public void testCheckPositionIndex_ok() {
    assertEquals(0, checkPositionIndex(0, 0));
    assertEquals(0, checkPositionIndex(0, 1));
    assertEquals(1, checkPositionIndex(1, 1));
  }

  public void testCheckPositionIndex_badSize() {
    assertThrows(IllegalArgumentException.class, () -> checkPositionIndex(1, -1));
  }

  public void testCheckPositionIndex_negative() {
    IndexOutOfBoundsException expected =