Gradle dependency on test resources from another sub-project

I'm converting a very large maven project to Gradle. I have 2 sub-projects:

A:B:C

and

A:G:X

Tests in A:G:X require test classes from A:B:C, how do I include them? I already have: compile project(':A:B:C') which I can see in debug output includes the jar but, of course, the jar doesn't contain test classes.