@Test
 public void testAddToCartEntry() {
   final CartModificationData modification = classUnderTest.addToCart(productId, quantity);
   assertNotNull(modification);
   final OrderEntryData entry = modification.getEntry();
   assertNotNull(entry);
   assertEquals(productId, entry.getProduct().getCode());
   assertEquals(new Long(quantity), entry.getQuantity());
 }