Running JUnit Test in parallel on Suite Level?

Question

I have a bunch of tests that are organized in JUnit test suites. These tests are greatly utilizing selenium to test a web application. So, naturaly for selenium, the runtime

Answer 1

Here is some code that worked for me. I did not write this. If you use @RunWith(ConcurrentSuite.class) instead of @RunWith(Suite.class) it should work. There is an annotation that is also needed which is found below.

package utilities.runners;

import org.junit.internal.builders.AllDefaultPossibilitiesBuilder;
import org.junit.runner.Runner;
import org.junit.runners.Suite;
import org.junit.runners.model.InitializationError;
import org.junit.runners.model.RunnerBuilder;
import org.junit.runners.model.RunnerScheduler;

import utilities.annotations.Concurrent;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @author Mathieu Carbou (mathieu.carbou@gmail.com)
 */
public final class ConcurrentSuite extends Suite {
    public ConcurrentSuite(final Class<?> klass) throws InitializationError {
        super(klass, new AllDefaultPossibilitiesBuilder(true) {
            @Override
            public Runner runnerForClass(Class<?> testClass) throws Throwable {
                List<RunnerBuilder> builders = Arrays.asList(
                        new RunnerBuilder() {
                            @Override
                            public Runner runnerForClass(Class<?> testClass) throws Throwable {
                                Concurrent annotation = testClass.getAnnotation(Concurrent.class);
                                if (annotation != null)
                                    return new ConcurrentJunitRunner(testClass);
                                return null;
                            }
                        },
                        ignoredBuilder(),
                        annotatedBuilder(),
                        suiteMethodBuilder(),
                        junit3Builder(),
                        junit4Builder());
                for (RunnerBuilder each : builders) {
                    Runner runner = each.safeRunnerForClass(testClass);
                    if (runner != null)
                        return runner;
                }
                return null;
            }
        });
        setScheduler(new RunnerScheduler() {
            ExecutorService executorService = Executors.newFixedThreadPool(
                    klass.isAnnotationPresent(Concurrent.class) ?
                            klass.getAnnotation(Concurrent.class).threads() :
                            (int) (Runtime.getRuntime().availableProcessors() * 1.5),
                    new NamedThreadFactory(klass.getSimpleName()));
            CompletionService<Void> completionService = new ExecutorCompletionService<Void>(executorService);
            Queue<Future<Void>> tasks = new LinkedList<Future<Void>>();

            @Override
            public void schedule(Runnable childStatement) {
                tasks.offer(completionService.submit(childStatement, null));
            }

            @Override
            public void finished() {
                try {
                    while (!tasks.isEmpty())
                        tasks.remove(completionService.take());
                } catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                } finally {
                    while (!tasks.isEmpty())
                        tasks.poll().cancel(true);
                    executorService.shutdownNow();
                }
            }
        });
    }

    static final class NamedThreadFactory implements ThreadFactory {
        static final AtomicInteger poolNumber = new AtomicInteger(1);
        final AtomicInteger threadNumber = new AtomicInteger(1);
        final ThreadGroup group;

        NamedThreadFactory(String poolName) {
            group = new ThreadGroup(poolName + "-" + poolNumber.getAndIncrement());
        }

        @Override
        public Thread newThread(Runnable r) {
            return new Thread(group, r, group.getName() + "-thread-" + threadNumber.getAndIncrement(), 0);
        }
    }

}

And the annotation is as follows.

package utilities.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @author Mathieu Carbou (mathieu.carbou@gmail.com)
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.TYPE })
public @interface Concurrent {
    int threads() default 5;
}

Answer 2

Since Suite is used to annotate a Class, so run the Suite-annotated class in JUnitCore.runClasses(ParallelComputer.classes(), cls) way. cls are Suite-annotated classes.

@RunWith(Suite.class)
@Suite.SuiteClasses({
Test1.class,
Test2.class})
public class Suite1 {
}

@RunWith(Suite.class)
@Suite.SuiteClasses({
Test3.class,
Test4.class})
public class Suite2 {
}
...
JUnitCore.runClasses(ParallelComputer.classes(), new Class[]{Suite1.class, Suite2.class})