Testing with Jest and Webpack aliases

This seems to have been fixed.

Below is a working setup:

Versions

"jest": "~20.0.4"

"webpack": "^3.5.6"

package.json

"jest": {
  "moduleNameMapper": {
    "^@root(.*)$": "<rootDir>/src$1",
    "^@components(.*)$": "<rootDir>/src/components$1",
  } 
}

webpack.shared.js

const paths = {
  APP_DIR: path.resolve(__dirname, '..', 'src'),
};

exports.resolveRoot = [paths.APP_DIR, 'node_modules'];

exports.aliases = {
  '@root': path.resolve(paths.APP_DIR, ''),
  '@components': path.resolve(paths.APP_DIR, 'components'),
};

Since I had the same problem before I read again, and this time more carefully the documentation. Correct config should be:

  "jest": {
    "moduleNameMapper": {
      "^@shared(.*)$": "<rootDir>/shared$1",
      "^@components(.*)$": "<rootDir>/shared/components$1"
    }
  },

Using: "jest": "^26.5.3", and "webpack": "4.41.5", I was able to properly match my webpack/typescript aliases in the jest.config.js with this pattern:

Webpack config:

module.exports = {
   // the rest of your config
    resolve: {
      alias: {
        'components': path.resolve(__dirname, 'js/app/components'),
        'modules': path.resolve(__dirname, 'js/app/modules'),
        'types': path.resolve(__dirname, 'js/types'),
        'hooks': path.resolve(__dirname, 'js/app/hooks'),
        'reducers': path.resolve(__dirname, 'js/app/reducers'),
        '__test-utils__': path.resolve(__dirname, 'js/app/__test-utils__') 
      }
    },
}

Jest.config.js:

  moduleNameMapper: {
    '^types/(.*)$':  '<rootDir>/js/types/$1',
    '^components/(.*)$': '<rootDir>/js/app/components/$1',
    '^modules/(.*)$':  '<rootDir>/js/app/modules/$1',
    '^hooks/(.*)$':  '<rootDir>/js/app/hooks/$1',
    '^reducers/(.*)$':  '<rootDir>/js/app/reducers/$1',
    '^__test-utils__/(.)$': '<rootDir>/js/app/__test-utils__/$1' 
  }

Here's an explanation of the symbols:

• (.*)$: capture whatever comes after the exact match (the directory)
• $1: map it to this value in the directory I specify.

and tsconfig.json:

    "paths": {
      "config": ["config/dev", "config/production"],
      "components/*": ["js/app/components/*"],
      "modules/*": ["js/app/modules/*"],
      "types/*": ["js/types/*"],
      "hooks/*": ["js/app/hooks/*"],
      "reducers/*": ["js/app/reducers/*"],
      "__test-utils__/*": ["js/app/__test-utils__/*"]
    }

For anyone using @ as the root of their modules, you have to be more specific since other libs can use the @ in node modules.

  moduleNameMapper: {
    "^@/(.*)$": "<rootDir>/src/$1"
  },

It translates to "anything that matches @/ should be sent to <rootDir>/src/<rest of the path>