解决jest处理es模块示例详解
作者:xueyou2000
这篇文章主要为大家介绍了解决jest处理es模块示例详解,有需要的朋友可以借鉴参考下,希望能够有所帮助,祝大家多多进步,早日升职加薪
问题场景
项目使用jest
进行测试时, 当引入外部库是es
模块时, jest
无法处理导致报错.
Test suite failed to run Jest encountered an unexpected token This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript. By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules". Here's what you can do: • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config. • If you need a custom transformation specify a "transform" option in your config. • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option. Details: /home/xueyou/workspace/projects/node_modules/lodash-es/lodash.js:10 import * as lodash from 'lodash-es' SyntaxError: Unexpected token *
解决方法
查阅issues
发现, 目前jest
不支持em
模块, 只有通过babel
去处理了
安装依赖
yarn add --dev babel-jest @babel/core @babel/preset-env babel-plugin-transform-es2015-modules-commonjs
配置babel.config.js
module.exports = { presets: [ [ "@babel/preset-env", { targets: { node: "current" } } ] ], plugins: ["transform-es2015-modules-commonjs"] };
配置jest.config.js
module.exports = { preset: "ts-jest", testMatch: ["<rootDir>/tests/**/*.(spec|test).ts?(x)"], transform: { // 将.js后缀的文件使用babel-jest处理 "^.+\\.js$": "babel-jest", "^.+\\.(ts|tsx)$": "ts-jest" }, // 下面非要从重要, 将不忽略 lodash-es, other-es-lib 这些es库, 从而使babel-jest去处理它们 transformIgnorePatterns: ["<rootDir>/node_modules/(?!(lodash-es|other-es-lib))"] };
脚注
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