An Updated JUnit AllTests Suite

import org.apache.log4j.Logger;
import org.junit.internal.runners.InitializationError;
import org.junit.runner.Description;
import org.junit.runner.RunWith;
import org.junit.runner.notification.RunListener;
import org.junit.runner.notification.RunNotifier;
import org.junit.runners.Suite;

/**
 * Discovers all JUnit tests and runs them in a suite.
 */
@RunWith(AllTests.AllTestsRunner.class)
public final class AllTests {

  private static final File CLASSES_DIR = findClassesDir();

  private AllTests() {
    // static only
  }

  /**
   * Finds and runs tests.
   */
  public static class AllTestsRunner extends Suite {

    private final Logger _log = Logger.getLogger(getClass());

    /**
     * Constructor.
     *
     * @param clazz  the suite class - <code>AllTests</code>
     * @throws InitializationError  if there's a problem
     */
    public AllTestsRunner(final Class<?> clazz) throws InitializationError {
      super(clazz, findClasses());
    }

    /**
     * {@inheritDoc}
     * @see org.junit.runners.Suite#run(org.junit.runner.notification.RunNotifier)
     */
    @Override
    public void run(final RunNotifier notifier) {
      initializeBeforeTests();

      notifier.addListener(new RunListener() {
        @Override
        public void testStarted(final Description description) {
          if (_log.isTraceEnabled()) {
            _log.trace("Before test " + description.getDisplayName());
          }
        }

        @Override
        public void testFinished(final Description description) {
          if (_log.isTraceEnabled()) {
            _log.trace("After test " + description.getDisplayName());
          }
        }
      });

      super.run(notifier);
    }

    private static Class<?>[] findClasses() {
      List<File> classFiles = new ArrayList<File>();
      findClasses(classFiles, CLASSES_DIR);
      List<Class<?>> classes = convertToClasses(classFiles, CLASSES_DIR);
      return classes.toArray(new Class[classes.size()]);
    }

    private static void initializeBeforeTests() {
      // do one-time initialization here
    }

    private static List<Class<?>> convertToClasses(
        final List<File> classFiles, final File classesDir) {

      List<Class<?>> classes = new ArrayList<Class<?>>();
      for (File file : classFiles) {
        if (!file.getName().endsWith("Test.class")) {
          continue;
        }
        String name = file.getPath().substring(classesDir.getPath().length() + 1)
          .replace('/', '.')
          .replace('\\', '.');
        name = name.substring(0, name.length() - 6);
        Class<?> c;
        try {
          c = Class.forName(name);
        }
        catch (ClassNotFoundException e) {
          throw new AssertionError(e);
        }
        if (!Modifier.isAbstract(c.getModifiers())) {
          classes.add(c);
        }
      }

      // sort so we have the same order as Ant
      Collections.sort(classes, new Comparator<Class<?>>() {
        public int compare(final Class<?> c1, final Class<?> c2) {
          return c1.getName().compareTo(c2.getName());
        }
      });

      return classes;
    }

    private static void findClasses(final List<File> classFiles, final File dir) {
      for (File file : dir.listFiles()) {
        if (file.isDirectory()) {
          findClasses(classFiles, file);
        }
        else if (file.getName().toLowerCase().endsWith(".class")) {
          classFiles.add(file);
        }
      }
    }
  }

  private static File findClassesDir() {
    try {
      String path = AllTests.class.getProtectionDomain()
        .getCodeSource().getLocation().getFile();
      return new File(URLDecoder.decode(path, "UTF-8"));
    }
    catch (UnsupportedEncodingException impossible) {
      // using default encoding, has to exist
      throw new AssertionError(impossible);
    }
  }
}