Acme Widget Co

A PHP-based shopping basket system demonstrating modern software engineering practices with clean architecture, dependency injection, and comprehensive testing.

How It Works

The system implements a flexible shopping basket with the following components:

Core Classes

Basket - The main shopping basket class that:

• Manages a product catalogue with prices
• Handles adding items to the basket
• Calculates totals including delivery charges
• Applies special offers automatically
• Uses cents internally to avoid floating-point arithmetic issues

DeliveryCharge - Implements delivery charge calculation:

• Free delivery for orders ≥ $90.00
• $2.95 delivery for orders ≥ $50.00
• $4.95 delivery for orders < $50.00

SpecialOffer - Implements "buy one, get one half price" offers:

• Applies to specified product codes
• Automatically reduces the price of the second item by 50%

Architecture Features

The system uses several design patterns and best practices:

• Strategy Pattern: Delivery charges and offers are pluggable via interfaces
• Dependency Injection: All dependencies are injected through constructors
• Interface Segregation: Small, focused interfaces for different responsibilities
• Type Safety: Comprehensive type hints and PHPDoc annotations
• Precision Handling: Uses integer cents internally to avoid floating-point errors

Test Cases

The included tests demonstrate various scenarios:

• Two R01 items: $54.37 (second R01 half price + delivery)
• B01 + G01: $37.85 (standard pricing + delivery)
• R01 + G01: $60.85 (standard pricing + delivery)
• Complex basket: $98.27 (multiple items with offers applied)

How to Use

With Dockerfile

git clone https://github.com/parthmp/acme-widget-co.git
cd acme-widget-co
docker build -t acme-app .
docker run --rm -it acme-app bash
vendor/bin/phpunit tests/BasketTest.php

With Docker Compose

git clone https://github.com/parthmp/acme-widget-co.git
cd acme-widget-co
docker compose up -d --build
docker compose exec app bash
vendor/bin/phpunit tests/BasketTest.php

Without Docker

git clone https://github.com/parthmp/acme-widget-co.git
cd acme-widget-co
composer install

# Linux/Mac
vendor/bin/phpunit tests/BasketTest.php

# Windows
vendor\bin\phpunit tests\BasketTest.php

Technologies & Practices Demonstrated

This repository showcases modern PHP development practices:

• Composer - Dependency management and autoloading
• PHPUnit - Unit and integration testing framework
• PHPStan - Static analysis for type safety and code quality
• Docker - Containerized development environment
• Docker Compose - Multi-container application orchestration
• Dependency Injection - Loose coupling and testability
• Strategy Pattern - Flexible, extensible design
• Sensible Types - Strong typing with comprehensive annotations
• Source Control - Git-based version control and code review workflows
• Good Separation/Encapsulation - Clear boundaries between components
• Small Accurate Interfaces - Focused, single-responsibility contracts

Product Catalogue

The system includes three sample products:

• R01: Red Widget - $32.95
• G01: Green Widget - $24.95
• B01: Blue Widget - $7.95

Example Usage

// Create basket with catalogue, delivery rules, and offers
$basket = new Basket(
    ['R01' => 32.95, 'G01' => 24.95, 'B01' => 7.95],
    new DeliveryCharge(),
    new SpecialOffer('R01')
);

// Add items
$basket->add('R01');
$basket->add('R01'); // Second R01 will be half price

// Calculate total (includes delivery)
$total = $basket->total(); // $54.37