"""Tests for 'site'.

Tests assume the initial paths in sys.path once the interpreter has begun
executing have not been removed.

"""
import unittest
import test.support
from test import support
from test.support.script_helper import assert_python_ok
from test.support import import_helper
from test.support import os_helper
from test.support import socket_helper
from test.support import captured_stderr
from test.support.os_helper import TESTFN, EnvironmentVarGuard
from test.support.script_helper import spawn_python, kill_python
import ast
import builtins
import contextlib
import glob
import io
import os
import re
import shutil
import stat
import subprocess
import sys
import sysconfig
import tempfile
from textwrap import dedent
from types import SimpleNamespace
import urllib.error
import urllib.request
from unittest import mock
from copy import copy

# These tests are not particularly useful if Python was invoked with -S.
# If you add tests that are useful under -S, this skip should be moved
# to the class level.
if sys.flags.no_site:
    raise unittest.SkipTest("Python was invoked with -S")

import site


HAS_USER_SITE = (site.USER_SITE is not None)
OLD_SYS_PATH = None


def setUpModule():
    global OLD_SYS_PATH
    OLD_SYS_PATH = sys.path[:]

    if site.ENABLE_USER_SITE and not os.path.isdir(site.USER_SITE):
        # need to add user site directory for tests
        try:
            os.makedirs(site.USER_SITE)
            # modify sys.path: will be restored by tearDownModule()
            site.addsitedir(site.USER_SITE)
        except PermissionError as exc:
            raise unittest.SkipTest('unable to create user site directory (%r): %s'
                                    % (site.USER_SITE, exc))


def tearDownModule():
    sys.path[:] = OLD_SYS_PATH


class HelperFunctionsTests(unittest.TestCase):
    """Tests for helper functions.
    """

    def setUp(self):
        """Save a copy of sys.path"""
        self.sys_path = sys.path[:]
        self.old_base = site.USER_BASE
        self.old_site = site.USER_SITE
        self.old_prefixes = site.PREFIXES
        self.original_vars = sysconfig._CONFIG_VARS
        self.old_vars = copy(sysconfig._CONFIG_VARS)

    def tearDown(self):
        """Restore sys.path"""
        sys.path[:] = self.sys_path
        site.USER_BASE = self.old_base
        site.USER_SITE = self.old_site
        site.PREFIXES = self.old_prefixes
        sysconfig._CONFIG_VARS = self.original_vars
        # _CONFIG_VARS is None before get_config_vars() is called
        if sysconfig._CONFIG_VARS is not None:
            sysconfig._CONFIG_VARS.clear()
            sysconfig._CONFIG_VARS.update(self.old_vars)

    def test_makepath(self):
        # Test makepath() have an absolute path for its first return value
        # and a case-normalized version of the absolute path for its
        # second value.
        path_parts = ("Beginning", "End")
        original_dir = os.path.join(*path_parts)
        abs_dir, norm_dir = site.makepath(*path_parts)
        self.assertEqual(os.path.abspath(original_dir), abs_dir)
        if original_dir == os.path.normcase(original_dir):
            self.assertEqual(abs_dir, norm_dir)
        else:
            self.assertEqual(os.path.normcase(abs_dir), norm_dir)

    def test_init_pathinfo(self):
        dir_set = site._init_pathinfo()
        for entry in [site.makepath(path)[1] for path in sys.path
                        if path and os.path.exists(path)]:
            self.assertIn(entry, dir_set,
                          "%s from sys.path not found in set returned "
                          "by _init_pathinfo(): %s" % (entry, dir_set))

    def pth_file_tests(self, pth_file):
        """Contain common code for testing results of reading a .pth file"""
        self.assertIn(pth_file.imported, sys.modules,
                      "%s not in sys.modules" % pth_file.imported)
        self.assertIn(site.makepath(pth_file.good_dir_path)[0], sys.path)
        self.assertFalse(os.path.exists(pth_file.bad_dir_path))

    def test_addpackage(self):
        # Make sure addpackage() imports if the line starts with 'import',
        # adds directories to sys.path for any line in the file that is not a
        # comment or import that is a valid directory name for where the .pth
        # file resides; invalid directories are not added
        pth_file = PthFile()
        # Ensure we have a clean slate.
        pth_file.cleanup(prep=True)
        with pth_file.create():
            site.addpackage(pth_file.base_dir, pth_file.filename, set())
            self.pth_file_tests(pth_file)

    def make_pth(self, contents, pth_dir='.', pth_name=TESTFN):
        # Create a .pth file and return its (abspath, basename).
        pth_dir = os.path.abspath(pth_dir)
        pth_basename = pth_name + '.pth'
        pth_fn = os.path.join(pth_dir, pth_basename)
        with open(pth_fn, 'w', encoding='utf-8') as pth_file:
            self.addCleanup(lambda: os.remove(pth_fn))
            pth_file.write(contents)
        return pth_dir, pth_basename

    def test_addpackage_import_bad_syntax(self):
        # Issue 10642
        pth_dir, pth_fn = self.make_pth("import bad-syntax\n")
        with captured_stderr() as err_out:
            site.addpackage(pth_dir, pth_fn, set())
        self.assertRegex(err_out.getvalue(), "line 1")
        self.assertRegex(err_out.getvalue(),
            re.escape(os.path.join(pth_dir, pth_fn)))
        self.assertRegex(err_out.getvalue(), 'Traceback')
        self.assertRegex(err_out.getvalue(), r'import bad-syntax')
        self.assertRegex(err_out.getvalue(), 'SyntaxError')

    def test_addpackage_import_bad_exec(self):
        # Issue 10642
        pth_dir, pth_fn = self.make_pth("randompath\nimport nosuchmodule\n")
        with captured_stderr() as err_out:
            site.addpackage(pth_dir, pth_fn, set())
        self.assertRegex(err_out.getvalue(),
            re.escape(os.path.join(pth_dir, pth_fn)))
        self.assertRegex(err_out.getvalue(), 'Traceback')
        self.assertRegex(err_out.getvalue(), 'ModuleNotFoundError')

    def test_addpackage_empty_lines(self):
        # Issue 33689
        pth_dir, pth_fn = self.make_pth("\n\n  \n\n")
        known_paths = site.addpackage(pth_dir, pth_fn, set())
        self.assertEqual(known_paths, set())

    def test_addpackage_import_bad_pth_file(self):
        # Issue 5258
        pth_dir, pth_fn = self.make_pth("abc\x00def\n")
        for path in sys.path:
            if isinstance(path, str):
                self.assertNotIn("abc\x00def", path)

    def test_addsitedir(self):
        # addsitedir() reads .pth files and, when called standalone
        # (known_paths=None), flushes paths and import lines immediately.
        pth_file = PthFile()
        # Ensure we have a clean slate.
        pth_file.cleanup(prep=True)
        with pth_file.create():
            site.addsitedir(pth_file.base_dir)
            self.pth_file_tests(pth_file)

    def test_addsitedir_explicit_flush(self):
        # addsitedir() reads .pth files and, with
        # defer_processing_start_files=True, accumulates pending state
        # without flushing.  A subsequent process_startup_files() call
        # then applies the paths and runs the import lines.
        pth_file = PthFile()
        # Ensure we have a clean slate.
        pth_file.cleanup(prep=True)
        with pth_file.create():
            # Pass defer_processing_start_files=True to prevent flushing.
            site.addsitedir(pth_file.base_dir, set(),
                            defer_processing_start_files=True)
            self.assertNotIn(pth_file.imported, sys.modules)
            site.process_startup_files()
            self.pth_file_tests(pth_file)

    def test_addsitedir_dotfile(self):
        pth_file = PthFile('.dotfile')
        # Ensure we have a clean slate.
        pth_file.cleanup(prep=True)
        with pth_file.create():
            site.addsitedir(pth_file.base_dir)
            self.assertNotIn(site.makepath(pth_file.good_dir_path)[0], sys.path)
            self.assertIn(pth_file.base_dir, sys.path)

