add ydb deps

1 files changed, 771 insertions, 0 deletions

diff --git a/contrib/python/pytest/py3/_pytest/doctest.py b/contrib/python/pytest/py3/_pytest/doctest.py
new file mode 100644
index 0000000000..ca41a98ea9
--- /dev/null
+++ b/contrib/python/pytest/py3/_pytest/doctest.py
@@ -0,0 +1,771 @@
+"""Discover and run doctests in modules and test files."""
+import bdb
+import functools
+import inspect
+import os
+import platform
+import sys
+import traceback
+import types
+import warnings
+from contextlib import contextmanager
+from pathlib import Path
+from typing import Any
+from typing import Callable
+from typing import Dict
+from typing import Generator
+from typing import Iterable
+from typing import List
+from typing import Optional
+from typing import Pattern
+from typing import Sequence
+from typing import Tuple
+from typing import Type
+from typing import TYPE_CHECKING
+from typing import Union
+
+from _pytest import outcomes
+from _pytest._code.code import ExceptionInfo
+from _pytest._code.code import ReprFileLocation
+from _pytest._code.code import TerminalRepr
+from _pytest._io import TerminalWriter
+from _pytest.compat import safe_getattr
+from _pytest.config import Config
+from _pytest.config.argparsing import Parser
+from _pytest.fixtures import fixture
+from _pytest.fixtures import FixtureRequest
+from _pytest.nodes import Collector
+from _pytest.nodes import Item
+from _pytest.outcomes import OutcomeException
+from _pytest.outcomes import skip
+from _pytest.pathlib import fnmatch_ex
+from _pytest.pathlib import import_path
+from _pytest.python import Module
+from _pytest.python_api import approx
+from _pytest.warning_types import PytestWarning
+
+if TYPE_CHECKING:
+    import doctest
+
+DOCTEST_REPORT_CHOICE_NONE = "none"
+DOCTEST_REPORT_CHOICE_CDIFF = "cdiff"
+DOCTEST_REPORT_CHOICE_NDIFF = "ndiff"
+DOCTEST_REPORT_CHOICE_UDIFF = "udiff"
+DOCTEST_REPORT_CHOICE_ONLY_FIRST_FAILURE = "only_first_failure"
+
+DOCTEST_REPORT_CHOICES = (
+    DOCTEST_REPORT_CHOICE_NONE,
+    DOCTEST_REPORT_CHOICE_CDIFF,
+    DOCTEST_REPORT_CHOICE_NDIFF,
+    DOCTEST_REPORT_CHOICE_UDIFF,
+    DOCTEST_REPORT_CHOICE_ONLY_FIRST_FAILURE,
+)
+
+# Lazy definition of runner class
+RUNNER_CLASS = None
+# Lazy definition of output checker class
+CHECKER_CLASS: Optional[Type["doctest.OutputChecker"]] = None
+
+
+def pytest_addoption(parser: Parser) -> None:
+    parser.addini(
+        "doctest_optionflags",
+        "Option flags for doctests",
+        type="args",
+        default=["ELLIPSIS"],
+    )
+    parser.addini(
+        "doctest_encoding", "Encoding used for doctest files", default="utf-8"
+    )
+    group = parser.getgroup("collect")
+    group.addoption(
+        "--doctest-modules",
+        action="store_true",
+        default=False,
+        help="Run doctests in all .py modules",
+        dest="doctestmodules",
+    )
+    group.addoption(
+        "--doctest-report",
+        type=str.lower,
+        default="udiff",
+        help="Choose another output format for diffs on doctest failure",
+        choices=DOCTEST_REPORT_CHOICES,
+        dest="doctestreport",
+    )
+    group.addoption(
+        "--doctest-glob",
+        action="append",
+        default=[],
+        metavar="pat",
+        help="Doctests file matching pattern, default: test*.txt",
+        dest="doctestglob",
+    )
+    group.addoption(
+        "--doctest-ignore-import-errors",
+        action="store_true",
+        default=False,
+        help="Ignore doctest ImportErrors",
+        dest="doctest_ignore_import_errors",
+    )
+    group.addoption(
+        "--doctest-continue-on-failure",
+        action="store_true",
+        default=False,
+        help="For a given doctest, continue to run after the first failure",
+        dest="doctest_continue_on_failure",
+    )
+
+
+def pytest_unconfigure() -> None:
+    global RUNNER_CLASS
+
+    RUNNER_CLASS = None
+
+
+def pytest_collect_file(
+    file_path: Path,
+    parent: Collector,
+) -> Optional[Union["DoctestModule", "DoctestTextfile"]]:
+    config = parent.config
+    if file_path.suffix == ".py":
+        if config.option.doctestmodules and not any(
+            (_is_setup_py(file_path), _is_main_py(file_path))
+        ):
+            mod: DoctestModule = DoctestModule.from_parent(parent, path=file_path)
+            return mod
+    elif _is_doctest(config, file_path, parent):
+        txt: DoctestTextfile = DoctestTextfile.from_parent(parent, path=file_path)
+        return txt
+    return None
+
+
+def _is_setup_py(path: Path) -> bool:
+    if path.name != "setup.py":
+        return False
+    contents = path.read_bytes()
+    return b"setuptools" in contents or b"distutils" in contents
+
+
+def _is_doctest(config: Config, path: Path, parent: Collector) -> bool:
+    if path.suffix in (".txt", ".rst") and parent.session.isinitpath(path):
+        return True
+    globs = config.getoption("doctestglob") or ["test*.txt"]
+    return any(fnmatch_ex(glob, path) for glob in globs)
+
+
+def _is_main_py(path: Path) -> bool:
+    return path.name == "__main__.py"
+
+
+class ReprFailDoctest(TerminalRepr):
+    def __init__(
+        self, reprlocation_lines: Sequence[Tuple[ReprFileLocation, Sequence[str]]]
+    ) -> None:
+        self.reprlocation_lines = reprlocation_lines
+
+    def toterminal(self, tw: TerminalWriter) -> None:
+        for reprlocation, lines in self.reprlocation_lines:
+            for line in lines:
+                tw.line(line)
+            reprlocation.toterminal(tw)
+
+
+class MultipleDoctestFailures(Exception):
+    def __init__(self, failures: Sequence["doctest.DocTestFailure"]) -> None:
+        super().__init__()
+        self.failures = failures
+
+
+def _init_runner_class() -> Type["doctest.DocTestRunner"]:
+    import doctest
+
+    class PytestDoctestRunner(doctest.DebugRunner):
+        """Runner to collect failures.
+
+        Note that the out variable in this case is a list instead of a
+        stdout-like object.
+        """
+
+        def __init__(
+            self,
+            checker: Optional["doctest.OutputChecker"] = None,
+            verbose: Optional[bool] = None,
+            optionflags: int = 0,
+            continue_on_failure: bool = True,
+        ) -> None:
+            super().__init__(checker=checker, verbose=verbose, optionflags=optionflags)
+            self.continue_on_failure = continue_on_failure
+
+        def report_failure(
+            self,
+            out,
+            test: "doctest.DocTest",
+            example: "doctest.Example",
+            got: str,
+        ) -> None:
+            failure = doctest.DocTestFailure(test, example, got)
+            if self.continue_on_failure:
+                out.append(failure)
+            else:
+                raise failure
+
+        def report_unexpected_exception(
+            self,
+            out,
+            test: "doctest.DocTest",
+            example: "doctest.Example",
+            exc_info: Tuple[Type[BaseException], BaseException, types.TracebackType],
+        ) -> None:
+            if isinstance(exc_info[1], OutcomeException):
+                raise exc_info[1]
+            if isinstance(exc_info[1], bdb.BdbQuit):
+                outcomes.exit("Quitting debugger")
+            failure = doctest.UnexpectedException(test, example, exc_info)
+            if self.continue_on_failure:
+                out.append(failure)
+            else:
+                raise failure
+
+    return PytestDoctestRunner
+
+
+def _get_runner(
+    checker: Optional["doctest.OutputChecker"] = None,
+    verbose: Optional[bool] = None,
+    optionflags: int = 0,
+    continue_on_failure: bool = True,
+) -> "doctest.DocTestRunner":
+    # We need this in order to do a lazy import on doctest
+    global RUNNER_CLASS
+    if RUNNER_CLASS is None:
+        RUNNER_CLASS = _init_runner_class()
+    # Type ignored because the continue_on_failure argument is only defined on
+    # PytestDoctestRunner, which is lazily defined so can't be used as a type.
