cpython/Lib/test/test_pydoc.py

import os
import sys
import contextlib
import importlib.util
import inspect
import pydoc
import py_compile
import keyword
import _pickle
import pkgutil
import re
import stat
import tempfile
import test.support
import types
import typing
import unittest
import urllib.parse
import xml.etree
import xml.etree.ElementTree
import textwrap
from io import StringIO
from collections import namedtuple
from urllib.request import urlopen, urlcleanup
from test.support import import_helper
from test.support import os_helper
from test.support.script_helper import assert_python_ok, assert_python_failure
from test.support import threading_helper
from test.support import (reap_children, captured_output, captured_stdout,
                          captured_stderr, is_emscripten, requires_docstrings)
from test.support.os_helper import (TESTFN, rmtree, unlink)
from test import pydoc_mod


class nonascii:
    'Це не латиниця'
    pass

if test.support.HAVE_DOCSTRINGS:
    expected_data_docstrings = (
        'dictionary for instance variables (if defined)',
        'list of weak references to the object (if defined)',
        ) * 2
else:
    expected_data_docstrings = ('', '', '', '')

expected_text_pattern = """
NAME
    test.pydoc_mod - This is a test module for test_pydoc
%s
CLASSES
    builtins.object
        A
        B
        C
\x20\x20\x20\x20
    class A(builtins.object)
     |  Hello and goodbye
     |\x20\x20
     |  Methods defined here:
     |\x20\x20
     |  __init__()
     |      Wow, I have no function!
     |\x20\x20
     |  ----------------------------------------------------------------------
     |  Data descriptors defined here:
     |\x20\x20
     |  __dict__%s
     |\x20\x20
     |  __weakref__%s
\x20\x20\x20\x20
    class B(builtins.object)
     |  Data descriptors defined here:
     |\x20\x20
     |  __dict__%s
     |\x20\x20
     |  __weakref__%s
     |\x20\x20
     |  ----------------------------------------------------------------------
     |  Data and other attributes defined here:
     |\x20\x20
     |  NO_MEANING = 'eggs'
     |\x20\x20
     |  __annotations__ = {'NO_MEANING': <class 'str'>}
\x20\x20\x20\x20
    class C(builtins.object)
     |  Methods defined here:
     |\x20\x20
     |  get_answer(self)
     |      Return say_no()
     |\x20\x20
     |  is_it_true(self)
     |      Return self.get_answer()
     |\x20\x20
     |  say_no(self)
     |\x20\x20
     |  ----------------------------------------------------------------------
     |  Class methods defined here:
     |\x20\x20
     |  __class_getitem__(item) from builtins.type
     |\x20\x20
     |  ----------------------------------------------------------------------
     |  Data descriptors defined here:
     |\x20\x20
     |  __dict__
     |      dictionary for instance variables (if defined)
     |\x20\x20
     |  __weakref__
     |      list of weak references to the object (if defined)

FUNCTIONS
    doc_func()
        This function solves all of the world's problems:
        hunger
        lack of Python
        war
\x20\x20\x20\x20
    nodoc_func()

DATA
    __xyz__ = 'X, Y and Z'
    c_alias = test.pydoc_mod.C[int]
    list_alias1 = typing.List[int]
    list_alias2 = list[int]
    type_union1 = typing.Union[int, str]
    type_union2 = int | str

VERSION
    1.2.3.4

AUTHOR
    Benjamin Peterson

CREDITS
    Nobody

FILE
    %s
""".strip()

expected_text_data_docstrings = tuple('\n     |      ' + s if s else ''
                                      for s in expected_data_docstrings)

html2text_of_expected = """
test.pydoc_mod (version 1.2.3.4)
This is a test module for test_pydoc

Modules
    types
    typing

Classes
    builtins.object
    A
    B
    C

class A(builtins.object)
    Hello and goodbye

    Methods defined here:
        __init__()
            Wow, I have no function!

    Data descriptors defined here:
        __dict__
            dictionary for instance variables (if defined)
        __weakref__
            list of weak references to the object (if defined)

class B(builtins.object)
    Data descriptors defined here:
        __dict__
            dictionary for instance variables (if defined)
        __weakref__
            list of weak references to the object (if defined)
    Data and other attributes defined here:
        NO_MEANING = 'eggs'
        __annotations__ = {'NO_MEANING': <class 'str'>}


class C(builtins.object)
    Methods defined here:
        get_answer(self)
            Return say_no()
        is_it_true(self)
            Return self.get_answer()
        say_no(self)
    Class methods defined here:
        __class_getitem__(item) from builtins.type
    Data descriptors defined here:
        __dict__
            dictionary for instance variables (if defined)
        __weakref__
             list of weak references to the object (if defined)

Functions
    doc_func()
        This function solves all of the world's problems:
        hunger
        lack of Python
        war
    nodoc_func()

Data
    __xyz__ = 'X, Y and Z'
    c_alias = test.pydoc_mod.C[int]
    list_alias1 = typing.List[int]
    list_alias2 = list[int]
    type_union1 = typing.Union[int, str]
    type_union2 = int | str

Author
    Benjamin Peterson

Credits
    Nobody
"""

expected_html_data_docstrings = tuple(s.replace(' ', '&nbsp;')
                                      for s in expected_data_docstrings)

# output pattern for missing module
missing_pattern = '''\
No Python documentation found for %r.
Use help() to get the interactive help utility.
Use help(str) for help on the str class.'''.replace('\n', os.linesep)

# output pattern for module with bad imports
badimport_pattern = "problem in %s - ModuleNotFoundError: No module named %r"

expected_dynamicattribute_pattern = """
Help on class DA in module %s:

class DA(builtins.object)
 |  Data descriptors defined here:
 |\x20\x20
 |  __dict__%s
 |\x20\x20
 |  __weakref__%s
 |\x20\x20
 |  ham
 |\x20\x20
 |  ----------------------------------------------------------------------
 |  Data and other attributes inherited from Meta:
 |\x20\x20
 |  ham = 'spam'
""".strip()

expected_virtualattribute_pattern1 = """
Help on class Class in module %s:

class Class(builtins.object)
 |  Data and other attributes inherited from Meta:
 |\x20\x20
 |  LIFE = 42
""".strip()

expected_virtualattribute_pattern2 = """
Help on class Class1 in module %s:

class Class1(builtins.object)
 |  Data and other attributes inherited from Meta1:
 |\x20\x20
 |  one = 1
""".strip()

expected_virtualattribute_pattern3 = """
Help on class Class2 in module %s:

class Class2(Class1)
 |  Method resolution order:
 |      Class2
 |      Class1
 |      builtins.object
 |\x20\x20
 |  Data and other attributes inherited from Meta1:
 |\x20\x20
 |  one = 1
 |\x20\x20
 |  ----------------------------------------------------------------------
 |  Data and other attributes inherited from Meta3:
 |\x20\x20
 |  three = 3
 |\x20\x20
 |  ----------------------------------------------------------------------
 |  Data and other attributes inherited from Meta2:
 |\x20\x20
 |  two = 2
""".strip()

