let's say you have a couple common test utils in a separate composite build: where do these go? into the main/ or test/ folder? because it looks like everything in test is not exported If they go into main/ then I'd also need to depend on junit via implementation Edit: found the solution: java-test-fixtures plugin

If the whole intention of that project is to provide the test code, then I would indeed put it to

main

because that is the main code for that project. But yes, you can also use the test fixtures plugin if you prefer.