testSuites not seeing non-api classes

Topic How to "read" component model information in a Copy task? mentions that the $.components works in Gradle 2.9, but not in 3.0. Is there a new way to do it in Gradle 3.0?

Nightly 3.1-20160820000021+0000 also does not like $.
I can’t test 2.9 because it does not seem to include junit-test-suite.
2.14 does not accept $.