nose-parallel

A plugin to help split up your tests runs across multiple machines.

In an ideal world, test suites should be fast enough that they can be run locally on a single machine without extra engineering. This plugin is there to help when you can't make that to happen.

This won't help you run tests in parallel on one machine in different threads; that's what the built-in multiprocess plugin is for.

This will help you split up your test suites so that you can run the suites on multiple machines and not have the same test run twice - think Jenkins with the multijob plugin, or CI services like CircleCI.

Install

pip install nose-parallel

Usage

On each machine:

1. Export environment variables NODE_TOTAL (the number of machines on which the suite will be run) and and NODE_INDEX (the 0-based index of the current machine)
2. Run nosetests with the --with-parallel flag
3. Do something to join the results from all the machines back together

For example, this is how we'd run nosetests on the second machine in a four-machine testing cluster:

NODE_TOTAL=4 NODE_INDEX=1 nosetests --with-parallel

If you don't set those variables, nose-parallel will do the right thing and run all your tests. It also supports natively the default environment variables from:

• CircleCI
• Buildkite
• GitLab CI

We welcome PRs that add native support for other CI alternatives.

If you want to further randomize the distribution of tests, so that the same test cases don't always run together on the same node, you may use the --parallel-salt option or NOSE_PARALLEL_SALT environment variable to specify a salt value for the randomization (e.g. a build number, the day of the month). The salt must be the same on each node during a parallel build, otherwise some test cases might be missed.

For example, on CircleCI you could do:

nosetests --with-parallel --parallel-salt-env CIRCLE_BUILD_NUM

By default nose-parallel will split tests based on method and function names. You can customize this strategy by setting the --parallel-strategy option. Supported strategies are: 'CLASS', 'DIRECTORY', 'FILE', 'METHOD', 'FUNCTION' and 'MODULE'.

For example, to split tests based on the file names:

nosetests --with-parallel --parallel-strategy=FILE

License

nose-parallel is released under the MIT license.

Contribute

• Check for open issues or open a fresh issue to start a discussion around a feature idea or a bug.
• Fork the repository on GitHub to start making your changes to the master branch (or branch off of it).
• Send a pull request and bug the maintainer until it gets merged and published.

Thanks To

• @mahmoudimus, whose nose-timer plugin this is based off of