given:
        def class1 = stubFileVisitDetails('class1')
        def class2 = stubFileVisitDetails('class2')

        when:
        scanner.run()

        then:
        1 * detector.startDetection(processor)
        then:
        1 * files.visit(_) >> { args ->
            FileVisitor visitor = args[0]
            assert visitor
            visitor.visitFile(class1)
            visitor.visitFile(class2)

import org.gradle.api.internal.file.RelativeFile;
import org.gradle.api.internal.tasks.testing.TestClassProcessor;

import java.io.File;
import java.util.List;

public interface TestFrameworkDetector {
    void startDetection(TestClassProcessor testClassProcessor);

    boolean processTestClass(RelativeFile testClassFile);

    void setTestClasses(List<File> testClasses);

    void setTestClasspath(List<File> classpath);

        if (testFrameworkDetector == null) {
            filenameScan();
        } else {
            detectionScan();
        }
    }

    private void detectionScan() {
        testFrameworkDetector.startDetection(testClassProcessor);
        candidateClassFiles.visit(new ClassFileVisitor() {
            @Override
            public void visitClassFile(FileVisitDetails fileDetails) {

            testClassProcessor.processTestClass(new DefaultTestClassRunInfo(className));
        }
    }

    @Override
    public void startDetection(TestClassProcessor testClassProcessor) {
        this.testClassProcessor = testClassProcessor;
    }

    private static class TestClass {
        private final boolean test;