Jest encountered an unexpected token

[jerone]

When adding any of the dev-plugins, Jest is throwing the following error:

    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:

    C:\Projects\xxx\node_modules\@dev-plugins\async-storage\build\index.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){export let useAsyncStorageDevTools;
                                                                                      ^^^^^^

    SyntaxError: Unexpected token 'export'

      3 |
      4 |
    > 5 | import { useAsyncStorageDevTools } from "@dev-plugins/async-storage";
        | ^
      6 | import { useNavigationContainerRef } from "expo-router";
      7 | import React, { PropsWithChildren } from "react";
      8 |

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1505:14)
      at Object.require (src/app/DevToolsPluginsContainer.tsx:5:1)
      at Object.require (src/app/_layout.tsx:11:1)
      at Object.require (__tests__/app/_layout.test.tsx:7:1)

---

  expo-env-info 1.2.2 environment info:
    System:
      OS: Windows 11 10.0.26100
    Binaries:
      Node: 22.12.0 - ~\AppData\Local\nvs\node\22.12.0\x64\node.EXE
      Yarn: 1.22.22 - ~\AppData\Local\nvs\node\22.12.0\x64\yarn.CMD
      npm: 11.0.0 - ~\AppData\Local\nvs\node\22.12.0\x64\npm.CMD
    IDEs:
      Android Studio: AI-242.23339.11.2421.12700392
    npmPackages:
      expo: ^52.0.25 => 52.0.25
      expo-router: ~4.0.16 => 4.0.16
      react: 18.3.1 => 18.3.1
      react-dom: 18.3.1 => 18.3.1
      react-native: 0.76.6 => 0.76.6
      react-native-web: ^0.19.13 => 0.19.13
    Expo Workflow: bare

[siggi-livekindred]

+1, adding @dev-plugins/* to transformIgnorePatterns in the jest config appears to mitigate
https://jestjs.io/docs/configuration#transformignorepatterns-arraystring

[jerone]

+1, adding @dev-plugins/* to transformIgnorePatterns in the jest config appears to mitigate jestjs.io/docs/configuration#transformignorepatterns-arraystring

That's a good solution too.

In the end I went with adding a custom hook:

src/hooks/useDevTools

/**
 * Import DevTools only in development mode.
 * @returns DevTools.
 */
/* eslint-disable @typescript-eslint/no-empty-function, @typescript-eslint/no-var-requires */
export default function useDevTools() {
  if (__DEV__) {
    const { useReactQueryDevTools } =
      require("@dev-plugins/react-query") as typeof import("@dev-plugins/react-query");
    const { useReactNavigationDevTools } =
      require("@dev-plugins/react-navigation") as typeof import("@dev-plugins/react-navigation");
    const { useAsyncStorageDevTools } =
      require("@dev-plugins/async-storage") as typeof import("@dev-plugins/async-storage");

    return {
      useReactQueryDevTools,
      useReactNavigationDevTools,
      useAsyncStorageDevTools,
    };
  }

  return {
    useReactQueryDevTools: () => {},
    useReactNavigationDevTools: () => {},
    useAsyncStorageDevTools: () => {},
  };
}

That I can mock where needed:

_layout.test.tsx

jest.mock("@/hooks/useDevTools", () => ({
  __esModule: true,
  default: jest.fn().mockReturnValue({
    useReactQueryDevTools: jest.fn(),
    useReactNavigationDevTools: jest.fn(),
    useAsyncStorageDevTools: jest.fn(),
  }),
}));