tox-pip-version

Overview

This is a tox plugin that preinstalls a specific version of pip in each tox environment.

pip install tox-pip-version

This works around the default behavior of tox/virtualenv that always installs the latest version pip. It is an improvment over the VIRTUALENV_NO_DOWNLOAD=1 option that does not install the latest version, but could result in usage of an outdated version of pip.

Recommendation: Do not pin the pip version long term. You get more stable repeatable builds, but at the cost of using an outdated (possibly vulnerable) package. This should be used as a temporary fix for breakages in upstream pip, or in conjunction with a regular process to update the version pin.

Note: This relies on an unstable tox plugin interface. You may experience breakage with new tox versions. If you do, please feel free to report the issue on Github.

Usage

Install the package and include pip_version in your tox.ini

[testenv]
pip_version = pip==19.0.1

Or, set the TOX_PIP_VERSION environment variable,

export TOX_PIP_VERSION=18.1
tox

The plugin will install that version of pip into the tox-created virtualenv, just after tox creates the virtualenv, but before dependencies are installed.

The pip_version within tox.ini, if present, is always used over the environment variable.

If neither pip_version or TOX_PIP_VERSION is present, the plugin does nothing.

Version Sets

Version sets/ranges are supported, enabling installation of a version of pip matching a set of specifiers. There are two basic formats: a plain version number, or the package name with optional PEP440-compatible version specifiers.

tox.ini	effective pip command
pip_version = 19.0	pip install -U pip==19.0
pip_version = pip==19.0	pip install -U pip==19.0
pip_version = pip>=19.0	pip install -U pip>=19.0
pip_version = pip!=19,>18	pip install -U pip!=19,>18
pip_version = pip	pip install -U pip

Tests

Use make test to run the tests, which includes linting and functional tests.

Each of the tests/* directories is a "feature" that needs testing. Each feature sub-directory contains a tox.ini file that sets pip version in a particular way, and then uses a tox command to check the correct pip version was installed.