I guess this really depends on how you run your tests…
Since you are posting here I assume you ‘Deploy’ your docker image on DockerCloud ‘nodes’. By using ‘NodeCluster’ you define ‘tags’ when creating the cluster, each ‘node’ under such cluster will inherit those tags on creation.
When deploying you ‘stack’, each ‘service’ would allow to have ‘tags’ to match your nodes. Let’s save you create a NodeCluster with tags ‘test’ and ‘app’, and have a Docker service with tag ‘test’, it can be run on any node with ‘test’ tag on it.
The screenshot below is how we use such mechanism. We have Jenkins server to build the Docker image, pushed to Docker.io, and then control DockerCloud to deploy on the servers with matching tags. Do not be confused with DockerCloud’s tags with Docker image’s tag. They are different thing.
FYI, please read: https://docs.docker.com/docker-cloud/apps/deploy-tags/