expected_missingattribute_pattern = """
Help on class C in module %s:

class C(builtins.object)
 |  Data and other attributes defined here:
 |\x20\x20
 |  here = 'present!'
""".strip()

def run_pydoc(module_name, *args, **env):
    """
    Runs pydoc on the specified module. Returns the stripped
    output of pydoc.
    """
    args = args + (module_name,)
    # do not write bytecode files to avoid caching errors
    rc, out, err = assert_python_ok('-B', pydoc.__file__, *args, **env)
    return out.strip()

def run_pydoc_fail(module_name, *args, **env):
    """
    Runs pydoc on the specified module expecting a failure.
    """
    args = args + (module_name,)
    rc, out, err = assert_python_failure('-B', pydoc.__file__, *args, **env)
    return out.strip()

def get_pydoc_html(module):
    "Returns pydoc generated output as html"
    doc = pydoc.HTMLDoc()
    output = doc.docmodule(module)
    loc = doc.getdocloc(pydoc_mod) or ""
    if loc:
        loc = "<br><a href=\"" + loc + "\">Module Docs</a>"
    return output.strip(), loc

def get_pydoc_link(module):
    "Returns a documentation web link of a module"
    abspath = os.path.abspath
    dirname = os.path.dirname
    basedir = dirname(dirname(abspath(__file__)))
    doc = pydoc.TextDoc()
    loc = doc.getdocloc(module, basedir=basedir)
    return loc

def get_pydoc_text(module):
    "Returns pydoc generated output as text"
    doc = pydoc.TextDoc()
    loc = doc.getdocloc(pydoc_mod) or ""
    if loc:
        loc = "\nMODULE DOCS\n    " + loc + "\n"

    output = doc.docmodule(module)

    # clean up the extra text formatting that pydoc performs
    patt = re.compile('\b.')
    output = patt.sub('', output)
    return output.strip(), loc

def get_html_title(text):
    # Bit of hack, but good enough for test purposes
    header, _, _ = text.partition("</head>")
    _, _, title = header.partition("<title>")
    title, _, _ = title.partition("</title>")
    return title


def html2text(html):
    """A quick and dirty implementation of html2text.

    Tailored for pydoc tests only.
    """
    html = html.replace("<dd>", "\n")
    html = re.sub("<.*?>", "", html)
    html = pydoc.replace(html, "&nbsp;", " ", "&gt;", ">", "&lt;", "<")
    return html


class PydocBaseTest(unittest.TestCase):

    def _restricted_walk_packages(self, walk_packages, path=None):
        """
        A version of pkgutil.walk_packages() that will restrict itself to
        a given path.
        """
        default_path = path or [os.path.dirname(__file__)]
        def wrapper(path=None, prefix='', onerror=None):
            return walk_packages(path or default_path, prefix, onerror)
        return wrapper

    @contextlib.contextmanager
    def restrict_walk_packages(self, path=None):
        walk_packages = pkgutil.walk_packages
        pkgutil.walk_packages = self._restricted_walk_packages(walk_packages,
                                                               path)
        try:
            yield
        finally:
            pkgutil.walk_packages = walk_packages

    def call_url_handler(self, url, expected_title):
        text = pydoc._url_handler(url, "text/html")
        result = get_html_title(text)
        # Check the title to ensure an unexpected error page was not returned
        self.assertEqual(result, expected_title, text)
        return text


class PydocDocTest(unittest.TestCase):
    maxDiff = None

    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                     'trace function introduces __locals__ unexpectedly')
    @requires_docstrings
    def test_html_doc(self):
        result, doc_loc = get_pydoc_html(pydoc_mod)
        text_result = html2text(result)
        text_lines = [line.strip() for line in text_result.splitlines()]
        text_lines = [line for line in text_lines if line]
        del text_lines[1]
        expected_lines = html2text_of_expected.splitlines()
        expected_lines = [line.strip() for line in expected_lines if line]
        self.assertEqual(text_lines, expected_lines)
        mod_file = inspect.getabsfile(pydoc_mod)
        mod_url = urllib.parse.quote(mod_file)
        self.assertIn(mod_url, result)
        self.assertIn(mod_file, result)
        self.assertIn(doc_loc, result)

    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                     'trace function introduces __locals__ unexpectedly')
    @requires_docstrings
    def test_text_doc(self):
        result, doc_loc = get_pydoc_text(pydoc_mod)
        expected_text = expected_text_pattern % (
                        (doc_loc,) +
                        expected_text_data_docstrings +
                        (inspect.getabsfile(pydoc_mod),))
        self.assertEqual(expected_text, result)

    def test_text_enum_member_with_value_zero(self):
        # Test issue #20654 to ensure enum member with value 0 can be
        # displayed. It used to throw KeyError: 'zero'.
        import enum
        class BinaryInteger(enum.IntEnum):
            zero = 0
            one = 1
        doc = pydoc.render_doc(BinaryInteger)
        self.assertIn('BinaryInteger.zero', doc)

    def test_mixed_case_module_names_are_lower_cased(self):
        # issue16484
        doc_link = get_pydoc_link(xml.etree.ElementTree)
        self.assertIn('xml.etree.elementtree', doc_link)

    def test_issue8225(self):
        # Test issue8225 to ensure no doc link appears for xml.etree
        result, doc_loc = get_pydoc_text(xml.etree)
        self.assertEqual(doc_loc, "", "MODULE DOCS incorrectly includes a link")

    def test_getpager_with_stdin_none(self):
        previous_stdin = sys.stdin
        try:
            sys.stdin = None
            pydoc.getpager() # Shouldn't fail.
        finally:
            sys.stdin = previous_stdin

    def test_non_str_name(self):
        # issue14638
        # Treat illegal (non-str) name like no name

        class A:
            __name__ = 42
        class B:
            pass
        adoc = pydoc.render_doc(A())
        bdoc = pydoc.render_doc(B())
        self.assertEqual(adoc.replace("A", "B"), bdoc)

    def test_not_here(self):
        missing_module = "test.i_am_not_here"
        result = str(run_pydoc_fail(missing_module), 'ascii')
        expected = missing_pattern % missing_module
        self.assertEqual(expected, result,
            "documentation for missing module found")

    @requires_docstrings
    def test_not_ascii(self):
        result = run_pydoc('test.test_pydoc.nonascii', PYTHONIOENCODING='ascii')
        encoded = nonascii.__doc__.encode('ascii', 'backslashreplace')
        self.assertIn(encoded, result)

    def test_input_strip(self):
        missing_module = " test.i_am_not_here "
        result = str(run_pydoc_fail(missing_module), 'ascii')
        expected = missing_pattern % missing_module.strip()
        self.assertEqual(expected, result)

    def test_stripid(self):
        # test with strings, other implementations might have different repr()
        stripid = pydoc.stripid
        # strip the id
        self.assertEqual(stripid('<function stripid at 0x88dcee4>'),
                         '<function stripid>')
        self.assertEqual(stripid('<function stripid at 0x01F65390>'),
                         '<function stripid>')
        # nothing to strip, return the same text
        self.assertEqual(stripid('42'), '42')
        self.assertEqual(stripid("<type 'exceptions.Exception'>"),
                         "<type 'exceptions.Exception'>")

    def test_builtin_with_more_than_four_children(self):
        """Tests help on builtin object which have more than four child classes.

