@Test
 public void shouldReturn_0_whenNoNormalPriceSpecified() {
   PriceHolder.updatePrices(new HashMap<>(), getDiscountPrices());
   HashMap<Item, Integer> items = new HashMap<>();
   items.put(A, 1);
   assertTrue(PriceCalculator.calculatePriceForItems(items) == 0);
 }
 @Before
 public void setUp() {
   PriceHolder.updatePrices(getNormalPrices(), getDiscountPrices());
 }