Tutorial ======== This tutorial will walk you through installing, configuring, and running Nox. Installation ------------ Nox can be easily installed via `pip`_: .. code-block:: console python3 -m pip install nox You may want to use the `user site`_ to avoid messing with your global Python install: .. code-block:: console python3 -m pip install --user nox Or you can be extra fancy and use `pipx`_: .. code-block:: console pipx install nox Either way, Nox is usually installed *globally*, similar to ``tox``, ``pip``, and other similar tools. If you're interested in running ``nox`` within `docker`_, you can use the `thekevjames/nox images`_ on DockerHub which contain builds for all ``nox`` versions and all supported ``python`` versions. Nox is also supported via ``pipx run nox`` in the `manylinux images`_. If you want to run ``nox`` within `GitHub Actions`_, you can use the ``wntrblm/nox`` action, which installs the latest ``nox`` and makes available all active CPython and PyPY versions provided by the GitHub Actions environment: .. code-block:: yaml # setup nox with all active CPython and PyPY versions provided by # the GitHub Actions environment i.e. # python-versions: "3.7, 3.8, 3.9, 3.10, pypy-3.7, pypy-3.8, pypy-3.9" # this uses version 2022.8.7 but any Nox tag will work here - uses: wntrblm/nox@2022.8.7 # setup nox only for a given list of python versions # Limitations: # - Version specifiers shall be supported by actions/setup-python # - There can only be one "major.minor" per interpreter i.e. "3.7.0, 3.7.1" is invalid # this uses version 2022.8.7 but any Nox tag will work here - uses: wntrblm/nox@2022.8.7 with: python-versions: "2.7, 3.5, 3.11, pypy-3.9" .. _pip: https://pip.readthedocs.org .. _user site: https://packaging.python.org/tutorials/installing-packages/#installing-to-the-user-site .. _pipx: https://packaging.python.org/guides/installing-stand-alone-command-line-tools/ .. _docker: https://www.docker.com/ .. _thekevjames/nox images: https://hub.docker.com/r/thekevjames/nox .. _GitHub Actions: https://github.com/features/actions .. _manylinux images: https://github.com/pypa/manylinux Writing the configuration file ------------------------------ Nox is configured via a file called ``noxfile.py`` in your project's directory. This file is a Python file that defines a set of *sessions*. A *session* is an environment and a set of commands to run in that environment. If you're familiar with tox sessions are analogous to *environments*. If you're familiar with GNU Make, sessions are analogous to *targets*. Sessions are declared using the ``@nox.session`` decorator. This is similar to how Flask uses ``@app.route``. Here's a basic Noxfile that runs `flake8`_ against ``example.py`` (you can create ``example.py`` yourself):: import nox @nox.session def lint(session): session.install("flake8") session.run("flake8", "example.py") .. _flake8: http://flake8.pycqa.org/en/latest/ Running Nox for the first time ------------------------------ Now that you've installed Nox and have a Noxfile you can run Nox! Open your project's directory in a terminal and run ``nox``. You should see something like this: .. code-block:: console $ nox nox > Running session lint nox > Creating virtualenv using python3.7 in .nox/lint nox > pip install flake8 nox > flake8 example.py nox > Session lint was successful. **✨ You've now successfully used Nox for the first time! ✨** The rest of this tutorial will take you through other common things you'll likely want to do with Nox. You can also jump into :doc:`usage` and :doc:`config` docs if you want. Installing dependencies ----------------------- Nox more or less passes ``session.install`` through to ``pip``, so you can install stuff in the usual way. Here's some examples: To install one or more packages at a time: .. code-block:: python @nox.session def tests(session): # same as pip install pytest protobuf>3.0.0 session.install("pytest", "protobuf>3.0.0") ... To install a ``requirements.txt`` file: .. code-block:: python @nox.session def tests(session): # same as pip install -r requirements.txt session.install("-r", "requirements.txt") ... If your project is a Python package and you want to install it: .. code-block:: python @nox.session def tests(session): # same as pip install . session.install(".") ... In some cases such as Python binary extensions, your package may depend on code compiled outside of the Python ecosystem. To make sure a low-level dependency (e.g. ``libfoo``) is available during installation: .. code-block:: python @nox.session def tests(session): ... session.run_install( "cmake", "-DCMAKE_BUILD_TYPE=Debug", "-S", libfoo_src_dir, "-B", build_dir, external=True, ) session.run_install( "cmake", "--build", build_dir, "--config", "Debug", "--target", "install", external=True, ) session.install(".") ... These commands will run even if you are only installing, and will not run if the environment is being reused without reinstallation. Running commands ---------------- The ``session.run`` function lets you run commands within the context of your session's virtual environment. Here's a few examples: You can install and run Python tools: .. code-block:: python @nox.session def tests(session): session.install("pytest") session.run("pytest") If you want to pass more arguments to a program just add more arguments to ``run``: .. code-block:: python @nox.session def tests(session): session.install("pytest") session.run("pytest", "-v", "tests") You can also pass environment variables: .. code-block:: python @nox.session def tests(session): session.install("pytest") session.run( "pytest", env={ "FLASK_DEBUG": "1" } ) See :func:`nox.sessions.Session.run` for more options and examples for running programs. Selecting which sessions to run ------------------------------- Once you have multiple sessions in your Noxfile you'll notice that Nox will run them all by default. While this is useful, it often useful to just run one or two at a time. You can use the ``--sessions`` argument (or ``-s``) to select which sessions to run. You can use the ``--list`` argument to show which sessions are available and which will be run. Here's some examples: Here's a Noxfile with three sessions: .. code-block:: python import nox @nox.session def test(session): ... @nox.session def lint(session): ... @nox.session def docs(session): ... If you just run ``nox --list`` you'll see that all sessions are selected: .. code-block:: console Sessions defined in noxfile.py: * test * lint * docs sessions marked with * are selected, sessions marked with - are skipped. If you run ``nox --list --sessions lint`` you'll see that only the lint session is selected: .. code-block:: console Sessions defined in noxfile.py: - test * lint - docs sessions marked with * are selected, sessions marked with - are skipped. And if you run ``nox --sessions lint`` Nox will just run the lint session: .. code-block:: console nox > Running session lint nox > Creating virtualenv using python3 in .nox/lint nox > ... nox > Session lint was successful. In the Noxfile, you can specify a default set of sessions to run. If so, a plain ``nox`` call will only trigger certain sessions: .. code-block:: python import nox nox.options.sessions = ["lint", "test"] If you set this to an empty list, Nox will not run any sessions by default, and will print a helpful message with the ``--list`` output when a user does not specify a session to run. There are many more ways to select and run sessions! You can read more about invoking Nox in :doc:`usage`. Queuing sessions ----------------- If you want to queue up (or "notify") another session from the current one, you can use the ``session.notify`` function: .. code-block:: python @nox.session def tests(session): session.install("pytest") session.run("pytest") # Here we queue up the test coverage session to run next session.notify("coverage") @nox.session def coverage(session): session.install("coverage") session.run("coverage") You can queue up any session you want, not just test and coverage sessions, but this is a very commonly used pattern. Now running ``nox --session tests`` will run the tests session and then the coverage session. You can also pass the notified session positional arguments: .. code-block:: python @nox.session def prepare_thing(session): thing_path = "./path/to/thing" session.run("prepare", "thing", thing_path) session.notify("consume_thing", posargs=[thing_path]) @nox.session def consume_thing(session): # The 'consume' command has the arguments # sent to it from the 'prepare_thing' session session.run("consume", "thing", *session.posargs) Note that this will only have the desired effect if selecting sessions to run via the ``--session/-s`` flag. If you simply run ``nox``, all selected sessions will be run. Testing against different and multiple Pythons ---------------------------------------------- Many projects need to support either a specific version of Python or multiple Python versions. You can have Nox run your session against multiple interpreters by specifying ``python`` to ``@nox.session``. Here's some examples: If you want your session to specifically run against a single version of Python only: .. code-block:: python @nox.session(python="3.7") def test(session): ... If you want your session to run against multiple versions of Python: .. code-block:: python @nox.session(python=["2.7", "3.6", "3.7"]) def test(session): ... You'll notice that running ``nox --list`` will show that this one session has been expanded into three distinct sessions: .. code-block:: console Sessions defined in noxfile.py: * test-2.7 * test-3.6 * test-3.7 You can run all of the ``test`` sessions using ``nox --sessions test`` or run an individual one using the full name as displayed in the list, for example, ``nox --sessions test-3.5``. More details on selecting sessions can be found over in the :doc:`usage` documentation. You can read more about configuring the virtual environment used by your sessions over at :ref:`virtualenv config`. Testing with conda ------------------ Some projects, especially in the data science community, need to test that they work in a conda environment. If you want your session to run in a conda environment: .. code-block:: python @nox.session(venv_backend="conda") def test(session): ... Install packages with conda: .. code-block:: python session.conda_install("pytest") It is possible to install packages with pip into the conda environment, but it's a best practice only install pip packages with the ``--no-deps`` option. This prevents pip from breaking the conda environment by installing incompatible versions of packages already installed with conda. .. code-block:: python session.install("contexter", "--no-deps") session.install("-e", ".", "--no-deps") ``"mamba"`` is also allowed as a choice for ``venv_backend``, which will use/require `mamba `_ instead of conda. Parametrization --------------- Just like Nox can handle running against multiple interpreters, Nox can also handle running your sessions with a list of different arguments using the :func:`nox.parametrize` decorator. Here's a short example of using parametrization to test against two different versions of Django: .. code-block:: python @nox.session @nox.parametrize("django", ["1.9", "2.0"]) def test(session, django): session.install(f"django=={django}") session.run("pytest") If you run ``nox --list`` you'll see that Nox expands your one session into multiple sessions. One for each argument value that you want to be passed to your session: .. code-block:: console Sessions defined in noxfile.py: * test(django='1.9') * test(django='2.0') :func:`nox.parametrize` has an interface and usage intentionally similar to `pytest's parametrize`_. It's an extremely powerful feature of Nox. You can read more about parametrization and see more examples over at :ref:`parametrized`. .. _pytest's parametrize: https://pytest.org/latest/parametrize.html#_pytest.python.Metafunc.parametrize Session tags ------------ You can add tags to your sessions to help you organize your development tasks: .. code-block:: python @nox.session(tags=["style", "fix"]) def black(session): session.install("black") session.run("black", "my_package") @nox.session(tags=["style", "fix"]) def isort(session): session.install("isort") session.run("isort", "my_package") @nox.session(tags=["style"]) def flake8(session): session.install("flake8") session.run("flake8", "my_package") If you run ``nox -t style``, Nox will run all three sessions: .. code-block:: console * black * isort * flake8 If you run ``nox -t fix``, Nox will only run the ``black`` and ``isort`` sessions: .. code-block:: console * black * isort - flake8 If you run ``nox -t style fix``, Nox will run all sessions that match *any* of the tags, so all three sessions: .. code-block:: console * black * isort * flake8 Next steps ---------- Look at you! You're now basically an expert at Nox! ✨ For this point you can: * Read more docs, such as :doc:`usage` and :doc:`config`. * Give us feedback or contribute, see :doc:`CONTRIBUTING`. For any projects using Nox, you may add its official badge somewhere prominent like the README. .. image:: https://img.shields.io/badge/%F0%9F%A6%8A-Nox-D85E00.svg :alt: Nox :target: https://github.com/wntrblm/nox .. tabs:: .. tab:: Markdown .. code-block:: markdown [![Nox](https://img.shields.io/badge/%F0%9F%A6%8A-Nox-D85E00.svg)](https://github.com/wntrblm/nox) .. tab:: reStructuredText .. code-block:: rst .. image:: https://img.shields.io/badge/%F0%9F%A6%8A-Nox-D85E00.svg :alt: Nox :target: https://github.com/wntrblm/nox Have fun! 💜