Ansible-test is a tool for testing your automation on local docker images. You can think of this as a slim version of Chef's test-kitchen.
$ cd /my/ansible/repository
$ ansible-test my_ansible_role
The above command will drop a Dockerfile at the root of your ansible repo and initialize a docker image with ansible installed. It will then run the ansible role "my_ansible_role".
Note that ansible-test also accepts arbitrary arguments. These arguments will be passed on to the ansible-playbook command while running tests.
See the example ansible flask project, which tests with ansible-test out-of-the-box
To install ansible-test:
$ pip install ansible-test
ansible-test requires that you have docker installed locally. If you are using Mac OSX, I recommend you use boot2docker.
NOTE: Given docker's inflexibility with Dockerfiles, ansible-test will overwrite the Dockerfile in the current working directory from which you run ansible-test. This is currently the simplest way to integrate docker as a testing tool.