如何使用使用 es6 的 node_modules 设置玩笑

Question

我有一个非常简单的测试：

describe('sanity', () => {
  it('sanity', () => {
    expect(true).toBeTruthy()
  })
})

我收到以下错误：

 FAIL  spec/javascript/sanity_test.js
  ● 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.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/en/configuration.html

    Details:

    /Users/piousbox/projects/ruby/<project>/node_modules/@atlaskit/tooltip/index.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){export { default } from './components/Tooltip';
                                                                                             ^^^^^^

    SyntaxError: Unexpected token export

      3 | import update from "immutability-helper";
      4 | import {components} from "react-select-2";
    > 5 | import Tooltip from "@atlaskit/tooltip";
        | ^
      6 | const isEqual = require("react-fast-compare");
      7 | import _, {replace} from "lodash";
      8 | import { get } from "$shared/request";

      at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:537:17)
      at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:579:25)
      at Object.<anonymous> (app/javascript/customer2/components/fob/fob_utils.js:5:1)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        1.593s

我有这个 .babelrc:

{
  "presets": ["@babel/react", "@babel/env"]
}

如何让琐碎的测试通过？

Answer 1

马特的回答被接受，因为它很有见地。为我所做的更改是在 package.json 中添加：

  "jest": {
    ...
    "transformIgnorePatterns": [
      "node_modules/(?!@atlaskit)"
    ],

您可以通过使用| 分隔多个包来一次添加对多个包的支持

  "jest": {
    ...
    "transformIgnorePatterns": [
      "node_modules/(?!module1|module2|etc)"
    ],

Answer 2

有两种方法可以通过此测试：

选项 1.) 通过添加测试 env 选项设置您的 babel 配置以处理 ES6 导入（testing 环境标志将在您的 package.json 脚本中定义，例如： "test": "NODE_ENV=testing jest" 或 "test": "BABEL_ENV=testing jest")...

babel.config.js

module.exports = api => {
  api.cache(true);

  return {
    presets: ["@babel/preset-env", "@babel/preset-react"],
    plugins: [
      "@babel/plugin-transform-runtime",
      ["@babel/plugin-proposal-class-properties", { loose: true }],
    ],
    env: {
      testing: {
        presets: [
          [ "@babel/preset-env", { targets: { node: "current" }}],
        ],
      },
    },
  };
};

选项 2.) 在 webpack.config.js 配置中将 ES6 模块转换为 ES5 语法：

webpack.config.js

const { NODE_ENV } = process.env
const inDevelopment = NODE_ENV === "development";

module.exports = {
  ...
  module: {
    rules: [
      ...
      {
        test: /\.(js|jsx)$/,
        loader: "babel-loader",
        exclude: !inDevelopment ? /node_modules\/(?!(@atlaskit\/tooltip))/ : /(node_modules)/,
        options: {
          cacheDirectory: inDevelopment,
          cacheCompression: false,
        },
      },
      ...
    ],
  }
  ...
}

这两个选项的主要区别在于第一个选项只能在测试环境中使用。如果您尝试在开发/生产环境中使用它，它可能会影响其他 3rd 方包并导致编译错误。因此，如果您打算将其移动到支持 IE11 及以下版本的生产环境中，则建议使用第二个选项。但是，请记住，每次创建生产构建和/或运行测试套件时，这都会转换包。因此，如果您正在处理一个非常大的项目（或编译多个 ES6 包），它可能会占用大量资源。因此，我建议将第 3 方包从 ES6 编译到 ES5 并在本地或私下安装它/它们（通过 NPM 包）。

工作示例（此示例包括第二个选项）： https://github.com/mattcarlotta/transpile-es6-module

安装：

1. cd ~/Desktop && git clone git@github.com:mattcarlotta/transpile-es6-module.git
2. cd transpile-es6-module
3. yarn install
4. yarn dev 运行演示
5. yarn test 运行测试套件