+    return RUNNER_CLASS(  # type: ignore
+        checker=checker,
+        verbose=verbose,
+        optionflags=optionflags,
+        continue_on_failure=continue_on_failure,
+    )
+
+
+class DoctestItem(Item):
+    def __init__(
+        self,
+        name: str,
+        parent: "Union[DoctestTextfile, DoctestModule]",
+        runner: Optional["doctest.DocTestRunner"] = None,
+        dtest: Optional["doctest.DocTest"] = None,
+    ) -> None:
+        super().__init__(name, parent)
+        self.runner = runner
+        self.dtest = dtest
+        self.obj = None
+        self.fixture_request: Optional[FixtureRequest] = None
+
+    @classmethod
+    def from_parent(  # type: ignore
+        cls,
+        parent: "Union[DoctestTextfile, DoctestModule]",
+        *,
+        name: str,
+        runner: "doctest.DocTestRunner",
+        dtest: "doctest.DocTest",
+    ):
+        # incompatible signature due to imposed limits on subclass
+        """The public named constructor."""
+        return super().from_parent(name=name, parent=parent, runner=runner, dtest=dtest)
+
+    def setup(self) -> None:
+        if self.dtest is not None:
+            self.fixture_request = _setup_fixtures(self)
+            globs = dict(getfixture=self.fixture_request.getfixturevalue)
+            for name, value in self.fixture_request.getfixturevalue(
+                "doctest_namespace"
+            ).items():
+                globs[name] = value
+            self.dtest.globs.update(globs)
+
+    def runtest(self) -> None:
+        assert self.dtest is not None
+        assert self.runner is not None
+        _check_all_skipped(self.dtest)
+        self._disable_output_capturing_for_darwin()
+        failures: List["doctest.DocTestFailure"] = []
+        # Type ignored because we change the type of `out` from what
+        # doctest expects.
+        self.runner.run(self.dtest, out=failures)  # type: ignore[arg-type]
+        if failures:
+            raise MultipleDoctestFailures(failures)
+
+    def _disable_output_capturing_for_darwin(self) -> None:
+        """Disable output capturing. Otherwise, stdout is lost to doctest (#985)."""
+        if platform.system() != "Darwin":
+            return
+        capman = self.config.pluginmanager.getplugin("capturemanager")
+        if capman:
+            capman.suspend_global_capture(in_=True)
+            out, err = capman.read_global_capture()
+            sys.stdout.write(out)
+            sys.stderr.write(err)
+
+    # TODO: Type ignored -- breaks Liskov Substitution.
+    def repr_failure(  # type: ignore[override]
+        self,
+        excinfo: ExceptionInfo[BaseException],
+    ) -> Union[str, TerminalRepr]:
+        import doctest
+
+        failures: Optional[
+            Sequence[Union[doctest.DocTestFailure, doctest.UnexpectedException]]
+        ] = None
+        if isinstance(
+            excinfo.value, (doctest.DocTestFailure, doctest.UnexpectedException)
+        ):
+            failures = [excinfo.value]
+        elif isinstance(excinfo.value, MultipleDoctestFailures):
+            failures = excinfo.value.failures
+
+        if failures is None:
+            return super().repr_failure(excinfo)
+
+        reprlocation_lines = []
+        for failure in failures:
+            example = failure.example
+            test = failure.test
+            filename = test.filename
+            if test.lineno is None:
+                lineno = None
+            else:
+                lineno = test.lineno + example.lineno + 1
+            message = type(failure).__name__
+            # TODO: ReprFileLocation doesn't expect a None lineno.
