前端自动化测试：Jest 测试框架应用

npm install --save-dev jest

//math.jsfunctionadd (a, b) {  return a * b}
functionsubtract (x, y) {  return x - y}
module.exports= {  add,  subtract}

//test.js ==> math.test.jsconst { add, subtract } =require('./math')
test('测试加法', () => {  expect(add(1,2)).toBe(3)})
test('测试减法', () => {  expect(subtract(2,1)).toBe(1)})

//package.json{  "scripts":{    "test":"jest"  }}

npm run test

npm i -D @types/jest

npx jest--init

//jest.config.js/* * For a detailedexplanation regarding each configuration property, visit: *https://jestjs.io/docs/en/configuration.html */
module.exports= {  // 自动 mock 所有导入的外部模块  // automock: false,
  // 在指定次数失败后停止运行测试  // bail: 0,
  // The directory where Jest should store its cached dependencyinformation  // cacheDirectory:"/private/var/folders/5h/_98rffpj1z95b_0dm76lvzm40000gn/T/jest_dx",
  // 在每个测试之间自动清除 mock 调用和实例  clearMocks:true,
  // 是否收集测试覆盖率信息  // collectCoverage: false,
  // 一个 glob 模式数组，指示应该为其收集覆盖率信息的一组文件  // collectCoverageFrom: undefined,
  // 测试覆盖率报错文件输出的目录  coverageDirectory:"coverage",
  // 忽略测试覆盖率统计  // coveragePathIgnorePatterns: [  //  "/node_modules/"  // ],
  // 指示应该使用哪个提供程序检测代码的覆盖率，默认是 babel，可选 v8，但是 v8 不太稳定，建议Node 14 以上版本使用  // coverageProvider: "babel",
  // A list of reporter names that Jest uses when writingcoverage reports  // coverageReporters: [  //   "json",  //   "text",  //   "lcov",  //   "clover"  // ],
  // An object that configures minimum threshold enforcement forcoverage results  // coverageThreshold: undefined,
  // A path to a custom dependency extractor  // dependencyExtractor: undefined,
  // Make calling deprecated APIs throw helpful error messages  // errorOnDeprecated: false,
  // Force coverage collection from ignored files using an arrayof glob patterns  // forceCoverageMatch: [],
  // A path to a module which exports an async function that istriggered once before all test suites  // globalSetup: undefined,
  // A path to a module which exports an async function that istriggered once after all test suites  // globalTeardown: undefined,
  // A set of global variables that need to be available in alltest environments  // globals: {},
  // The maximum amount of workers used to run your tests. Canbe specified as % or a number. E.g. maxWorkers: 10% will use 10% of your CPUamount + 1 as the maximum worker number. maxWorkers: 2 will use a maximum of 2workers.  // maxWorkers: "50%",
  // An array of directory names to be searched recursively upfrom the requiring module's location  // moduleDirectories: [  //  "node_modules"  // ],
  // An array of file extensions your modules use  // moduleFileExtensions: [  //   "js",  //   "json",  //   "jsx",  //   "ts",  //   "tsx",  //   "node"  // ],
  // A map from regular expressions to module names or to arraysof module names that allow to stub out resources with a single module  // moduleNameMapper: {},
  // An array of regexp pattern strings, matched against allmodule paths before considered 'visible' to the module loader  // modulePathIgnorePatterns: [],
  // Activates notifications for test results  // notify: false,
  // An enum that specifies notification mode. Requires {notify: true }  // notifyMode: "failure-change",
  // A preset that is used as a base for Jest's configuration  // preset: undefined,
  // Run tests from one or more projects  // projects: undefined,
  // Use this configuration option to add custom reporters toJest  // reporters: undefined,
  // Automatically reset mock state between every test  // resetMocks: false,
  // Reset the module registry before running each individualtest  // resetModules: false,
  // A path to a custom resolver  // resolver: undefined,
  // Automatically restore mock state between every test  // restoreMocks: false,
  // The root directory that Jest should scan for tests andmodules within  // rootDir: undefined,
  // A list of paths to directories that Jest should use tosearch for files in  // roots: [  //  "<rootDir>"  // ],
  // Allows you to use a custom runner instead of Jest's defaulttest runner  // runner: "jest-runner",
  // The paths to modules that run some code to configure or setup the testing environment before each test  // setupFiles: [],
  // A list of paths to modules that run some code to configureor set up the testing framework before each test  // setupFilesAfterEnv: [],
  // The number of seconds after which a test is considered asslow and reported as such in the results.  // slowTestThreshold: 5,
  // A list of paths to snapshot serializer modules Jest shoulduse for snapshot testing  // snapshotSerializers: [],
  // The test environment that will be used for testing  // testEnvironment: "jest-environment-jsdom",
  // Options that will be passed to the testEnvironment  // testEnvironmentOptions: {},
  // Adds a location field to test results  // testLocationInResults: false,
  // The glob patterns Jest uses to detect test files  // testMatch: [  //  "**/__tests__/**/*.[jt]s?(x)",  //  "**/?(*.)+(spec|test).[tj]s?(x)"  // ],
  // An array of regexp pattern strings that are matched againstall test paths, matched tests are skipped  // testPathIgnorePatterns: [  //  "/node_modules/"  // ],
  // The regexp pattern or array of patterns that Jest uses todetect test files  // testRegex: [],
  // This option allows the use of a custom results processor  // testResultsProcessor: undefined,
  // This option allows use of a custom test runner  // testRunner: "jasmine2",
  // This option sets the URL for the jsdom environment. It isreflected in properties such as location.href  // testURL: "http://localhost",
  // Setting this value to "fake" allows the use offake timers for functions such as "setTimeout"  // timers: "real",
  // A map from regular expressions to paths to transformers  // transform: undefined,
  // An array of regexp pattern strings that are matched againstall source file paths, matched files will skip transformation  // transformIgnorePatterns: [  //  "/node_modules/",  //  "\\.pnp\\.[^\\/]+$"  // ],
  // An array of regexp pattern strings that are matched againstall modules before the module loader will automatically return a mock for them  // unmockedModulePathPatterns: undefined,
  // Indicates whether each individual test should be reportedduring the run  // verbose: undefined,
  // An array of regexp patterns that are matched against allsource file paths before re-running tests in watch mode  // watchPathIgnorePatterns: [],
  // Whether to use watchman for file crawling  // watchman: true,};

  "scripts":{    "test":"jest ./math.test.js"  },

 "scripts": {   "test": "jest --watchAll"  },

import { describe, expect, test } from'@jest/globals'

test('should ', () => {  console.log('test--api')})

test('should ', () => {  console.log('test--api')})test('should1 ', () => {  console.log('test--api1')})
// 上面两个不运行test.only('should2 ', () => {  console.log('test--api2')})

test('two plus two is four', () => {  expect(2+2).toBe(6)  expect({ name:'jack' }).toEqual({ name:'jack' })  expect('Christoph').toMatch(/stop/)  expect(4).toBeGreaterThan(3)  expect(4).toBeLessThan(5)})

const myBeverage = {  delicious:true,  sour:false,};
describe('my beverage', () => {  test('is delicious', () => {    expect(myBeverage.delicious).toBeTruthy();  });
  test('is not sour', () => {    expect(myBeverage.sour).toBeFalsy();  });});