Initial introduction to JavaScript unit testing

1. Using the Mocha tool for unit testing

① first prepare the node environment

② installation MOCHA:NPM Install Mocha can also be installed globally with NPM install global mocha

③ Install Assertion Library: NPM Install Chai Address: http://chaijs.com/

④ Test Cases:

To edit a simple addition function

Add.js
functionreturn a+b; } module.exports = add;

Writing Test Unit files

Introducing the Add Module
var add = require ('./add ')
The expectvar expect = require (' Chai ') in the assertion Library Chai is introduced. Expect; describe (function() {     It (function() {         expect (add). To.be.equal (2);     }) ;

where the describe () function is a test description that represents a set of related test cases for which module is tested. It () is a test case in which a test case (it block) can be executed inside a describe block.
The test script should include one or more describe blocks, and each describe block should include one or more it blocks.

How do I execute a test file?

Direct command:mocha add.test or mocha add.test.js

Results show:

Reference article: Test Framework Mocha Example Tutorial

Getting Started with JavaScript unit tests