About

Based on the given problem statement this is a program that calculates sales tax and prints out a receipt which has the pricing details(including tax) related to the purchase of each item. One can read more about design decisions based on which how this app is built from this section. You can see how a purchase receipt looks like from the sample program output section.

Code related design decisions

• The entities related to the problem domain are - Line Item, Receipt, Shopping Cart and Tax
• A shopping cart has - line items, a tax calculator and a receipt generator. They satisfy the "has_a" relationship hence I've made use of composition in appropriate places.

• Have made use of BigDecimal class in Ruby to represent money related values in a more accurate manner

• Items that are exempt from basic sales tax(st) are specified as part of the LineItem class

  • Items are categorized as food, medical products and books based on certain keywords in the item names. Those categories that'll help check if an item is exempt from sales tax are also specified as part of the LineItem class

• Imported items are those that have the word imported in them.

• With Single Responsiblity Principle in mind the responsibility of each class is:

  • A CsvParser class that is used to read the input from a CSV file and remove all unnecessary leading and trailing whitespaces
  • A LineItem class that is used to contain the different properties related to each line item.
  • A TaxCalculator class that calculates
    • The price of an item inclusive of tax
    • The total sales tax per item
  • A ReceiptGenerator class that is mainly used to generate a receipt
  • A ShoppingCart class that is used to facilitate the purchase/checkout process

Assumptions

• The program accepts Comma Separated Values(CSV) as input. Hence I've made use of a CsvParser to read CSV data.
• The CSV files are to be placed in the input directory inorder to be read by the program
• Price is a positive number
• Product quantity is a positive integer.

Usage

Dependencies

• Ruby 2.7.4
• Please refer to the Gemfile for the other dependencies

Setup

• Run bundle install from a project's root directory to install the related dependencies.

Running the program

One can run the program with the below command from the projects root directory.

Format:

ruby bin/generate_sales_receipt.rb path_to_csv_file_name_present_in_input_directory.csv

Example:

ruby bin/generate_sales_receipt.rb shopping_basket3.csv

Running the tests

• One can run the specs from the project's root directory with the command rspec

Program Output

• Below is a sample program output run against the command ruby bin/generate_sales_receipt.rb shopping_basket3.csv

1, imported bottle of perfume, 32.19
1, bottle of perfume, 20.89
1, packet of headache pills, 9.75
1, imported box of chocolates, 11.85

Sales Taxes: 6.7
Total: 74.68