@Test
public void testOverlay() throws IOException{

  out=new BufferedWriter(new FileWriter(CONFIG));
  startConfig();
  appendProperty("a","b");
  appendProperty("b","c");
  appendProperty("d","e");
  appendProperty("e","f", true);
  endConfig();
  out=new BufferedWriter(new FileWriter(CONFIG2));
  startConfig();
  appendProperty("a","b");
  appendProperty("b","d");
  appendProperty("e","e");
  endConfig();
  Path fileResource = new Path(CONFIG);
  conf.addResource(fileResource);
  //set dynamically something
  conf.set("c","d");
  conf.set("a","d");
  Configuration clone=new Configuration(conf);
  clone.addResource(new Path(CONFIG2));
  assertEquals(clone.get("a"), "d");
  assertEquals(clone.get("b"), "d");
  assertEquals(clone.get("c"), "d");
  assertEquals(clone.get("d"), "e");
  assertEquals(clone.get("e"), "f");
}