Agile Web Development with Rails, Edition 4

11.1 Iteration F1: Moving the Cart 10.3 Iteration E3: Finishing the Cart

10.4 Playtime

Once again, get the tests working, and add tests for the smarter cart.

See that the tests fail.

rake test
Run options: --seed 21736
 
# Running:
 
........F...................
 
Finished in 0.298864s, 93.6881 runs/s, 227.5281 assertions/s.
 
  1) Failure:
CartsControllerTest#test_should_destroy_cart [/home/rubys/git/awdwr/edition4/work-215-41/depot/test/controllers/carts_controller_test.rb:43]:
"Cart.count" didn't change by -1.
Expected: 1
  Actual: 2
 
28 runs, 68 assertions, 1 failures, 0 errors, 0 skips

Update expected target of redirect: Cart#destroy.

edit test/controllers/carts_controller_test.rb
  test "should destroy cart" do
    session[:cart_id] = @cart.id
    assert_difference('Cart.count', -1) do
      delete :destroy, id: @cart
    end
 
    assert_redirected_to store_path
  end

Test both unique and duplicate products.

edit test/models/cart_test.rb
require 'test_helper'
 
class CartTest < ActiveSupport::TestCase
  test "add unique products" do
    cart = Cart.create
    book_one = products(:one)
    book_two  = products(:two)
    cart.add_product(book_one.id).save!
    cart.add_product(book_two.id).save!
    assert_equal 2, cart.line_items.size
    assert_equal book_one.price + book_two.price, cart.total_price
  end
  
  test "add_duplicate_product" do
    cart = Cart.create
    ruby_book = products(:ruby)
    cart.add_product(ruby_book.id).save!
    cart.add_product(ruby_book.id).save!
    assert_equal 2*book_one.price, cart.total_price
    assert_equal 1, cart.line_items.size
    assert_equal 2, cart.line_items[0].quantity
  end 
end
rake test test/models/cart_test.rb
Run options: --seed 33551
 
# Running:
 
E.
 
Finished in 0.070124s, 28.5210 runs/s, 28.5210 assertions/s.
 
  1) Error:
CartTest#test_add_duplicate_product:
NameError: undefined local variable or method `book_one' for #<CartTest:0x00000004c392c8>
    test/models/cart_test.rb:24:in `block in <class:CartTest>'
 
2 runs, 2 assertions, 0 failures, 1 errors, 0 skips

Refactor.

edit test/models/cart_test.rb
require 'test_helper'
 
class CartTest < ActiveSupport::TestCase
  def setup
    @cart  = Cart.create
    @book_one = products(:ruby)
    @book_two  = products(:two)
  end
  
  test "add unique products" do
    @cart.add_product(@book_one.id).save!
    @cart.add_product(@book_two.id).save!
    assert_equal 2, @cart.line_items.size
    assert_equal @book_one.price + @book_two.price, @cart.total_price
  end
 
  test "add duplicate product" do
    @cart.add_product(@book_one.id).save!
    @cart.add_product(@book_one.id).save!
    assert_equal 2*@book_one.price, @cart.total_price
    assert_equal 1, @cart.line_items.size
    assert_equal 2, @cart.line_items[0].quantity
  end 
end
rake test test/models/cart_test.rb
Run options: --seed 6342
 
# Running:
 
..
 
Finished in 0.079509s, 25.1542 runs/s, 62.8856 assertions/s.
 
2 runs, 5 assertions, 0 failures, 0 errors, 0 skips

Verify that the tests pass.

rake test
Run options: --seed 41607
 
# Running:
 
..............................
 
Finished in 0.273739s, 109.5936 runs/s, 273.9841 assertions/s.
 
30 runs, 75 assertions, 0 failures, 0 errors, 0 skips

Now the tests should pass.

rake test
Run options: --seed 32939
 
# Running:
 
..............................
 
Finished in 0.275301s, 108.9715 runs/s, 272.4287 assertions/s.
 
30 runs, 75 assertions, 0 failures, 0 errors, 0 skips

Add price to line item

rails generate migration add_price_to_line_item price:decimal
      invoke  active_record
      create    db/migrate/20160306174122_add_price_to_line_item.rb
edit db/migrate/20160306174122_add_price_to_line_item.rb
class AddPriceToLineItem < ActiveRecord::Migration
  def change
    add_column :line_items, :price, :decimal
    LineItem.all.each do |li|
      li.price = li.product.price
    end
  end
end
rake db:migrate
mv 20160306174122_add_price_to_line_item.rb 20160306000006_add_price_to_line_item.rb
== 20160306000006 AddPriceToLineItem: migrating ===============================
-- add_column(:line_items, :price, :decimal)
   -> 0.0018s
== 20160306000006 AddPriceToLineItem: migrated (0.0172s) ======================
 
edit app/models/cart.rb
class Cart < ActiveRecord::Base
  has_many :line_items, dependent: :destroy
 
  def add_product(product_id)
    current_item = line_items.find_by(product_id: product_id)
    if current_item
      current_item.quantity += 1
    else
      current_item = line_items.build(product_id: product_id)
      current_item.price = current_item.product.price
    end
    current_item
  end
 
  def total_price
    line_items.to_a.sum { |item| item.total_price }
  end
end
git commit -a -m "Adding a Cart"
[master d414943] Adding a Cart
 4 files changed, 61 insertions(+), 11 deletions(-)
git tag iteration-d

11.1 Iteration F1: Moving the Cart 10.3 Iteration E3: Finishing the Cart