AnnotationsAndMarkerInterfaces

import java.lang.annotation.Annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Arrays;

public class AnnotationsAndMarkerInterfaces {
    public static void main(String[] args) {

        // Should we run this test?
        final Annotation theSlowTestAnnotation = ((Class) TestClass.class).getAnnotation(SlowTestAnnotation.class);
        if (theSlowTestAnnotation != null) {
            System.out.println(TestClass.class.getName() + " has the @SlowTestAnnotation.  I don't want to run its tests.");
        }

        // Is there another reason not to run the tests?
        if (Arrays.stream(TestClass.class.getInterfaces()).anyMatch(interfaceClass -> interfaceClass == SlowTestMarkerInterface.class)) {
            System.out.println(TestClass.class.getName() + " implements SlowTestMarkerInterface.  I don't want to run its tests.");
        }

        // If I gave you an instance of the test...
        final TestClass testClass = new TestClass();

        // Would you run the tests?
        if (testClass instanceof SlowTestMarkerInterface) {
            System.out.println(testClass + " implements SlowTestMarkerInterface.  I don't want to run its test!");
        }

        // Heck; run the test anyway:
        testClass.run();
    }
}

@Retention(RetentionPolicy.RUNTIME)
@interface SlowTestAnnotation {
}

interface SlowTestMarkerInterface {
}

interface Test {
    void run();
}

@SlowTestAnnotation
class TestClass implements Test, SlowTestMarkerInterface {
    @Override
    public void run() {
        System.out.println("This test takes a long time to run!");
        try {
            Thread.sleep(5000);
        } catch (final InterruptedException ex) {
            // (This is one of those rare cases where it's OK to throw away the exception.)
        }
        System.out.println("OK; I finished running this test.");
    }
}