@Test
    public void oneTablespoonEqualThreeTeaspoon(){
        ArithmeticQuantity tbs = new ArithmeticQuantity(1, Volume.TABLESPOON);
        ArithmeticQuantity tsp = new ArithmeticQuantity(3, Volume.TEASPOON);

        //assertEquals(tbs.convert(TEASPOON), tsp);
        //assertEquals(tsp.convert(TABLESPOON), tbs);
        assertEquals(tbs, tsp);
        assertEquals(tsp, tbs);

    }