        When running help() on a builtin class which has child classes, it
        should contain a "Built-in subclasses" section and only 4 classes
        should be displayed with a hint on how many more subclasses are present.
        For example:

        >>> help(object)
        Help on class object in module builtins:

        class object
         |  The most base type
         |
         |  Built-in subclasses:
         |      async_generator
         |      BaseException
         |      builtin_function_or_method
         |      bytearray
         |      ... and 82 other subclasses
        """
        doc = pydoc.TextDoc()
        text = doc.docclass(object)
        snip = (" |  Built-in subclasses:\n"
                " |      async_generator\n"
                " |      BaseException\n"
                " |      builtin_function_or_method\n"
                " |      bytearray\n"
                " |      ... and \\d+ other subclasses")
        self.assertRegex(text, snip)

    def test_builtin_with_child(self):
        """Tests help on builtin object which have only child classes.

        When running help() on a builtin class which has child classes, it
        should contain a "Built-in subclasses" section. For example:

        >>> help(ArithmeticError)
        Help on class ArithmeticError in module builtins:

        class ArithmeticError(Exception)
         |  Base class for arithmetic errors.
         |
         ...
         |
         |  Built-in subclasses:
         |      FloatingPointError
         |      OverflowError
         |      ZeroDivisionError
        """
        doc = pydoc.TextDoc()
        text = doc.docclass(ArithmeticError)
        snip = (" |  Built-in subclasses:\n"
                " |      FloatingPointError\n"
                " |      OverflowError\n"
                " |      ZeroDivisionError")
        self.assertIn(snip, text)

    def test_builtin_with_grandchild(self):
        """Tests help on builtin classes which have grandchild classes.

        When running help() on a builtin class which has child classes, it
        should contain a "Built-in subclasses" section. However, if it also has
        grandchildren, these should not show up on the subclasses section.
        For example:

        >>> help(Exception)
        Help on class Exception in module builtins:

        class Exception(BaseException)
         |  Common base class for all non-exit exceptions.
         |
         ...
         |
         |  Built-in subclasses:
         |      ArithmeticError
         |      AssertionError
         |      AttributeError
         ...
        """
        doc = pydoc.TextDoc()
        text = doc.docclass(Exception)
        snip = (" |  Built-in subclasses:\n"
                " |      ArithmeticError\n"
                " |      AssertionError\n"
                " |      AttributeError")
        self.assertIn(snip, text)
        # Testing that the grandchild ZeroDivisionError does not show up
        self.assertNotIn('ZeroDivisionError', text)

    def test_builtin_no_child(self):
        """Tests help on builtin object which have no child classes.

        When running help() on a builtin class which has no child classes, it
        should not contain any "Built-in subclasses" section. For example:

        >>> help(ZeroDivisionError)

        Help on class ZeroDivisionError in module builtins:

        class ZeroDivisionError(ArithmeticError)
         |  Second argument to a division or modulo operation was zero.
         |
         |  Method resolution order:
         |      ZeroDivisionError
         |      ArithmeticError
         |      Exception
         |      BaseException
         |      object
         |
         |  Methods defined here:
         ...
        """
        doc = pydoc.TextDoc()
        text = doc.docclass(ZeroDivisionError)
        # Testing that the subclasses section does not appear
        self.assertNotIn('Built-in subclasses', text)

    def test_builtin_on_metaclasses(self):
        """Tests help on metaclasses.

        When running help() on a metaclasses such as type, it
        should not contain any "Built-in subclasses" section.
        """
        doc = pydoc.TextDoc()
        text = doc.docclass(type)
        # Testing that the subclasses section does not appear
        self.assertNotIn('Built-in subclasses', text)

    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                     'trace function introduces __locals__ unexpectedly')
    @requires_docstrings
    def test_help_output_redirect(self):
        # issue 940286, if output is set in Helper, then all output from
        # Helper.help should be redirected
        getpager_old = pydoc.getpager
        getpager_new = lambda: (lambda x: x)
        self.maxDiff = None

        buf = StringIO()
        helper = pydoc.Helper(output=buf)
        unused, doc_loc = get_pydoc_text(pydoc_mod)
        module = "test.pydoc_mod"
        help_header = """
        Help on module test.pydoc_mod in test:

        """.lstrip()
        help_header = textwrap.dedent(help_header)
        expected_help_pattern = help_header + expected_text_pattern

        pydoc.getpager = getpager_new
        try:
            with captured_output('stdout') as output, \
                 captured_output('stderr') as err:
                helper.help(module)
                result = buf.getvalue().strip()
                expected_text = expected_help_pattern % (
                                (doc_loc,) +
                                expected_text_data_docstrings +
                                (inspect.getabsfile(pydoc_mod),))
                self.assertEqual('', output.getvalue())
                self.assertEqual('', err.getvalue())
                self.assertEqual(expected_text, result)
        finally:
            pydoc.getpager = getpager_old

    def test_namedtuple_fields(self):
        Person = namedtuple('Person', ['nickname', 'firstname'])
        with captured_stdout() as help_io:
            pydoc.help(Person)
        helptext = help_io.getvalue()
        self.assertIn("nickname", helptext)
        self.assertIn("firstname", helptext)
        self.assertIn("Alias for field number 0", helptext)
        self.assertIn("Alias for field number 1", helptext)

    def test_namedtuple_public_underscore(self):
        NT = namedtuple('NT', ['abc', 'def'], rename=True)
        with captured_stdout() as help_io:
            pydoc.help(NT)
        helptext = help_io.getvalue()
        self.assertIn('_1', helptext)
        self.assertIn('_replace', helptext)
        self.assertIn('_asdict', helptext)

    def test_synopsis(self):
        self.addCleanup(unlink, TESTFN)
        for encoding in ('ISO-8859-1', 'UTF-8'):
            with open(TESTFN, 'w', encoding=encoding) as script:
                if encoding != 'UTF-8':
                    print('#coding: {}'.format(encoding), file=script)
                print('"""line 1: h\xe9', file=script)
                print('line 2: hi"""', file=script)
            synopsis = pydoc.synopsis(TESTFN, {})
            self.assertEqual(synopsis, 'line 1: h\xe9')

