teolandon/string-calculator

An exercise in Test Driven Development using Node.js, Mocha and Chai

String Calculator

Based on the famous String Calculator Kata popularized by Roy Osherove.

This is an exercise suitable for gaining familiarity with Test Driven Development (TDD), as well as a quick interview exercise.

The goal of this Kata is to create an add() function that takes a variable number of strings, converts them to integers, and returns their sum.

In order to achieve this goal we will use the principles of TDD to incrementally develop a fully tested add() function. Please read each requirement below (without reading ahead), and for each requirement:

1. Create a failing test describing the feature.
2. Extend the application to make the feature pass.
3. Refactor the code into a more structured and extensible version.

Setup

Use Node 8.

Run npm i to install all dependencies.

Use npm run start to run the application.

Use npm run test to run the tests.

Refer to the Mocha and Chai documentation for guidance on tests.

Steps

1. The StringCalculator class's add() method should return 0 when called without any arguments.

StringCalculator.add() --> 0

2. add(str) should return str's contents as an integer.

StringCalculator.add('12') --> 12
StringCalculator.add('5') --> 5

3. add(a, b) should return the sum of a and b when parsed as integers.

StringCalculator.add('7', '4') --> 11
StringCalculator.add('1', '9') --> 10

4. add(n1, n2, n3, ...ni) should return the sum of all n1, n2, ..., ni when parsed as integers.

StringCalculator.add('1', '3', 5', '2') --> 11

Notes: The string arguments should be parsed using the provided IntegerParser.parse(String number) function.