使用 Jest 测试 Angular 应用程序时，从 ol-contextmenu 中意外的令牌“导出”

问：

当我在导入 ol-contextmenu 的服务上运行 jest 测试时，出现错误：

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:

    path/to/project/node_modules/ol-contextmenu/dist/ol-contextmenu.d.ts:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){export * from './main'
                                                                                      ^^^^^^

    SyntaxError: Unexpected token 'export'

      4 | import { Graticule, ImageTile, Map, Overlay, Tile, View } from 'ol';
    > 5 | import ContextMenu, { CallbackObject } from 'ol-contextmenu';
        | ^
      6 | import TileState from 'ol/TileState';
      7 | import { ScaleLine, defaults as defaultControls } from 'ol/control';
      8 | import ControlMousePosition from 'ol/control/MousePosition';

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1505:14)
      at Object.<anonymous> (src/app/services/my-service/my-service.service.ts:10:1)
      at Object.<anonymous> (src/app/services/my-service/my-service.service.spec.ts:10:1)

它与测试无关，因为测试文件仍然是默认文件，仅检查服务是否创建良好。

我在导入 openlayers 依赖项时遇到了同样的问题，我通过运行 babel 脚本解决了这个问题：

babel node_modules/ol --extensions .js --out-dir node_modules/.compiled/ol --presets @babel/preset-env --source-maps 

并在文件中添加：jest.config.ts

  ...
  transformIgnorePatterns: ['node_modules/(?!.*\\.mjs$)'],
  moduleNameMapper: {
    'lodash-es': 'lodash',
    '^ol/(.*)$': 'node_modules/.compiled/ol/$1.js',
  },
  moduleDirectories: ['node_modules/.compiled', 'node_modules'],
  ...

所以我对ol-contextmenu依赖项做了同样的事情，首先运行babel脚本：

babel node_modules/ol-contextmenu/dist --extensions .js --out-dir node_modules/.compiled/ol-contextmenu/dist --presets @babel/preset-env --source-maps

并将文件的“moduleNameMapper”更改为：jest.config.ts

  moduleNameMapper: {
    'lodash-es': 'lodash',
    '^ol/(.*)$': 'node_modules/.compiled/ol/$1.js',
    '^ol-contextmenu/(.*)$': 'node_modules/.compiled/ol-contextmenu/$1.js',
  },