moduleNameMapper with next/jest no longer works well with absolute imports

[stefanprobst]

Verify canary release

• I verified that the issue exists in Next.js canary release

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #45~20.04.1-Ubuntu SMP Mon Apr 4 09:38:31 UTC 2022
Binaries:
  Node: 16.15.0
  npm: 8.5.5
  Yarn: 1.22.18
  pnpm: 6.32.6
Relevant packages:
  next: 12.1.6
  react: 17.0.2
  react-dom: 17.0.2

What browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

Describe the Bug

i have absolute imports configured in tsconfig, as well as in my jest config:

const nextJest = require('next/jest')
const createJestConfig = nextJest({ dir: './' })

const config = {
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1',
  },
}

module.exports = createJestConfig(config)

with this config, importing a .module.css file in a component via absolute import was handled correctly before next@12.1.6:

import styles from '@/components/my-component/my-component.module.css

since next/jest@12.1.6 however (specifically with #36312) this changed because now user-provided moduleNameMapper will match before anything auto-configured by next/jest, which means i would have to manually copy the mapping for .css, .module.css, images etc.

Expected Behavior

see above

To Reproduce

see above

[Parnswir]

This also seems to break the with-jest example. On next@12.1.5 the tests in the example can be run, while on next@12.1.6 I get errors:

 FAIL  __tests__/snapshot.tsx
  ● 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:

    C:\dev\gp9000\test\with-jest-app\pages\index.module.css:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){.container {
                                                                                      ^

    SyntaxError: Unexpected token '.'

      2 | import Image from 'next/image'
      3 |
    > 4 | import styles from '@/pages/index.module.css'
        |                                              ^
      5 |
      6 | export default function Home() {
      7 |   return (

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1728:14)
      at Object.<anonymous> (pages/index.tsx:4:46)

[sabertazimi]

Solution:

const nextJest = require('next/jest');

const customJestConfig = {/* With custom configuration */};

const createJestConfig = nextJest({
  dir: './',
})(customJestConfig);

module.exports = async () => {
  // Create Next.js jest configuration presets
  const jestConfig = await createJestConfig();

  // Custom `moduleNameMapper` configuration
  const moduleNameMapper = {
    ...jestConfig.moduleNameMapper,
    '^@/(.*)$': '<rootDir>/src/$1',
  };

  return { ...jestConfig, moduleNameMapper };
};

See next@12.1.6 pull request #36312 changed moduleNameMapper configuration.

[github-actions]

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