niceSOFT/python3-pytest: The pytest framework makes it easy to write small tests, yet scales to support complex functional testing

src/_pytest/main.py
1 076 строк37 KB
Bruno Oliveira
Merge pull request #11997 from nicoddemus/11475-importlib
03 мар 2024, 15:43
03 мар 2024, 15:4389ee449
"""Core implementation of the testing process: init, session, runtest loop."""

import argparse
import dataclasses
import fnmatch
import functools
import importlib
import importlib.util
import os
from pathlib import Path
import sys
from typing import AbstractSet
from typing import Callable
from typing import Dict
from typing import final
from typing import FrozenSet
from typing import Iterable
from typing import Iterator
from typing import List
from typing import Literal
from typing import Optional
from typing import overload
from typing import Sequence
from typing import Tuple
from typing import TYPE_CHECKING
from typing import Union
import warnings

import pluggy

from _pytest import nodes
import _pytest._code
from _pytest.config import Config
from _pytest.config import directory_arg
from _pytest.config import ExitCode
from _pytest.config import hookimpl
from _pytest.config import PytestPluginManager
from _pytest.config import UsageError
from _pytest.config.argparsing import Parser
from _pytest.fixtures import FixtureManager
from _pytest.outcomes import exit
from _pytest.pathlib import absolutepath
from _pytest.pathlib import bestrelpath
from _pytest.pathlib import fnmatch_ex
from _pytest.pathlib import safe_exists
from _pytest.pathlib import scandir
from _pytest.reports import CollectReport
from _pytest.reports import TestReport
from _pytest.runner import collect_one_node
from _pytest.runner import SetupState
from _pytest.warning_types import PytestWarning


if TYPE_CHECKING:
    from typing import Self


def pytest_addoption(parser: Parser) -> None:
    parser.addini(
        "norecursedirs",
        "Directory patterns to avoid for recursion",
        type="args",
        default=[
            "*.egg",
            ".*",
            "_darcs",
            "build",
            "CVS",
            "dist",
            "node_modules",
            "venv",
            "{arch}",
        ],
    )
    parser.addini(
        "testpaths",
        "Directories to search for tests when no files or directories are given on the "
        "command line",
        type="args",
        default=[],
    )
    group = parser.getgroup("general", "Running and selection options")
    group._addoption(
        "-x",
        "--exitfirst",
        action="store_const",
        dest="maxfail",
        const=1,
        help="Exit instantly on first error or failed test",
    )
    group = parser.getgroup("pytest-warnings")
    group.addoption(
        "-W",
        "--pythonwarnings",
        action="append",
        help="Set which warnings to report, see -W option of Python itself",
    )
    parser.addini(
        "filterwarnings",
        type="linelist",
        help="Each line specifies a pattern for "
        "warnings.filterwarnings. "
        "Processed after -W/--pythonwarnings.",
    )
    group._addoption(
        "--maxfail",
        metavar="num",
        action="store",
        type=int,
        dest="maxfail",
        default=0,
        help="Exit after first num failures or errors",
    )
    group._addoption(
        "--strict-config",
        action="store_true",
        help="Any warnings encountered while parsing the `pytest` section of the "
        "configuration file raise errors",
    )
    group._addoption(
        "--strict-markers",
        action="store_true",
        help="Markers not registered in the `markers` section of the configuration "
        "file raise errors",
    )
    group._addoption(
        "--strict",
        action="store_true",
        help="(Deprecated) alias to --strict-markers",
    )
    group._addoption(
        "-c",
        "--config-file",
        metavar="FILE",
        type=str,
        dest="inifilename",
        help="Load configuration from `FILE` instead of trying to locate one of the "
        "implicit configuration files.",
    )
    group._addoption(
        "--continue-on-collection-errors",
        action="store_true",
        default=False,
        dest="continue_on_collection_errors",
        help="Force test execution even if collection errors occur",
    )
    group._addoption(
        "--rootdir",
        action="store",
        dest="rootdir",
        help="Define root directory for tests. Can be relative path: 'root_dir', './root_dir', "
        "'root_dir/another_dir/'; absolute path: '/home/user/root_dir'; path with variables: "
        "'$HOME/root_dir'.",
    )

    group = parser.getgroup("collect", "collection")
    group.addoption(
        "--collectonly",
        "--collect-only",
        "--co",
        action="store_true",
        help="Only collect tests, don't execute them",
    )
    group.addoption(
        "--pyargs",
        action="store_true",
        help="Try to interpret all arguments as Python packages",
    )
    group.addoption(
        "--ignore",
        action="append",
        metavar="path",
        help="Ignore path during collection (multi-allowed)",
    )
    group.addoption(
        "--ignore-glob",
        action="append",
        metavar="path",
        help="Ignore path pattern during collection (multi-allowed)",
    )
    group.addoption(
        "--deselect",
        action="append",
        metavar="nodeid_prefix",
        help="Deselect item (via node id prefix) during collection (multi-allowed)",
    )
    group.addoption(
        "--confcutdir",
        dest="confcutdir",
        default=None,
        metavar="dir",
        type=functools.partial(directory_arg, optname="--confcutdir"),
        help="Only load conftest.py's relative to specified dir",
    )
    group.addoption(
        "--noconftest",
        action="store_true",
        dest="noconftest",
        default=False,
        help="Don't load any conftest.py files",
    )
    group.addoption(
        "--keepduplicates",
        "--keep-duplicates",
        action="store_true",
        dest="keepduplicates",
        default=False,
        help="Keep duplicate tests",
    )
    group.addoption(
        "--collect-in-virtualenv",
        action="store_true",
        dest="collect_in_virtualenv",
        default=False,
        help="Don't ignore tests in a local virtualenv directory",
    )
    group.addoption(
        "--import-mode",
        default="prepend",
        choices=["prepend", "append", "importlib"],
        dest="importmode",
        help="Prepend/append to sys.path when importing test modules and conftest "
        "files. Default: prepend.",
    )
    parser.addini(
        "consider_namespace_packages",
        type="bool",
        default=False,
        help="Consider namespace packages when resolving module names during import",
    )

    group = parser.getgroup("debugconfig", "test session debugging and configuration")
    group.addoption(
        "--basetemp",
        dest="basetemp",
        default=None,
        type=validate_basetemp,
        metavar="dir",
        help=(
            "Base temporary directory for this test run. "
            "(Warning: this directory is removed if it exists.)"
        ),
    )


def validate_basetemp(path: str) -> str:
    # GH 7119
    msg = "basetemp must not be empty, the current working directory or any parent directory of it"

    # empty path
    if not path:
        raise argparse.ArgumentTypeError(msg)

    def is_ancestor(base: Path, query: Path) -> bool:
        """Return whether query is an ancestor of base."""
        if base == query:
            return True
        return query in base.parents

    # check if path is an ancestor of cwd
    if is_ancestor(Path.cwd(), Path(path).absolute()):
        raise argparse.ArgumentTypeError(msg)

    # check symlinks for ancestors
    if is_ancestor(Path.cwd().resolve(), Path(path).resolve()):
        raise argparse.ArgumentTypeError(msg)

    return path


def wrap_session(
    config: Config, doit: Callable[[Config, "Session"], Optional[Union[int, ExitCode]]]
) -> Union[int, ExitCode]:
    """Skeleton command line program."""
    session = Session.from_config(config)
    session.exitstatus = ExitCode.OK
    initstate = 0
    try:
        try:
            config._do_configure()
            initstate = 1
            config.hook.pytest_sessionstart(session=session)
            initstate = 2
            session.exitstatus = doit(config, session) or 0
        except UsageError:
            session.exitstatus = ExitCode.USAGE_ERROR
            raise
        except Failed:
            session.exitstatus = ExitCode.TESTS_FAILED
        except (KeyboardInterrupt, exit.Exception):
            excinfo = _pytest._code.ExceptionInfo.from_current()
            exitstatus: Union[int, ExitCode] = ExitCode.INTERRUPTED
            if isinstance(excinfo.value, exit.Exception):
                if excinfo.value.returncode is not None:
                    exitstatus = excinfo.value.returncode
                if initstate < 2:
                    sys.stderr.write(f"{excinfo.typename}: {excinfo.value.msg}\n")
            config.hook.pytest_keyboard_interrupt(excinfo=excinfo)
            session.exitstatus = exitstatus
        except BaseException:
            session.exitstatus = ExitCode.INTERNAL_ERROR
            excinfo = _pytest._code.ExceptionInfo.from_current()
            try:
                config.notify_exception(excinfo, config.option)
            except exit.Exception as exc:
                if exc.returncode is not None:
                    session.exitstatus = exc.returncode
                sys.stderr.write(f"{type(exc).__name__}: {exc}\n")
            else:
                if isinstance(excinfo.value, SystemExit):
                    sys.stderr.write("mainloop: caught unexpected SystemExit!\n")