    @requires_docstrings
    def test_synopsis_sourceless(self):
        os = import_helper.import_fresh_module('os')
        expected = os.__doc__.splitlines()[0]
        filename = os.__cached__
        synopsis = pydoc.synopsis(filename)

        self.assertEqual(synopsis, expected)

    def test_synopsis_sourceless_empty_doc(self):
        with os_helper.temp_cwd() as test_dir:
            init_path = os.path.join(test_dir, 'foomod42.py')
            cached_path = importlib.util.cache_from_source(init_path)
            with open(init_path, 'w') as fobj:
                fobj.write("foo = 1")
            py_compile.compile(init_path)
            synopsis = pydoc.synopsis(init_path, {})
            self.assertIsNone(synopsis)
            synopsis_cached = pydoc.synopsis(cached_path, {})
            self.assertIsNone(synopsis_cached)

    def test_splitdoc_with_description(self):
        example_string = "I Am A Doc\n\n\nHere is my description"
        self.assertEqual(pydoc.splitdoc(example_string),
                         ('I Am A Doc', '\nHere is my description'))

    def test_is_package_when_not_package(self):
        with os_helper.temp_cwd() as test_dir:
            self.assertFalse(pydoc.ispackage(test_dir))

    def test_is_package_when_is_package(self):
        with os_helper.temp_cwd() as test_dir:
            init_path = os.path.join(test_dir, '__init__.py')
            open(init_path, 'w').close()
            self.assertTrue(pydoc.ispackage(test_dir))
            os.remove(init_path)

    def test_allmethods(self):
        # issue 17476: allmethods was no longer returning unbound methods.
        # This test is a bit fragile in the face of changes to object and type,
        # but I can't think of a better way to do it without duplicating the
        # logic of the function under test.

        class TestClass(object):
            def method_returning_true(self):
                return True

        # What we expect to get back: everything on object...
        expected = dict(vars(object))
        # ...plus our unbound method...
        expected['method_returning_true'] = TestClass.method_returning_true
        # ...but not the non-methods on object.
        del expected['__doc__']
        del expected['__class__']
        # inspect resolves descriptors on type into methods, but vars doesn't,
        # so we need to update __subclasshook__ and __init_subclass__.
        expected['__subclasshook__'] = TestClass.__subclasshook__
        expected['__init_subclass__'] = TestClass.__init_subclass__

        methods = pydoc.allmethods(TestClass)
        self.assertDictEqual(methods, expected)

    @requires_docstrings
    def test_method_aliases(self):
        class A:
            def tkraise(self, aboveThis=None):
                """Raise this widget in the stacking order."""
            lift = tkraise
            def a_size(self):
                """Return size"""
        class B(A):
            def itemconfigure(self, tagOrId, cnf=None, **kw):
                """Configure resources of an item TAGORID."""
            itemconfig = itemconfigure
            b_size = A.a_size

        doc = pydoc.render_doc(B)
        # clean up the extra text formatting that pydoc performs
        doc = re.sub('\b.', '', doc)
        self.assertEqual(doc, '''\
Python Library Documentation: class B in module %s

class B(A)
 |  Method resolution order:
 |      B
 |      A
 |      builtins.object
 |\x20\x20
 |  Methods defined here:
 |\x20\x20
 |  b_size = a_size(self)
 |\x20\x20
 |  itemconfig = itemconfigure(self, tagOrId, cnf=None, **kw)
 |\x20\x20
 |  itemconfigure(self, tagOrId, cnf=None, **kw)
 |      Configure resources of an item TAGORID.
 |\x20\x20
 |  ----------------------------------------------------------------------
 |  Methods inherited from A:
 |\x20\x20
 |  a_size(self)
 |      Return size
 |\x20\x20
 |  lift = tkraise(self, aboveThis=None)
 |\x20\x20
 |  tkraise(self, aboveThis=None)
 |      Raise this widget in the stacking order.
 |\x20\x20
 |  ----------------------------------------------------------------------
 |  Data descriptors inherited from A:
 |\x20\x20
 |  __dict__
 |      dictionary for instance variables (if defined)
 |\x20\x20
 |  __weakref__
 |      list of weak references to the object (if defined)
''' % __name__)

        doc = pydoc.render_doc(B, renderer=pydoc.HTMLDoc())
        expected_text = f"""
Python Library Documentation

class B in module {__name__}
class B(A)
    Method resolution order:
        B
        A
        builtins.object

    Methods defined here:
        b_size = a_size(self)
        itemconfig = itemconfigure(self, tagOrId, cnf=None, **kw)
        itemconfigure(self, tagOrId, cnf=None, **kw)
            Configure resources of an item TAGORID.

    Methods inherited from A:
        a_size(self)
            Return size
        lift = tkraise(self, aboveThis=None)
        tkraise(self, aboveThis=None)
            Raise this widget in the stacking order.

    Data descriptors inherited from A:
        __dict__
            dictionary for instance variables (if defined)
        __weakref__
            list of weak references to the object (if defined)
"""
        as_text = html2text(doc)
        expected_lines = [line.strip() for line in expected_text.split("\n") if line]
        for expected_line in expected_lines:
            self.assertIn(expected_line, as_text)

    def test__future__imports(self):
        # __future__ features are excluded from module help,
        # except when it's the __future__ module itself
        import __future__
        future_text, _ = get_pydoc_text(__future__)
        future_html, _ = get_pydoc_html(__future__)
        pydoc_mod_text, _ = get_pydoc_text(pydoc_mod)
        pydoc_mod_html, _ = get_pydoc_html(pydoc_mod)

        for feature in __future__.all_feature_names:
            txt = f"{feature} = _Feature"
            html = f"<strong>{feature}</strong> = _Feature"
            self.assertIn(txt, future_text)
            self.assertIn(html, future_html)
            self.assertNotIn(txt, pydoc_mod_text)
            self.assertNotIn(html, pydoc_mod_html)


class PydocImportTest(PydocBaseTest):

    def setUp(self):
        self.test_dir = os.mkdir(TESTFN)
        self.addCleanup(rmtree, TESTFN)
        importlib.invalidate_caches()

    def test_badimport(self):
        # This tests the fix for issue 5230, where if pydoc found the module
        # but the module had an internal import error pydoc would report no doc
        # found.
        modname = 'testmod_xyzzy'
        testpairs = (
            ('i_am_not_here', 'i_am_not_here'),
            ('test.i_am_not_here_either', 'test.i_am_not_here_either'),
            ('test.i_am_not_here.neither_am_i', 'test.i_am_not_here'),
            ('i_am_not_here.{}'.format(modname), 'i_am_not_here'),
            ('test.{}'.format(modname), 'test.{}'.format(modname)),
            )

