单元测试框架Jest搭配TypeScript的安装与配置方式
__Simon 人气:0为项目安装并配置Jest单元测试环境
分步指南
传送门:Jest - 快速入门
1. 安装jest
npm i jest ts-jest @types/jest -D
2. 初始化
npx jest --init
按照图中所示选择
tip:
- -
no
;不使用ts,使用jest.config.js作为jest的配置文件; - -
jsdom
;使用jsdom作为测试环境(jsdom:一个类似浏览器的环境,项目是运行在浏览器的,需要在浏览器dom环境下测试); - -
yes
;是否添加测试报告; - -
babel
;使用babel提供的测试报告(官网说明v8仍处于试验阶段,需node14以上使用,效果未知,不稳定,因此选用babel);
3. 安装jsdom环境
- jest 28及以上版本不再内置jsdom插件,需要单独安装
- 安装官方eslint插件
npm i jest-environment-jsdom eslint-plugin-jest eslint-import-resolver-typescript jest-canvas-mock -D
4. 创建test目录
在项目根目录下创建test目录,然后在test下创建__mocks和__tests__目录,创建.eslintrc.js和tsconfig.json文件
附:配置示例
jest.config.js
/* * For a detailed explanation regarding each configuration property, visit: * https://jestjs.io/docs/configuration */ const { pathsToModuleNameMapper } = require('ts-jest'); const { compilerOptions } = require('./tsconfig.json'); module.exports = { // A preset that is used as a base for Jest's configuration preset: 'ts-jest', // The test environment that will be used for testing testEnvironment: 'jsdom', // The paths to modules that run some code to configure or set up the testing environment before each test setupFiles: ['jest-canvas-mock'], // Automatically clear mock calls, instances, contexts and results before every test clearMocks: true, // Indicates whether the coverage information should be collected while executing the test collectCoverage: true, // The directory where Jest should output its coverage files coverageDirectory: 'test/coverage', // The root directory that Jest should scan for tests and modules within // rootDir: undefined, // rootDir: __dirname, // An array of file extensions your modules use moduleFileExtensions: ['ts', 'js'], // A map from regular expressions to module names or to arrays of module names that allow to stub out resources with a single module moduleNameMapper: pathsToModuleNameMapper(compilerOptions.paths, { prefix: '<rootDir>/', }), // The glob patterns Jest uses to detect test files testMatch: ['<rootDir>/test/__tests__/**/*.test.ts'], // A map from regular expressions to paths to transformers transform: { '^.+\\.ts$': 'ts-jest', }, };
配置测试用例的eslint规则
/test/.eslintrc.js
module.exports = { extends: ['../.eslintrc.js'], settings: { 'import/resolver': { typescript: { alwaysTryTypes: true, // always try to resolve types under `<root>@types` directory even it doesn't contain any source code, like `@types/unist` // Choose from one of the "project" configs below or omit to use <root>/tsconfig.json by default // use <root>/path/to/folder/tsconfig.json project: 'tsconfig.json', }, }, }, plugins: ['jest'], overrides: [ // unit-tests { files: ['**/__tests__/**'], rules: { 'jest/no-disabled-tests': 'warn', 'jest/no-focused-tests': 'error', 'jest/no-identical-title': 'error', 'jest/prefer-to-have-length': 'warn', 'jest/valid-expect': 'error', }, }, ], };
代码覆盖率报告无需加入git版本管理,将test/coverage目录追加至.gitignore
... # Unit test / coverage reports test/coverage
tsconfig.json中配置路径别名
5. 愉快地开始单元测试
在 test/__test__ 目录下新增自己模块的单元测试目录及文件,开始单元测试代码编写
文件命名规范: *.test.ts
6. 总结 - 踩坑记录
- 默认preset为babel-jest,由于 Babel 对 Typescript 的支持是通过代码转换(Transpilation)实现的,而 Jest 在运行时并不会对你的测试用例做类型检查。 因此建议安装ts-jest来开启此功能
- 主要是在配置tsconfig.json路径别名时花费了大量时间,处理ts的报错以及eslint的报错问题;
- 以上配置的路径别名只需在tsconfig.json一处配置,随处可用,包括ts、eslint、jest都能读取同一个别名配置;
- 另外对于webpack的别名配置,网上也有读取tsconfig配置的方案;
以上为个人经验,希望能给大家一个参考,也希望大家多多支持。
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