Compose is a part of the Docker project, and follows the same rules and principles. Take a read of [Docker's contributing guidelines](https://github.com/docker/docker/blob/master/CONTRIBUTING.md) to get an overview.
1. Fork [https://github.com/docker/compose](https://github.com/docker/compose) to your username.
1. Clone your forked repository locally `git clone git@github.com:yourusername/compose.git`.
1. Enter the local directory `cd compose`.
1. Set up a development environment by running `python setup.py develop`. This will install the dependencies and set up a symlink from your `docker-compose` executable to the checkout of the repository. When you now run `docker-compose` from anywhere on your machine, it will run your development version of Compose.
Tests are run against a Docker daemon inside a container, so that we can test against multiple Docker versions. By default they'll run against only the latest Docker version - set the `DOCKER_VERSIONS` environment variable to "all" to run against all supported versions:
$ DOCKER_VERSIONS=all script/test
Arguments to `script/test` are passed through to the `nosetests` executable, so you can specify a test directory, file, module, class or method:
4. Build OS X version on Mountain Lion with `script/build-osx` and attach to release as `docker-compose-Darwin-x86_64` and `docker-compose-Linux-x86_64`.