create coupon of length N

README.md

@@ -2,7 +2,7 @@
 This is a simple coupon creation project using NodeJS.
 
 [![license](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/yusufshakeel/couponjs)
-[![npm version](https://img.shields.io/badge/npm-0.1.0-blue.svg)](https://www.npmjs.com/package/couponjs)
+[![npm version](https://img.shields.io/badge/npm-0.2.0-blue.svg)](https://www.npmjs.com/package/couponjs)
 [![Build Status](https://travis-ci.com/yusufshakeel/couponjs.svg?branch=master)](https://travis-ci.com/yusufshakeel/couponjs)
 
 # Getting Started
@@ -20,6 +20,8 @@ Using the following for testing:
 ## Generate coupon
 Create an object of Coupon.
 ```javascript
+const Coupon = require('couponjs');
+
 const coupon = new Coupon();
 ```
 
@@ -30,6 +32,15 @@ const myCoupon = coupon.generate();
 
 By default, `generate` will return coupon code of length 6 using uppercase alphabet.
 
+### Coupon of length N
+To generate coupon of a given length we pass the following option to the `generate` method.
+```javascript
+const myCoupon = coupon.generate({
+  length: 8
+});
+```
+Where, 8 in the above code represent the total number of characters that will be present in the coupon.
+
 
 ## License
 It's free :smiley:

app/constants.js

@@ -1,7 +1,7 @@
 /**
- * Constants
- * @type {{ALPHABET_UPPERCASE: string, ALPHABET_LOWERCASE: string, DIGIT: string}}
+ * @type {{DEFAULT_LENGTH: number, ALPHABET_UPPERCASE: string}}
  */
 module.exports = {
+  DEFAULT_LENGTH: 6,
   ALPHABET_UPPERCASE: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
 };

app/engine.js

@@ -1,10 +1,12 @@
+const { DEFAULT_LENGTH } = require('./constants.js');
 /**
  * Engine to produce coupon.
  * @param {string} characters This is the set of characters used to generate coupon.
  * @param {function} randomInteger This is the function that will generate random integer value.
+ * @param {number} length This is the length of the coupon.
  * @constructor
  */
-const Engine = function (characters, randomInteger) {
+const Engine = function (characters, randomInteger, length = DEFAULT_LENGTH) {
 
   function characterSet() {
     return characters.split('');
@@ -13,9 +15,9 @@ const Engine = function (characters, randomInteger) {
   function generateCoupon() {
     const generatedCouponCharacters = [];
     const charSet = characterSet();
-    for(let i = 0; i < 6; i++) {
+    for(let i = 0; i < length; i++) {
       generatedCouponCharacters.push(
-        charSet[randomInteger(0, 6)]
+        charSet[randomInteger(0, length - 1)]
       );
     }
     return generatedCouponCharacters.join('');

app/option.js

@@ -0,0 +1,6 @@
+const { DEFAULT_LENGTH, ALPHABET_UPPERCASE } = require('./constants.js');
+
+module.exports = {
+  length: DEFAULT_LENGTH,
+  characters: ALPHABET_UPPERCASE
+};

index.js

@@ -1,5 +1,5 @@
 const Engine = require('./app/engine.js');
-const { ALPHABET_UPPERCASE } = require('./app/constants.js');
+const defaultOptions = require('./app/option.js');
 const randomInteger = require('./app/random-integer.js');
 
 /**
@@ -9,10 +9,13 @@ const randomInteger = require('./app/random-integer.js');
 const Coupon = function () {
   /**
    * This will generate coupons.
+   *
+   * @param {object} option This is the configuration option.
    * @returns {string}
    */
-  this.generate = function () {
-    const engine = new Engine(ALPHABET_UPPERCASE, randomInteger);
+  this.generate = function (option) {
+    const { length, characters } = Object.assign(defaultOptions, option);
+    const engine = new Engine(characters, randomInteger, length);
     return engine.run();
   };
 };

tests/app/engine.test.js

@@ -16,4 +16,13 @@ test('Should return zzzzzz as coupon when character set is "z" and randomInteger
   });
   const engine = new Engine(characters, mockRandomInteger);
   expect(engine.run()).toBe('zzzzzz');
+});
+
+test('Should return aaa as coupon when character set is "a" and rendomInteger generates always 0 and length is 3', () => {
+  const characters = "a";
+  const mockRandomInteger = jest.fn((min, max) => {
+    return 0;
+  });
+  const engine = new Engine(characters, mockRandomInteger, 3);
+  expect(engine.run()).toBe('aaa');
 });

tests/index.test.js

@@ -5,3 +5,9 @@ test('Should generate coupon code using uppercase alphabet A-Z of length 6.', ()
   const result = coupon.generate();
   expect(/^[A-Z]{6}$/.test(result)).toBeTruthy();
 });
+
+test('Should generate coupon code using uppercase alphabet A-Z of length 8.', () => {
+  const coupon = new Coupon();
+  const result = coupon.generate({ length: 8 });
+  expect(/^[A-Z]{8}$/.test(result)).toBeTruthy();
+});