Run commands from within a specific directory

[cblegare]

How would this feature be useful?

Since many commands have specific usages of the current working directory,
running commands from within a specific directory would smooth integrating nox
is existing projects.

Describe the solution you'd like

from pathlib import Path

import nox


@nox.session()
def test(session: nox.Session):
    session.install('pytest')
    python_package_root = Path("somewhere/deep/in/monorepo")
    session.run(sys.executable, "-m", "pytest", cwd=python_package_root)

Describe alternatives you've considered

import os
from pathlib import Path

import nox


@nox.session()
def test(session: nox.Session):
    session.install('pytest')
    python_package_root = Path("somewhere/deep/in/monorepo")
    before_cwd = os.getcwd()
    os.chdir(python_package_root)
    session.run(sys.executable, "-m", "pytest")
    os.chdir(before_cwd)

[cblegare]

As a workaround, see the following context manager implementation

from contextlib import contextmanager
from pathlib import Path
from typing import Union
import os

import nox


@nox.session()
def test(session: nox.Session):
    session.install('pytest')
    with current_working_directory(Path("somewhere/deep/in/monorepo")):
        session.run(sys.executable, "-m", "pytest")


@contextmanager
def current_working_directory(path: Union[Path, str]):
    """Sets the cwd within the context

    Args:
        path: The path to the cwd

    Yields:
        None
    """

    origin = Path().absolute()
    try:
        os.chdir(path)
        yield
    finally:
        os.chdir(origin)