README.md

nox

Nox is a command-line tool that automates testing in multiple Python environments, s imilar to tox. Unlike tox, Nox uses a standard Python file for configuration.

How to install it?

Install nox via pip:

$ pip install --user nox

How to use it?

Nox is configured via a noxfile.py file in your project’s directory. For example,

import nox

@nox.session
def tests(session):
    session.install('pytest')
    session.run('pytest')

@nox.session
def lint(session):
    session.install('flake8')
    session.run('flake8', '--import-order-style', 'google')

1. Create the virtual environment

By default, nox uses virtualenv as default backend to create the virtual environment. You are not limited to virtualenv though, there is a selection of backends you can choose from as venv, conda, mamba:

@nox.session(venv_backend="venv")
def tests(session):
    pass

By default, when calling nox command (see 2. Activate the environment), nox will create a new virtual environment for each session using the same interpreter that Nox uses.

2. Activate the virtual environment

Same as tox, you do not need to activate the virtual environment manually. to run both of these sessions mentioned above, use the following command:

$ nox

By default, under the project directory, nox will create a cache directory .nox which contains the virtual environments defined with nox sessions.

3. Manage Python packages

You can specify the Python packages that are required for running the tests in the virtual environment, like this:

session.install("package1", "package2", ...)

If you have a list of packages in requirements.txt, you can use

session.install("-r", "requirements.txt")

If your project is a Python package and you want to to install it:

session.install("-e", ".")

4. Deactivate the virtual environment

No need to deactivate the virtual environment manually, nox will take care of it automatically.

5. Remove the virtual environment

To remove the cached virtual environments, you can run the following command:

$ rm -rf .nox

Different Python versions?

You can tell Nox to use a different Python interpreter/version by specifying the python argument (or its alias py) to @nox.session:

@nox.session(python="3.12")
def tests(session):
    pass

You can also tell Nox to run your session against multiple Python interpreters. Nox will create a separate virtualenv and run the session for each interpreter you specify.

@nox.session(python=["3.11", "3.12", "pypy-6.0"])
def tests(session):
    pass

For more information about nox, please look into the official documentation

Happy Coding!