public virtual void test_tenor()
        {
            double test1 = VOLS.tenor(VAL_DATE, VAL_DATE);

            assertEquals(test1, 0d);
            double test2 = VOLS.tenor(VAL_DATE, date(2018, 2, 28));

            assertEquals(test2, 3d);
            double test3 = VOLS.tenor(VAL_DATE, date(2018, 2, 10));

            assertEquals(test3, 3d);
        }