React应用程序：Jest遇到了意外的标记。

Question

我尝试测试通过 create-react-app 创建的应用程序。自动生成了一个测试文件：

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

it('renders without crashing', () => {
  const div = document.createElement('div');
  ReactDOM.render(<App />, div);
  ReactDOM.unmountComponentAtNode(div);
});

这是我的package.json文件（还有一个大约15,000行的package-lock.json文件）：

   {
      "name": "project",
      "version": "0.1.0",
      "private": true,
      "dependencies": {
        "avro-js": "^1.9.1",
        "axios": "^0.19.0",
        "bootstrap": "^4.3.1",
        "jquery": "^3.4.1",
        "prop-types": "^15.7.2",
        "react": "^16.10.2",
        "react-dom": "^16.10.2",
        "react-redux": "^7.1.1",
        "react-scripts": "3.2.0",
        "react-syntax-highlighter": "^11.0.2",
        "reactstrap": "^8.0.1",
        "redux": "^4.0.4",
        "redux-thunk": "^2.3.0"
      },
      "scripts": {
        "start": "react-scripts start",
        "build": "react-scripts build",
        "test": "react-scripts test",
        "eject": "react-scripts eject"
      },
      "eslintConfig": {
        "extends": "react-app"
      },
      "browserslist": {
        "production": [
          ">0.2%",
          "not dead",
          "not op_mini all"
        ],
        "development": [
          "last 1 chrome version",
          "last 1 firefox version",
          "last 1 safari version"
        ]
      }
    }

当我尝试使用测试脚本进行测试时，出现以下错误：

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".

Details:

({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){export

{ default as a11yDark } from './a11y-dark';

另外，我没有 .babelrc 文件。我试过添加 .babelrc 但是没有帮助（或者我可能添加有误）。

- Nikita Ryanov

---

你有一个 babel.config.js 吗？这相当于一个 .babelrc。 - Jacob

不，我只有 package.json 和 package-lock.json。 - Nikita Ryanov

我不熟悉create-react-app的功能，但是如果在package.json或babel配置文件中没有一些babel配置，Jest是无法工作的。也许生成的文件有问题？希望有使用过create-react-app的人可以对此发表意见（已添加该工具的标签）。 - Jacob

Answer 1

如果您在尝试导入组件的JavaScript样式时遇到此错误，请确保您的目标是

react-syntax-highlighter/dist/cjs/...

而不是

react-syntax-highlighter/dist/esm/...

Jest应该能够解析它。

- Imonitmedia

Answer 2

最终我解决了这个问题。

babel.config.js：

module.exports = {
    presets: ['@babel/preset-env', '@babel/preset-react'],
};

package.json:

{
  "name": "project",
  "version": "1.0",
  "private": true,
  "dependencies": {
    "avro-js": "^1.9.1",
    "axios": "^0.19.0",
    "bootstrap": "^4.3.1",
    "jquery": "^3.4.1",
    "prop-types": "^15.7.2",
    "react": "^16.10.2",
    "react-dom": "^16.10.2",
    "react-redux": "^7.1.1",
    "react-scripts": "3.2.0",
    "react-syntax-highlighter": "^11.0.2",
    "reactstrap": "^8.0.1",
    "redux": "^4.0.4",
    "redux-thunk": "^2.3.0"
  },
  "jest": {
    "transformIgnorePatterns": [
      "/node_modules/(?!(react-syntax-highlighter)/)"
    ]
  },
  "devDependencies": {
    "@babel/cli": "^7.0.0",
    "@babel/core": "^7.0.0",
    "@babel/preset-env": "^7.0.0",
    "@babel/preset-react": "^7.0.0",
    "babel-core": "^7.0.0-bridge.0",
    "babel-eslint": "^10.0.3",
    "babel-jest": "^24.9.0",
    "babel-loader": "^8.0.0",
    "enzyme": "^3.10.0",
    "enzyme-adapter-react-16": "^1.15.1",
    "eslint": "^6.7.1",
    "jest": "^24.9.0",
    "jest-cli": "^24.9.0",
    "react-test-renderer": "^16.12.0",
    "redux-mock-store": "^1.5.3"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}

我不确定这是否是最佳解决方案，但至少它可行。

- Nikita Ryanov