code: private Class<?> instantiate(String className) {
      try {
        return Class.forName(className, false, Thread.currentThread().getContextClassLoader());
      } catch (Throwable t) {
        try {
          serializer.serialize(
              new SuiteFailureEvent(
                  new Failure(Description.createSuiteDescription(className), t)));
          if (flushFrequently)
            serializer.flush();
        } catch (Exception e) {
          warn("Could not report failure back to master.", t);
        }
        return null;
      }
    }
docs: Instantiate test classes (or try to).