buildFile << """
            import org.gradle.api.internal.project.taskfactory.ITaskFactory

            interface CustomTestBinary extends TestSuiteBinarySpec {
                String getData()
            }

            class DefaultCustomTestBinary extends BaseBinarySpec implements CustomTestBinary {
                TestSuiteSpec testSuite
                BinarySpec testedBinary
                String data = "foo"
            }

    ComponentSpec testedComponent

    void testing(ComponentSpec component) { this.testedComponent = component }
}

interface CustomTestBinary extends TestSuiteBinarySpec {
    String getData()
}

class DefaultCustomTestBinary extends BaseBinarySpec implements CustomTestBinary {
    TestSuiteSpec testSuite
    BinarySpec testedBinary
    String data
}