+            reprlocation = ReprFileLocation(filename, lineno, message)  # type: ignore[arg-type]
+            checker = _get_checker()
+            report_choice = _get_report_choice(self.config.getoption("doctestreport"))
+            if lineno is not None:
+                assert failure.test.docstring is not None
+                lines = failure.test.docstring.splitlines(False)
+                # add line numbers to the left of the error message
+                assert test.lineno is not None
+                lines = [
+                    "%03d %s" % (i + test.lineno + 1, x) for (i, x) in enumerate(lines)
+                ]
+                # trim docstring error lines to 10
+                lines = lines[max(example.lineno - 9, 0) : example.lineno + 1]
+            else:
+                lines = [
+                    "EXAMPLE LOCATION UNKNOWN, not showing all tests of that example"
+                ]
+                indent = ">>>"
+                for line in example.source.splitlines():
+                    lines.append(f"??? {indent} {line}")
+                    indent = "..."
+            if isinstance(failure, doctest.DocTestFailure):
+                lines += checker.output_difference(
+                    example, failure.got, report_choice
+                ).split("\n")
+            else:
+                inner_excinfo = ExceptionInfo.from_exc_info(failure.exc_info)
+                lines += ["UNEXPECTED EXCEPTION: %s" % repr(inner_excinfo.value)]
+                lines += [
+                    x.strip("\n") for x in traceback.format_exception(*failure.exc_info)
+                ]
+            reprlocation_lines.append((reprlocation, lines))
+        return ReprFailDoctest(reprlocation_lines)
+
+    def reportinfo(self) -> Tuple[Union["os.PathLike[str]", str], Optional[int], str]:
+        assert self.dtest is not None
+        return self.path, self.dtest.lineno, "[doctest] %s" % self.name
+
+
+def _get_flag_lookup() -> Dict[str, int]:
+    import doctest
+
+    return dict(
+        DONT_ACCEPT_TRUE_FOR_1=doctest.DONT_ACCEPT_TRUE_FOR_1,
+        DONT_ACCEPT_BLANKLINE=doctest.DONT_ACCEPT_BLANKLINE,
+        NORMALIZE_WHITESPACE=doctest.NORMALIZE_WHITESPACE,
+        ELLIPSIS=doctest.ELLIPSIS,
+        IGNORE_EXCEPTION_DETAIL=doctest.IGNORE_EXCEPTION_DETAIL,
+        COMPARISON_FLAGS=doctest.COMPARISON_FLAGS,
+        ALLOW_UNICODE=_get_allow_unicode_flag(),
+        ALLOW_BYTES=_get_allow_bytes_flag(),
+        NUMBER=_get_number_flag(),
+    )
+
+
+def get_optionflags(parent):
+    optionflags_str = parent.config.getini("doctest_optionflags")
+    flag_lookup_table = _get_flag_lookup()
+    flag_acc = 0
+    for flag in optionflags_str:
+        flag_acc |= flag_lookup_table[flag]
+    return flag_acc
+
+
+def _get_continue_on_failure(config):
+    continue_on_failure = config.getvalue("doctest_continue_on_failure")
+    if continue_on_failure:
+        # We need to turn off this if we use pdb since we should stop at
+        # the first failure.
+        if config.getvalue("usepdb"):
+            continue_on_failure = False
+    return continue_on_failure
+
+
+class DoctestTextfile(Module):
+    obj = None
+
+    def collect(self) -> Iterable[DoctestItem]:
+        import doctest
+
+        # Inspired by doctest.testfile; ideally we would use it directly,
+        # but it doesn't support passing a custom checker.
