NextJS应用运行Jest测试无法解析SVG图片的问题及解决

报错现象 #

运行yarn test执行测试时Jest抛出如下错误：

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".

Here's what you can do:
 • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/en/ecmascript-modules for how to enable it.
 • 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:

/home/marouane/projects/manage-landing-page/jest.setup.ts:1
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){import "@testing-library/jest-dom/extend-expect";
                                                                                         ^^^^^^

SyntaxError: Cannot use import statement outside a module

  at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1350:14)

核心报错点为SyntaxError: Cannot use import statement outside a module，错误出现在.ts后缀的jest配置启动文件中。

已尝试的操作 #

安装jest-svg-transformer依赖，并添加了如下jest.config.js配置：

module.exports = {
  setupFilesAfterEnv: ["<rootDir>/jest.setup.ts"],
  transform: {
    '^.+\.jsx?$': 'babel-jest',
    '^.+\.svg$': 'jest-svg-transformer',
  },
};

配置后问题未解决。

根因与修复方案 #

报错原因是transform配置的匹配规则书写错误：原规则^.+\.jsx?$仅匹配.js、.jsx后缀的文件，未覆盖项目中使用的.ts、.tsx后缀文件，导致TypeScript文件没有被正确转译，ESModule的import语法无法被识别。
将匹配规则修改为^.+\.tsx?$即可覆盖所有TS/TSX文件，修复后完整配置如下：

module.exports = {
  setupFilesAfterEnv: ["<rootDir>/jest.setup.ts"],
  transform: {
    '^.+\.tsx?$': 'babel-jest',
    '^.+\.svg$': 'jest-svg-transformer',
  },
};

如果项目同时存在JS和TS文件，可以将规则合并为^.+\.[jt]sx?$，同时匹配两类后缀的文件。

内容的提问来源于stack exchange，提问作者Marsou001