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tox automation project

Command line driven CI frontend and development task automation tool

At its core tox provides a convenient way to run arbitrary commands in isolated environments to serve as a single entry point for build, test and release activities.

tox is highly configurable and pluggable.

Example: run tests with Python 3.7 and Python 3.8

tox is mainly used as a command line tool and needs a tox.ini or a tool.tox section in pyproject.toml containing the configuration.

To test a simple project that has some tests, here is an example with a tox.ini in the root of the project:

envlist = py37,py38

deps = pytest
commands = pytest
$ tox

[lots of output from what tox does]
[lots of output from commands that were run]

__________________ summary _________________
  py37: commands succeeded
  py38: commands succeeded
  congratulations :)

tox created two testenvs - one based on Python3.7 and one based on Python3.8, it installed pytest in them and ran the tests. The report at the end summarizes which testenvs have failed and which have succeeded.

Note: To learn more about what you can do with tox, have a look at the collection of examples in the documentation or existing projects using tox.

How it works

tox creates virtual environments for all configured so called testenvs, it then installs the project and other necessary dependencies and runs the configured set of commands. See system overview for more details.

tox flow

tox can be used for ...

  • creating development environments
  • running static code analysis and test tools
  • automating package builds
  • running tests against the package build by tox
  • checking that packages install correctly with different Python versions/interpreters
  • unifying Continuous Integration and command line based testing
  • building and deploying project documentation
  • releasing a package to PyPI or any other platform
  • limit: your imagination


Documentation for tox can be found at Read The Docs.

Communication and questions

If you have questions or suggestions you can first check if they have already been answered or discussed on our issue tracker on Stack Overflow (tagged with tox).

If you want to discuss topics or propose changes that might not (yet) fit into an issue, you can get in touch via mail through

We also have a Gitter community.


Contributions are welcome. See contributing and our Contributor Covenant Code of Conduct.

Currently the code and the issues are hosted on Github.

The project is licensed under MIT.

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