    @unittest.skipUnless(hasattr(os, 'chflags'), 'test needs os.chflags()')
    def test_addsitedir_hidden_flags(self):
        pth_file = PthFile()
        # Ensure we have a clean slate.
        pth_file.cleanup(prep=True)
        with pth_file.create():
            st = os.stat(pth_file.file_path)
            os.chflags(pth_file.file_path, st.st_flags | stat.UF_HIDDEN)
            site.addsitedir(pth_file.base_dir)
            self.assertNotIn(site.makepath(pth_file.good_dir_path)[0], sys.path)
            self.assertIn(pth_file.base_dir, sys.path)

    @unittest.skipUnless(sys.platform == 'win32', 'test needs Windows')
    @support.requires_subprocess()
    def test_addsitedir_hidden_file_attribute(self):
        pth_file = PthFile()
        # Ensure we have a clean slate.
        pth_file.cleanup(prep=True)
        with pth_file.create():
            subprocess.check_call(['attrib', '+H', pth_file.file_path])
            site.addsitedir(pth_file.base_dir)
            self.assertNotIn(site.makepath(pth_file.good_dir_path)[0], sys.path)
            self.assertIn(pth_file.base_dir, sys.path)

    # This tests _getuserbase, hence the double underline
    # to distinguish from a test for getuserbase
    def test__getuserbase(self):
        self.assertEqual(site._getuserbase(), sysconfig._getuserbase())

    @unittest.skipUnless(HAS_USER_SITE, 'need user site')
    def test_get_path(self):
        if sys.platform == 'darwin' and sys._framework:
            scheme = 'osx_framework_user'
        else:
            scheme = os.name + '_user'
        self.assertEqual(os.path.normpath(site._get_path(site._getuserbase())),
                         sysconfig.get_path('purelib', scheme))

    @unittest.skipUnless(site.ENABLE_USER_SITE, "requires access to PEP 370 "
                          "user-site (site.ENABLE_USER_SITE)")
    @support.requires_subprocess()
    def test_s_option(self):
        # (ncoghlan) Change this to use script_helper...
        usersite = os.path.normpath(site.USER_SITE)
        self.assertIn(usersite, sys.path)

        env = os.environ.copy()
        rc = subprocess.call([sys.executable, '-c',
            'import sys; sys.exit(%r in sys.path)' % usersite],
            env=env)
        self.assertEqual(rc, 1)

        env = os.environ.copy()
        rc = subprocess.call([sys.executable, '-s', '-c',
            'import sys; sys.exit(%r in sys.path)' % usersite],
            env=env)
        if usersite == site.getsitepackages()[0]:
            self.assertEqual(rc, 1)
        else:
            self.assertEqual(rc, 0, "User site still added to path with -s")

        env = os.environ.copy()
        env["PYTHONNOUSERSITE"] = "1"
        rc = subprocess.call([sys.executable, '-c',
            'import sys; sys.exit(%r in sys.path)' % usersite],
            env=env)
        if usersite == site.getsitepackages()[0]:
            self.assertEqual(rc, 1)
        else:
            self.assertEqual(rc, 0,
                        "User site still added to path with PYTHONNOUSERSITE")

        env = os.environ.copy()
        env["PYTHONUSERBASE"] = "/tmp"
        rc = subprocess.call([sys.executable, '-c',
            'import sys, site; sys.exit(site.USER_BASE.startswith("/tmp"))'],
            env=env)
        self.assertEqual(rc, 1,
                        "User base not set by PYTHONUSERBASE")

    @unittest.skipUnless(HAS_USER_SITE, 'need user site')
    def test_getuserbase(self):
        site.USER_BASE = None
        user_base = site.getuserbase()

        # the call sets site.USER_BASE
        self.assertEqual(site.USER_BASE, user_base)

        # let's set PYTHONUSERBASE and see if it uses it
        site.USER_BASE = None
        import sysconfig
        sysconfig._CONFIG_VARS = None

        with EnvironmentVarGuard() as environ:
            environ['PYTHONUSERBASE'] = 'xoxo'
            self.assertStartsWith(site.getuserbase(), 'xoxo')

    @unittest.skipUnless(HAS_USER_SITE, 'need user site')
    def test_getusersitepackages(self):
        site.USER_SITE = None
        site.USER_BASE = None
        user_site = site.getusersitepackages()

        # the call sets USER_BASE *and* USER_SITE
        self.assertEqual(site.USER_SITE, user_site)
        self.assertStartsWith(user_site, site.USER_BASE)
        self.assertEqual(site.USER_BASE, site.getuserbase())

    def test_getsitepackages(self):
        site.PREFIXES = ['xoxo']
        dirs = site.getsitepackages()
        if os.sep == '/':
            # OS X, Linux, FreeBSD, etc
            if sys.platlibdir != "lib":
                self.assertEqual(len(dirs), 2)
                wanted = os.path.join('xoxo', sys.platlibdir,
                                      f'python{sysconfig._get_python_version_abi()}',
                                      'site-packages')
                self.assertEqual(dirs[0], wanted)
            else:
                self.assertEqual(len(dirs), 1)
            wanted = os.path.join('xoxo', 'lib',
                                  f'python{sysconfig._get_python_version_abi()}',
                                  'site-packages')
            self.assertEqual(dirs[-1], wanted)
        else:
            # other platforms
            self.assertEqual(len(dirs), 2)
            self.assertEqual(dirs[0], 'xoxo')
            wanted = os.path.join('xoxo', 'lib', 'site-packages')
            self.assertEqual(os.path.normcase(dirs[1]),
                             os.path.normcase(wanted))

    @unittest.skipUnless(HAS_USER_SITE, 'need user site')
    def test_no_home_directory(self):
        # bpo-10496: getuserbase() and getusersitepackages() must not fail if
        # the current user has no home directory (if expanduser() returns the
        # path unchanged).
        site.USER_SITE = None
        site.USER_BASE = None

        with EnvironmentVarGuard() as environ, \
             mock.patch('os.path.expanduser', lambda path: path):
            environ.unset('PYTHONUSERBASE', 'APPDATA')

            user_base = site.getuserbase()
            self.assertStartsWith(user_base, '~' + os.sep)

            user_site = site.getusersitepackages()
            self.assertStartsWith(user_site, user_base)

        with mock.patch('os.path.isdir', return_value=False) as mock_isdir, \
             mock.patch.object(site, 'addsitedir') as mock_addsitedir, \
             support.swap_attr(site, 'ENABLE_USER_SITE', True):

