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Be careful ： Use mocha, We just need to focus on writing unit tests themselves , And then let mocha To run all tests automatically , And the test results are given

mocha The main characteristics of

It can test simple js function , You can also test asynchronous code , Because asynchrony is js One of the characteristics of
All tests can be run automatically , You can also run only specific tests
Can support before、after、beforeEach、afterEach To write initialization code

Write tests

node.js Built-in module assert No installation required

Built-in module assert Use

introduce assert：var assert=require("assert")

assert.strictEqural()

grammar ： assert.strictEqural( Test results , Expected results )
effect ： If the test result is the same as the expected result, it is successful , If it is different, it will fail , Success without any prompt , If you fail, you will report an error

function sum(...rest){
    var sum=0
    for(var one of rest){
        sum+=one
    }
    return sum
}
// node.js Built-in module , Assertion module 
var assert=require("assert")
assert.strictEqual(sum(),0)// Strict equality method 
assert.strictEqual(sum(1),1)
assert.strictEqual(sum(1,2),3)

About node.js Built in module assertion

It can assert whether our results and expected results are the same , If it is the same, no error will be reported , If it's different, it's wrong
No result will appear after the assertion is successful , Unless the assertion goes wrong
Once the first test case goes wrong , It will directly affect the execution of subsequent test cases

Be careful ：mocha Many test cases can be combined for unified execution , And there are good test results

mocha Use

Preface

npm initialization ：npm init -y
install mocha modular ：npm i mocha

1. establish test Folder will drag all the files that need to be tested into test In the folder

2. take package.json In the document scripts In script file test Of value Value changed to mocha

"scripts": {
    "test": "mocha"
  }

3. Output in the current project console npm run test To perform tests , After execution, it will automatically scan the current project test Folder , Find it and put it inside js Files are executed one by one

keyword

describe： Specify a set of tests , Can be nested
it： Specify individual tests

function sum(...rest) {
    var sum = 0
    for (var one of rest) {
        sum += one
    }
    return sum
}
// node.js Built-in module , Assertion module 
var assert = require("assert")
describe(" Big group 1 test ", () => {
    describe(" Small group 1 test ", () => {
        it("sum() 0", () => {
            assert.strictEqual(sum(), 0)// The test case 
        })
    })
    describe(" Small group 2 test ", () => {
        it("sum(1) 1", () => {
            assert.strictEqual(sum(1), 2)
        })
        it("sum(1,2) 3", () => {
            assert.strictEqual(sum(1, 2), 3)
        })
    })
})
describe(" Big group 2 test ", () => {

})

Be careful ：descripe There must be it Single test , however it A single test can exist alone

chai Assertions library

Use

npm initialization ：npm init -y
install chai modular ：npm i chai

introduce chai modular ：var chai=require("chai")

assert style

var chai=require("chai")
var assert=chai.assert
describe("test2 Large group within ",()=>{
    it("assert unit 1",()=>{
        var value="hello"
    assert.typeOf(value,"string")// monitoring value Is it right? string type 
    assert.equal(value,"hello")// testing value Is the value equal to hello
    assert.lengthOf(value,5)// testing value Is the length equal to 5
    })
})

should style

var chai=require("chai")
chai.should()
describe("test3 Large group within ",()=>{
    it("should unit 1",()=>{
    var value="hello"
    value.should.exist.and.equal("hello").and.have.length(5).and.be.a("string")
    // Read from head to back 
    })
})

expect style

var chai=require("chai")
var expect=chai.expect
describe("test4 Large group within ",()=>{
    it("expect unit 1",()=>{
    var value="hello"
    var number=3
    expect(number).to.be.at.most(5)// The expected result is less than 5
    expect(number).to.be.at.least(3)// The expected result is greater than 3
    expect(number).to.be.at.within(1,4)// The expected result is 1 and 4 Between 

    expect(value).to.exist// expect value There is 
    expect(value).to.be.a("string")// expect value yes string type 
    expect(value).to.equal("hello")// expect value by hello
    expect(value).to.not.equal(" Hello! ")// expect value Not for your good 
    expect(value).to.have.length(5)// expect value The length is 5
    })
})

Asynchronous test

done() The role of ： Tell the test case not to rush to the result ,done Then it means that the test case has been executed

const fs=require("fs")
const assert=require("assert")
//  The way 1
describe(" Asynchronous test 1",()=>{
    // Be careful ： Asynchronously reading files requires adding done Parameters 
    it(" Asynchronous read file ",(done)=>{
        fs.readFile("./1.txt","utf8",(err,data)=>{
            if(err){
                done(err)
            }else{
                assert.strictEqual(data,"hello")// test 1.txt Is the content of the document in hello
                done()
            }
        })
    })
})
// The way 2
const fsp=fs.promises// Back to fsp by promise object 
describe(" Asynchronous test 2",()=>{
    it(" Asynchronous read file ",async ()=>{
      var data= await fsp.readFile("./1.txt","utf8")
      assert.strictEqual(data,"hello")// test 1.txt Is the content of the document in hello
    })
})

mocha Of http Test and hook functions

install supertest modular ：npm i supertest

//server.js In the file 
var http=require("http")
var app=http.createServer((req,res)=>{
    res.end("hello")
})
module.exports=app

var supertest=require("supertest")
const app = require("../server")
describe(" Test interface 1",()=>{
    var server
    it(" Return to the fragment test ",async ()=>{
       await supertest(server).get("/")
       .expect(200,"hello")
    })
    // Hook function mocha Bring their own 
    //before Represents the function executed at the beginning of this set of tests 
    before(()=>{
        server=app.listen(3000)
    })
    //after Indicates when the test group ends , Complete all test cases of this group , Is executed after Method 
    after(()=>{
        server.close()
    })
    // Functions executed before the start of each test case 
    beforeEach(()=>{
        console.log(" The test case begins ");
    })
    // The function executed after the end of each test case 
    afterEach(()=>{
        console.log(" The test case is over ");
    })
})

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