+        encoding = self.config.getini("doctest_encoding")
+        text = self.path.read_text(encoding)
+        filename = str(self.path)
+        name = self.path.name
+        globs = {"__name__": "__main__"}
+
+        optionflags = get_optionflags(self)
+
+        runner = _get_runner(
+            verbose=False,
+            optionflags=optionflags,
+            checker=_get_checker(),
+            continue_on_failure=_get_continue_on_failure(self.config),
+        )
+
+        parser = doctest.DocTestParser()
+        test = parser.get_doctest(text, globs, name, filename, 0)
+        if test.examples:
+            yield DoctestItem.from_parent(
+                self, name=test.name, runner=runner, dtest=test
+            )
+
+
+def _check_all_skipped(test: "doctest.DocTest") -> None:
+    """Raise pytest.skip() if all examples in the given DocTest have the SKIP
+    option set."""
+    import doctest
+
+    all_skipped = all(x.options.get(doctest.SKIP, False) for x in test.examples)
+    if all_skipped:
+        skip("all tests skipped by +SKIP option")
+
+
+def _is_mocked(obj: object) -> bool:
+    """Return if an object is possibly a mock object by checking the
+    existence of a highly improbable attribute."""
+    return (
+        safe_getattr(obj, "pytest_mock_example_attribute_that_shouldnt_exist", None)
+        is not None
+    )
+
+
+@contextmanager
+def _patch_unwrap_mock_aware() -> Generator[None, None, None]:
+    """Context manager which replaces ``inspect.unwrap`` with a version
+    that's aware of mock objects and doesn't recurse into them."""
+    real_unwrap = inspect.unwrap
+
+    def _mock_aware_unwrap(
+        func: Callable[..., Any], *, stop: Optional[Callable[[Any], Any]] = None
+    ) -> Any:
+        try:
+            if stop is None or stop is _is_mocked:
+                return real_unwrap(func, stop=_is_mocked)
+            _stop = stop
+            return real_unwrap(func, stop=lambda obj: _is_mocked(obj) or _stop(func))
+        except Exception as e:
+            warnings.warn(
+                "Got %r when unwrapping %r.  This is usually caused "
+                "by a violation of Python's object protocol; see e.g. "
+                "https://github.com/pytest-dev/pytest/issues/5080" % (e, func),
+                PytestWarning,
+            )
+            raise
+
+    inspect.unwrap = _mock_aware_unwrap
+    try:
+        yield
+    finally:
+        inspect.unwrap = real_unwrap
+
+
+class DoctestModule(Module):
+    def collect(self) -> Iterable[DoctestItem]:
+        import doctest
+
+        class MockAwareDocTestFinder(doctest.DocTestFinder):
+            """A hackish doctest finder that overrides stdlib internals to fix a stdlib bug.
+
+            https://github.com/pytest-dev/pytest/issues/3456
+            https://bugs.python.org/issue25532
+            """
+
+            def _find_lineno(self, obj, source_lines):
+                """Doctest code does not take into account `@property`, this
+                is a hackish way to fix it. https://bugs.python.org/issue17446
+
+                Wrapped Doctests will need to be unwrapped so the correct
+                line number is returned. This will be reported upstream. #8796
+                """
+                if isinstance(obj, property):
+                    obj = getattr(obj, "fget", obj)
+
+                if hasattr(obj, "__wrapped__"):
+                    # Get the main obj in case of it being wrapped
+                    obj = inspect.unwrap(obj)
+
+                # Type ignored because this is a private function.
+                return super()._find_lineno(  # type:ignore[misc]
+                    obj,
+                    source_lines,
+                )
+
+            def _find(
+                self, tests, obj, name, module, source_lines, globs, seen
+            ) -> None:
+                if _is_mocked(obj):
+                    return
+                with _patch_unwrap_mock_aware():
+                    # Type ignored because this is a private function.
+                    super()._find(  # type:ignore[misc]
+                        tests, obj, name, module, source_lines, globs, seen
+                    )
+
+            if sys.version_info < (3, 13):
+
+                def _from_module(self, module, object):
+                    """`cached_property` objects are never considered a part
+                    of the 'current module'. As such they are skipped by doctest.
+                    Here we override `_from_module` to check the underlying
+                    function instead. https://github.com/python/cpython/issues/107995
+                    """
+                    if hasattr(functools, "cached_property") and isinstance(
+                        object, functools.cached_property
+                    ):
+                        object = object.func
+
+                    # Type ignored because this is a private function.
