@Test
public void down() {

    final FieldConstraint[] fieldConstraints = new FieldConstraint[2];
    final FieldConstraint top = mock(FieldConstraint.class);
    fieldConstraints[0] = top;
    fieldConstraints[1] = mock(FieldConstraint.class);
    FieldConstraintArrayUtil.moveDown(0, fieldConstraints);
    assertEquals(top, fieldConstraints[1]);
}