            # addusersitepackages() must not add user_site to sys.path
            # if it is not an existing directory
            known_paths = set()
            site.addusersitepackages(known_paths)

            mock_isdir.assert_called_once_with(user_site)
            mock_addsitedir.assert_not_called()
            self.assertFalse(known_paths)

    def test_gethistoryfile(self):
        filename = 'file'
        rc, out, err = assert_python_ok('-c',
            f'import site; assert site.gethistoryfile() == "{filename}"',
            PYTHON_HISTORY=filename)
        self.assertEqual(rc, 0)

        # Check that PYTHON_HISTORY is ignored in isolated mode.
        rc, out, err = assert_python_ok('-I', '-c',
            f'import site; assert site.gethistoryfile() != "{filename}"',
            PYTHON_HISTORY=filename)
        self.assertEqual(rc, 0)

    def test_trace(self):
        message = "bla-bla-bla"
        for verbose, out in (True, message + "\n"), (False, ""):
            with mock.patch('sys.flags', mock.Mock(verbose=verbose)), \
                    mock.patch('sys.stderr', io.StringIO()):
                site._trace(message)
                self.assertEqual(sys.stderr.getvalue(), out)


class PthFile:
    """Helper class for handling testing of .pth files"""

    def __init__(self, filename_base=TESTFN, imported="time",
                    good_dirname="__testdir__", bad_dirname="__bad"):
        """Initialize instance variables"""
        self.filename = filename_base + ".pth"
        self.base_dir = os.path.abspath('')
        self.file_path = os.path.join(self.base_dir, self.filename)
        self.imported = imported
        self.good_dirname = good_dirname
        self.bad_dirname = bad_dirname
        self.good_dir_path = os.path.join(self.base_dir, self.good_dirname)
        self.bad_dir_path = os.path.join(self.base_dir, self.bad_dirname)

    @contextlib.contextmanager
    def create(self):
        """Create a .pth file with a comment, blank lines, an ``import
        <self.imported>``, a line with self.good_dirname, and a line with
        self.bad_dirname.

        Creation of the directory for self.good_dir_path (based off of
        self.good_dirname) is also performed.

        Used as a context manager: self.cleanup() is called on exit.
        """
        FILE = open(self.file_path, 'w')
        try:
            print("#import @bad module name", file=FILE)
            print("\n", file=FILE)
            print("import %s" % self.imported, file=FILE)
            print(self.good_dirname, file=FILE)
            print(self.bad_dirname, file=FILE)
        finally:
            FILE.close()
        os.mkdir(self.good_dir_path)
        try:
            yield self
        finally:
            self.cleanup()

    def cleanup(self, prep=False):
        """Make sure that the .pth file is deleted, self.imported is not in
        sys.modules, and that both self.good_dirname and self.bad_dirname are
        not existing directories."""
        if os.path.exists(self.file_path):
            os.remove(self.file_path)
        if prep:
            self.imported_module = sys.modules.get(self.imported)
            if self.imported_module:
                del sys.modules[self.imported]
        else:
            if self.imported_module:
                sys.modules[self.imported] = self.imported_module
        if os.path.exists(self.good_dir_path):
            os.rmdir(self.good_dir_path)
        if os.path.exists(self.bad_dir_path):
            os.rmdir(self.bad_dir_path)

class ImportSideEffectTests(unittest.TestCase):
    """Test side-effects from importing 'site'."""

    def setUp(self):
        """Make a copy of sys.path"""
        self.sys_path = sys.path[:]

    def tearDown(self):
        """Restore sys.path"""
        sys.path[:] = self.sys_path

    def test_no_duplicate_paths(self):
        # No duplicate paths should exist in sys.path
        # Handled by removeduppaths()
        site.removeduppaths()
        seen_paths = set()
        for path in sys.path:
            self.assertNotIn(path, seen_paths)
            seen_paths.add(path)

    @unittest.skip('test not implemented')
    def test_add_build_dir(self):
        # Test that the build directory's Modules directory is used when it
        # should be.
        # XXX: implement
        pass

    def test_setting_quit(self):
        # 'quit' and 'exit' should be injected into builtins
        self.assertHasAttr(builtins, "quit")
        self.assertHasAttr(builtins, "exit")

    def test_setting_copyright(self):
        # 'copyright', 'credits', and 'license' should be in builtins
        self.assertHasAttr(builtins, "copyright")
        self.assertHasAttr(builtins, "credits")
        self.assertHasAttr(builtins, "license")

    def test_setting_help(self):
        # 'help' should be set in builtins
        self.assertHasAttr(builtins, "help")

    def test_sitecustomize_executed(self):
        # If sitecustomize is available, it should have been imported.
        if "sitecustomize" not in sys.modules:
            try:
                import sitecustomize  # noqa: F401
            except ImportError:
                pass
            else:
                self.fail("sitecustomize not imported automatically")

    @support.requires_subprocess()
    def test_customization_modules_on_startup(self):
        mod_names = [
            'sitecustomize'
        ]

        if site.ENABLE_USER_SITE:
            mod_names.append('usercustomize')

        temp_dir = tempfile.mkdtemp()
        self.addCleanup(os_helper.rmtree, temp_dir)

        with EnvironmentVarGuard() as environ:
            environ['PYTHONPATH'] = temp_dir

            for module_name in mod_names:
                os_helper.rmtree(temp_dir)
                os.mkdir(temp_dir)

                customize_path = os.path.join(temp_dir, f'{module_name}.py')
                eyecatcher = f'EXECUTED_{module_name}'

                with open(customize_path, 'w') as f:
                    f.write(f'print("{eyecatcher}")')

                output = subprocess.check_output([sys.executable, '-c', '""'])
                self.assertIn(eyecatcher, output.decode('utf-8'))

                # -S blocks any site-packages
                output = subprocess.check_output([sys.executable, '-S', '-c', '""'])
                self.assertNotIn(eyecatcher, output.decode('utf-8'))

                # -s blocks user site-packages
                if 'usercustomize' == module_name:
                    output = subprocess.check_output([sys.executable, '-s', '-c', '""'])
                    self.assertNotIn(eyecatcher, output.decode('utf-8'))


    @unittest.skipUnless(hasattr(urllib.request, "HTTPSHandler"),
                         'need SSL support to download license')
    @test.support.requires_resource('network')
    @test.support.system_must_validate_cert
    def test_license_exists_at_url(self):
        # This test is a bit fragile since it depends on the format of the
        # string displayed by license in the absence of a LICENSE file.
        url = license._Printer__data.split()[1]
        req = urllib.request.Request(url, method='HEAD')
        # Reset global urllib.request._opener
        self.addCleanup(urllib.request.urlcleanup)
        try:
            with socket_helper.transient_internet(url):
                with urllib.request.urlopen(req) as data:
                    code = data.getcode()
        except urllib.error.HTTPError as e:
            code = e.code
        self.assertEqual(code, 200, msg="Can't find " + url)

    @support.cpython_only
    def test_lazy_imports(self):
        import_helper.ensure_lazy_imports("site", [
            "io",
            "locale",
            "traceback",
            "atexit",
            "warnings",
            "textwrap",
        ])


class StartupImportTests(unittest.TestCase):

    @support.requires_subprocess()
    def test_startup_imports(self):
        # Get sys.path in isolated mode (python3 -I)
        popen = subprocess.Popen([sys.executable, '-X', 'utf8', '-I',
                                  '-c', 'import sys; print(repr(sys.path))'],
                                 stdout=subprocess.PIPE,
                                 encoding='utf-8',
                                 errors='surrogateescape')
        stdout = popen.communicate()[0]
        self.assertEqual(popen.returncode, 0, repr(stdout))
        isolated_paths = ast.literal_eval(stdout)