+                    return super()._from_module(module, object)  # type: ignore[misc]
+
+            else:  # pragma: no cover
+                pass
+
+        if self.path.name == "conftest.py":
+            module = self.config.pluginmanager._importconftest(
+                self.path,
+                self.config.getoption("importmode"),
+                rootpath=self.config.rootpath,
+            )
+        else:
+            try:
+                module = import_path(
+                    self.path,
+                    root=self.config.rootpath,
+                    mode=self.config.getoption("importmode"),
+                )
+            except ImportError:
+                if self.config.getvalue("doctest_ignore_import_errors"):
+                    skip("unable to import module %r" % self.path)
+                else:
+                    raise
+        # Uses internal doctest module parsing mechanism.
+        finder = MockAwareDocTestFinder()
+        optionflags = get_optionflags(self)
+        runner = _get_runner(
+            verbose=False,
+            optionflags=optionflags,
+            checker=_get_checker(),
+            continue_on_failure=_get_continue_on_failure(self.config),
+        )
+
+        for test in finder.find(module, module.__name__):
+            if test.examples:  # skip empty doctests
+                yield DoctestItem.from_parent(
+                    self, name=test.name, runner=runner, dtest=test
+                )
+
+
+def _setup_fixtures(doctest_item: DoctestItem) -> FixtureRequest:
+    """Used by DoctestTextfile and DoctestItem to setup fixture information."""
+
+    def func() -> None:
+        pass
+
+    doctest_item.funcargs = {}  # type: ignore[attr-defined]
+    fm = doctest_item.session._fixturemanager
+    doctest_item._fixtureinfo = fm.getfixtureinfo(  # type: ignore[attr-defined]
+        node=doctest_item, func=func, cls=None, funcargs=False
+    )
+    fixture_request = FixtureRequest(doctest_item, _ispytest=True)
+    fixture_request._fillfixtures()
+    return fixture_request
+
+
+def _init_checker_class() -> Type["doctest.OutputChecker"]:
+    import doctest
+    import re
+
+    class LiteralsOutputChecker(doctest.OutputChecker):
+        # Based on doctest_nose_plugin.py from the nltk project
+        # (https://github.com/nltk/nltk) and on the "numtest" doctest extension
+        # by Sebastien Boisgerault (https://github.com/boisgera/numtest).
+
+        _unicode_literal_re = re.compile(r"(\W|^)[uU]([rR]?[\'\"])", re.UNICODE)
+        _bytes_literal_re = re.compile(r"(\W|^)[bB]([rR]?[\'\"])", re.UNICODE)
+        _number_re = re.compile(
+            r"""
+            (?P<number>
+              (?P<mantissa>
+                (?P<integer1> [+-]?\d*)\.(?P<fraction>\d+)
+                |
+                (?P<integer2> [+-]?\d+)\.
+              )
+              (?:
+                [Ee]
+                (?P<exponent1> [+-]?\d+)
+              )?
