.assertEqual(app.log_level, logging.CRITICAL)
        # this would be app.config.Application.log_level if it failed:
        self.assertEqual(app.config.MyApp.log_level, logging.CRITICAL)

    def test_flatten_aliases(self):
        cfg = Config()
        cfg.MyApp.log_level = logging.WARN
        app = MyApp()
        app.update_config(cfg)
        self.assertEqual(app.log_level, logging.WARN)
        self.assertEqual(app.config.MyApp.log_level, logging.WARN)
        app.initialize(["--log-level", "CRITICAL"])
        self.assertEqual(app.log_level, logging.CRITICAL)
        # this would be app.config.Application.log_level if it failed:
        self.assertEqual(app.config.MyApp.log_level, "CRITICAL")

    def test_flatten_aliases_tuple_keys(self):
        # tuple alias keys must be exploded into one entry per name, so
        # that the loader can detect collisions between flags and aliases
        app = MyApp()
        flags, aliases = app.flatten_flags()
        self.assertEqual(aliases["fooi"], "Foo.i")
        self.assertEqual(aliases["i"], "Foo.i")
        self.assertNotIn(("fooi", "i"), aliases)

    def test_flag_tuple_alias_collision(self):
        # a flag sharing a name with one member of a tuple alias used to
        # crash argparse with 'conflicting option strings'
        class CollisionApp(Application):
            classes = List([Bar])  # type:ignore[assignment]
            aliases = {("b", "bee"): "Bar.b"}
            flags = {"b": ({"Bar": {"enabled": False}}, "Disable Bar")}

        # with an argument it acts as the alias
        app = CollisionApp()
        app.parse_command_line(["-b", "5"])
        self.assertEqual(app.config.Bar.b, 5)

        # without an argument it acts as the flag
        app = CollisionApp()
        app.parse_command_line(["-b"])
        self.assertEqual(app.config.Bar.enabled, False)

    def test_extra_args(self):
        app = MyApp()
        app.parse_command_line(["--Bar.b=5", "extra", "args", "--disable"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, False)
        self.assertEqual(app.bar.b, 5)
        self.assertEqual(app.extra_args, ["extra", "args"])

        app = MyApp()
        app.parse_command_line(["--Bar.b=5", "--", "extra", "--disable", "args"])
        app.init_bar()
        self.assertEqual(app.bar.enabled, True)
        self.assertEqual(app.bar.b, 5)
        self.assertEqual(app.extra_args, ["extra", "--disable", "args"])

        app = MyApp()
        app.parse_command_line(["--disable", "--la", "-", "-", "--Bar.b=1", "--", "-", "extra"])
        self.assertEqual(app.extra_args, ["-", "-", "extra"])

    def test_unicode_argv(self):
        app = MyApp()
        app.parse_command_line(["ünîcødé"])

    def test_document_config_option(self):
        app = MyApp()
        app.document_config_options()

    def test_generate_config_file(self):
        app = MyApp()
        assert "The integer b." in app.generate_config_file()

    def test_generate_config_file_classes_to_include(self):
        class NotInConfig(HasTraits):
            from_hidden = Unicode(
                "x",
                help="""From hidden class

            Details about from_hidden.
            """,
            ).tag(config=True)

        class NoTraits(Foo, Bar, NotInConfig):
            pass

        app = MyApp()
        app.classes.append(NoTraits)  # type:ignore

        conf_txt = app.generate_config_file()
        print(conf_txt)
        self.assertIn("The integer b.", conf_txt)
        self.assertIn("# Foo(Configurable)", conf_txt)
        self.assertNotIn("# Configurable", conf_txt)
        self.assertIn("# NoTraits(Foo, Bar)", conf_txt)

        # inherited traits, parent in class list:
        self.assertIn("# c.NoTraits.i", conf_txt)
        self.assertIn("# c.NoTraits.j", conf_txt)
        self.assertIn("# c.NoTraits.n", conf_txt)
        self.assertIn("#  See also: Foo.j", conf_txt)
        self.assertIn("#  See also: Bar.b", conf_txt)
        self.assertEqual(conf_txt.count("Details about i."), 1)