    finally:
        # Explicitly break reference cycle.
        excinfo = None  # type: ignore
        os.chdir(session.startpath)
        if initstate >= 2:
            try:
                config.hook.pytest_sessionfinish(
                    session=session, exitstatus=session.exitstatus
                )
            except exit.Exception as exc:
                if exc.returncode is not None:
                    session.exitstatus = exc.returncode
                sys.stderr.write(f"{type(exc).__name__}: {exc}\n")
        config._ensure_unconfigure()
    return session.exitstatus


def pytest_cmdline_main(config: Config) -> Union[int, ExitCode]:
    return wrap_session(config, _main)


def _main(config: Config, session: "Session") -> Optional[Union[int, ExitCode]]:
    """Default command line protocol for initialization, session,
    running tests and reporting."""
    config.hook.pytest_collection(session=session)
    config.hook.pytest_runtestloop(session=session)

    if session.testsfailed:
        return ExitCode.TESTS_FAILED
    elif session.testscollected == 0:
        return ExitCode.NO_TESTS_COLLECTED
    return None


def pytest_collection(session: "Session") -> None:
    session.perform_collect()


def pytest_runtestloop(session: "Session") -> bool:
    if session.testsfailed and not session.config.option.continue_on_collection_errors:
        raise session.Interrupted(
            "%d error%s during collection"
            % (session.testsfailed, "s" if session.testsfailed != 1 else "")
        )

    if session.config.option.collectonly:
        return True

    for i, item in enumerate(session.items):
        nextitem = session.items[i + 1] if i + 1 < len(session.items) else None
        item.config.hook.pytest_runtest_protocol(item=item, nextitem=nextitem)
        if session.shouldfail:
            raise session.Failed(session.shouldfail)
        if session.shouldstop:
            raise session.Interrupted(session.shouldstop)
    return True


def _in_venv(path: Path) -> bool:
    """Attempt to detect if ``path`` is the root of a Virtual Environment by
    checking for the existence of the appropriate activate script."""
    bindir = path.joinpath("Scripts" if sys.platform.startswith("win") else "bin")
    try:
        if not bindir.is_dir():
            return False
    except OSError:
        return False
    activates = (
        "activate",
        "activate.csh",
        "activate.fish",
        "Activate",
        "Activate.bat",
        "Activate.ps1",
    )
    return any(fname.name in activates for fname in bindir.iterdir())


def pytest_ignore_collect(collection_path: Path, config: Config) -> Optional[bool]:
    if collection_path.name == "__pycache__":
        return True

    ignore_paths = config._getconftest_pathlist(
        "collect_ignore", path=collection_path.parent
    )
    ignore_paths = ignore_paths or []
    excludeopt = config.getoption("ignore")
    if excludeopt:
        ignore_paths.extend(absolutepath(x) for x in excludeopt)

    if collection_path in ignore_paths:
        return True

    ignore_globs = config._getconftest_pathlist(
        "collect_ignore_glob", path=collection_path.parent
    )
    ignore_globs = ignore_globs or []
    excludeglobopt = config.getoption("ignore_glob")
    if excludeglobopt:
        ignore_globs.extend(absolutepath(x) for x in excludeglobopt)

    if any(fnmatch.fnmatch(str(collection_path), str(glob)) for glob in ignore_globs):
        return True

    allow_in_venv = config.getoption("collect_in_virtualenv")
    if not allow_in_venv and _in_venv(collection_path):
        return True

