search
HomeWeChat AppletWeChat DevelopmentThe use of Mocha and chai

This time I will bring you the use of Mocha and chai. What are the precautions when using Mocha and chai? The following is a practical case, let’s take a look.

Introduction to Mocha

Mocha is one of the popular JavaScript testing frameworks through which you can add and run tests to ensure code quality

Mocha’sInstallation and configuration

Global installation of Mocha

npm install -g mocha

Also install Mocha in the project

npm install --save-dev mocha

Add the following to package.json Script:

"scripts": {
    "test": "mocha"
}

Usage of Mocha

Before using it, let’s take a look at the structure of the test project we use:
The use of Mocha and chai

As shown above As shown, the test files need to be placed in the test directory. When mocka is running, all js files in the test directory will be executed (limited to the level below test, for test/subtest Level one is not executed).

where index.js is our tested code:

/**
 * 加法函数
 * @param {第一个数} a 
 * @param {第二个数} b 
 */
function addNum(a,b){
    return a+b;
}
module.exports=addNum;

and index.test.js is our test code (note that a test is added to the name here, which is not necessary. Just to distinguish which are test files):

var addNum=require('../src/index')

describe('测试index.js', function() {
  describe('测试addNum函数', function() {
    it('两数相加结果为两个数字的和', function() {
       if(addNum(1,2)!==3){
         throw new Error("两数相加结果不为两个数字的和");
       }
    });
  });
});

Analyze the syntax of the above code:

The test script should include one or more describe blocks, and each describe block should Include one or more it blocks.
The describe block is called a "test suite" and represents a set of related tests. It is a function whose first parameter is the name of the test suite ("testindex.js") and the second parameter is a function that is actually executed.
It block is called "test case" (test case), which represents a single test and is the smallest unit of testing. It is also a function. The first parameter is the name of the test case ("The addition of two numbers is the sum of two numbers"), and the second parameter is a function that is actually executed.

In the above example, test the addNum function. If runs wrong, throws an exception

Run at this time

npm test

You can get the following results
The use of Mocha and chai

In order to see the result of the running error, we modify the code of index.js at this time:

function addNum(a,b){
    return a+b-1;
}
module.exports=addNum;

Run again

npm test

The results are as follows:
The use of Mocha and chai

Mocha and assertion library chai

In the above Mocha example, test failure is handled by throwing an exception, which is somewhat cumbersome. , so the assertion library emerged.
Here we introduce a commonly used assertion library chai.
It can be simply understood that this is an encapsulation of our exception-throwing method above. When the judgment fails, an exception will be thrown.
First install chai:

npm install --save-dev chai

Then let us use chai to modify the above index.test.js:

var expect = require('chai').expect;
var addNum=require('../src/index')

describe('测试index.js', function() {
  describe('测试addNum函数', function() {
    it('两数相加结果为两个数字的和', function() {
      expect(addNum(1,2)).to.be.equal(3);
    });
  });
});

The above grammar is very close to natural language, expect (expect) is an expression The result of an expression is equal to an expression.
Run

npm test

and get the following results:
The use of Mocha and chai

It can be seen that the assertion library in the picture also printed the expected result 3 and the actual result 2.
It would be much more cumbersome to use judgment to throw exceptions.

The above syntax is chai's expect syntax, which also has should syntax and asset syntax.
If you have used java and .NET before, you may be more comfortable with assets:

var assert = require('chai').assert;

assert.typeOf(foo, 'string');
assert.equal(foo, 'bar');
assert.lengthOf(foo, 3)
assert.property(tea, 'flavors');
assert.lengthOf(tea.flavors, 3);

The grammatical meaning of this is obvious, so I won’t go into details here.

Mocha's more uses

If you want to test a single test js, you can use:

mocha test/index.test.js

Or multiple js

mocha test/index.test.js test/add.test.js

Of course you can also use it Wildcard Test all js and jsx in a certain folder:

mocha 'test/some/*.@(js|jsx)'

Mocha and ES6

We are not using ES6 syntax above, so let us The code has been changed to ES6 syntax.
The index.js is:

/**
 * 加法函数
 * @param {第一个数} a 
 * @param {第二个数} b 
 */
export default (a,b)=>{
    return a+b-1;
}

and the index.test.js is:

import {assert} from 'chai'
import addNum from '../src/index'

describe('测试index.js',()=> {
  describe('测试addNum函数', ()=> {
    it('两数相加结果为两个数字的和', ()=> {
      assert.equal(addNum(1,2),3)
    })
  })
})

It is definitely not possible to run the mock directly at this time. We now need to install babel:

npm install babel-core babel-preset-es2015 --save-dev

Then, create a new .babelrc file under the project directory:

{
  "presets": [ "es2015" ]
}

Then change the script in package.json to:

"scripts": {
  "test": "mocha --compilers js:babel-core/register"
},

The --compilers parameter is used Specify the transcoder of the test script. This line of command means to first use the babel-core/register module to process the .js file when running mocha

Note:
--compilers will be used in the future Removed, the official said it is redundant, and as an alternative, the

"scripts": {
  "test": "mocha --require babel-core/register"
},

command has become simpler

Mocha测试用例执行的超时和高亮

Mocha默认每个测试用例最多执行2000毫秒,如果到时没有得到结果,就报错。以下命令设置超时时间为5000:

mocha -t 5000 index.test.js

Mocha默认会高亮显示超过75毫秒的测试用例,以下命令设置高亮判断的临界值:

mocha -s 1000 index.test.js

Mocha测试的钩子

Mocha在describe块之中,提供测试用例的四个钩子:before()、after()、beforeEach()和afterEach()。它们会在指定时间执行。

describe('测试index.js',()=> {
  before(()=>console.info("在本区块的所有测试用例之前执行"))

  after(()=>console.info("在本区块的所有测试用例之后执行"))

  beforeEach(()=>console.info("在本区块的每个测试用例之前执行"))

  afterEach(()=>console.info("在本区块的每个测试用例之后执行"))

  describe('测试addNum函数', ()=> {
    it('两数相加结果为两个数字的和', ()=> {
      assert.equal(addNum(1,2),3)
    })
  })
})

小结

关于mock和chai常用的一些玩法都讲了,更多的关于mock的测试结果输出格式,以及skip跳过测试和only仅测试当前用例等玩法就不讲述了。

相信看了本文案例你已经掌握了方法,更多精彩请关注php中文网其它相关文章!

