Activity Description

Add unit tests which add unique products and duplicate products. Note that you will need to modify the fixture to refer to products and carts by name, for example product: ruby.

Author’s Solutions

Solution – search for “Test both unique and duplicate products”

Readers’ Solutions

Long says

My attempt:

In test/unit/cart_test.rb: 

  def new_cart_with_one_product(product_name)
    cart = Cart.create
    cart.add_product(products(product_name).id)
    cart
  end

  test 'cart should create a new line item when adding a new product' do
    cart = new_cart_with_one_product(:one)
    assert_equal 1, cart.line_items.count
    # Add a new product
    cart.add_product(products(:ruby).id)
    assert_equal 2, cart.line_items.count
  end

  test 'cart should update an existing line item when adding an existing product' do
    cart = new_cart_with_one_product(:one)
    # Re-add the same product
    cart.add_product(products(:one).id)
    assert_equal 1, cart.line_items.count
  end

Arun says

I am doubtful whether the question was about creating a new and duplicate line items or products. I thought the answer is along the lines of 


  test "unique_product_should_be_saved" 
    product = Product.new(:title => "unique-title",
                          :description => "a unique product",
                          :image_url => "unique.png",
                          :price => 22)
    assert product.save

  end

  test "non_unique_product_should_error_out" 
    product = Product.new(:title => "unique-title",
                          :description => "a unique product",
                          :image_url => "unique.png",
                          :price => 22)
    assert !product.save
    assert_equal "has  not been saved since it is a duplicate ", product.errors[:title].join('; ')
  end

Doc says

File: test/unit/cart_test.rb 

require 'test_helper'

class CartTest < ActiveSupport::TestCase
  test "cart line item should save price" do
    cart = carts(:cart1)
    [:ruby, :loremipsum, :ruby].each do |which_product|
      product = products(which_product)
      item = cart.add_product product.id
      assert_equal item.price, product.price,
        "cart line item did not save price" 
    end
  end

  test "cart line item quantity should increment" do
    cart = carts(:cart2)
    product = products(:ruby)
    multiple = 3
    multiple.times { cart.add_product product.id }
    item = cart.line_items.find_by_product_id product.id    
    assert_equal multiple, item.quantity,
      "cart line item quantity is incorrect" 
  end

  test "cart line item price should equal most-recent price" do
    cart = carts(:cart3)
    product = products(:ruby)
    sale_price = 0.8 * product.price
    [product.price, sale_price, 100].each do |price|
      cart.add_product product.id, price
      item = cart.line_items.find_by_product_id product.id
      assert_equal price, item.price,
        "price #{item.price} is incorrect; should be #{price}" 
    end
  end

  test "cart should be created and destroyed" do
    assert_same Cart.count, Cart.destroy_all.count,
      "unable to destroy existing carts" 
    Cart.create
    assert_equal 1, Cart.count, "unable to create cart" 
    assert_equal 1, Cart.destroy_all.count, "unable to destroy cart" 
  end
end
File: test/fixtures/carts.yml 

...
one: {}
cart1: {}
cart2: {}
cart3: {}

Updating Cart

Worth mentioning that there’s an error in one of these previous posts. It should be “assert_equal XXX, @cart.line_items.length” not count…..

Sean says

Doc,

Try using 

multiple.times { cart.add_product(product.id).save! }
instead of 

multiple.times { cart.add_product product.id }