NotSingleThreadedRunner.java

package com.telenor.runners;

import org.junit.runner.notification.RunNotifier;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.FrameworkMethod;
import org.junit.runners.model.InitializationError;
import org.junit.runners.model.Statement;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * A simple Multi-threaded runner. Haven't you always wanted that extra speed of your JUnit tests?
 * Use this thingie instead, then! :-)
 * Add: 
 * @RunWith(NotSingleThreadedRunner.class)
 *
 * @author <a href="[email protected]">t769765</a>
 */
public final class NotSingleThreadedRunner extends BlockJUnit4ClassRunner {

    private static final int MAX_THREADS = 8;
    private static final int SLEEP_TIME = 25;
    private static final int INITIAL_VALUE = 0;

    private AtomicInteger numThreads;

    public NotSingleThreadedRunner(Class<?> klass) throws InitializationError {
        super(klass);
        numThreads = new AtomicInteger(INITIAL_VALUE);
    }

    @Override
    protected void runChild(final FrameworkMethod method, final RunNotifier notifier) {
        while (numThreads.get() > MAX_THREADS) {
            try {
                Thread.sleep(SLEEP_TIME);
            } catch (InterruptedException e) {
                e.printStackTrace();
                return;
            }
        }
        numThreads.incrementAndGet();
        new Thread(new Test(method, notifier)).start();
    }

    @Override
    protected Statement childrenInvoker(final RunNotifier notifier) {
        return new Statement() {
            @Override
            public void evaluate() throws Throwable {
                NotSingleThreadedRunner.super.childrenInvoker(notifier).evaluate();
                while (numThreads.get() > 0) {
                    Thread.sleep(SLEEP_TIME);
                }
            }
        };
    }

    private final class Test implements Runnable {

        private final FrameworkMethod method;
        private final RunNotifier notifier;

        public Test(final FrameworkMethod method, final RunNotifier notifier) {
            this.method = method;
            this.notifier = notifier;
        }

        @Override
        public void run() {
            NotSingleThreadedRunner.super.runChild(method, notifier);
            numThreads.decrementAndGet();
        }
    }

}