推荐阅读:

Vue指令的使用

JS闭包的使用

The above is the detailed content of The use of Mocha and chai. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
如何在Go中使用命名管道?如何在Go中使用命名管道?May 11, 2023 pm 04:22 PM

命名管道是一种在操作系统中相对比较低级的进程通信方式,它是一种以文件为中介的进程通信方式。在Go语言中,通过os包提供了对命名管道的支持。在本文中,我们将介绍如何在Go中使用命名管道来实现进程间通信。一、命名管道的概念命名管道是一种特殊的文件,可以被多个进程同时访问。在Linux系统中,命名管道是一种特殊的文件类型,它们存在于文件系统的某个位置上,并且可以在

如何在Go中使用第三方库?如何在Go中使用第三方库?May 11, 2023 pm 03:30 PM

在Go语言中,使用第三方库是非常方便的。许多优秀的第三方库和框架可以帮助我们快速地开发应用程序,同时也减少了我们自己编写代码的工作量。但是如何正确地使用第三方库,确保其稳定性和可靠性,是我们必须了解的一个问题。本文将从以下几个方面介绍如何使用第三方库,并结合具体例子进行讲解。一、第三方库的获取Go语言中获取第三方库有以下两种方式:1.使用goget命令首先

如何在PHP中使用协程?如何在PHP中使用协程?May 12, 2023 am 08:10 AM

随着传统的多线程模型在高并发场景下的性能瓶颈,协程成为了PHP编程领域的热门话题。协程是一种轻量级的线程,能够在单线程中实现多任务的并发执行。在PHP的语言生态中,协程得到了广泛的应用,比如Swoole、Workerman等框架就提供了对协程的支持。那么,如何在PHP中使用协程呢?本文将介绍一些基本的使用方法以及常见的注意事项,帮助读者了解协程的运作原理,以

如何在PHP中使用数据聚合函数如何在PHP中使用数据聚合函数May 18, 2023 pm 02:51 PM

数据聚合函数是一种用于处理数据库表中多行数据的函数。在PHP中使用数据聚合函数可以使得我们方便地进行数据分析和处理,例如求和、平均数、最大值、最小值等。下面将介绍如何在PHP中使用数据聚合函数。一、介绍常用的数据聚合函数COUNT():计算某一列的行数。SUM():计算某一列的总和。AVG():计算某一列的平均值。MAX():取出某一列的最大值。MIN():

如何在PHP中使用变量函数如何在PHP中使用变量函数May 18, 2023 pm 03:52 PM

变量函数是指可以使用变量来调用函数的一种特殊语法。在PHP中,变量函数是非常有用的,因为它可以让我们更加灵活地使用函数。在本文中,我们将介绍如何在PHP中使用变量函数。定义变量函数在PHP中,变量函数的定义方式非常简单,只需要将要调用的函数名赋值给一个变量即可。例如,下面的代码定义了一个变量函数:$func='var_dump';这里将var_dump函

如何在Go中使用音频处理?如何在Go中使用音频处理?May 11, 2023 pm 04:37 PM

随着音频处理在各种应用场景中的普及,越来越多的程序员开始使用Go编写音频处理程序。Go语言作为一种现代化的编程语言,具有优秀的并发性和高效率的特点,使用它进行音频处理十分方便。本文将介绍如何在Go中使用音频处理技术,包括读取、写入、处理和分析音频数据等方面的内容。一、读取音频数据在Go中读取音频数据有多种方式。其中比较常用的是使用第三方库进行读取,比如go-

如何在 Windows 11 中按需使用 OneDrive 的文件如何在 Windows 11 中按需使用 OneDrive 的文件Apr 14, 2023 pm 12:34 PM

<p>Windows 系统上的 OneDrive 应用程序允许您将文件存储在高达 5 GB 的云上。OneDrive 应用程序中还有另一个功能,它允许用户选择一个选项,是将文件保留在系统空间上还是在线提供,而不占用您的系统存储空间。此功能称为按需文件。在这篇文章中,我们进一步探索了此功能,并解释了有关如何在 Windows 11 电脑上的 OneDrive 中按需使用文件的各种选项。</p><h2>如何使用 On

如何在Go中使用WebSocket?如何在Go中使用WebSocket?May 11, 2023 pm 04:17 PM

近年来,WebSocket技术已经成为了Web开发中不可或缺的一部分。WebSocket是一种在单个TCP连接上进行全双工通信的协议,它使得客户端和服务器之间的通信更加流畅和高效。如今,很多现代的Web应用程序都使用了WebSocket技术,例如实时聊天、在线游戏以及实时数据可视化等。Go语言作为一个现代的编程语言,自然也提供了很好的支持WebSock

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Best Graphic Settings
2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. How to Fix Audio if You Can't Hear Anyone
2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

SublimeText3 English version

SublimeText3 English version

Recommended: Win version, supports code prompts!

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Atom editor mac version download

Atom editor mac version download

The most popular open source editor

MinGW - Minimalist GNU for Windows

MinGW - Minimalist GNU for Windows

This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.