        # bpo-27807: Even with -I, the site module executes all .pth files
        # found in sys.path (see site.addpackage()). Skip the test if at least
        # one .pth file is found.
        for path in isolated_paths:
            pth_files = glob.glob(os.path.join(glob.escape(path), "*.pth"))
            if pth_files:
                self.skipTest(f"found {len(pth_files)} .pth files in: {path}")

        # This tests checks which modules are loaded by Python when it
        # initially starts upon startup.
        popen = subprocess.Popen([sys.executable, '-X', 'utf8', '-I', '-v',
                                  '-c', 'import sys; print(set(sys.modules))'],
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.PIPE,
                                 encoding='utf-8',
                                 errors='surrogateescape')
        stdout, stderr = popen.communicate()
        self.assertEqual(popen.returncode, 0, (stdout, stderr))
        modules = ast.literal_eval(stdout)

        self.assertIn('site', modules)

        # http://bugs.python.org/issue19205
        re_mods = {'re', '_sre', 're._compiler', 're._constants', 're._parser'}
        self.assertFalse(modules.intersection(re_mods), stderr)

        # http://bugs.python.org/issue9548
        self.assertNotIn('locale', modules, stderr)

        # http://bugs.python.org/issue19209
        self.assertNotIn('copyreg', modules, stderr)

        # http://bugs.python.org/issue19218
        collection_mods = {'_collections', 'collections', 'functools',
                           'heapq', 'itertools', 'keyword', 'operator',
                           'reprlib', 'types', 'weakref'
                          }.difference(sys.builtin_module_names)
        self.assertFalse(modules.intersection(collection_mods), stderr)

    @support.requires_subprocess()
    def test_startup_interactivehook(self):
        r = subprocess.Popen([sys.executable, '-c',
            'import sys; sys.exit(hasattr(sys, "__interactivehook__"))']).wait()
        self.assertTrue(r, "'__interactivehook__' not added by site")

    @support.requires_subprocess()
    def test_startup_interactivehook_isolated(self):
        # issue28192 readline is not automatically enabled in isolated mode
        r = subprocess.Popen([sys.executable, '-I', '-c',
            'import sys; sys.exit(hasattr(sys, "__interactivehook__"))']).wait()
        self.assertFalse(r, "'__interactivehook__' added in isolated mode")

    @support.requires_subprocess()
    def test_startup_interactivehook_isolated_explicit(self):
        # issue28192 readline can be explicitly enabled in isolated mode
        r = subprocess.Popen([sys.executable, '-I', '-c',
            'import site, sys; site.enablerlcompleter(); sys.exit(hasattr(sys, "__interactivehook__"))']).wait()
        self.assertTrue(r, "'__interactivehook__' not added by enablerlcompleter()")

class _pthFileTests(unittest.TestCase):

    if sys.platform == 'win32':
        def _create_underpth_exe(self, lines, exe_pth=True):
            import _winapi
            temp_dir = tempfile.mkdtemp()
            self.addCleanup(os_helper.rmtree, temp_dir)
            exe_file = os.path.join(temp_dir, os.path.split(sys.executable)[1])
            dll_src_file = _winapi.GetModuleFileName(sys.dllhandle)
            dll_file = os.path.join(temp_dir, os.path.split(dll_src_file)[1])
            shutil.copy(sys.executable, exe_file)
            shutil.copy(dll_src_file, dll_file)
            for fn in glob.glob(os.path.join(os.path.split(dll_src_file)[0], "vcruntime*.dll")):
                shutil.copy(fn, os.path.join(temp_dir, os.path.split(fn)[1]))
            if exe_pth:
                _pth_file = os.path.splitext(exe_file)[0] + '._pth'
            else:
                _pth_file = os.path.splitext(dll_file)[0] + '._pth'
            with open(_pth_file, 'w', encoding='utf8') as f:
                for line in lines:
                    print(line, file=f)
            return exe_file
    else:
        def _create_underpth_exe(self, lines, exe_pth=True):
            if not exe_pth:
                raise unittest.SkipTest("library ._pth file not supported on this platform")
            temp_dir = tempfile.mkdtemp()
            self.addCleanup(os_helper.rmtree, temp_dir)
            exe_file = os.path.join(temp_dir, os.path.split(sys.executable)[1])
            os.symlink(sys.executable, exe_file)
            _pth_file = exe_file + '._pth'
            with open(_pth_file, 'w') as f:
                for line in lines:
                    print(line, file=f)
            return exe_file

    def _calc_sys_path_for_underpth_nosite(self, sys_prefix, lines):
        sys_path = []
        for line in lines:
            if not line or line[0] == '#':
                continue
            abs_path = os.path.abspath(os.path.join(sys_prefix, line))
            sys_path.append(abs_path)
        return sys_path

    def _get_pth_lines(self, libpath: str, *, import_site: bool):
        pth_lines = ['fake-path-name']
        # include 200 lines of `libpath` in _pth lines (or fewer
        # if the `libpath` is long enough to get close to 32KB
        # see https://github.com/python/cpython/issues/113628)
        encoded_libpath_length = len(libpath.encode("utf-8"))
        repetitions = min(200, 30000 // encoded_libpath_length)
        if repetitions <= 2:
            self.skipTest(
                f"Python stdlib path is too long ({encoded_libpath_length:,} bytes)")
        pth_lines.extend(libpath for _ in range(repetitions))
        pth_lines.extend(['', '# comment'])
        if import_site:
            pth_lines.append('import site')
        return pth_lines

    @support.requires_subprocess()
    def test_underpth_basic(self):
        pth_lines = ['#.', '# ..', *sys.path, '.', '..']
        exe_file = self._create_underpth_exe(pth_lines)
        sys_path = self._calc_sys_path_for_underpth_nosite(
            os.path.dirname(exe_file),
            pth_lines)

        output = subprocess.check_output([exe_file, '-X', 'utf8', '-c',
            'import sys; print("\\n".join(sys.path) if sys.flags.no_site else "")'
        ], encoding='utf-8', errors='surrogateescape')
        actual_sys_path = output.rstrip().split('\n')
        self.assertTrue(actual_sys_path, "sys.flags.no_site was False")
        self.assertEqual(
            actual_sys_path,
            sys_path,
            "sys.path is incorrect"
        )

    @support.requires_subprocess()
    def test_underpth_nosite_file(self):
        libpath = test.support.STDLIB_DIR
        exe_prefix = os.path.dirname(sys.executable)
        pth_lines = self._get_pth_lines(libpath, import_site=False)
        exe_file = self._create_underpth_exe(pth_lines)
        sys_path = self._calc_sys_path_for_underpth_nosite(
            os.path.dirname(exe_file),
            pth_lines)

        env = os.environ.copy()
        env['PYTHONPATH'] = 'from-env'
        env['PATH'] = '{}{}{}'.format(exe_prefix, os.pathsep, os.getenv('PATH'))
        output = subprocess.check_output([exe_file, '-c',
            'import sys; print("\\n".join(sys.path) if sys.flags.no_site else "")'
        ], env=env, encoding='utf-8', errors='surrogateescape')
        actual_sys_path = output.rstrip().split('\n')
        self.assertTrue(actual_sys_path, "sys.flags.no_site was False")
        self.assertEqual(
            actual_sys_path,
            sys_path,
            "sys.path is incorrect"
        )

