Zeller Checkout System

A flexible checkout system for Zeller's computer store, designed for easy product scanning, pricing, and promotional offers.

Key Features

• Product Handling: Items can be scanned and totals calculated.
• Flexible Pricing: A powerful rule engine supports various promotions (e.g., Buy X Get Y Free, bulk discounts).
• Robust & Accurate: Built with TypeScript for type safety, comprehensive tests, and uses integer cents for precise monetary calculations.
• Configurable: The product catalog and pricing rules are easily updated via config.json.

Setup

npm install
npm run build

Usage Example

import { createDefaultCheckout } from './src';

const checkout = createDefaultCheckout();

checkout.scan('atv');
checkout.scan('atv');
checkout.scan('atv');
checkout.scan('vga');

console.log(checkout.total()); // Expected: $249.00

Testing

npm test                # Runs all tests
npm run test:coverage   # Runs tests with coverage report
npm run test:watch      # Runs tests in watch mode

Architecture Overview

The system is modular and extensible:

• Checkout: Orchestrates scanning and total calculation.
• PricingRule: Defines the interface for all promotional rules.
• ProductCatalog: Manages product information, loaded from config.json.
• Pricing Rules: Implement specific promotional logic.

Extending with New Pricing Rules

To add a new promotion, a new rule can be added to config.json and ensured it is included in the Checkout setup.

Test Coverage

----------------------|---------|----------|---------|---------|-------------------

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Line #s
All files	97.33	87.5	90	97.29
src	95.65	71.42	83.33	95.45
Checkout.ts	95.65	71.42	83.33	95.45	50
src/models	100	100	100	100
Product.ts	100	100	100	100
src/pricing-rules	100	92.3	100	100
BulkDiscountRule.ts	100	100	100	100
BuyXGetYFreeRule.ts	100	85.71	100	100	7
PricingRule.ts	100	100	100	100
src/services	93.75	100	85.71	93.75
ProductCatalog.ts	93.75	100	85.71	93.75	23
----------------------	---------	----------	---------	---------	-------------------
Test Suites: 1 passed, 1 total
Tests: 27 passed, 27 total
Snapshots: 0 total
Time: 1.408 s