+              |
+              (?P<integer3> [+-]?\d+)
+              (?:
+                [Ee]
+                (?P<exponent2> [+-]?\d+)
+              )
+            )
+            """,
+            re.VERBOSE,
+        )
+
+        def check_output(self, want: str, got: str, optionflags: int) -> bool:
+            if super().check_output(want, got, optionflags):
+                return True
+
+            allow_unicode = optionflags & _get_allow_unicode_flag()
+            allow_bytes = optionflags & _get_allow_bytes_flag()
+            allow_number = optionflags & _get_number_flag()
+
+            if not allow_unicode and not allow_bytes and not allow_number:
+                return False
+
+            def remove_prefixes(regex: Pattern[str], txt: str) -> str:
+                return re.sub(regex, r"\1\2", txt)
+
+            if allow_unicode:
+                want = remove_prefixes(self._unicode_literal_re, want)
+                got = remove_prefixes(self._unicode_literal_re, got)
+
+            if allow_bytes:
+                want = remove_prefixes(self._bytes_literal_re, want)
+                got = remove_prefixes(self._bytes_literal_re, got)
+
+            if allow_number:
+                got = self._remove_unwanted_precision(want, got)
+
+            return super().check_output(want, got, optionflags)
+
+        def _remove_unwanted_precision(self, want: str, got: str) -> str:
+            wants = list(self._number_re.finditer(want))
+            gots = list(self._number_re.finditer(got))
+            if len(wants) != len(gots):
+                return got
+            offset = 0
+            for w, g in zip(wants, gots):
+                fraction: Optional[str] = w.group("fraction")
+                exponent: Optional[str] = w.group("exponent1")
+                if exponent is None:
+                    exponent = w.group("exponent2")
+                precision = 0 if fraction is None else len(fraction)
+                if exponent is not None:
+                    precision -= int(exponent)
+                if float(w.group()) == approx(float(g.group()), abs=10**-precision):
+                    # They're close enough. Replace the text we actually
+                    # got with the text we want, so that it will match when we
+                    # check the string literally.
+                    got = (
+                        got[: g.start() + offset] + w.group() + got[g.end() + offset :]
+                    )
+                    offset += w.end() - w.start() - (g.end() - g.start())
+            return got
+
+    return LiteralsOutputChecker
+
+
+def _get_checker() -> "doctest.OutputChecker":
+    """Return a doctest.OutputChecker subclass that supports some
+    additional options:
+
+    * ALLOW_UNICODE and ALLOW_BYTES options to ignore u'' and b''
+      prefixes (respectively) in string literals. Useful when the same
+      doctest should run in Python 2 and Python 3.
+
+    * NUMBER to ignore floating-point differences smaller than the
+      precision of the literal number in the doctest.
+
+    An inner class is used to avoid importing "doctest" at the module
+    level.
+    """
+    global CHECKER_CLASS
+    if CHECKER_CLASS is None:
+        CHECKER_CLASS = _init_checker_class()
+    return CHECKER_CLASS()
+
+
+def _get_allow_unicode_flag() -> int:
+    """Register and return the ALLOW_UNICODE flag."""
+    import doctest
+
+    return doctest.register_optionflag("ALLOW_UNICODE")
+
+
+def _get_allow_bytes_flag() -> int:
+    """Register and return the ALLOW_BYTES flag."""
+    import doctest
+
+    return doctest.register_optionflag("ALLOW_BYTES")
+
+
+def _get_number_flag() -> int:
+    """Register and return the NUMBER flag."""
+    import doctest
+
+    return doctest.register_optionflag("NUMBER")
+
+
+def _get_report_choice(key: str) -> int:
+    """Return the actual `doctest` module flag value.
+
+    We want to do it as late as possible to avoid importing `doctest` and all
+    its dependencies when parsing options, as it adds overhead and breaks tests.
+    """
+    import doctest
+
+    return {
+        DOCTEST_REPORT_CHOICE_UDIFF: doctest.REPORT_UDIFF,
+        DOCTEST_REPORT_CHOICE_CDIFF: doctest.REPORT_CDIFF,
+        DOCTEST_REPORT_CHOICE_NDIFF: doctest.REPORT_NDIFF,
+        DOCTEST_REPORT_CHOICE_ONLY_FIRST_FAILURE: doctest.REPORT_ONLY_FIRST_FAILURE,
+        DOCTEST_REPORT_CHOICE_NONE: 0,
+    }[key]
+
+
+@fixture(scope="session")
+def doctest_namespace() -> Dict[str, Any]:
+    """Fixture that returns a :py:class:`dict` that will be injected into the
+    namespace of doctests.
+
+    Usually this fixture is used in conjunction with another ``autouse`` fixture:
+
+    .. code-block:: python
+
+        @pytest.fixture(autouse=True)
+        def add_np(doctest_namespace):
+            doctest_namespace["np"] = numpy
+
+    For more details: :ref:`doctest_namespace`.
+    """
+    return dict()