CartProcessing

Simple cart processing gem (https://github.com/cabify/rubyChallenge challenge solution)

Ruby version >= 2.0

Installation

Clone the repository

$ git clone git@github.com:Landria/cart_processing.git

Build the gem and install it

$ cd cart_processing && bin/setup
$ gem build cart_processing.gemspec
$ gem install ./cart_processing-0.1.0.gem

Configuration

Before test the gem copy products test data

$ cp spec/cart_processing/test_data/test_products.csv /tmp/test_products.csv

Or specify your custom products.csv file

Now you can use the gem. Just add it to your .rb file

require 'cart_processing'

Set checkout data source type and source path. Only :text source is available (:sql source is planned to be added).

CartProcessing.configure do |config|
  config.source = :text
  config.source_path = '/tmp/test_products.csv'
end

Usage

You can set up two types of pricing policies:

XMorePricing if you want to set a discount to specific product over x items.
TwoForOnePricing if you want to offer every second item for free

pricing_rules = [
  CartProcessing::XMorePricing.new('TSHIRT', 3, 19.0),
  CartProcessing::TwoForOnePricing.new('VOUCHER')
]

co = CartProcessing::Checkout.new(pricing_rules)
co.scan("VOUCHER")
co.scan("VOUCHER")
co.scan("TSHIRT")
price = co.total

Use spec/cart_processing/test_data/test_products.csv to test the gem or copy it contents.

Solution notes

Challenge task is impelemnted as a ruby gem to let it be maintainable and used in a most simple way. It's designed to make adding new functionality as simple as possible.

Gem is configurable so you can easly switch the products source if needed. (only :text is are available right now, :sql is planned to be added).

SQL source is unavailable yet cause we have only 3 products to process and csv file is enougth.

If several pricing rules passed for the same product only the last one will be applyed at checkout.

If several products with the same code exists only the first one will be found (we assume that products are uniq.

If nonexisting product code scanned error will be added to CartProcerssing::Checkout instance. Error is not raised cause that type of errors is noncritical for calculations. When using the gem developer have to decide how to handle such errors: interrupt whole the process or just show warning on product scan.

Error is to be raised when

gem is not configured,
source is unreachable,
source type is unavailable.

Gem could be improved with products pricing rules factory. Ex:

pricing_rules = [
  CartProcessing::TshirtXMorePricingRule.new(3, 19.0),
  CartProcessing::MugTwoForOnePricingRule.new
]

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

License

The gem is available as open source under the terms of the MIT License.