        sourcefn = os.path.join(TESTFN, modname) + os.extsep + "py"
        for importstring, expectedinmsg in testpairs:
            with open(sourcefn, 'w') as f:
                f.write("import {}\n".format(importstring))
            result = run_pydoc_fail(modname, PYTHONPATH=TESTFN).decode("ascii")
            expected = badimport_pattern % (modname, expectedinmsg)
            self.assertEqual(expected, result)

    def test_apropos_with_bad_package(self):
        # Issue 7425 - pydoc -k failed when bad package on path
        pkgdir = os.path.join(TESTFN, "syntaxerr")
        os.mkdir(pkgdir)
        badsyntax = os.path.join(pkgdir, "__init__") + os.extsep + "py"
        with open(badsyntax, 'w') as f:
            f.write("invalid python syntax = $1\n")
        with self.restrict_walk_packages(path=[TESTFN]):
            with captured_stdout() as out:
                with captured_stderr() as err:
                    pydoc.apropos('xyzzy')
            # No result, no error
            self.assertEqual(out.getvalue(), '')
            self.assertEqual(err.getvalue(), '')
            # The package name is still matched
            with captured_stdout() as out:
                with captured_stderr() as err:
                    pydoc.apropos('syntaxerr')
            self.assertEqual(out.getvalue().strip(), 'syntaxerr')
            self.assertEqual(err.getvalue(), '')

    def test_apropos_with_unreadable_dir(self):
        # Issue 7367 - pydoc -k failed when unreadable dir on path
        self.unreadable_dir = os.path.join(TESTFN, "unreadable")
        os.mkdir(self.unreadable_dir, 0)
        self.addCleanup(os.rmdir, self.unreadable_dir)
        # Note, on Windows the directory appears to be still
        #   readable so this is not really testing the issue there
        with self.restrict_walk_packages(path=[TESTFN]):
            with captured_stdout() as out:
                with captured_stderr() as err:
                    pydoc.apropos('SOMEKEY')
        # No result, no error
        self.assertEqual(out.getvalue(), '')
        self.assertEqual(err.getvalue(), '')

    def test_apropos_empty_doc(self):
        pkgdir = os.path.join(TESTFN, 'walkpkg')
        os.mkdir(pkgdir)
        self.addCleanup(rmtree, pkgdir)
        init_path = os.path.join(pkgdir, '__init__.py')
        with open(init_path, 'w') as fobj:
            fobj.write("foo = 1")
        current_mode = stat.S_IMODE(os.stat(pkgdir).st_mode)
        try:
            os.chmod(pkgdir, current_mode & ~stat.S_IEXEC)
            with self.restrict_walk_packages(path=[TESTFN]), captured_stdout() as stdout:
                pydoc.apropos('')
            self.assertIn('walkpkg', stdout.getvalue())
        finally:
            os.chmod(pkgdir, current_mode)

    def test_url_search_package_error(self):
        # URL handler search should cope with packages that raise exceptions
        pkgdir = os.path.join(TESTFN, "test_error_package")
        os.mkdir(pkgdir)
        init = os.path.join(pkgdir, "__init__.py")
        with open(init, "wt", encoding="ascii") as f:
            f.write("""raise ValueError("ouch")\n""")
        with self.restrict_walk_packages(path=[TESTFN]):
            # Package has to be importable for the error to have any effect
            saved_paths = tuple(sys.path)
            sys.path.insert(0, TESTFN)
            try:
                with self.assertRaisesRegex(ValueError, "ouch"):
                    import test_error_package  # Sanity check

                text = self.call_url_handler("search?key=test_error_package",
                    "Pydoc: Search Results")
                found = ('<a href="test_error_package.html">'
                    'test_error_package</a>')
                self.assertIn(found, text)
            finally:
                sys.path[:] = saved_paths

    @unittest.skip('causes undesirable side-effects (#20128)')
    def test_modules(self):
        # See Helper.listmodules().
        num_header_lines = 2
        num_module_lines_min = 5  # Playing it safe.
        num_footer_lines = 3
        expected = num_header_lines + num_module_lines_min + num_footer_lines

        output = StringIO()
        helper = pydoc.Helper(output=output)
        helper('modules')
        result = output.getvalue().strip()
        num_lines = len(result.splitlines())

        self.assertGreaterEqual(num_lines, expected)

    @unittest.skip('causes undesirable side-effects (#20128)')
    def test_modules_search(self):
        # See Helper.listmodules().
        expected = 'pydoc - '

        output = StringIO()
        helper = pydoc.Helper(output=output)
        with captured_stdout() as help_io:
            helper('modules pydoc')
        result = help_io.getvalue()

        self.assertIn(expected, result)

    @unittest.skip('some buildbots are not cooperating (#20128)')
    def test_modules_search_builtin(self):
        expected = 'gc - '

        output = StringIO()
        helper = pydoc.Helper(output=output)
        with captured_stdout() as help_io:
            helper('modules garbage')
        result = help_io.getvalue()

        self.assertTrue(result.startswith(expected))

    def test_importfile(self):
        loaded_pydoc = pydoc.importfile(pydoc.__file__)

        self.assertIsNot(loaded_pydoc, pydoc)
        self.assertEqual(loaded_pydoc.__name__, 'pydoc')
        self.assertEqual(loaded_pydoc.__file__, pydoc.__file__)
        self.assertEqual(loaded_pydoc.__spec__, pydoc.__spec__)


class TestDescriptions(unittest.TestCase):

    def test_module(self):
        # Check that pydocfodder module can be described
        from test import pydocfodder
        doc = pydoc.render_doc(pydocfodder)
        self.assertIn("pydocfodder", doc)

    def test_class(self):
        class C: "New-style class"
        c = C()

        self.assertEqual(pydoc.describe(C), 'class C')
        self.assertEqual(pydoc.describe(c), 'C')
        expected = 'C in module %s object' % __name__
        self.assertIn(expected, pydoc.render_doc(c))

    def test_generic_alias(self):
        self.assertEqual(pydoc.describe(typing.List[int]), '_GenericAlias')
        doc = pydoc.render_doc(typing.List[int], renderer=pydoc.plaintext)
        self.assertIn('_GenericAlias in module typing', doc)
        self.assertIn('List = class list(object)', doc)
        self.assertIn(list.__doc__.strip().splitlines()[0], doc)

        self.assertEqual(pydoc.describe(list[int]), 'GenericAlias')
        doc = pydoc.render_doc(list[int], renderer=pydoc.plaintext)
        self.assertIn('GenericAlias in module builtins', doc)
        self.assertIn('\nclass list(object)', doc)
        self.assertIn(list.__doc__.strip().splitlines()[0], doc)

