@Test
public void testIndexOf() {

  ObservableList<String> list = new ObservableList<>();
  list.add("A");
  list.add("B");
  list.add("C");
  list.add("B");
  assertThat(list.indexOf("B")).isEqualTo(1);
  assertThat(list.get(2)).isEqualTo("C");
  assertThat(list.lastIndexOf("B")).isEqualTo(3);
}