    @support.requires_subprocess()
    def test_underpth_file(self):
        libpath = test.support.STDLIB_DIR
        exe_prefix = os.path.dirname(sys.executable)
        exe_file = self._create_underpth_exe(
            self._get_pth_lines(libpath, import_site=True))
        sys_prefix = os.path.dirname(exe_file)
        env = os.environ.copy()
        env['PYTHONPATH'] = 'from-env'
        env['PATH'] = '{};{}'.format(exe_prefix, os.getenv('PATH'))
        rc = subprocess.call([exe_file, '-c',
            'import sys; sys.exit(not sys.flags.no_site and '
            '%r in sys.path and %r in sys.path and %r not in sys.path and '
            'all("\\r" not in p and "\\n" not in p for p in sys.path))' % (
                os.path.join(sys_prefix, 'fake-path-name'),
                libpath,
                os.path.join(sys_prefix, 'from-env'),
            )], env=env)
        self.assertTrue(rc, "sys.path is incorrect")

    @support.requires_subprocess()
    def test_underpth_dll_file(self):
        libpath = test.support.STDLIB_DIR
        exe_prefix = os.path.dirname(sys.executable)
        exe_file = self._create_underpth_exe(
            self._get_pth_lines(libpath, import_site=True), exe_pth=False)
        sys_prefix = os.path.dirname(exe_file)
        env = os.environ.copy()
        env['PYTHONPATH'] = 'from-env'
        env['PATH'] = '{};{}'.format(exe_prefix, os.getenv('PATH'))
        rc = subprocess.call([exe_file, '-c',
            'import sys; sys.exit(not sys.flags.no_site and '
            '%r in sys.path and %r in sys.path and %r not in sys.path and '
            'all("\\r" not in p and "\\n" not in p for p in sys.path))' % (
                os.path.join(sys_prefix, 'fake-path-name'),
                libpath,
                os.path.join(sys_prefix, 'from-env'),
            )], env=env)
        self.assertTrue(rc, "sys.path is incorrect")

    @support.requires_subprocess()
    def test_underpth_no_user_site(self):
        pth_lines = [test.support.STDLIB_DIR, 'import site']
        exe_file = self._create_underpth_exe(pth_lines)
        p = subprocess.run([exe_file, '-X', 'utf8', '-c',
                            'import sys; '
                            'sys.exit(not sys.flags.no_user_site)'])
        self.assertEqual(p.returncode, 0, "sys.flags.no_user_site was 0")


class CommandLineTests(unittest.TestCase):
    def exists(self, path):
        if path is not None and os.path.isdir(path):
            return "exists"
        else:
            return "doesn't exist"

    def get_excepted_output(self, *args):
        if len(args) == 0:
            user_base = site.getuserbase()
            user_site = site.getusersitepackages()
            output = io.StringIO()
            output.write("sys.path = [\n")
            for dir in sys.path:
                output.write("    %r,\n" % (dir,))
            output.write("]\n")
            output.write(f"USER_BASE: {user_base} ({self.exists(user_base)})\n")
            output.write(f"USER_SITE: {user_site} ({self.exists(user_site)})\n")
            output.write(f"ENABLE_USER_SITE: {site.ENABLE_USER_SITE}\n")
            return 0, dedent(output.getvalue()).strip()

        buffer = []
        if '--user-base' in args:
            buffer.append(site.getuserbase())
        if '--user-site' in args:
            buffer.append(site.getusersitepackages())

        if buffer:
            return_code = 3
            if site.ENABLE_USER_SITE:
                return_code = 0
            elif site.ENABLE_USER_SITE is False:
                return_code = 1
            elif site.ENABLE_USER_SITE is None:
                return_code = 2
            output = os.pathsep.join(buffer)
            return return_code, os.path.normpath(dedent(output).strip())
        else:
            return 10, None

    def invoke_command_line(self, *args):
        cmd_args = []
        if sys.flags.no_user_site:
            cmd_args.append("-s")
        cmd_args.extend(["-m", "site", *args])

        with EnvironmentVarGuard() as env:
            env["PYTHONUTF8"] = "1"
            env["PYTHONIOENCODING"] = "utf-8"
            proc = spawn_python(*cmd_args, text=True, env=env,
                                encoding='utf-8', errors='replace')

        output = kill_python(proc)
        return_code = proc.returncode
        return return_code, os.path.normpath(dedent(output).strip())

    @support.requires_subprocess()
    def test_no_args(self):
        return_code, output = self.invoke_command_line()
        excepted_return_code, _ = self.get_excepted_output()
        self.assertEqual(return_code, excepted_return_code)
        lines = output.splitlines()
        self.assertEqual(lines[0], "sys.path = [")
        self.assertEqual(lines[-4], "]")
        excepted_base = f"USER_BASE: '{site.getuserbase()}'" +\
            f" ({self.exists(site.getuserbase())})"
        self.assertEqual(lines[-3], excepted_base)
        excepted_site = f"USER_SITE: '{site.getusersitepackages()}'" +\
            f" ({self.exists(site.getusersitepackages())})"
        self.assertEqual(lines[-2], excepted_site)
        self.assertEqual(lines[-1], f"ENABLE_USER_SITE: {site.ENABLE_USER_SITE}")

    @support.requires_subprocess()
    def test_unknown_args(self):
        return_code, output = self.invoke_command_line("--unknown-arg")
        excepted_return_code, _ = self.get_excepted_output("--unknown-arg")
        self.assertEqual(return_code, excepted_return_code)
        self.assertIn('[--user-base] [--user-site]', output)

    @support.requires_subprocess()
    def test_base_arg(self):
        return_code, output = self.invoke_command_line("--user-base")
        excepted = self.get_excepted_output("--user-base")
        excepted_return_code, excepted_output = excepted
        self.assertEqual(return_code, excepted_return_code)
        self.assertEqual(output, excepted_output)

    @support.requires_subprocess()
    def test_site_arg(self):
        return_code, output = self.invoke_command_line("--user-site")
        excepted = self.get_excepted_output("--user-site")
        excepted_return_code, excepted_output = excepted
        self.assertEqual(return_code, excepted_return_code)
        self.assertEqual(output, excepted_output)

    @support.requires_subprocess()
    def test_both_args(self):
        return_code, output = self.invoke_command_line("--user-base",
                                                       "--user-site")
        excepted = self.get_excepted_output("--user-base", "--user-site")
        excepted_return_code, excepted_output = excepted
        self.assertEqual(return_code, excepted_return_code)
        self.assertEqual(output, excepted_output)


class StartFileTests(unittest.TestCase):
    """Tests for .start file processing (PEP 829)."""

