@Test
public void testSystemClasses() {

  final List<String> systemClasses =
      Arrays.asList(MRApps.getSystemClasses(new Configuration()));
  for (String defaultXml : DEFAULT_XMLS) {
    assertTrue(defaultXml + " must be system resource",
        ApplicationClassLoader.isSystemClass(defaultXml, systemClasses));
  }
  for (String klass : SYS_CLASSES) {
    assertTrue(klass + " must be system class",
        ApplicationClassLoader.isSystemClass(klass, systemClasses));
  }
  assertFalse("/fake/Klass must not be a system class",
      ApplicationClassLoader.isSystemClass("/fake/Klass", systemClasses));
}