Vite / Jest / React-Testing

Question

我正在尝试使用 Jest 在 React 应用程序中进行测试；我的应用程序使用 Vite 作为模块捆绑器。问题是，每次我运行测试时都会收到以下错误：

   > react-test@0.0.0 test
> jest

 FAIL  src/test/App.test.jsx
  ● 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:

    SyntaxError: C:\Users\Tomas\Desktop\react-test\src\test\App.test.jsx: Support for the experimental syntax 'jsx' isn't currently enabled (8:30):

       6 |
       7 | test("renders content", ()=>{
    >  8 |     const component = render(<App></App>)
         |                              ^
       9 |     console.log(component)
      10 | })

    Add @babel/preset-react (https://git.io/JfeDR) to the 'presets' section of your Babel config to enable transformation.
    If you want to leave it as-is, add @babel/plugin-syntax-jsx (https://git.io/vb4yA) to the 'plugins' section to enable parsing.

      at Parser._raise (node_modules/@babel/parser/src/parser/error.js:150:45)
      at Parser.raiseWithData (node_modules/@babel/parser/src/parser/error.js:145:17)
      at Parser.expectOnePlugin (node_modules/@babel/parser/src/parser/util.js:214:18)
      at Parser.parseExprAtom (node_modules/@babel/parser/src/parser/expression.js:1238:16)
      at Parser.parseExprSubscripts (node_modules/@babel/parser/src/parser/expression.js:682:23)
      at Parser.parseUpdate (node_modules/@babel/parser/src/parser/expression.js:662:21)
      at Parser.parseMaybeUnary (node_modules/@babel/parser/src/parser/expression.js:633:23)
      at Parser.parseMaybeUnaryOrPrivate (node_modules/@babel/parser/src/parser/expression.js:388:14)        
      at Parser.parseExprOps (node_modules/@babel/parser/src/parser/expression.js:398:23)
      at Parser.parseMaybeConditional (node_modules/@babel/parser/src/parser/expression.js:356:23)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        1.379 s
Ran all test suites.

包.json

{
  "name": "react-test",
  "private": true,
  "version": "0.0.0",
  "type": "module",
  "scripts": {
    "dev": "vite",
    "build": "vite build",
    "preview": "vite preview",
    "test": "jest"
  },
  "dependencies": {
    "react": "^17.0.2",
    "react-dom": "^17.0.2"
  },
  "jest": {
    "verbose": true,
    "testEnvironment": "jsdom",
    "transform": {
      "^.+\\.(js|jsx)$": "babel-jest"
    },
    "moduleFileExtensions": [
      "js",
      "jsx"
    ],
    "moduleNameMapper": {
      "\\.(gif|ttf|eot|svg|png)$": "<rootDir>/test/__mocks__/fileMock.js",
      "\\.(css|less|sass|scss)$": "identity-obj-proxy"
    }
  },
  "devDependencies": {
    "@babel/plugin-syntax-jsx": "^7.16.7",
    "@testing-library/jest-dom": "^5.16.2",
    "@testing-library/react": "^12.1.3",
    "@types/jest": "^27.4.1",
    "@vitejs/plugin-react": "^1.0.7",
    "jest": "^27.5.1",
    "vite": "^2.8.0"
  }
}

App.test.jsx

import React from "react";
import "@testing-library/jest-dom/extend-expect"
import { render } from "@testing-library/react";
import App from "../App.jsx";


test("renders content", ()=>{
    const component = render(<App></App>)
    console.log(component)
})

Answer 1

错误输出是正确的，Jest 在你的本地节点二进制文件上运行，并且需要将你的 jsx 文件转换成它可以理解的语法。

Vite 默认不做这种转换。它旨在将您的代码转换并捆绑到适合浏览器的 bundle.js 中（它可以执行其他类型的输出，例如库。您需要调整您的 vite.config.js） .

幸运的是，其他人已经为您解决了这个问题。我推荐使用vitest，因为您不需要下载另一个转换器或花费大量时间来设置棘手的构建脚本。

以下是有关如何快速设置的指南：

https://www.eternaldev.com/blog/testing-a-react-application-with-vitest/

还有一份迁移指南：

https://vitest.dev/guide/migration.html