sessions.py

# Copyright 2016 Alethea Katherine Flowers
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import argparse
import enum
import hashlib
import os
import pathlib
import re
import sys
import unicodedata
import warnings
from typing import (
    Any,
    Callable,
    Dict,
    Iterable,
    List,
    Mapping,
    Optional,
    Sequence,
    Tuple,
    Union,
)

import py

import nox.command
from nox import _typing
from nox._decorators import Func
from nox.logger import logger
from nox.virtualenv import CondaEnv, PassthroughEnv, ProcessEnv, VirtualEnv

if _typing.TYPE_CHECKING:
    from nox.manifest import Manifest


def _normalize_path(envdir: str, path: Union[str, bytes]) -> str:
    """Normalizes a string to be a "safe" filesystem path for a virtualenv."""
    if isinstance(path, bytes):
        path = path.decode("utf-8")

    path = unicodedata.normalize("NFKD", path).encode("ascii", "ignore")
    path = path.decode("ascii")
    path = re.sub(r"[^\w\s-]", "-", path).strip().lower()
    path = re.sub(r"[-\s]+", "-", path)
    path = path.strip("-")

    full_path = os.path.join(envdir, path)
    if len(full_path) > 100 - len("bin/pythonX.Y"):
        if len(envdir) < 100 - 9:
            path = hashlib.sha1(path.encode("ascii")).hexdigest()[:8]
            full_path = os.path.join(envdir, path)
            logger.warning("The virtualenv name was hashed to avoid being too long.")
        else:
            logger.error(
                f"The virtualenv path {full_path} is too long and will cause issues on "
                "some environments. Use the --envdir path to modify where "
                "nox stores virtualenvs."
            )

    return full_path


def _dblquote_pkg_install_args(args: Tuple[str, ...]) -> Tuple[str, ...]:
    """Double-quote package install arguments in case they contain '>' or '<' symbols"""

    # routine used to handle a single arg
    def _dblquote_pkg_install_arg(pkg_req_str: str) -> str:
        # sanity check: we need an even number of double-quotes
        if pkg_req_str.count('"') % 2 != 0:
            raise ValueError(
                f"ill-formated argument with odd number of quotes: {pkg_req_str}"
            )

        if "<" in pkg_req_str or ">" in pkg_req_str:
            if pkg_req_str[0] == '"' and pkg_req_str[-1] == '"':
                # already double-quoted string
                return pkg_req_str
            else:
                # need to double-quote string
                if '"' in pkg_req_str:
                    raise ValueError(f"Cannot escape requirement string: {pkg_req_str}")
                return f'"{pkg_req_str}"'
        else:
            # no dangerous char: no need to double-quote string
            return pkg_req_str

    # double-quote all args that need to be and return the result
    return tuple(_dblquote_pkg_install_arg(a) for a in args)


class _SessionQuit(Exception):
    pass


class _SessionSkip(Exception):
    pass


class Status(enum.Enum):
    ABORTED = -1
    FAILED = 0
    SUCCESS = 1
    SKIPPED = 2


class Session:
    """The Session object is passed into each user-defined session function.

    This is your primary means for installing package and running commands in
    your Nox session.
    """

    __slots__ = ("_runner",)

    def __init__(self, runner: "SessionRunner") -> None:
        self._runner = runner

    @property
    def __dict__(self) -> "Dict[str, SessionRunner]":  # type: ignore[override]
        """Attribute dictionary for object inspection.

        This is needed because ``__slots__`` turns off ``__dict__`` by
        default. Unlike a typical object, modifying the result of this
        dictionary won't allow modification of the instance.
        """
        return {"_runner": self._runner}

    @property
    def name(self) -> str:
        """The name of this session."""
        return self._runner.friendly_name

    @property
    def env(self) -> dict:
        """A dictionary of environment variables to pass into all commands."""
        return self.virtualenv.env

    @property
    def posargs(self) -> List[str]:
        """Any extra arguments from the ``nox`` commandline or :class:`Session.notify`."""
        return self._runner.posargs

    @property
    def virtualenv(self) -> ProcessEnv:
        """The virtualenv that all commands are run in."""
        venv = self._runner.venv
        if venv is None:
            raise ValueError("A virtualenv has not been created for this session")
        return venv

    @property
    def python(self) -> Optional[Union[str, Sequence[str], bool]]:
        """The python version passed into ``@nox.session``."""
        return self._runner.func.python