        # inherited traits, parent not in class list:
        self.assertIn("# c.NoTraits.from_hidden", conf_txt)
        self.assertNotIn("#  See also: NotInConfig.", conf_txt)
        self.assertEqual(conf_txt.count("Details about from_hidden."), 1)
        self.assertNotIn("NotInConfig", conf_txt)

    def test_multi_file(self):
        app = MyApp()
        app.log = logging.getLogger()
        name = "config.py"
        with TemporaryDirectory("_1") as td1:
            with open(pjoin(td1, name), "w") as f1:
                f1.write("get_config().MyApp.Bar.b = 1")
            with TemporaryDirectory("_2") as td2:
                with open(pjoin(td2, name), "w") as f2:
                    f2.write("get_config().MyApp.Bar.b = 2")
                app.load_config_file(name, path=[td2, td1])
                app.init_bar()
                self.assertEqual(app.bar.b, 2)
                app.load_config_file(name, path=[td1, td2])
                app.init_bar()
                self.assertEqual(app.bar.b, 1)

    @pytest.mark.skipif(not hasattr(TestCase, "assertLogs"), reason="requires TestCase.assertLogs")
    def test_log_collisions(self):
        app = MyApp()
        app.log = logging.getLogger()
        app.log.setLevel(logging.INFO)
        name = "config"
        with TemporaryDirectory("_1") as td:
            with open(pjoin(td, name + ".py"), "w") as f:
                f.write("get_config().Bar.b = 1")
            with open(pjoin(td, name + ".json"), "w") as f:
                json.dump({"Bar": {"b": 2}}, f)
            with self.assertLogs(app.log, logging.WARNING) as captured:
                app.load_config_file(name, path=[td])
                app.init_bar()
        assert app.bar.b == 2
        output = "\n".join(captured.output)
        assert "Collision" in output
        assert "1 ignored, using 2" in output
        assert pjoin(td, name + ".py") in output
        assert pjoin(td, name + ".json") in output

    @pytest.mark.skipif(not hasattr(TestCase, "assertLogs"), reason="requires TestCase.assertLogs")
    def test_log_bad_config(self):
        app = MyApp()
        app.log = logging.getLogger()
        name = "config.py"
        with TemporaryDirectory() as td:
            with open(pjoin(td, name), "w") as f:
                f.write("syntax error()")
            with self.assertLogs(app.log, logging.ERROR) as captured:
                app.load_config_file(name, path=[td])
        output = "\n".join(captured.output)
        self.assertIn("SyntaxError", output)

    def test_raise_on_bad_config(self):
        app = MyApp()
        app.raise_config_file_errors = True
        app.log = logging.getLogger()
        name = "config.py"
        with TemporaryDirectory() as td:
            with open(pjoin(td, name), "w") as f:
                f.write("syntax error()")
            with self.assertRaises(SyntaxError):
                app.load_config_file(name, path=[td])

    def test_subcommands_instantiation(self):
        """Try all ways to specify how to create sub-apps."""
        app = Root.instance()
        app.parse_command_line(["sub1"])

        self.assertIsInstance(app.subapp, Sub1)
        # Check parent hierarchy.
        self.assertIs(app.subapp.parent, app)

        Root.clear_instance()
        Sub1.clear_instance()  # Otherwise, replaced spuriously and hierarchy check fails.
        app = Root.instance()

        app.parse_command_line(["sub1", "sub2"])
        self.assertIsInstance(app.subapp, Sub1)
        self.assertIsInstance(app.subapp.subapp, Sub2)
        # Check parent hierarchy.
        self.assertIs(app.subapp.parent, app)
        self.assertIs(app.subapp.subapp.parent, app.subapp)

        Root.clear_instance()
        Sub1.clear_instance()  # Otherwise, replaced spuriously and hierarchy check fails.
        app = Root.instance()

        app.parse_command_line(["sub1", "sub3"])
        self.assertIsInstance(app.subapp, Sub1)
        self.assertIsInstance(app.subapp.subapp, Sub3)
        self.assertTrue(app.subapp.subapp.flag)  # Set by factory.
        # Check parent hierarchy.
        self.assertIs(app.subapp.parent, app)
        self.assertIs(app.subapp.subapp.parent, app.subapp)  # Set by factory.

