🧪 TDD Kata 1: String Calculator

A TypeScript implementation of the classic String Calculator Kata, built using a Test-Driven Development (TDD) approach with Jest.

---

📋 Problem Statement

Create a class StringCalculator with a method add(numbers: string): number that can accept a string of numbers and return their sum, following a series of progressively complex rules.

---

✅ Features Implemented

Step	Feature
1	Returns 0 for an empty string ("" → 0)
2	Returns the number itself for a single value ("1" → 1)
3	Returns the sum of two comma-separated numbers ("1,2" → 3)
4	Handles an unknown amount of comma-separated numbers
5	Supports newlines as valid delimiters ("1\n2,3" → 6)
6	Supports custom delimiters ("//;\n1;2" → 3)
7	Throws an exception for negative numbers ("negatives not allowed: -1")
8	Shows all negative numbers in the exception ("negatives not allowed: -1, -4")
9	Tracks method invocations via getCalledCount()
10	Ignores numbers greater than 1000 ("2,1001" → 2)
11	Supports custom delimiters of any length ("//[***]\n1***2***3" → 6)
12	Supports multiple delimiters ("//[*][%]\n1*2%3" → 6)
13	Supports multiple delimiters with length > 1 ("//[**][%%]\n1**2%%3" → 6)

🛠 Getting Started

📁 Clone the Repository

git clone https://github.com/SSBarik/string-calculator-tdd-kata.git
cd string-calculator-kata

📦 Install Dependencies

npm install

🚀 Run Tests

npm test

---

🧪 Example Usage

import { StringCalculator } from './StringCalculator';

const calculator = new StringCalculator();

console.log(calculator.add(""));              // Output: 0
console.log(calculator.add("1"));             // Output: 1
console.log(calculator.add("1,2"));           // Output: 3
console.log(calculator.add("1\n2,3"));        // Output: 6
console.log(calculator.add("//;\n1;2"));      // Output: 3

console.log(calculator.getCalledCount());     // Output: 5


## 📚 References

- Original Kata: [TDD Kata by Roy Osherove](https://osherove.com/tdd-kata-1)