@Test
  public void testFromMethod() {
    IntOpenHashSet list2 = new IntOpenHashSet();
    list2.add(1, 3, 5);

    IntDoubleLinkedSet s1 = IntDoubleLinkedSet.from(1, 3, 5);
    IntDoubleLinkedSet s2 = IntDoubleLinkedSet.from(1, 3, 5);

    assertSortedListEquals(list2.toArray(), s1.toArray());
    assertSortedListEquals(list2.toArray(), s2.toArray());
  }
 @Test
 public void testToString() {
   assertEquals("[1, 3, 5]", IntDoubleLinkedSet.from(1, 3, 5).toString());
 }