        Root.clear_instance()
        Sub1.clear_instance()

    def test_loaded_config_files(self):
        app = MyApp()
        app.log = logging.getLogger()
        name = "config.py"
        with TemporaryDirectory("_1") as td1:
            config_file = pjoin(td1, name)
            with open(config_file, "w") as f:
                f.writelines(["c.MyApp.running = True\n"])

            app.load_config_file(name, path=[td1])
            self.assertEqual(len(app.loaded_config_files), 1)
            self.assertEqual(app.loaded_config_files[0], config_file)

            app.start()
            self.assertEqual(app.running, True)

            # emulate an app that allows dynamic updates and update config file
            with open(config_file, "w") as f:
                f.writelines(["c.MyApp.running = False\n"])

            # reload and verify update, and that loaded_configs was not increased
            app.load_config_file(name, path=[td1])
            self.assertEqual(len(app.loaded_config_files), 1)
            self.assertEqual(app.running, False)

            # Attempt to update, ensure error...
            with self.assertRaises(AttributeError):
                app.loaded_config_files = "/foo"  # type:ignore

            # ensure it can't be updated via append
            app.loaded_config_files.append("/bar")
            self.assertEqual(len(app.loaded_config_files), 1)

            # repeat to ensure no unexpected changes occurred
            app.load_config_file(name, path=[td1])
            self.assertEqual(len(app.loaded_config_files), 1)
            self.assertEqual(app.running, False)


def test_cli_multi_scalar(caplog):
    class App(Application):
        aliases = {"opt": "App.opt"}
        opt = Unicode(config=True)

    app = App(log=logging.getLogger())
    with pytest.raises(SystemExit):
        app.parse_command_line(["--opt", "1", "--opt", "2"])
    record = caplog.get_records("call")[-1]
    message = record.message

    assert "Error loading argument" in message
    assert "App.opt=['1', '2']" in message
    assert "opt only accepts one value" in message
    assert record.levelno == logging.CRITICAL


class Root(Application):
    subcommands = {
        "sub1": ("tests.config.test_application.Sub1", "import string"),
    }


class Sub3(Application):
    flag = Bool(False)


class Sub2(Application):
    pass


class Sub1(Application):
    subcommands: dict = {  # type:ignore
        "sub2": (Sub2, "Application class"),
        "sub3": (lambda root: Sub3(parent=root, flag=True), "factory"),
    }


class DeprecatedApp(Application):
    override_called = False
    parent_called = False

    def _config_changed(self, name, old, new):
        self.override_called = True

        def _capture(*args):
            self.parent_called = True

        with mock.patch.object(self.log, "debug", _capture):
            super()._config_changed(name, old, new)


def test_deprecated_notifier():
    app = DeprecatedApp()
    assert not app.override_called
    assert not app.parent_called
    app.config = Config({"A": {"b": "c"}})
    assert app.override_called
    assert app.parent_called


def test_help_output():
    check_help_output(__name__)


def test_help_all_output():
    check_help_all_output(__name__)


def test_show_config_cli():
    out, err, ec = get_output_error_code([sys.executable, "-m", __name__, "--show-config"])
    assert ec == 0
    assert "show_config" not in out


def test_show_config_json_cli():
    out, err, ec = get_output_error_code([sys.executable, "-m", __name__, "--show-config-json"])
    assert ec == 0
    assert "show_config" not in out


def test_show_config(capsys):
    cfg = Config()
    cfg.MyApp.i = 5
    # don't show empty
    cfg.OtherApp

    app = MyApp(config=cfg, show_config=True)
    app.start()
    out, err = capsys.readouterr()
    assert "MyApp" in out
    assert "i = 5" in out
    assert "OtherApp" not in out


def test_show_config_json(capsys):
    cfg = Config()
    cfg.MyApp.i = 5
    cfg.OtherApp

