获取 Babel 将配置文件转换为 CommonJS

Question

我有一个 Nuxt 应用程序，我想用 Jest 进行测试，但我无法让它工作。 我有一个 setupFilesAfterEnv 属性集，其中包含一个导入翻译文件的 setupTests.ts。此翻译文件使用 ES6 导入/导出模块语法，但似乎我当前的配置无法转换它。

由于transform 属性，babel-jest 不应该转译 .js 文件吗？

setupTests.ts

import { config } from '@vue/test-utils';
import flat from 'flat';
import '@testing-library/jest-dom/extend-expect';
import 'jest-axe/extend-expect';
import frenchTranslations from '~/config/translations/fr-FR';
...

babel.config.json

{
  "presets": ["@babel/preset-env", { "targets": { "node": "current" } }]
}

jest.config.js

module.exports = {
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/$1',
    '^~/(.*)$': '<rootDir>/$1',
    '^vue$': 'vue/dist/vue.common.js',
  },
  moduleFileExtensions: ['ts', 'js', 'vue', 'json'],
  resolver: '<rootDir>/test/integration/resolver.js',
  transform: {
    '^.+\\.ts$': 'ts-jest',
    '^.+\\.js$': 'babel-jest',
    '^.+\\.vue$': '@vue/vue2-jest',
  },
  collectCoverage: true,
  collectCoverageFrom: [
    '<rootDir>/components/**/*.vue',
    '<rootDir>/pages/**/*.vue',
  ],
  testEnvironment: 'jsdom',
  passWithNoTests: true,
  setupFilesAfterEnv: ['<rootDir>/test/integration/setupTests.ts'],
};

/config/translations/fr-FR.js

export default {
 ...
}

笑话输出

FAIL  test/integration/components/ui/RegistrationForm.test.ts
  ● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • 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/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /my-project/config/translations/fr-FR.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){export default {
                                                                                      ^^^^^^

    SyntaxError: Unexpected token 'export'

      1 | import { config } from '@vue/test-utils';
      2 | import flat from 'flat';
      3 | import '@testing-library/jest-dom/extend-expect';
      4 | import 'jest-axe/extend-expect';
    > 5 | import frenchTranslations from '~/config/translations/fr-FR';

      at Runtime.createScriptFromCode (node_modules/.pnpm/jest-runtime@28.1.1/node_modules/jest-runtime/build/index.js:1796:14)
      at Object.<anonymous> (test/integration/setupTests.ts:3:1)
      at TestScheduler.scheduleTests (node_modules/.pnpm/@jest+core@28.1.1/node_modules/@jest/core/build/TestScheduler.js:317:13)

----------------------|---------|----------|---------|---------|-------------------
File                  | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------------------|---------|----------|---------|---------|-------------------
All files             |       0 |        0 |       0 |       0 |
 RegistrationForm.vue |       0 |        0 |       0 |       0 | 1-113
----------------------|---------|----------|---------|---------|-------------------
Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        1.35 s
Ran all test suites related to changed files.

Answer 1

尝试将 setupFilesAfterEnv 更改为 setupFilesAfterEnv: ['@testing-library/jest-dom/extend-expect'], 并在必要时安装依赖项。

您可能还想尝试将 babel.config.js 文件更改为：

// Need to convert modules to commonjs format so Jest can undertstand them.
const isTest = String(process.env.NODE_ENV) === 'test'
const isProd = String(process.env.NODE_ENV) === 'production'

module.exports = {
    // For transformation of TSX and other react related bable plugins
    presets: [
        // Allows smart transpilation according to target environments
        ['@babel/preset-env', { modules: isTest ? 'commonjs' : false }],
        // Enabling Babel to understand TypeScript
        '@babel/preset-typescript',
    ],
}

注意：如果您的代码库不在 typescript 中，请忽略 typescript 预设。

注意 2：将 babel.config.json 更改为 babel.config.js 也可能会有所帮助。