    if collection_path.is_dir():
        norecursepatterns = config.getini("norecursedirs")
        if any(fnmatch_ex(pat, collection_path) for pat in norecursepatterns):
            return True

    return None


def pytest_collect_directory(
    path: Path, parent: nodes.Collector
) -> Optional[nodes.Collector]:
    return Dir.from_parent(parent, path=path)


def pytest_collection_modifyitems(items: List[nodes.Item], config: Config) -> None:
    deselect_prefixes = tuple(config.getoption("deselect") or [])
    if not deselect_prefixes:
        return

    remaining = []
    deselected = []
    for colitem in items:
        if colitem.nodeid.startswith(deselect_prefixes):
            deselected.append(colitem)
        else:
            remaining.append(colitem)

    if deselected:
        config.hook.pytest_deselected(items=deselected)
        items[:] = remaining


class FSHookProxy:
    def __init__(
        self,
        pm: PytestPluginManager,
        remove_mods: AbstractSet[object],
    ) -> None:
        self.pm = pm
        self.remove_mods = remove_mods

    def __getattr__(self, name: str) -> pluggy.HookCaller:
        x = self.pm.subset_hook_caller(name, remove_plugins=self.remove_mods)
        self.__dict__[name] = x
        return x


class Interrupted(KeyboardInterrupt):
    """Signals that the test run was interrupted."""

    __module__ = "builtins"  # For py3.


class Failed(Exception):
    """Signals a stop as failed test run."""


@dataclasses.dataclass
class _bestrelpath_cache(Dict[Path, str]):
    __slots__ = ("path",)

    path: Path

    def __missing__(self, path: Path) -> str:
        r = bestrelpath(self.path, path)
        self[path] = r
        return r


@final
class Dir(nodes.Directory):
    """Collector of files in a file system directory.

    .. versionadded:: 8.0

    .. note::

        Python directories with an `__init__.py` file are instead collected by
        :class:`~pytest.Package` by default. Both are :class:`~pytest.Directory`
        collectors.
    """

    @classmethod
    def from_parent(  # type: ignore[override]
        cls,
        parent: nodes.Collector,
        *,
        path: Path,
    ) -> "Self":
        """The public constructor.

        :param parent: The parent collector of this Dir.
        :param path: The directory's path.
        """
        return super().from_parent(parent=parent, path=path)

    def collect(self) -> Iterable[Union[nodes.Item, nodes.Collector]]:
        config = self.config
        col: Optional[nodes.Collector]
        cols: Sequence[nodes.Collector]
        ihook = self.ihook
        for direntry in scandir(self.path):
            if direntry.is_dir():
                path = Path(direntry.path)
                if not self.session.isinitpath(path, with_parents=True):
                    if ihook.pytest_ignore_collect(collection_path=path, config=config):
                        continue
                col = ihook.pytest_collect_directory(path=path, parent=self)
                if col is not None:
                    yield col

            elif direntry.is_file():
                path = Path(direntry.path)
                if not self.session.isinitpath(path):
                    if ihook.pytest_ignore_collect(collection_path=path, config=config):
                        continue
                cols = ihook.pytest_collect_file(file_path=path, parent=self)
                yield from cols


@final
class Session(nodes.Collector):
    """The root of the collection tree.

    ``Session`` collects the initial paths given as arguments to pytest.
    """

    Interrupted = Interrupted
    Failed = Failed
    # Set on the session by runner.pytest_sessionstart.
    _setupstate: SetupState
    # Set on the session by fixtures.pytest_sessionstart.
    _fixturemanager: FixtureManager
    exitstatus: Union[int, ExitCode]

    def __init__(self, config: Config) -> None:
        super().__init__(
            name="",
            path=config.rootpath,
            parent=None,
            config=config,
            session=self,
            nodeid="",
        )
        self.testsfailed = 0
        self.testscollected = 0
        self._shouldstop: Union[bool, str] = False
        self._shouldfail: Union[bool, str] = False
        self.trace = config.trace.root.get("collection")
        self._initialpaths: FrozenSet[Path] = frozenset()
        self._initialpaths_with_parents: FrozenSet[Path] = frozenset()
        self._notfound: List[Tuple[str, Sequence[nodes.Collector]]] = []
        self._initial_parts: List[CollectionArgument] = []
        self._collection_cache: Dict[nodes.Collector, CollectReport] = {}
        self.items: List[nodes.Item] = []

        self._bestrelpathcache: Dict[Path, str] = _bestrelpath_cache(config.rootpath)

        self.config.pluginmanager.register(self, name="session")

