So IIUC the package will contain __init__.py (what is now support.py), script_helper, and pkg_helper.

One reason why I proposed to merge script_helper with support.py is that functions like assert_python*() are used in several modules already, and are generic enough to belong in support.py IMHO (that's also why I was looking for them there).  I count almost 20 modules that are currently using these functions, and there might be more that could benefit from them.

In script_helper I also see two functions that seem to deal with packages: make_pkg and make_zip_pkg.  If these get moved to pkg_helper, script_helper will be left with just an handful of generic functions.

In addition, if the functions you want to add in pkg_helper are also generic enough, it might still be better to put everything in support.py.

To summarize I think that adding a package with 3 modules is still better than having modules around in test/, but merging everything in support.py might be even better (this depends on the functions that will end up in each module, how generic they are, and how the modules are divide).