@SuppressWarnings("unchecked")
@Test
public void testMapWritable() {

  Text[] keys = {
      new Text("key1"),
      new Text("key2"),
      new Text("Key3"),
  };
  
  BytesWritable[] values = {
      new BytesWritable("value1".getBytes()),
      new BytesWritable("value2".getBytes()),
      new BytesWritable("value3".getBytes())
  };
  MapWritable inMap = new MapWritable();
  for (int i = 0; i < keys.length; i++) {
    inMap.put(keys[i], values[i]);
  }
  MapWritable outMap = new MapWritable(inMap);
  assertEquals(inMap.size(), outMap.size());
  
  for (Map.Entry<Writable, Writable> e: inMap.entrySet()) {
    assertTrue(outMap.containsKey(e.getKey()));
    assertEquals(0, ((WritableComparable) outMap.get(e.getKey())).compareTo(
        e.getValue()));
  }
  
  // Now for something a little harder...
  
  Text[] maps = {
      new Text("map1"),
      new Text("map2")
  };
  
  MapWritable mapOfMaps = new MapWritable();
  mapOfMaps.put(maps[0], inMap);
  mapOfMaps.put(maps[1], outMap);
  
  MapWritable copyOfMapOfMaps = new MapWritable(mapOfMaps);
  for (int i = 0; i < maps.length; i++) {
    assertTrue(copyOfMapOfMaps.containsKey(maps[i]));
    MapWritable a = (MapWritable) mapOfMaps.get(maps[i]);
    MapWritable b = (MapWritable) copyOfMapOfMaps.get(maps[i]);
    assertEquals(a.size(), b.size());
    for (Writable key: a.keySet()) {
      assertTrue(b.containsKey(key));
      
      // This will work because we know what we put into each set
      
      WritableComparable aValue = (WritableComparable) a.get(key);
      WritableComparable bValue = (WritableComparable) b.get(key);
      assertEquals(0, aValue.compareTo(bValue));
    }
  }
}