    def setUp(self):
        self.enterContext(import_helper.DirsOnSysPath())
        self.tmpdir = self.sitedir = self.enterContext(os_helper.temp_dir())
        # Save and clear all pending dicts.
        self.saved_entrypoints = site._pending_entrypoints.copy()
        self.saved_syspaths = site._pending_syspaths.copy()
        self.saved_importexecs = site._pending_importexecs.copy()
        site._pending_entrypoints.clear()
        site._pending_syspaths.clear()
        site._pending_importexecs.clear()

    def tearDown(self):
        site._pending_entrypoints = self.saved_entrypoints.copy()
        site._pending_syspaths = self.saved_syspaths.copy()
        site._pending_importexecs = self.saved_importexecs.copy()

    def _make_start(self, content, name='testpkg'):
        """Write a <name>.start file and return its basename."""
        basename = f"{name}.start"
        filepath = os.path.join(self.tmpdir, basename)
        with open(filepath, 'w', encoding='utf-8') as f:
            f.write(content)
        return basename

    def _make_pth(self, content, name='testpkg'):
        """Write a <name>.pth file and return its basename."""
        basename = f"{name}.pth"
        filepath = os.path.join(self.tmpdir, basename)
        with open(filepath, 'w', encoding='utf-8') as f:
            f.write(content)
        return basename

    def _all_entrypoints(self):
        """Flatten _pending_entrypoints dict into a list of (filename, entry) tuples."""
        result = []
        for filename, entries in site._pending_entrypoints.items():
            for entry in entries:
                result.append((filename, entry))
        return result

    def _just_entrypoints(self):
        return [entry for filename, entry in self._all_entrypoints()]

    # --- _read_start_file tests ---

    def test_read_start_file_basic(self):
        self._make_start("os.path:join\n", name='foo')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints[fullname], ['os.path:join'])

    def test_read_start_file_multiple_entries(self):
        self._make_start("os.path:join\nos.path:exists\n", name='foo')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints[fullname],
                         ['os.path:join', 'os.path:exists'])

    def test_read_start_file_comments_and_blanks(self):
        self._make_start("# a comment\n\nos.path:join\n  \n", name='foo')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints[fullname], ['os.path:join'])

    def test_read_start_file_accepts_all_non_blank_lines(self):
        # Syntax validation is deferred to entry-point execution time
        # (where pkgutil.resolve_name(strict=True) enforces the strict
        # pkg.mod:callable form), so parsing accepts every non-blank,
        # non-comment line, including syntactically invalid ones.
        content = (
            "os.path\n"                 # no colon
            "pkg.mod:\n"                # empty callable
            ":callable\n"               # empty module
            "pkg.mod:callable:extra\n"  # multiple colons
            "os.path:join\n"            # valid
        )
        self._make_start(content, name='foo')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints[fullname], [
            'os.path',
            'pkg.mod:',
            ':callable',
            'pkg.mod:callable:extra',
            'os.path:join',
        ])

    def test_read_start_file_empty(self):
        # PEP 829: an empty .start file is still registered as present
        # (with an empty entry-point list) so that it suppresses `import`
        # lines in any matching .pth file.
        self._make_start("", name='foo')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints, {fullname: []})

    def test_read_start_file_comments_only(self):
        # As with an empty file, a comments-only .start file is registered
        # as present so it can suppress matching .pth `import` lines.
        self._make_start("# just a comment\n# another\n", name='foo')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints, {fullname: []})

    def test_read_start_file_nonexistent(self):
        with captured_stderr():
            site._read_start_file(self.tmpdir, 'nonexistent.start')
        self.assertEqual(site._pending_entrypoints, {})

    @unittest.skipUnless(hasattr(os, 'chflags'), 'test needs os.chflags()')
    def test_read_start_file_hidden_flags(self):
        self._make_start("os.path:join\n", name='foo')
        filepath = os.path.join(self.tmpdir, 'foo.start')
        st = os.stat(filepath)
        os.chflags(filepath, st.st_flags | stat.UF_HIDDEN)
        site._read_start_file(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints, {})

    def test_read_start_file_duplicates_not_deduplicated(self):
        # PEP 829: duplicate entry points are NOT deduplicated.
        self._make_start("os.path:join\nos.path:join\n", name='foo')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints[fullname],
                         ['os.path:join', 'os.path:join'])

    def test_read_start_file_accepts_utf8_bom(self):
        # PEP 829: .start files MUST be utf-8-sig (UTF-8 with optional BOM).
        filepath = os.path.join(self.tmpdir, 'foo.start')
        with open(filepath, 'wb') as f:
            f.write(b'\xef\xbb\xbf' + b'os.path:join\n')
        site._read_start_file(self.sitedir, 'foo.start')
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertEqual(
            site._pending_entrypoints[fullname], ['os.path:join'])

    def test_read_start_file_invalid_utf8_silently_skipped(self):
        # PEP 829: .start files MUST be utf-8-sig.  Unlike .pth, there is
        # no locale-encoding fallback -- a .start file that is not valid
        # UTF-8 is silently skipped, with no key registered in
        # _pending_entrypoints and no output to stderr (parsing errors
        # are reported only under -v).
        filepath = os.path.join(self.tmpdir, 'foo.start')
        with open(filepath, 'wb') as f:
            # Bare continuation byte -- invalid as a UTF-8 start byte.
            f.write(b'\x80\x80\x80\n')
        with captured_stderr() as err:
            site._read_start_file(self.sitedir, 'foo.start')
        self.assertEqual(site._pending_entrypoints, {})
        self.assertEqual(err.getvalue(), "")

    def test_two_start_files_with_duplicates_not_deduplicated(self):
        self._make_start("os.path:join", name="foo")
        self._make_start("os.path:join", name="bar")
        site._read_start_file(self.sitedir, 'foo.start')
        site._read_start_file(self.sitedir, 'bar.start')
        self.assertEqual(self._just_entrypoints(),
                         ['os.path:join', 'os.path:join'])

    # --- _read_pth_file tests ---

    def test_read_pth_file_paths(self):
        subdir = os.path.join(self.sitedir, 'mylib')
        os.mkdir(subdir)
        self._make_pth("mylib\n", name='foo')
        site._read_pth_file(self.sitedir, 'foo.pth', set())
        fullname = os.path.join(self.sitedir, 'foo.pth')
        self.assertIn(subdir, site._pending_syspaths[fullname])

    def test_read_pth_file_imports_collected(self):
        self._make_pth("import sys\n", name='foo')
        site._read_pth_file(self.sitedir, 'foo.pth', set())
        fullname = os.path.join(self.sitedir, 'foo.pth')
        self.assertEqual(site._pending_importexecs[fullname], ['import sys'])

    def test_read_pth_file_comments_and_blanks(self):
        self._make_pth("# comment\n\n  \n", name='foo')
        site._read_pth_file(self.sitedir, 'foo.pth', set())
        self.assertEqual(site._pending_syspaths, {})
        self.assertEqual(site._pending_importexecs, {})

    def test_read_pth_file_deduplication(self):
        subdir = os.path.join(self.sitedir, 'mylib')
        os.mkdir(subdir)
        known_paths = set()
        self._make_pth("mylib\n", name='a')
        self._make_pth("mylib\n", name='b')
        site._read_pth_file(self.sitedir, 'a.pth', known_paths)
        site._read_pth_file(self.sitedir, 'b.pth', known_paths)
        # Only one entry across both files.
        all_dirs = []
        for dirs in site._pending_syspaths.values():
            all_dirs.extend(dirs)
        self.assertEqual(all_dirs, [subdir])

