Executing tests in another build.gradle project

I am finishing a Continuous Integration system with Jenkins and Gradle for a REST service. It will build the App and dependent sub-libraries, build a Docker, start main docker and secondary ones (database, ...) all in Gradle. As it is a REST service I have a separate project that executes the REST tests completely from outside my project just as it is a REST client, and works ok...

Once my project is built and everything running I need to execute the build in the other project (which is just for tests) as a subproject, and wether it passes or not the tests I want to continue the main script as Dockers need to be stopped and deleted. What is the best approach for this?

Thanks