@Test
  public void testGetShoppingListForDiscountItem() throws Exception {
    ShoppingChart shoppingChart = new ShoppingChart();
    shoppingChart.add(new Item("ITEM000004", "电池", "个", 2.00, 0.8));
    ShoppingListChart shoppingListChart = new ShoppingListChart(shoppingChart);
    Pos pos = new Pos();
    String result = pos.getShoppingList(shoppingListChart);

    String expectedShoppingList =
        "***商店购物清单***\n"
            + "名称:电池,数量:1个,单价:2.00(元),小计:1.60(元)\n"
            + "----------------------\n"
            + "总计:1.60(元)\n"
            + "节省:0.40(元)\n"
            + "**********************\n";
    assertThat(result, is(expectedShoppingList));
  }
  @Test
  public void testGetShoppingListForDoubleItem() throws Exception {
    ShoppingChart shoppingChart = new ShoppingChart();
    shoppingChart.add(new Item("ITEM000000", "可口可乐", "瓶", 3.00, 1));
    shoppingChart.add(new Item("ITEM000000", "可口可乐", "瓶", 3.00, 1));
    ShoppingListChart shoppingListChart = new ShoppingListChart(shoppingChart);
    Pos pos = new Pos();
    String result = pos.getShoppingList(shoppingListChart);

    String expectedShoppingList =
        "***商店购物清单***\n"
            + "名称:可口可乐,单价:3.00(元),小计:6.00(元)\n"
            + "----------------------\n"
            + "总计:6.00(元)\n"
            + "**********************\n";
    assertThat(result, is(expectedShoppingList));
  }