Supported technologies: Jest, Snapshot Testing

Wallaby.js supports the Facebook Jest testing framework.

module.exports = function () {

  return {
    files: ['src/**/*.js', '!src/**/__tests__/*.js'],

    tests: ['src/**/__tests__/*.js'],

    env: {
      type: 'node'
    },

    testFramework: 'jest'
  };
};

You may find the working sample of wallaby.js configuration for Jest in this repository.

Please note that wallaby.js is using its own cache to run your tests from, not the local project folder. You should include all files (except node modules) that your tests need, for example __mocks__/*.*, etc.

Jest configuration

If Jest in your project is configured using a package.json or jest.config.js/jest.config.json file, then wallaby will automatically load the configuration. If you would like to adjust the configuration, you may use the setup function, and pass require('./package.json').jest (or require('./jest.config')) to the wallaby.testFramework.configure function. Don’t forget to include package.json/jest.config.js/jest.config.json in your files list in this case.

 module.exports = function () {

   return {
     files: [
       'src/**/*.js',
       'package.json', // <--
       '!src/**/__tests__/*.js'
       ],

     tests: ['src/**/__tests__/*.js'],

     env: {
       type: 'node'
     },

     testFramework: 'jest',

     setup: function (wallaby) {
       var jestConfig = require('./package.json').jest;
       /* for example:
        * jestConfig.globals = { "__DEV__": true }; */
       wallaby.testFramework.configure(jestConfig);
     }
   };
 };

If you have some other Jest config, or would like to override some configuration values, you may pass any config object to the configure function of the test framework in wallaby setup function.

Babel

If you are using Babel compilation in your project, you need to add Babel compiler to your config:

module.exports = function (wallaby) {

  return {
    ...

    testFramework: 'jest',

    compilers: {
      '**/*.js': wallaby.compilers.babel()
    }
  };
};

TypeScript

TypeScript Jest configuration (ts-jest modules to be more specific) requires the access to the tsconfig.json file, so if you are using Jest with TypeScript, you’ll need to add the file to your files list:

module.exports = function () {

  return {
    files: [
      'tsconfig.json', // <--
      'src/**/*.ts',
      '!src/**/__tests__/*.ts'
      ],

    tests: ['src/**/__tests__/*.ts'],

    env: {
      type: 'node'
    },

    testFramework: 'jest'
  };
};

Jest with TypeScript and jest.mock calls

If you are using TypeScript with Jest and your tests are making jest.mock calls, then you will need to run Babel (babel-preset-jest) transformation on top of TypeScript compilation (just like ts-jest is doing) to hoist the calls:

module.exports = function (w) {
  return {
    files: [
      ...
    ],

    tests: [
      ...
    ],

    ...

    preprocessors: {
      '**/*.js?(x)': file => require('@babel/core').transform(
        file.content,
        {sourceMap: true, filename: file.path, presets: [require('babel-preset-jest')]})
    }
  };
};

create-react-app

You may find the full config for create-react-app generated app in this docs section. You may find the full config for create-react-app --typescript generated app in this sample repository.

Watchman

If you want to stop Jest to use watchman when running from Wallaby, you may use the process.env.NO_WATCHMAN setting.

module.exports = function () {

  process.env.NO_WATCHMAN = true;

  return {
    ...
  };
};