    @classmethod
    def from_config(cls, config: Config) -> "Session":
        session: Session = cls._create(config=config)
        return session

    def __repr__(self) -> str:
        return "<%s %s exitstatus=%r testsfailed=%d testscollected=%d>" % (
            self.__class__.__name__,
            self.name,
            getattr(self, "exitstatus", "<UNSET>"),
            self.testsfailed,
            self.testscollected,
        )

    @property
    def shouldstop(self) -> Union[bool, str]:
        return self._shouldstop

    @shouldstop.setter
    def shouldstop(self, value: Union[bool, str]) -> None:
        # The runner checks shouldfail and assumes that if it is set we are
        # definitely stopping, so prevent unsetting it.
        if value is False and self._shouldstop:
            warnings.warn(
                PytestWarning(
                    "session.shouldstop cannot be unset after it has been set; ignoring."
                ),
                stacklevel=2,
            )
            return
        self._shouldstop = value

    @property
    def shouldfail(self) -> Union[bool, str]:
        return self._shouldfail

    @shouldfail.setter
    def shouldfail(self, value: Union[bool, str]) -> None:
        # The runner checks shouldfail and assumes that if it is set we are
        # definitely stopping, so prevent unsetting it.
        if value is False and self._shouldfail:
            warnings.warn(
                PytestWarning(
                    "session.shouldfail cannot be unset after it has been set; ignoring."
                ),
                stacklevel=2,
            )
            return
        self._shouldfail = value

    @property
    def startpath(self) -> Path:
        """The path from which pytest was invoked.

        .. versionadded:: 7.0.0
        """
        return self.config.invocation_params.dir

    def _node_location_to_relpath(self, node_path: Path) -> str:
        # bestrelpath is a quite slow function.
        return self._bestrelpathcache[node_path]

    @hookimpl(tryfirst=True)
    def pytest_collectstart(self) -> None:
        if self.shouldfail:
            raise self.Failed(self.shouldfail)
        if self.shouldstop:
            raise self.Interrupted(self.shouldstop)

    @hookimpl(tryfirst=True)
    def pytest_runtest_logreport(
        self, report: Union[TestReport, CollectReport]
    ) -> None:
        if report.failed and not hasattr(report, "wasxfail"):
            self.testsfailed += 1
            maxfail = self.config.getvalue("maxfail")
            if maxfail and self.testsfailed >= maxfail:
                self.shouldfail = "stopping after %d failures" % (self.testsfailed)

    pytest_collectreport = pytest_runtest_logreport

    def isinitpath(
        self,
        path: Union[str, "os.PathLike[str]"],
        *,
        with_parents: bool = False,
    ) -> bool:
        """Is path an initial path?

        An initial path is a path explicitly given to pytest on the command
        line.

        :param with_parents:
            If set, also return True if the path is a parent of an initial path.

        .. versionchanged:: 8.0
            Added the ``with_parents`` parameter.
        """
        # Optimization: Path(Path(...)) is much slower than isinstance.
        path_ = path if isinstance(path, Path) else Path(path)
        if with_parents:
            return path_ in self._initialpaths_with_parents
        else:
            return path_ in self._initialpaths

    def gethookproxy(self, fspath: "os.PathLike[str]") -> pluggy.HookRelay:
        # Optimization: Path(Path(...)) is much slower than isinstance.
        path = fspath if isinstance(fspath, Path) else Path(fspath)
        pm = self.config.pluginmanager
        # Check if we have the common case of running
        # hooks with all conftest.py files.
        my_conftestmodules = pm._getconftestmodules(path)
        remove_mods = pm._conftest_plugins.difference(my_conftestmodules)
        proxy: pluggy.HookRelay
        if remove_mods:
            # One or more conftests are not in use at this path.
            proxy = FSHookProxy(pm, remove_mods)  # type: ignore[arg-type,assignment]
        else:
            # All plugins are active for this fspath.
            proxy = self.config.hook
        return proxy

    def _collect_path(
        self,
        path: Path,
        path_cache: Dict[Path, Sequence[nodes.Collector]],
    ) -> Sequence[nodes.Collector]:
        """Create a Collector for the given path.

