How do I import classes from one project's testpackages to another project's testpackages in netbeans?

In netbeans I can setup several classpaths for a project: compile, processor, run, compile tests, run tests.

In compile tests I added another project. I can now use that other project's src packaged classes, in my own project's test packages.

But I can't use that other project's test packaged classes.

How can I make this happen?

(Do I need to use maven projects instead of regular projects?)