    def test_union_type(self):
        self.assertEqual(pydoc.describe(typing.Union[int, str]), '_UnionGenericAlias')
        doc = pydoc.render_doc(typing.Union[int, str], renderer=pydoc.plaintext)
        self.assertIn('_UnionGenericAlias in module typing', doc)
        self.assertIn('Union = typing.Union', doc)
        if typing.Union.__doc__:
            self.assertIn(typing.Union.__doc__.strip().splitlines()[0], doc)

        self.assertEqual(pydoc.describe(int | str), 'UnionType')
        doc = pydoc.render_doc(int | str, renderer=pydoc.plaintext)
        self.assertIn('UnionType in module types object', doc)
        self.assertIn('\nclass UnionType(builtins.object)', doc)
        self.assertIn(types.UnionType.__doc__.strip().splitlines()[0], doc)

    def test_special_form(self):
        self.assertEqual(pydoc.describe(typing.NoReturn), '_SpecialForm')
        doc = pydoc.render_doc(typing.NoReturn, renderer=pydoc.plaintext)
        self.assertIn('_SpecialForm in module typing', doc)
        if typing.NoReturn.__doc__:
            self.assertIn('NoReturn = typing.NoReturn', doc)
            self.assertIn(typing.NoReturn.__doc__.strip().splitlines()[0], doc)
        else:
            self.assertIn('NoReturn = class _SpecialForm(_Final)', doc)

    def test_typing_pydoc(self):
        def foo(data: typing.List[typing.Any],
                x: int) -> typing.Iterator[typing.Tuple[int, typing.Any]]:
            ...
        T = typing.TypeVar('T')
        class C(typing.Generic[T], typing.Mapping[int, str]): ...
        self.assertEqual(pydoc.render_doc(foo).splitlines()[-1],
                         'f\x08fo\x08oo\x08o(data: List[Any], x: int)'
                         ' -> Iterator[Tuple[int, Any]]')
        self.assertEqual(pydoc.render_doc(C).splitlines()[2],
                         'class C\x08C(collections.abc.Mapping, typing.Generic)')

    def test_builtin(self):
        for name in ('str', 'str.translate', 'builtins.str',
                     'builtins.str.translate'):
            # test low-level function
            self.assertIsNotNone(pydoc.locate(name))
            # test high-level function
            try:
                pydoc.render_doc(name)
            except ImportError:
                self.fail('finding the doc of {!r} failed'.format(name))

        for name in ('notbuiltins', 'strrr', 'strr.translate',
                     'str.trrrranslate', 'builtins.strrr',
                     'builtins.str.trrranslate'):
            self.assertIsNone(pydoc.locate(name))
            self.assertRaises(ImportError, pydoc.render_doc, name)

    @staticmethod
    def _get_summary_line(o):
        text = pydoc.plain(pydoc.render_doc(o))
        lines = text.split('\n')
        assert len(lines) >= 2
        return lines[2]

    @staticmethod
    def _get_summary_lines(o):
        text = pydoc.plain(pydoc.render_doc(o))
        lines = text.split('\n')
        return '\n'.join(lines[2:])

    # these should include "self"
    def test_unbound_python_method(self):
        self.assertEqual(self._get_summary_line(textwrap.TextWrapper.wrap),
            "wrap(self, text)")

    @requires_docstrings
    def test_unbound_builtin_method(self):
        self.assertEqual(self._get_summary_line(_pickle.Pickler.dump),
            "dump(self, obj, /)")

    # these no longer include "self"
    def test_bound_python_method(self):
        t = textwrap.TextWrapper()
        self.assertEqual(self._get_summary_line(t.wrap),
            "wrap(text) method of textwrap.TextWrapper instance")
    def test_field_order_for_named_tuples(self):
        Person = namedtuple('Person', ['nickname', 'firstname', 'agegroup'])
        s = pydoc.render_doc(Person)
        self.assertLess(s.index('nickname'), s.index('firstname'))
        self.assertLess(s.index('firstname'), s.index('agegroup'))

        class NonIterableFields:
            _fields = None

        class NonHashableFields:
            _fields = [[]]

        # Make sure these doesn't fail
        pydoc.render_doc(NonIterableFields)
        pydoc.render_doc(NonHashableFields)

    @requires_docstrings
    def test_bound_builtin_method(self):
        s = StringIO()
        p = _pickle.Pickler(s)
        self.assertEqual(self._get_summary_line(p.dump),
            "dump(obj, /) method of _pickle.Pickler instance")

    # this should *never* include self!
    @requires_docstrings
    def test_module_level_callable(self):
        self.assertEqual(self._get_summary_line(os.stat),
            "stat(path, *, dir_fd=None, follow_symlinks=True)")

    @requires_docstrings
    def test_staticmethod(self):
        class X:
            @staticmethod
            def sm(x, y):
                '''A static method'''
                ...
        self.assertEqual(self._get_summary_lines(X.__dict__['sm']),
                         'sm(x, y)\n'
                         '    A static method\n')
        self.assertEqual(self._get_summary_lines(X.sm), """\
sm(x, y)
    A static method
""")
        self.assertIn("""
 |  Static methods defined here:
 |\x20\x20
 |  sm(x, y)
 |      A static method
""", pydoc.plain(pydoc.render_doc(X)))

    @requires_docstrings
    def test_classmethod(self):
        class X:
            @classmethod
            def cm(cls, x):
                '''A class method'''
                ...
        self.assertEqual(self._get_summary_lines(X.__dict__['cm']),
                         'cm(...)\n'
                         '    A class method\n')
        self.assertEqual(self._get_summary_lines(X.cm), """\
cm(x) method of builtins.type instance
    A class method
""")
        self.assertIn("""
 |  Class methods defined here:
 |\x20\x20
 |  cm(x) from builtins.type
 |      A class method
""", pydoc.plain(pydoc.render_doc(X)))

    @requires_docstrings
    def test_getset_descriptor(self):
        # Currently these attributes are implemented as getset descriptors
        # in CPython.
        self.assertEqual(self._get_summary_line(int.numerator), "numerator")
        self.assertEqual(self._get_summary_line(float.real), "real")
        self.assertEqual(self._get_summary_line(Exception.args), "args")
        self.assertEqual(self._get_summary_line(memoryview.obj), "obj")

    @requires_docstrings
    def test_member_descriptor(self):
        # Currently these attributes are implemented as member descriptors
        # in CPython.
        self.assertEqual(self._get_summary_line(complex.real), "real")
        self.assertEqual(self._get_summary_line(range.start), "start")
        self.assertEqual(self._get_summary_line(slice.start), "start")
        self.assertEqual(self._get_summary_line(property.fget), "fget")
        self.assertEqual(self._get_summary_line(StopIteration.value), "value")

    @requires_docstrings
    def test_slot_descriptor(self):
        class Point:
            __slots__ = 'x', 'y'
        self.assertEqual(self._get_summary_line(Point.x), "x")

    @requires_docstrings
    def test_dict_attr_descriptor(self):
        class NS:
            pass
        self.assertEqual(self._get_summary_line(NS.__dict__['__dict__']),
                         "__dict__")

    @requires_docstrings
    def test_structseq_member_descriptor(self):
        self.assertEqual(self._get_summary_line(type(sys.hash_info).width),
                         "width")
        self.assertEqual(self._get_summary_line(type(sys.flags).debug),
                         "debug")
        self.assertEqual(self._get_summary_line(type(sys.version_info).major),
                         "major")
        self.assertEqual(self._get_summary_line(type(sys.float_info).max),
                         "max")

    @requires_docstrings
    def test_namedtuple_field_descriptor(self):
        Box = namedtuple('Box', ('width', 'height'))
        self.assertEqual(self._get_summary_lines(Box.width), """\
    Alias for field number 0
""")

    @requires_docstrings
    def test_property(self):
        class Rect:
            @property
            def area(self):
                '''Area of the rect'''
                return self.w * self.h

        self.assertEqual(self._get_summary_lines(Rect.area), """\
    Area of the rect
""")
        self.assertIn("""
 |  area
 |      Area of the rect
""", pydoc.plain(pydoc.render_doc(Rect)))

    @requires_docstrings
    def test_custom_non_data_descriptor(self):
        class Descr:
            def __get__(self, obj, cls):
                if obj is None:
                    return self
                return 42
        class X:
            attr = Descr()

        self.assertEqual(self._get_summary_lines(X.attr), f"""\
<{__name__}.TestDescriptions.test_custom_non_data_descriptor.<locals>.Descr object>""")

        X.attr.__doc__ = 'Custom descriptor'
        self.assertEqual(self._get_summary_lines(X.attr), f"""\
<{__name__}.TestDescriptions.test_custom_non_data_descriptor.<locals>.Descr object>
    Custom descriptor
""")

        X.attr.__name__ = 'foo'
        self.assertEqual(self._get_summary_lines(X.attr), """\
foo(...)
    Custom descriptor
""")

    @requires_docstrings
    def test_custom_data_descriptor(self):
        class Descr:
            def __get__(self, obj, cls):
                if obj is None:
                    return self
                return 42
            def __set__(self, obj, cls):
                1/0
        class X:
            attr = Descr()

        self.assertEqual(self._get_summary_lines(X.attr), "")

        X.attr.__doc__ = 'Custom descriptor'
        self.assertEqual(self._get_summary_lines(X.attr), """\
    Custom descriptor
""")

        X.attr.__name__ = 'foo'
        self.assertEqual(self._get_summary_lines(X.attr), """\
foo
    Custom descriptor
""")

    def test_async_annotation(self):
        async def coro_function(ign) -> int:
            return 1

        text = pydoc.plain(pydoc.plaintext.document(coro_function))
        self.assertIn('async coro_function', text)

        html = pydoc.HTMLDoc().document(coro_function)
        self.assertIn(
            'async <a name="-coro_function"><strong>coro_function',
            html)

    def test_async_generator_annotation(self):
        async def an_async_generator():
            yield 1

        text = pydoc.plain(pydoc.plaintext.document(an_async_generator))
        self.assertIn('async an_async_generator', text)

        html = pydoc.HTMLDoc().document(an_async_generator)
        self.assertIn(
            'async <a name="-an_async_generator"><strong>an_async_generator',
            html)

    @requires_docstrings
    def test_html_for_https_links(self):
        def a_fn_with_https_link():
            """a link https://localhost/"""
            pass

        html = pydoc.HTMLDoc().document(a_fn_with_https_link)
        self.assertIn(
            '<a href="https://localhost/">https://localhost/</a>',
            html
        )


@unittest.skipIf(is_emscripten, "Socket server not available on Emscripten.")
class PydocServerTest(unittest.TestCase):
    """Tests for pydoc._start_server"""

    def test_server(self):
        # Minimal test that starts the server, checks that it works, then stops
        # it and checks its cleanup.
        def my_url_handler(url, content_type):
            text = 'the URL sent was: (%s, %s)' % (url, content_type)
            return text

        serverthread = pydoc._start_server(
            my_url_handler,
            hostname='localhost',
            port=0,
            )
        self.assertEqual(serverthread.error, None)
        self.assertTrue(serverthread.serving)
        self.addCleanup(
            lambda: serverthread.stop() if serverthread.serving else None
            )
        self.assertIn('localhost', serverthread.url)

        self.addCleanup(urlcleanup)
        self.assertEqual(
            b'the URL sent was: (/test, text/html)',
            urlopen(urllib.parse.urljoin(serverthread.url, '/test')).read(),
            )
        self.assertEqual(
            b'the URL sent was: (/test.css, text/css)',
            urlopen(urllib.parse.urljoin(serverthread.url, '/test.css')).read(),
            )

        serverthread.stop()
        self.assertFalse(serverthread.serving)
        self.assertIsNone(serverthread.docserver)
        self.assertIsNone(serverthread.url)


class PydocUrlHandlerTest(PydocBaseTest):
    """Tests for pydoc._url_handler"""

    def test_content_type_err(self):
        f = pydoc._url_handler
        self.assertRaises(TypeError, f, 'A', '')
        self.assertRaises(TypeError, f, 'B', 'foobar')

    def test_url_requests(self):
        # Test for the correct title in the html pages returned.
        # This tests the different parts of the URL handler without
        # getting too picky about the exact html.
        requests = [
            ("", "Pydoc: Index of Modules"),
            ("get?key=", "Pydoc: Index of Modules"),
            ("index", "Pydoc: Index of Modules"),
            ("topics", "Pydoc: Topics"),
            ("keywords", "Pydoc: Keywords"),
            ("pydoc", "Pydoc: module pydoc"),
            ("get?key=pydoc", "Pydoc: module pydoc"),
            ("search?key=pydoc", "Pydoc: Search Results"),
            ("topic?key=def", "Pydoc: KEYWORD def"),
            ("topic?key=STRINGS", "Pydoc: TOPIC STRINGS"),
            ("foobar", "Pydoc: Error - foobar"),
            ]

        with self.restrict_walk_packages():
            for url, title in requests:
                self.call_url_handler(url, title)


class TestHelper(unittest.TestCase):
    def test_keywords(self):
        self.assertEqual(sorted(pydoc.Helper.keywords),
                         sorted(keyword.kwlist))


class PydocWithMetaClasses(unittest.TestCase):
    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                     'trace function introduces __locals__ unexpectedly')
    @requires_docstrings
    def test_DynamicClassAttribute(self):
        class Meta(type):
            def __getattr__(self, name):
                if name == 'ham':
                    return 'spam'
                return super().__getattr__(name)
        class DA(metaclass=Meta):
            @types.DynamicClassAttribute
            def ham(self):
                return 'eggs'
        expected_text_data_docstrings = tuple('\n |      ' + s if s else ''
                                      for s in expected_data_docstrings)
        output = StringIO()
        helper = pydoc.Helper(output=output)
        helper(DA)
        expected_text = expected_dynamicattribute_pattern % (
                (__name__,) + expected_text_data_docstrings[:2])
        result = output.getvalue().strip()
        self.assertEqual(expected_text, result)

