@Test
public void filter() {

  List<Object> objects = new ArrayList<Object>();
  objects.add(comparable);
  objects.add(comparable);
  doReturn(0).doReturn(1).when(comparable).compareTo(any());
  doReturn(comparable).when(etFilter).getAttributeValue(comparable);
  List<Object> actualObjects = etFilter.filter(objects);
  assertEquals(comparable, actualObjects.get(0));
}