        `path_cache` makes it so the same Collectors are returned for the same
        path.
        """
        if path in path_cache:
            return path_cache[path]

        if path.is_dir():
            ihook = self.gethookproxy(path.parent)
            col: Optional[nodes.Collector] = ihook.pytest_collect_directory(
                path=path, parent=self
            )
            cols: Sequence[nodes.Collector] = (col,) if col is not None else ()

        elif path.is_file():
            ihook = self.gethookproxy(path)
            cols = ihook.pytest_collect_file(file_path=path, parent=self)

        else:
            # Broken symlink or invalid/missing file.
            cols = ()

        path_cache[path] = cols
        return cols

    @overload
    def perform_collect(
        self, args: Optional[Sequence[str]] = ..., genitems: "Literal[True]" = ...
    ) -> Sequence[nodes.Item]:
        ...

    @overload
    def perform_collect(
        self, args: Optional[Sequence[str]] = ..., genitems: bool = ...
    ) -> Sequence[Union[nodes.Item, nodes.Collector]]:
        ...

    def perform_collect(
        self, args: Optional[Sequence[str]] = None, genitems: bool = True
    ) -> Sequence[Union[nodes.Item, nodes.Collector]]:
        """Perform the collection phase for this session.

        This is called by the default :hook:`pytest_collection` hook
        implementation; see the documentation of this hook for more details.
        For testing purposes, it may also be called directly on a fresh
        ``Session``.

        This function normally recursively expands any collectors collected
        from the session to their items, and only items are returned. For
        testing purposes, this may be suppressed by passing ``genitems=False``,
        in which case the return value contains these collectors unexpanded,
        and ``session.items`` is empty.
        """
        if args is None:
            args = self.config.args

        self.trace("perform_collect", self, args)
        self.trace.root.indent += 1

        hook = self.config.hook

        self._notfound = []
        self._initial_parts = []
        self._collection_cache = {}
        self.items = []
        items: Sequence[Union[nodes.Item, nodes.Collector]] = self.items
        try:
            initialpaths: List[Path] = []
            initialpaths_with_parents: List[Path] = []
            for arg in args:
                collection_argument = resolve_collection_argument(
                    self.config.invocation_params.dir,
                    arg,
                    as_pypath=self.config.option.pyargs,
                )
                self._initial_parts.append(collection_argument)
                initialpaths.append(collection_argument.path)
                initialpaths_with_parents.append(collection_argument.path)
                initialpaths_with_parents.extend(collection_argument.path.parents)
            self._initialpaths = frozenset(initialpaths)
            self._initialpaths_with_parents = frozenset(initialpaths_with_parents)

            rep = collect_one_node(self)
            self.ihook.pytest_collectreport(report=rep)
            self.trace.root.indent -= 1
            if self._notfound:
                errors = []
                for arg, collectors in self._notfound:
                    if collectors:
                        errors.append(
                            f"not found: {arg}\n(no match in any of {collectors!r})"
                        )
                    else:
                        errors.append(f"found no collectors for {arg}")

                raise UsageError(*errors)

            if not genitems:
                items = rep.result
            else:
                if rep.passed:
                    for node in rep.result:
                        self.items.extend(self.genitems(node))

            self.config.pluginmanager.check_pending()
            hook.pytest_collection_modifyitems(
                session=self, config=self.config, items=items
            )
        finally:
            self._notfound = []
            self._initial_parts = []
            self._collection_cache = {}
            hook.pytest_collection_finish(session=self)

        if genitems:
            self.testscollected = len(items)

        return items

    def _collect_one_node(
        self,
        node: nodes.Collector,
        handle_dupes: bool = True,
    ) -> Tuple[CollectReport, bool]:
        if node in self._collection_cache and handle_dupes:
            rep = self._collection_cache[node]
            return rep, True
        else:
            rep = collect_one_node(node)
            self._collection_cache[node] = rep
            return rep, False

