@Test
  public void testRange2() {

    // create a combinatorics vector ()
    IntegerVector vector = IntegerFactory.range(0);

    System.out.println(vector);

    assertEquals(0, vector.getSize());
    assertEquals(false, vector.hasDuplicates());
  }
  @Test
  public void testRange1() {

    // create a combinatorics vector (1, 2, 3)
    IntegerVector vector = IntegerFactory.range(3);

    System.out.println(vector);

    assertEquals(3, vector.getSize());
    assertEquals(false, vector.hasDuplicates());

    assertEquals(1, vector.getValue(0));
    assertEquals(2, vector.getValue(1));
    assertEquals(3, vector.getValue(2));
  }
  @Test(expected = IllegalArgumentException.class)
  public void testRange3() {

    // create a combinatorics vector from -1
    IntegerFactory.range(-1);
  }