    @property
    def bin_paths(self) -> Optional[List[str]]:
        """The bin directories for the virtualenv."""
        return self.virtualenv.bin_paths

    @property
    def bin(self) -> str:
        """The first bin directory for the virtualenv."""
        paths = self.bin_paths
        if paths is None:
            raise ValueError("The environment does not have a bin directory.")
        return paths[0]

    def create_tmp(self) -> str:
        """Create, and return, a temporary directory."""
        tmpdir = os.path.join(self._runner.envdir, "tmp")
        os.makedirs(tmpdir, exist_ok=True)
        self.env["TMPDIR"] = tmpdir
        return tmpdir

    @property
    def cache_dir(self) -> pathlib.Path:
        """Create and return a 'shared cache' directory to be used across sessions."""
        path = pathlib.Path(self._runner.global_config.envdir).joinpath(".cache")
        path.mkdir(exist_ok=True)
        return path

    @property
    def interactive(self) -> bool:
        """Returns True if Nox is being run in an interactive session or False otherwise."""
        return not self._runner.global_config.non_interactive and sys.stdin.isatty()

    @property
    def invoked_from(self) -> str:
        """The directory that Nox was originally invoked from.

        Since you can use the ``--noxfile / -f`` command-line
        argument to run a Noxfile in a location different from your shell's
        current working directory, Nox automatically changes the working directory
        to the Noxfile's directory before running any sessions. This gives
        you the original working directory that Nox was invoked form.
        """
        return self._runner.global_config.invoked_from

    def chdir(self, dir: Union[str, os.PathLike]) -> None:
        """Change the current working directory."""
        self.log(f"cd {dir}")
        os.chdir(dir)

    cd = chdir
    """An alias for :meth:`chdir`."""

    def _run_func(
        self, func: Callable, args: Iterable[Any], kwargs: Mapping[str, Any]
    ) -> Any:
        """Legacy support for running a function through :func`run`."""
        self.log(f"{func}(args={args!r}, kwargs={kwargs!r})")
        try:
            return func(*args, **kwargs)
        except Exception as e:
            logger.exception(f"Function {func!r} raised {e!r}.")
            raise nox.command.CommandFailed()

    def run(
        self, *args: str, env: Optional[Mapping[str, str]] = None, **kwargs: Any
    ) -> Optional[Any]:
        """Run a command.

        Commands must be specified as a list of strings, for example::

            session.run('pytest', '-k', 'fast', 'tests/')
            session.run('flake8', '--import-order-style=google')

        You **can not** just pass everything as one string. For example, this
        **will not work**::

            session.run('pytest -k fast tests/')

        You can set environment variables for the command using ``env``::

            session.run(
                'bash', '-c', 'echo $SOME_ENV',
                env={'SOME_ENV': 'Hello'})

        You can also tell nox to treat non-zero exit codes as success using
        ``success_codes``. For example, if you wanted to treat the ``pytest``
        "tests discovered, but none selected" error as success::

            session.run(
                'pytest', '-k', 'not slow',
                success_codes=[0, 5])

        On Windows, builtin commands like ``del`` cannot be directly invoked,
        but you can use ``cmd /c`` to invoke them::

            session.run('cmd', '/c', 'del', 'docs/modules.rst')

        If ``session.run`` fails, it will stop the session and will not run the next steps.
        Basically, this will raise a Python exception. Taking this in count, you can use a
        ``try...finally`` block for cleanup runs, that will run even if the other runs fail::

           try:
               session.run("coverage", "run", "-m", "pytest")
           finally:
               # Display coverage report even when tests fail.
               session.run("coverage", "report")

        :param env: A dictionary of environment variables to expose to the
            command. By default, all environment variables are passed.
        :type env: dict or None
        :param bool silent: Silence command output, unless the command fails.
            ``False`` by default.
        :param success_codes: A list of return codes that are considered
            successful. By default, only ``0`` is considered success.
        :type success_codes: list, tuple, or None
        :param external: If False (the default) then programs not in the
            virtualenv path will cause a warning. If True, no warning will be
            emitted. These warnings can be turned into errors using
            ``--error-on-external-run``. This has no effect for sessions that
            do not have a virtualenv.
        :type external: bool
        """
        if not args:
            raise ValueError("At least one argument required to run().")

        if self._runner.global_config.install_only:
            logger.info(f"Skipping {args[0]} run, as --install-only is set.")
            return None

        return self._run(*args, env=env, **kwargs)

    def run_always(
        self, *args: str, env: Optional[Mapping[str, str]] = None, **kwargs: Any
    ) -> Optional[Any]:
        """Run a command **always**.

