You can download it from https://jaxb.dev.java.net/tck.html . It's still beta, but I hope we can see a final version as JAXB 2.0 spec and RI is also finalized (very soon).
Your use of this web site or any of its content or software indicates your agreement to be bound by these Terms of Participation.
Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners.