Test helpers introduced in JDK-8230726 lack some functionality that prevent using them in all tests. To address this the following should be done:
- Add support for testing modular apps. Currently only non-modular apps can be tested.
- Add tools to run test classes multiple times with jpackage used as standalone executable and as tool provider without need to alter test classes source code.

It would be also good to have ability to allow selective execution of a particular test functions from test classes without need to alter test classes source code.