        This is a variant of :meth:`run` that runs even in the presence of
        ``--install-only``. This method returns early if ``--no-install`` is
        specified and the virtualenv is being reused.

        Here are some cases where this method is useful:

        - You need to install packages using a command other than ``pip
          install`` or ``conda install``.
        - You need to run a command as a prerequisite of package installation,
          such as building a package or compiling a binary extension.

        :param env: A dictionary of environment variables to expose to the
            command. By default, all environment variables are passed.
        :type env: dict or None
        :param bool silent: Silence command output, unless the command fails.
            ``False`` by default.
        :param success_codes: A list of return codes that are considered
            successful. By default, only ``0`` is considered success.
        :type success_codes: list, tuple, or None
        :param external: If False (the default) then programs not in the
            virtualenv path will cause a warning. If True, no warning will be
            emitted. These warnings can be turned into errors using
            ``--error-on-external-run``. This has no effect for sessions that
            do not have a virtualenv.
        :type external: bool
        """
        if (
            self._runner.global_config.no_install
            and self._runner.venv is not None
            and self._runner.venv._reused
        ):
            return None

        if not args:
            raise ValueError("At least one argument required to run_always().")

        return self._run(*args, env=env, **kwargs)

    def _run(
        self, *args: str, env: Optional[Mapping[str, str]] = None, **kwargs: Any
    ) -> Any:
        """Like run(), except that it runs even if --install-only is provided."""
        # Legacy support - run a function given.
        if callable(args[0]):
            return self._run_func(args[0], args[1:], kwargs)

        # Combine the env argument with our virtualenv's env vars.
        if env is not None:
            overlay_env = env
            env = self.env.copy()
            env.update(overlay_env)
        else:
            env = self.env

        # If --error-on-external-run is specified, error on external programs.
        if self._runner.global_config.error_on_external_run:
            kwargs.setdefault("external", "error")

        # Allow all external programs when running outside a sandbox.
        if not self.virtualenv.is_sandboxed:
            kwargs["external"] = True

        if args[0] in self.virtualenv.allowed_globals:
            kwargs["external"] = True

        # Run a shell command.
        return nox.command.run(args, env=env, paths=self.bin_paths, **kwargs)

    def conda_install(
        self,
        *args: str,
        auto_offline: bool = True,
        channel: Union[str, Sequence[str]] = "",
        **kwargs: Any,
    ) -> None:
        """Install invokes `conda install`_ to install packages inside of the
        session's environment.

        To install packages directly::

            session.conda_install('pandas')
            session.conda_install('numpy', 'scipy')
            session.conda_install('dask==2.1.0', channel='conda-forge')

        To install packages from a ``requirements.txt`` file::

            session.conda_install('--file', 'requirements.txt')
            session.conda_install('--file', 'requirements-dev.txt')

        By default this method will detect when internet connection is not
        available and will add the `--offline` flag automatically in that case.
        To disable this behaviour, set `auto_offline=False`.

        To install the current package without clobbering conda-installed
        dependencies::

            session.install('.', '--no-deps')
            # Install in editable mode.
            session.install('-e', '.', '--no-deps')

        You can specify a conda channel using `channel=`; a falsy value will
        not change the current channels. You can specify a list of channels if
        needed.

        Additional keyword args are the same as for :meth:`run`.

        .. _conda install:
        """
        venv = self._runner.venv

        prefix_args: Tuple[str, ...] = ()
        if isinstance(venv, CondaEnv):
            prefix_args = ("--prefix", venv.location)
        elif not isinstance(venv, PassthroughEnv):  # pragma: no cover
            raise ValueError(
                "A session without a conda environment can not install dependencies from conda."
            )

        if not args:
            raise ValueError("At least one argument required to install().")

        if self._runner.global_config.no_install and venv._reused:
            return None

        # Escape args that should be (conda-specific; pip install does not need this)
        args = _dblquote_pkg_install_args(args)

        if "silent" not in kwargs:
            kwargs["silent"] = True

        extraopts: List[str] = []
        if auto_offline and venv.is_offline():
            logger.warning(
                "Automatically setting the `--offline` flag as conda repo seems unreachable."
            )
            extraopts.append("--offline")

        if channel:
            if isinstance(channel, str):
                extraopts.append(f"--channel={channel}")
            else:
                extraopts += [f"--channel={c}" for c in channel]

        self._run(
            venv.conda_cmd,
            "install",
            "--yes",
            *extraopts,
            *prefix_args,
            *args,
            external="error",
            **kwargs,
        )

    def install(self, *args: str, **kwargs: Any) -> None:
        """Install invokes `pip`_ to install packages inside of the session's
        virtualenv.