    def test_read_pth_file_bad_line_continues(self):
        # PEP 829: errors on individual lines don't abort the file.
        subdir = os.path.join(self.sitedir, 'goodpath')
        os.mkdir(subdir)
        self._make_pth("abc\x00def\ngoodpath\n", name='foo')
        with captured_stderr():
            site._read_pth_file(self.sitedir, 'foo.pth', set())
        fullname = os.path.join(self.sitedir, 'foo.pth')
        self.assertIn(subdir, site._pending_syspaths.get(fullname, []))

    def _flags_with_verbose(self, verbose):
        # Build a sys.flags clone with verbose overridden but every
        # other field preserved, so unrelated reads like
        # sys.flags.optimize during io.open_code() continue to work.
        attrs = {name: getattr(sys.flags, name)
                 for name in sys.flags.__match_args__}
        attrs['verbose'] = verbose
        return SimpleNamespace(**attrs)

    def test_read_pth_file_parse_error_silent_by_default(self):
        # PEP 829: parse-time errors are silent unless -v is given.
        # Force the error path by making makepath() raise.
        self._make_pth("badline\n", name='foo')
        with mock.patch('site.makepath', side_effect=ValueError("boom")), \
                mock.patch('sys.flags', self._flags_with_verbose(False)), \
                captured_stderr() as err:
            site._read_pth_file(self.sitedir, 'foo.pth', set())
        self.assertEqual(err.getvalue(), "")

    def test_read_pth_file_parse_error_reported_under_verbose(self):
        # PEP 829: parse-time errors are reported when -v is given.
        self._make_pth("badline\n", name='foo')
        with mock.patch('site.makepath', side_effect=ValueError("boom")), \
                mock.patch('sys.flags', self._flags_with_verbose(True)), \
                captured_stderr() as err:
            site._read_pth_file(self.sitedir, 'foo.pth', set())
        out = err.getvalue()
        self.assertIn('Error in', out)
        self.assertIn('foo.pth', out)

    def test_read_pth_file_locale_fallback(self):
        # PEP 829: .pth files that fail UTF-8 decoding fall back to the
        # locale encoding for backward compatibility (deprecated in
        # 3.15, to be removed in 3.20).  Mock locale.getencoding() so
        # the test does not depend on the host's actual locale.
        subdir = os.path.join(self.sitedir, 'mylib')
        os.mkdir(subdir)
        filepath = os.path.join(self.tmpdir, 'foo.pth')
        # \xe9 is invalid UTF-8 but valid in latin-1.
        with open(filepath, 'wb') as f:
            f.write(b'# caf\xe9 comment\nmylib\n')
        with mock.patch('locale.getencoding', return_value='latin-1'), \
                captured_stderr():
            site._read_pth_file(self.sitedir, 'foo.pth', set())
        fullname = os.path.join(self.sitedir, 'foo.pth')
        self.assertIn(subdir, site._pending_syspaths.get(fullname, []))

    # --- _execute_start_entrypoints tests ---

    def test_execute_entrypoints_with_callable(self):
        # Entrypoint with callable is invoked.
        mod_dir = os.path.join(self.sitedir, 'epmod')
        os.mkdir(mod_dir)
        init_file = os.path.join(mod_dir, '__init__.py')
        with open(init_file, 'w') as f:
            f.write("""\
called = False
def startup():
    global called
    called = True
""")
        sys.path.insert(0, self.sitedir)
        self.addCleanup(sys.modules.pop, 'epmod', None)
        fullname = os.path.join(self.sitedir, 'epmod.start')
        site._pending_entrypoints[fullname] = ['epmod:startup']
        site._execute_start_entrypoints()
        import epmod
        self.assertTrue(epmod.called)

    def test_execute_entrypoints_import_error(self):
        # Import error prints traceback but continues.
        fullname = os.path.join(self.sitedir, 'bad.start')
        site._pending_entrypoints[fullname] = [
            'nosuchmodule_xyz:func', 'os.path:join']
        with captured_stderr() as err:
            site._execute_start_entrypoints()
        self.assertIn('nosuchmodule_xyz', err.getvalue())
        # os.path:join should still have been called (no exception for it)

    def test_execute_entrypoints_strict_syntax_rejection(self):
        # PEP 829: only the strict pkg.mod:callable form is valid.
        # At entry-point execution, pkgutil.resolve_name(strict=True)
        # raises ValueError for invalid syntax; the invalid entry is
        # reported and execution continues with the next one.
        fullname = os.path.join(self.sitedir, 'bad.start')
        site._pending_entrypoints[fullname] = [
            'os.path',                  # no colon
            'pkg.mod:',                 # empty callable
            ':callable',                # empty module
            'pkg.mod:callable:extra',   # multiple colons
        ]
        with captured_stderr() as err:
            site._execute_start_entrypoints()
        out = err.getvalue()
        self.assertIn('Invalid entry point syntax', out)
        for bad in ('os.path', 'pkg.mod:', ':callable',
                    'pkg.mod:callable:extra'):
            self.assertIn(bad, out)

    def test_execute_entrypoints_callable_error(self):
        # Callable that raises prints traceback but continues.
        mod_dir = os.path.join(self.sitedir, 'badmod')
        os.mkdir(mod_dir)
        init_file = os.path.join(mod_dir, '__init__.py')
        with open(init_file, 'w') as f:
            f.write("""\
def fail():
    raise RuntimeError("boom")
""")
        sys.path.insert(0, self.sitedir)
        self.addCleanup(sys.modules.pop, 'badmod', None)
        fullname = os.path.join(self.sitedir, 'badmod.start')
        site._pending_entrypoints[fullname] = ['badmod:fail']
        with captured_stderr() as err:
            site._execute_start_entrypoints()
        self.assertIn('RuntimeError', err.getvalue())
        self.assertIn('boom', err.getvalue())

    def test_execute_entrypoints_duplicates_called_twice(self):
        # PEP 829: duplicate entry points execute multiple times.
        mod_dir = os.path.join(self.sitedir, 'countmod')
        os.mkdir(mod_dir)
        init_file = os.path.join(mod_dir, '__init__.py')
        with open(init_file, 'w') as f:
            f.write("""\
call_count = 0
def bump():
    global call_count
    call_count += 1
""")
        sys.path.insert(0, self.sitedir)
        self.addCleanup(sys.modules.pop, 'countmod', None)
        fullname = os.path.join(self.sitedir, 'countmod.start')
        site._pending_entrypoints[fullname] = [
            'countmod:bump', 'countmod:bump']
        site._execute_start_entrypoints()
        import countmod
        self.assertEqual(countmod.call_count, 2)

    # --- _exec_imports tests ---

    def test_exec_imports_suppressed_by_matching_start(self):
        # Import lines from foo.pth are suppressed when foo.start exists.
        pth_fullname = os.path.join(self.sitedir, 'foo.pth')
        start_fullname = os.path.join(self.sitedir, 'foo.start')
        site._pending_importexecs[pth_fullname] = ['import sys']
        site._pending_entrypoints[start_fullname] = ['os.path:join']
        # Should not exec the import line; no error expected.
        site._exec_imports()

    def test_exec_imports_not_suppressed_by_different_start(self):
        # Import lines from foo.pth are NOT suppressed by bar.start.
        pth_fullname = os.path.join(self.sitedir, 'foo.pth')
        start_fullname = os.path.join(self.sitedir, 'bar.start')
        site._pending_importexecs[pth_fullname] = ['import sys']
        site._pending_entrypoints[start_fullname] = ['os.path:join']
        # Should execute the import line without error.
        site._exec_imports()

    def test_exec_imports_suppressed_by_empty_matching_start(self):
        self._make_start("", name='foo')
        self._make_pth("import epmod; epmod.startup()", name='foo')
        mod_dir = os.path.join(self.sitedir, 'epmod')
        os.mkdir(mod_dir)
        init_file = os.path.join(mod_dir, '__init__.py')
        with open(init_file, 'w') as f:
            f.write("""\
called = False
def startup():
    global called
    called = True
""")
        sys.path.insert(0, self.sitedir)
        self.addCleanup(sys.modules.pop, 'epmod', None)
        site._read_pth_file(self.sitedir, 'foo.pth', set())
        site._read_start_file(self.sitedir, 'foo.start')
        site._exec_imports()
        import epmod
        self.assertFalse(epmod.called)