    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                     'trace function introduces __locals__ unexpectedly')
    @requires_docstrings
    def test_virtualClassAttributeWithOneMeta(self):
        class Meta(type):
            def __dir__(cls):
                return ['__class__', '__module__', '__name__', 'LIFE']
            def __getattr__(self, name):
                if name =='LIFE':
                    return 42
                return super().__getattr(name)
        class Class(metaclass=Meta):
            pass
        output = StringIO()
        helper = pydoc.Helper(output=output)
        helper(Class)
        expected_text = expected_virtualattribute_pattern1 % __name__
        result = output.getvalue().strip()
        self.assertEqual(expected_text, result)

    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                     'trace function introduces __locals__ unexpectedly')
    @requires_docstrings
    def test_virtualClassAttributeWithTwoMeta(self):
        class Meta1(type):
            def __dir__(cls):
                return ['__class__', '__module__', '__name__', 'one']
            def __getattr__(self, name):
                if name =='one':
                    return 1
                return super().__getattr__(name)
        class Meta2(type):
            def __dir__(cls):
                return ['__class__', '__module__', '__name__', 'two']
            def __getattr__(self, name):
                if name =='two':
                    return 2
                return super().__getattr__(name)
        class Meta3(Meta1, Meta2):
            def __dir__(cls):
                return list(sorted(set(
                    ['__class__', '__module__', '__name__', 'three'] +
                    Meta1.__dir__(cls) + Meta2.__dir__(cls))))
            def __getattr__(self, name):
                if name =='three':
                    return 3
                return super().__getattr__(name)
        class Class1(metaclass=Meta1):
            pass
        class Class2(Class1, metaclass=Meta3):
            pass
        output = StringIO()
        helper = pydoc.Helper(output=output)
        helper(Class1)
        expected_text1 = expected_virtualattribute_pattern2 % __name__
        result1 = output.getvalue().strip()
        self.assertEqual(expected_text1, result1)
        output = StringIO()
        helper = pydoc.Helper(output=output)
        helper(Class2)
        expected_text2 = expected_virtualattribute_pattern3 % __name__
        result2 = output.getvalue().strip()
        self.assertEqual(expected_text2, result2)

    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                     'trace function introduces __locals__ unexpectedly')
    @requires_docstrings
    def test_buggy_dir(self):
        class M(type):
            def __dir__(cls):
                return ['__class__', '__name__', 'missing', 'here']
        class C(metaclass=M):
            here = 'present!'
        output = StringIO()
        helper = pydoc.Helper(output=output)
        helper(C)
        expected_text = expected_missingattribute_pattern % __name__
        result = output.getvalue().strip()
        self.assertEqual(expected_text, result)

    def test_resolve_false(self):
        # Issue #23008: pydoc enum.{,Int}Enum failed
        # because bool(enum.Enum) is False.
        with captured_stdout() as help_io:
            pydoc.help('enum.Enum')
        helptext = help_io.getvalue()
        self.assertIn('class Enum', helptext)


class TestInternalUtilities(unittest.TestCase):

    def setUp(self):
        tmpdir = tempfile.TemporaryDirectory()
        self.argv0dir = tmpdir.name
        self.argv0 = os.path.join(tmpdir.name, "nonexistent")
        self.addCleanup(tmpdir.cleanup)
        self.abs_curdir = abs_curdir = os.getcwd()
        self.curdir_spellings = ["", os.curdir, abs_curdir]

    def _get_revised_path(self, given_path, argv0=None):
        # Checking that pydoc.cli() actually calls pydoc._get_revised_path()
        # is handled via code review (at least for now).
        if argv0 is None:
            argv0 = self.argv0
        return pydoc._get_revised_path(given_path, argv0)

    def _get_starting_path(self):
        # Get a copy of sys.path without the current directory.
        clean_path = sys.path.copy()
        for spelling in self.curdir_spellings:
            for __ in range(clean_path.count(spelling)):
                clean_path.remove(spelling)
        return clean_path

    def test_sys_path_adjustment_adds_missing_curdir(self):
        clean_path = self._get_starting_path()
        expected_path = [self.abs_curdir] + clean_path
        self.assertEqual(self._get_revised_path(clean_path), expected_path)

    def test_sys_path_adjustment_removes_argv0_dir(self):
        clean_path = self._get_starting_path()
        expected_path = [self.abs_curdir] + clean_path
        leading_argv0dir = [self.argv0dir] + clean_path
        self.assertEqual(self._get_revised_path(leading_argv0dir), expected_path)
        trailing_argv0dir = clean_path + [self.argv0dir]
        self.assertEqual(self._get_revised_path(trailing_argv0dir), expected_path)

    def test_sys_path_adjustment_protects_pydoc_dir(self):
        def _get_revised_path(given_path):
            return self._get_revised_path(given_path, argv0=pydoc.__file__)
        clean_path = self._get_starting_path()
        leading_argv0dir = [self.argv0dir] + clean_path
        expected_path = [self.abs_curdir] + leading_argv0dir
        self.assertEqual(_get_revised_path(leading_argv0dir), expected_path)
        trailing_argv0dir = clean_path + [self.argv0dir]
        expected_path = [self.abs_curdir] + trailing_argv0dir
        self.assertEqual(_get_revised_path(trailing_argv0dir), expected_path)

    def test_sys_path_adjustment_when_curdir_already_included(self):
        clean_path = self._get_starting_path()
        for spelling in self.curdir_spellings:
            with self.subTest(curdir_spelling=spelling):
                # If curdir is already present, no alterations are made at all
                leading_curdir = [spelling] + clean_path
                self.assertIsNone(self._get_revised_path(leading_curdir))
                trailing_curdir = clean_path + [spelling]
                self.assertIsNone(self._get_revised_path(trailing_curdir))
                leading_argv0dir = [self.argv0dir] + leading_curdir
                self.assertIsNone(self._get_revised_path(leading_argv0dir))
                trailing_argv0dir = trailing_curdir + [self.argv0dir]
                self.assertIsNone(self._get_revised_path(trailing_argv0dir))


def setUpModule():
    thread_info = threading_helper.threading_setup()
    unittest.addModuleCleanup(threading_helper.threading_cleanup, *thread_info)
    unittest.addModuleCleanup(reap_children)


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