        To install packages directly::

            session.install('pytest')
            session.install('requests', 'mock')
            session.install('requests[security]==2.9.1')

        To install packages from a ``requirements.txt`` file::

            session.install('-r', 'requirements.txt')
            session.install('-r', 'requirements-dev.txt')

        To install the current package::

            session.install('.')
            # Install in editable mode.
            session.install('-e', '.')

        Additional keyword args are the same as for :meth:`run`.

        .. _pip: https://pip.readthedocs.org
        """
        venv = self._runner.venv

        if not isinstance(
            venv, (CondaEnv, VirtualEnv, PassthroughEnv)
        ):  # pragma: no cover
            raise ValueError(
                "A session without a virtualenv can not install dependencies."
            )
        if isinstance(venv, PassthroughEnv):
            warnings.warn(
                f"Session {self.name} does not have a virtual environment, "
                "so use of session.install() is deprecated since it would modify "
                "the global Python environment. If you're really sure that is "
                'what you want to do, use session.run("pip", "install", ...) instead.',
                category=FutureWarning,
                stacklevel=2,
            )
        if not args:
            raise ValueError("At least one argument required to install().")

        if self._runner.global_config.no_install and venv._reused:
            return None

        if "silent" not in kwargs:
            kwargs["silent"] = True

        self._run("python", "-m", "pip", "install", *args, external="error", **kwargs)

    def notify(
        self,
        target: "Union[str, SessionRunner]",
        posargs: Optional[Iterable[str]] = None,
    ) -> None:
        """Place the given session at the end of the queue.

        This method is idempotent; multiple notifications to the same session
        have no effect.

        A common use case is to notify a code coverage analysis session
        from a test session::

            @nox.session
            def test(session):
                session.run("pytest")
                session.notify("coverage")

            @nox.session
            def coverage(session):
                session.run("coverage")

        Now if you run `nox -s test`, the coverage session will run afterwards.

        Args:
            target (Union[str, Callable]): The session to be notified. This
                may be specified as the appropriate string (same as used for
                ``nox -s``) or using the function object.
            posargs (Optional[Iterable[str]]): If given, sets the positional
                arguments *only* for the queued session. Otherwise, the
                standard globally available positional arguments will be
                used instead.
        """
        if posargs is not None:
            posargs = list(posargs)
        self._runner.manifest.notify(target, posargs)

    def log(self, *args: Any, **kwargs: Any) -> None:
        """Outputs a log during the session."""
        logger.info(*args, **kwargs)

    def warn(self, *args: Any, **kwargs: Any) -> None:
        """Outputs a warning during the session."""
        logger.warning(*args, **kwargs)

    def debug(self, *args: Any, **kwargs: Any) -> None:
        """Outputs a debug-level message during the session."""
        logger.debug(*args, **kwargs)

    def error(self, *args: Any) -> "_typing.NoReturn":
        """Immediately aborts the session and optionally logs an error."""
        raise _SessionQuit(*args)

    def skip(self, *args: Any) -> "_typing.NoReturn":
        """Immediately skips the session and optionally logs a warning."""
        raise _SessionSkip(*args)


class SessionRunner:
    def __init__(
        self,
        name: str,
        signatures: List[str],
        func: Func,
        global_config: argparse.Namespace,
        manifest: "Manifest",
    ) -> None:
        self.name = name
        self.signatures = signatures
        self.func = func
        self.global_config = global_config
        self.manifest = manifest
        self.venv: Optional[ProcessEnv] = None
        self.posargs: List[str] = global_config.posargs[:]

    @property
    def description(self) -> Optional[str]:
        doc = self.func.__doc__
        if doc:
            first_line = doc.strip().split("\n")[0]
            return first_line
        return None

    def __str__(self) -> str:
        sigs = ", ".join(self.signatures)
        return f"Session(name={self.name}, signatures={sigs})"