    def collect(self) -> Iterator[Union[nodes.Item, nodes.Collector]]:
        # This is a cache for the root directories of the initial paths.
        # We can't use collection_cache for Session because of its special
        # role as the bootstrapping collector.
        path_cache: Dict[Path, Sequence[nodes.Collector]] = {}

        pm = self.config.pluginmanager

        for collection_argument in self._initial_parts:
            self.trace("processing argument", collection_argument)
            self.trace.root.indent += 1

            argpath = collection_argument.path
            names = collection_argument.parts
            module_name = collection_argument.module_name

            # resolve_collection_argument() ensures this.
            if argpath.is_dir():
                assert not names, f"invalid arg {(argpath, names)!r}"

            paths = [argpath]
            # Add relevant parents of the path, from the root, e.g.
            #   /a/b/c.py -> [/, /a, /a/b, /a/b/c.py]
            if module_name is None:
                # Paths outside of the confcutdir should not be considered.
                for path in argpath.parents:
                    if not pm._is_in_confcutdir(path):
                        break
                    paths.insert(0, path)
            else:
                # For --pyargs arguments, only consider paths matching the module
                # name. Paths beyond the package hierarchy are not included.
                module_name_parts = module_name.split(".")
                for i, path in enumerate(argpath.parents, 2):
                    if i > len(module_name_parts) or path.stem != module_name_parts[-i]:
                        break
                    paths.insert(0, path)

            # Start going over the parts from the root, collecting each level
            # and discarding all nodes which don't match the level's part.
            any_matched_in_initial_part = False
            notfound_collectors = []
            work: List[
                Tuple[Union[nodes.Collector, nodes.Item], List[Union[Path, str]]]
            ] = [(self, [*paths, *names])]
            while work:
                matchnode, matchparts = work.pop()

                # Pop'd all of the parts, this is a match.
                if not matchparts:
                    yield matchnode
                    any_matched_in_initial_part = True
                    continue

                # Should have been matched by now, discard.
                if not isinstance(matchnode, nodes.Collector):
                    continue

                # Collect this level of matching.
                # Collecting Session (self) is done directly to avoid endless
                # recursion to this function.
                subnodes: Sequence[Union[nodes.Collector, nodes.Item]]
                if isinstance(matchnode, Session):
                    assert isinstance(matchparts[0], Path)
                    subnodes = matchnode._collect_path(matchparts[0], path_cache)
                else:
                    # For backward compat, files given directly multiple
                    # times on the command line should not be deduplicated.
                    handle_dupes = not (
                        len(matchparts) == 1
                        and isinstance(matchparts[0], Path)
                        and matchparts[0].is_file()
                    )
                    rep, duplicate = self._collect_one_node(matchnode, handle_dupes)
                    if not duplicate and not rep.passed:
                        # Report collection failures here to avoid failing to
                        # run some test specified in the command line because
                        # the module could not be imported (#134).
                        matchnode.ihook.pytest_collectreport(report=rep)
                    if not rep.passed:
                        continue
                    subnodes = rep.result

                # Prune this level.
                any_matched_in_collector = False
                for node in reversed(subnodes):
                    # Path part e.g. `/a/b/` in `/a/b/test_file.py::TestIt::test_it`.
                    if isinstance(matchparts[0], Path):
                        is_match = node.path == matchparts[0]
                        if sys.platform == "win32" and not is_match:
                            # In case the file paths do not match, fallback to samefile() to
                            # account for short-paths on Windows (#11895).
                            same_file = os.path.samefile(node.path, matchparts[0])
                            # We don't want to match links to the current node,
                            # otherwise we would match the same file more than once (#12039).
                            is_match = same_file and (
                                os.path.islink(node.path)
                                == os.path.islink(matchparts[0])
                            )

