Introducing Mocha js Testing Framework For Node.Js

• Mocha is a JavaScript testing framework for running on NodeJS in asynchronous mode.
• In this demo,”We will learn to install and run Mocha test framework”.
• The Mocha test framework can be installed using npm install mocha –save-dev command.The following screenshot shows the installation of Mocha framework.

• To demonstrate Mocha framework we have creates MochaTestDemo project.The structure of this project is as follows.

• The number-operation.js file contains the javascript code for exporting operation object which contains a method named addTwoNumber() for adding 2 input numbers and returns the result.The code content of number-operation.js file are as follows:-

var operation ={
    addTwoNumber : function(number1, number2){
        return number1 + number2;
    }
};
module.exports = operation;

• The index.js file contains the code to import number-operation.js file using require statement and calls the addTwoNumber() for 5 and 10.The code content of index.js file are as follows:-

var operation = require('./number-operation'),
    result = operation.addTwoNumber(5,10);
console.log("Result: ",result);

• The demo code can be run using node index.js command.The following screenshot shows the terminal with index.js in execution.

• Now we can create  a test directory and a test.js file for writing Mocha test cases.The following screenshot shows the terminal with test directory and test.js file creation.

• The test.js file contains test case using describe and assert method.The code content of test.js file are as follows:-

var assert = require("assert"),
    operation = require('../number-operation');

describe('Testing addTwoNumber', function() {
    it('should return 4 when the input number are 1 and 3', function () {
        assert.equal(4, operation.addTwoNumber(1,3));
    });
});

• As we have installed Mocha as local dependency to  the project we need add a script entry in package.json file to run Mocha.The code content of package.json file are as follows:-

{
  "name": "mocha-test-demo",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "test": "mocha"
  },
  "license": "ISC",
  "devDependencies": {
    "mocha": "^2.3.2"
  }
}

• No we can run the Mocha using npm run test command.The following screenshot shows the terminal with Mocha in execution and test case is passed.

• you can download this demo using following link:-

https://github.com/saan1984/MochaTestDemo