    @property
    def friendly_name(self) -> str:
        return self.signatures[0] if self.signatures else self.name

    @property
    def envdir(self) -> str:
        return _normalize_path(self.global_config.envdir, self.friendly_name)

    def _create_venv(self) -> None:
        backend = (
            self.global_config.force_venv_backend
            or self.func.venv_backend
            or self.global_config.default_venv_backend
        )

        if backend == "none" or self.func.python is False:
            self.venv = PassthroughEnv()
            return

        reuse_existing = (
            self.func.reuse_venv or self.global_config.reuse_existing_virtualenvs
        )

        if backend is None or backend == "virtualenv":
            self.venv = VirtualEnv(
                self.envdir,
                interpreter=self.func.python,  # type: ignore[arg-type]
                reuse_existing=reuse_existing,
                venv_params=self.func.venv_params,
            )
        elif backend in {"conda", "mamba"}:
            self.venv = CondaEnv(
                self.envdir,
                interpreter=self.func.python,  # type: ignore[arg-type]
                reuse_existing=reuse_existing,
                venv_params=self.func.venv_params,
                conda_cmd=backend,
            )
        elif backend == "venv":
            self.venv = VirtualEnv(
                self.envdir,
                interpreter=self.func.python,  # type: ignore[arg-type]
                reuse_existing=reuse_existing,
                venv=True,
                venv_params=self.func.venv_params,
            )
        else:
            raise ValueError(
                f"Expected venv_backend one of ('virtualenv', 'conda', 'venv'), but got '{backend}'."
            )

        self.venv.create()

    def execute(self) -> "Result":
        logger.warning(f"Running session {self.friendly_name}")

        try:
            # By default, nox should quietly change to the directory where
            # the noxfile.py file is located.
            cwd = py.path.local(
                os.path.realpath(os.path.dirname(self.global_config.noxfile))
            ).as_cwd()

            with cwd:
                self._create_venv()
                session = Session(self)
                self.func(session)

            # Nothing went wrong; return a success.
            return Result(self, Status.SUCCESS)

        except nox.virtualenv.InterpreterNotFound as exc:
            if self.global_config.error_on_missing_interpreters:
                return Result(self, Status.FAILED, reason=str(exc))
            else:
                return Result(self, Status.SKIPPED, reason=str(exc))

        except _SessionQuit as exc:
            return Result(self, Status.ABORTED, reason=str(exc))

        except _SessionSkip as exc:
            return Result(self, Status.SKIPPED, reason=str(exc))

        except nox.command.CommandFailed:
            return Result(self, Status.FAILED)

        except KeyboardInterrupt:
            logger.error(f"Session {self.friendly_name} interrupted.")
            raise

        except Exception as exc:
            logger.exception(f"Session {self.friendly_name} raised exception {exc!r}")
            return Result(self, Status.FAILED)


class Result:
    """An object representing the result of a session."""

    def __init__(
        self, session: SessionRunner, status: Status, reason: Optional[str] = None
    ) -> None:
        """Initialize the Result object.

        Args:
            session (~nox.sessions.SessionRunner):
                The session runner which ran.
            status (~nox.sessions.Status): The final result status.
            reason (str): Additional info.
        """
        self.session = session
        self.status = status
        self.reason = reason

    def __bool__(self) -> bool:
        return self.status.value > 0

    def __nonzero__(self) -> bool:
        return self.__bool__()

    @property
    def imperfect(self) -> str:
        """Return the English imperfect tense for the status.

        Returns:
            str: A word or phrase representing the status.
        """
        if self.status == Status.SUCCESS:
            return "was successful"
        status = self.status.name.lower()
        if self.reason:
            return f"{status}: {self.reason}"
        else:
            return status

    def log(self, message: str) -> None:
        """Log a message using the appropriate log function.

        Args:
            message (str): The message to be logged.
        """
        log_function = logger.info
        if self.status == Status.SUCCESS:
            log_function = logger.success
        if self.status == Status.SKIPPED:
            log_function = logger.warning
        if self.status.value <= 0:
            log_function = logger.error
        log_function(message)

    def serialize(self) -> Dict[str, Any]:
        """Return a serialized representation of this result.

        Returns:
            dict: The serialized result.
        """
        return {
            "args": getattr(self.session.func, "call_spec", {}),
            "name": self.session.name,
            "result": self.status.name.lower(),
            "result_code": self.status.value,
            "signatures": self.session.signatures,
        }