                    # Name part e.g. `TestIt` in `/a/b/test_file.py::TestIt::test_it`.
                    else:
                        # TODO: Remove parametrized workaround once collection structure contains
                        # parametrization.
                        is_match = (
                            node.name == matchparts[0]
                            or node.name.split("[")[0] == matchparts[0]
                        )
                    if is_match:
                        work.append((node, matchparts[1:]))
                        any_matched_in_collector = True

                if not any_matched_in_collector:
                    notfound_collectors.append(matchnode)

            if not any_matched_in_initial_part:
                report_arg = "::".join((str(argpath), *names))
                self._notfound.append((report_arg, notfound_collectors))

            self.trace.root.indent -= 1

    def genitems(
        self, node: Union[nodes.Item, nodes.Collector]
    ) -> Iterator[nodes.Item]:
        self.trace("genitems", node)
        if isinstance(node, nodes.Item):
            node.ihook.pytest_itemcollected(item=node)
            yield node
        else:
            assert isinstance(node, nodes.Collector)
            keepduplicates = self.config.getoption("keepduplicates")
            # For backward compat, dedup only applies to files.
            handle_dupes = not (keepduplicates and isinstance(node, nodes.File))
            rep, duplicate = self._collect_one_node(node, handle_dupes)
            if duplicate and not keepduplicates:
                return
            if rep.passed:
                for subnode in rep.result:
                    yield from self.genitems(subnode)
            if not duplicate:
                node.ihook.pytest_collectreport(report=rep)


def search_pypath(module_name: str) -> Optional[str]:
    """Search sys.path for the given a dotted module name, and return its file
    system path if found."""
    try:
        spec = importlib.util.find_spec(module_name)
    # AttributeError: looks like package module, but actually filename
    # ImportError: module does not exist
    # ValueError: not a module name
    except (AttributeError, ImportError, ValueError):
        return None
    if spec is None or spec.origin is None or spec.origin == "namespace":
        return None
    elif spec.submodule_search_locations:
        return os.path.dirname(spec.origin)
    else:
        return spec.origin


@dataclasses.dataclass(frozen=True)
class CollectionArgument:
    """A resolved collection argument."""

    path: Path
    parts: Sequence[str]
    module_name: Optional[str]


def resolve_collection_argument(
    invocation_path: Path, arg: str, *, as_pypath: bool = False
) -> CollectionArgument:
    """Parse path arguments optionally containing selection parts and return (fspath, names).

    Command-line arguments can point to files and/or directories, and optionally contain
    parts for specific tests selection, for example:

        "pkg/tests/test_foo.py::TestClass::test_foo"

    This function ensures the path exists, and returns a resolved `CollectionArgument`:

        CollectionArgument(
            path=Path("/full/path/to/pkg/tests/test_foo.py"),
            parts=["TestClass", "test_foo"],
            module_name=None,
        )

    When as_pypath is True, expects that the command-line argument actually contains
    module paths instead of file-system paths:

        "pkg.tests.test_foo::TestClass::test_foo"

    In which case we search sys.path for a matching module, and then return the *path* to the
    found module, which may look like this:

        CollectionArgument(
            path=Path("/home/u/myvenv/lib/site-packages/pkg/tests/test_foo.py"),
            parts=["TestClass", "test_foo"],
            module_name="pkg.tests.test_foo",
        )

    If the path doesn't exist, raise UsageError.
    If the path is a directory and selection parts are present, raise UsageError.
    """
    base, squacket, rest = str(arg).partition("[")
    strpath, *parts = base.split("::")
    if parts:
        parts[-1] = f"{parts[-1]}{squacket}{rest}"
    module_name = None
    if as_pypath:
        pyarg_strpath = search_pypath(strpath)
        if pyarg_strpath is not None:
            module_name = strpath
            strpath = pyarg_strpath
    fspath = invocation_path / strpath
    fspath = absolutepath(fspath)
    if not safe_exists(fspath):
        msg = (
            "module or package not found: {arg} (missing __init__.py?)"
            if as_pypath
            else "file or directory not found: {arg}"
        )
        raise UsageError(msg.format(arg=arg))
    if parts and fspath.is_dir():
        msg = (
            "package argument cannot contain :: selection parts: {arg}"
            if as_pypath
            else "directory argument cannot contain :: selection parts: {arg}"
        )
        raise UsageError(msg.format(arg=arg))
    return CollectionArgument(
        path=fspath,
        parts=parts,
        module_name=module_name,
    )