    # --- _extend_syspath tests ---

    def test_extend_syspath_existing_dir(self):
        subdir = os.path.join(self.sitedir, 'extlib')
        os.mkdir(subdir)
        site._pending_syspaths['test.pth'] = [subdir]
        site._extend_syspath()
        self.assertIn(subdir, sys.path)

    def test_extend_syspath_nonexistent_dir(self):
        nosuch = os.path.join(self.sitedir, 'nosuchdir')
        site._pending_syspaths['test.pth'] = [nosuch]
        with captured_stderr() as err:
            site._extend_syspath()
        self.assertNotIn(nosuch, sys.path)
        self.assertIn('does not exist', err.getvalue())

    # --- addsitedir integration tests ---

    def test_addsitedir_discovers_start_files(self):
        # addsitedir() should discover .start files and accumulate entries.
        self._make_start("os.path:join\n", name='foo')
        site.addsitedir(self.sitedir, set(),
                        defer_processing_start_files=True)
        fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertIn('os.path:join', site._pending_entrypoints[fullname])

    def test_addsitedir_start_suppresses_pth_imports(self):
        # When foo.start exists, import lines in foo.pth are skipped
        # at flush time by _exec_imports().
        self._make_start("os.path:join\n", name='foo')
        self._make_pth("import sys\n", name='foo')
        site.addsitedir(self.sitedir, set(),
                        defer_processing_start_files=True)
        pth_fullname = os.path.join(self.sitedir, 'foo.pth')
        start_fullname = os.path.join(self.sitedir, 'foo.start')
        # Import line was collected...
        self.assertIn('import sys',
                      site._pending_importexecs.get(pth_fullname, []))
        # ...but _exec_imports() will skip it because foo.start exists.
        site._exec_imports()

    def test_addsitedir_pth_paths_still_work_with_start(self):
        # Path lines in .pth files still work even when a .start file exists.
        subdir = os.path.join(self.sitedir, 'mylib')
        os.mkdir(subdir)
        self._make_start("os.path:join\n", name='foo')
        self._make_pth("mylib\n", name='foo')
        site.addsitedir(self.sitedir, set(),
                        defer_processing_start_files=True)
        fullname = os.path.join(self.sitedir, 'foo.pth')
        self.assertIn(subdir, site._pending_syspaths.get(fullname, []))

    def test_addsitedir_start_alphabetical_order(self):
        # Multiple .start files are discovered alphabetically.
        self._make_start("os.path:join\n", name='zzz')
        self._make_start("os.path:exists\n", name='aaa')
        site.addsitedir(self.sitedir, set(),
                        defer_processing_start_files=True)
        all_entries = self._all_entrypoints()
        entries = [entry for _, entry in all_entries]
        idx_a = entries.index('os.path:exists')
        idx_z = entries.index('os.path:join')
        self.assertLess(idx_a, idx_z)

    def test_addsitedir_pth_before_start(self):
        # PEP 829: .pth files are scanned before .start files.
        # Create a .pth and .start with the same basename; verify
        # the .pth data is collected before .start data.
        subdir = os.path.join(self.sitedir, 'mylib')
        os.mkdir(subdir)
        self._make_pth("mylib\n", name='foo')
        self._make_start("os.path:join\n", name='foo')
        site.addsitedir(self.sitedir, set(),
                        defer_processing_start_files=True)
        # Both should be collected.
        pth_fullname = os.path.join(self.sitedir, 'foo.pth')
        start_fullname = os.path.join(self.sitedir, 'foo.start')
        self.assertIn(subdir, site._pending_syspaths.get(pth_fullname, []))
        self.assertIn('os.path:join',
                      site._pending_entrypoints.get(start_fullname, []))

    def test_addsitedir_dotfile_start_ignored(self):
        # .start files starting with '.' are skipped.  Defer flushing so
        # the assertion against _pending_entrypoints is meaningful;
        # otherwise process_startup_files() would clear the dict
        # regardless of whether the dotfile was picked up.
        self._make_start("os.path:join\n", name='.hidden')
        site.addsitedir(self.sitedir, set(),
                        defer_processing_start_files=True)
        self.assertEqual(site._pending_entrypoints, {})

    def test_addsitedir_standalone_flushes(self):
        # When called with known_paths=None (standalone), addsitedir
        # flushes immediately so the caller sees the effect.
        subdir = os.path.join(self.sitedir, 'flushlib')
        os.mkdir(subdir)
        self._make_pth("flushlib\n", name='foo')
        site.addsitedir(self.sitedir)  # known_paths=None
        self.assertIn(subdir, sys.path)
        # Pending dicts should be cleared after flush.
        self.assertEqual(site._pending_syspaths, {})

    def test_addsitedir_defer_does_not_flush(self):
        # With defer_processing_start_files=True, addsitedir accumulates
        # pending state but does not flush; sys.path is updated only when
        # process_startup_files() is called explicitly.
        subdir = os.path.join(self.sitedir, 'acclib')
        os.mkdir(subdir)
        self._make_pth("acclib\n", name='foo')
        site.addsitedir(self.sitedir, set(),
                        defer_processing_start_files=True)
        # Path is pending, not yet on sys.path.
        self.assertNotIn(subdir, sys.path)
        fullname = os.path.join(self.sitedir, 'foo.pth')
        self.assertIn(subdir, site._pending_syspaths.get(fullname, []))

    def test_pth_path_is_available_to_start_entrypoint(self):
        # Core PEP 829 invariant: all .pth path extensions are applied to
        # sys.path *before* any .start entry point runs, so an entry
        # point may live in a module reachable only via a .pth-extended
        # path.  If the flush phases were inverted, resolving the entry
        # point would fail with ModuleNotFoundError.
        extdir = os.path.join(self.sitedir, 'extdir')
        os.mkdir(extdir)
        modpath = os.path.join(extdir, 'mod.py')
        with open(modpath, 'w') as f:
            f.write("""\
called = False
def hook():
    global called
    called = True
""")
        self.addCleanup(sys.modules.pop, 'mod', None)

        # extdir is not on sys.path; only the .pth file makes it so.
        self.assertNotIn(extdir, sys.path)
        self._make_pth("extdir\n", name='extlib')
        self._make_start("mod:hook\n", name='extlib')

        # Standalone addsitedir() triggers the full flush sequence.
        site.addsitedir(self.sitedir)

        self.assertIn(extdir, sys.path)
        import mod
        self.assertTrue(
            mod.called,
            "entry point did not run; .pth path was likely not applied "
            "before .start entry-point execution")


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