Supermarket Checkout System

A flexible and extensible checkout system implemented in Elixir, designed to handle dynamic pricing rules while maintaining simplicity and reliability. This project was developed using Test-Driven Development (TDD) methodology.

• Evaluate Programming Style: Demonstrate clean, maintainable, and idiomatic Elixir code.
• Showcase Elixir Expertise: Build a robust and flexible solution.
• Test-Driven Development: Ensure code reliability with comprehensive unit tests.

1. Add Items to Cart:
   • Dynamically add products to a shopping cart.
2. Calculate Total:
   • Display the total price based on the items in the cart.
3. Customizable Pricing Rules:
   • Flexible rules to meet stakeholder requirements:
     • Buy-One-Get-One-Free: Applies to "Green Tea (GR1)".
     • Bulk Discount: For "Strawberries (SR1)", price drops to £4.50 each if buying 3 or more.
     • Coffee Discount: For "Coffee (CF1)", price drops to two-thirds the original price if buying 3 or more.

• Language: Elixir
• Testing Framework: ExUnit
• Database: Not required (in-memory state for simplicity)

git clone https://github.com/imahmedismail/supermarket.git
cd supermarket

mix test

1. Start an Elixir interactive session:

iex -S mix

2. Use the Checkout module to scan items and calculate totals:

alias Supermarket.Checkout

checkout = Checkout.new()
checkout = Checkout.scan(checkout, "GR1")
checkout = Checkout.scan(checkout, "SR1")
checkout = Checkout.scan(checkout, "GR1")
checkout = Checkout.scan(checkout, "GR1")
checkout = Checkout.scan(checkout, "CF1")
IO.puts("Total: £#{Checkout.total(checkout)}")

A Postman collection is included to test the checkout system's functionality with the following scenarios:

1. Basket: GR1, SR1, GR1, GR1, CF1

   Expected Total Price: £22.45

2. Basket: GR1, GR1

   Expected Total Price: £3.11

3. Basket: SR1, SR1, GR1, SR1

   Expected Total Price: £16.61

4. Basket: GR1, CF1, SR1, CF1, CF1

   Expected Total Price: £30.57

To import and use the collection:

• Just import this file supermarket_checkout.postman_collection.json from project-directory to Postman
• Test the endpoints with the predefined requests.

Contributions are welcome! Feel free to submit issues or create pull requests to improve this project.