as different parts of the test libraries are different in their modules dependencies, it makes sense to divide the libraries into jigsaw modules, this will also make it easier and less error-prone to use and build test libraries.

the proposal suggests using classes' dependency as a guideline of this division and using the name of JDK module they depend in the test library module's name. i.e. the majority of the test library which depends only on public API of  'java.base' will be placed in 'test.base' module; classes which depend on 'java.compiler' -- 'test.compiler', etc.

it's important to mention, as this is necessary for a certain group of tests, e.g. ones which are strict on the list of available modules, that modularization of the test libraries won't prohibit their usage as regular test library, it will still be possible to use them as a regular source-path extension as before.