Testing requires docker to be installed and running
You can test by simply doing rake spec.
If you wish to test with specific versions, you can use the VERSIONS environment variable. This variable is a comma delimited value of which versions of the source should be used when launching the docker containers. The value of each version is a git ref, INDEX for the current index, or '' (empty string) for the current working directory.
For example:
VERSIONS=HEAD,1.2.3,,INDEX,master bundle exec rake spec
This will launch 5 instances of the application, one using HEAD, one using the tag 1.2.3, one using the current working directory, one usin the current index (files added via git add), and one using the current master branch. Tests will be performed out of the current working directory.
If VERSIONS is not specified, it defaults to 3 containers using the current working directory.