    app = MyApp(config=cfg, show_config_json=True)
    app.start()
    out, err = capsys.readouterr()
    displayed = json.loads(out)
    assert Config(displayed) == cfg


def test_deep_alias():
    from traitlets.config import Application, Configurable

    class Foo(Configurable):
        val = Int(default_value=5).tag(config=True)

    class Bar(Configurable):
        def __init__(self, *args, **kwargs):
            super().__init__(*args, **kwargs)
            self.foo = Foo(parent=self)

    class TestApp(Application):
        name = "test"

        aliases = {"val": "Bar.Foo.val"}
        classes = [Foo, Bar]

        def initialize(self, *args, **kwargs):
            super().initialize(*args, **kwargs)
            self.bar = Bar(parent=self)

    app = TestApp()
    app.initialize(["--val=10"])
    assert app.bar.foo.val == 10
    assert len(list(app.emit_alias_help())) > 0


def test_logging_config(tmp_path, capsys):
    """We should be able to configure additional log handlers."""
    log_file = tmp_path / "log_file"
    app = Application(
        logging_config={
            "version": 1,
            "handlers": {
                "file": {
                    "class": "logging.FileHandler",
                    "level": "DEBUG",
                    "filename": str(log_file),
                },
            },
            "loggers": {
                "Application": {
                    "level": "DEBUG",
                    "handlers": ["console", "file"],
                },
            },
        }
    )
    # the default "console" handler + our new "file" handler
    assert len(app.log.handlers) == 2

    # log a couple of messages
    app.log.info("info")
    app.log.warning("warn")

    # test that log messages get written to the file
    with open(log_file) as log_handle:
        assert log_handle.read() == "info\nwarn\n"

    # test that log messages get written to stderr (default console handler)
    assert capsys.readouterr().err == "[Application] WARNING | warn\n"


def test_get_default_logging_config_pythonw(monkeypatch):
    """Ensure logging is correctly disabled for pythonw usage."""
    monkeypatch.setattr("traitlets.config.application.IS_PYTHONW", True)
    config = Application().get_default_logging_config()
    assert "handlers" not in config
    assert "loggers" not in config

    monkeypatch.setattr("traitlets.config.application.IS_PYTHONW", False)
    config = Application().get_default_logging_config()
    assert "handlers" in config
    assert "loggers" in config


@pytest.fixture()
def caplogconfig(monkeypatch):
    """Capture logging config events for DictConfigurator objects.

    This suppresses the event (so the configuration doesn't happen).

    Returns a list of (args, kwargs).
    """
    calls = []

    def _configure(*args, **kwargs):
        nonlocal calls
        calls.append((args, kwargs))

    monkeypatch.setattr(
        "logging.config.DictConfigurator.configure",
        _configure,
    )

    return calls


@pytest.mark.skipif(sys.implementation.name == "pypy", reason="Test does not work on pypy")
def test_logging_teardown_on_error(capsys, caplogconfig):
    """Ensure we don't try to open logs in order to close them (See #722).

    If you try to configure logging handlers whilst Python is shutting down
    you may get traceback.
    """
    # create and destroy an app (without configuring logging)
    # (ensure that the logs were not configured)
    app = Application()
    del app
    assert len(caplogconfig) == 0  # logging was not configured
    out, err = capsys.readouterr()
    assert "Traceback" not in err

    # ensure that the logs would have been configured otherwise
    # (to prevent this test from yielding false-negatives)
    app = Application()
    app._logging_configured = True  # make it look like logging was configured
    del app
    assert len(caplogconfig) == 1  # logging was configured


def test_get_logger_after_application():
    # get_logger must pick up the Application's logger even if it was
    # first called (returning the fallback) before the Application existed,
    # and fall back again once the Application is torn down
    import traitlets.log

    Application.clear_instance()
    try:
        fallback = traitlets.log.get_logger()
        assert fallback.name == "traitlets"
        app = Application.instance()
        assert traitlets.log.get_logger() is app.log
    finally:
        Application.clear_instance()
    assert traitlets.log.get_logger() is fallback


if __name__ == "__main__":
    # for test_help_output:
    MyApp.launch_instance()