Agile Web Development with Rails, Edition 4

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
Loaded suite /home/rubys/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/rake_test_loader
Started
.....
Finished in 0.424745 seconds.
 
5 tests, 23 assertions, 0 failures, 0 errors, 0 skips
 
Test run options: --seed 36563
Loaded suite /home/rubys/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/rake_test_loader
Started
.F....................
Finished in 1.238343 seconds.
 
  1) Failure:
test_should_destroy_cart(CartsControllerTest) [/home/rubys/git/awdwr/edition4/work-192/depot/test/functional/carts_controller_test.rb:43]:
"Cart.count" didn't change by -1.
<1> expected but was
<2>.
 
22 tests, 34 assertions, 1 failures, 0 errors, 0 skips
 
Test run options: --seed 19975
Errors running test:functionals! #<RuntimeError: Command failed with status (1): [/home/rubys/.rvm/rubies/ruby-1.9.2-p290/bi...]>

Substitute names of products and carts for numbers

edit test/fixtures/line_items.yml
# Read about fixtures at http://api.rubyonrails.org/classes/ActiveRecord/Fixtures.html
 
one:
  product: ruby
  cart: one
 
two:
  product: ruby
  cart: one

Update expected target of redirect: Cart#destroy.

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

Test both unique and duplicate products.

edit test/unit/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
ruby -I test test/unit/cart_test.rb
Loaded suite test/unit/cart_test
Started
E.
Finished in 0.359381 seconds.
 
  1) Error:
test_add_duplicate_product(CartTest):
NameError: undefined local variable or method `book_one' for #<CartTest:0x000000039868b0>
    test/unit/cart_test.rb:24:in `block in <class:CartTest>'
 
2 tests, 2 assertions, 0 failures, 1 errors, 0 skips
 
Test run options: --seed 24376

Refactor.

edit test/unit/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
ruby -I test test/unit/cart_test.rb
Loaded suite test/unit/cart_test
Started
..
Finished in 0.376549 seconds.
 
2 tests, 5 assertions, 0 failures, 0 errors, 0 skips
 
Test run options: --seed 12813

Verify that the tests pass.

rake test
Loaded suite /home/rubys/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/rake_test_loader
Started
.......
Finished in 0.531393 seconds.
 
7 tests, 28 assertions, 0 failures, 0 errors, 0 skips
 
Test run options: --seed 34565
Loaded suite /home/rubys/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/rake_test_loader
Started
......................
Finished in 1.235029 seconds.
 
22 tests, 35 assertions, 0 failures, 0 errors, 0 skips
 
Test run options: --seed 46659

Add a test ensuring that non-empty carts can't be deleted.

edit test/functional/products_controller_test.rb
  test "can't delete product in cart" do
    assert_difference('Product.count', 0) do
      delete :destroy, id: products(:ruby)
    end
 
    assert_redirected_to products_path
  end
 
  test "should destroy product" do
    assert_difference('Product.count', -1) do
      delete :destroy, id: @product
    end
 
    assert_redirected_to products_path
  end

Now the tests should pass.

rake test
Loaded suite /home/rubys/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/rake_test_loader
Started
.......
Finished in 0.535173 seconds.
 
7 tests, 28 assertions, 0 failures, 0 errors, 0 skips
 
Test run options: --seed 15345
Loaded suite /home/rubys/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/rake_test_loader
Started
.......................
Finished in 1.269939 seconds.
 
23 tests, 37 assertions, 0 failures, 0 errors, 0 skips
 
Test run options: --seed 31659

Add price to line item

rails generate migration add_price_to_line_item price:decimal
      invoke  active_record
      create    db/migrate/20111029071707_add_price_to_line_item.rb
edit db/migrate/20111029071707_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 20111029071707_add_price_to_line_item.rb 20110711000006_add_price_to_line_item.rb
==  AddPriceToLineItem: migrating =============================================
-- add_column(:line_items, :price, :decimal)
   -> 0.0012s
==  AddPriceToLineItem: migrated (0.2307s) ====================================
 
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 34e6502] Adding a Cart
 5 files changed, 72 insertions(+), 11 deletions(-)
git tag iteration-d

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