It has generally been difficult to test new updates for the rpm-ostree or ostree packages for Atomic Host. This is because in the past you had to build your own tree in order to test them. Now, however, Fedora has starting building a tree based off the updates-testing yum repositories. This means that you can easily test updates by simply running Fedora Atomic Host and rebasing to the fedora-atomic/f22/x86_64/testing/docker-host ref:
