Supported technologies: Jest, Snapshot Testing

Select configuration mode

Wallaby can be run either with or without a configuration file. We recommend using Automatic configuration - Wallaby requires no configuration file, however if you choose Manual configuration then the tutorial will be adjusted with additional sections demonstrating the contents of the configuration file.

Automatic configuration is supported starting from Jest v24, so if you are using a previous version please update your Jest package version or else switch to Manual configuration mode.

Select your editor

The instructions in this docs section are adjusted to your editor of choice. Please select your editor by clicking on your editor’s logo below before proceeding with the tutorial:

module.exports = function () {

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

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

    env: {
      type: 'node'
    },

    testFramework: 'jest'
  };
};

 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);
     }
   };
 };

module.exports = function (wallaby) {

  return {
    ...

    testFramework: 'jest',

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

module.exports = function () {

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

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

    env: {
      type: 'node'
    },

    testFramework: 'jest'
  };
};

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')]})
    }
  };
};

module.exports = function () {

  process.env.NO_WATCHMAN = true;

  return {
    ...
  };
};

Overriding Automatic Configuration

If you are not using jest’s default configuration file naming convention (i.e. jest.config.js in your project root), or if jest exists outside of your project’s default node_modules directory (e.g. @microsoft/rush) then you may configure these locations by specifying a configuration file.

For example, to use Jest auto-configuration with a custom Jest config path, you may create the following Wallaby config file:

module.exports = () => {
  return {
    // tell wallaby to use automatic configuration
    autoDetect: true,

    testFramework: {
      // the jest configuration file path
      // (relative to project root)
      configFile: './jest.config.wallaby.js'
    }
  }
};

Or, if jest exists outside of your project’s default node_modules directory, you may specify its path:

module.exports = () => {
  return {
    // tell wallaby to use automatic configuration
    autoDetect: true,

    testFramework: {
      // the path to locate jest
      // (relative to project root)
      path: './subfolder/node_modules'
    }
  }
};

If you don’t want to create Wallaby config file, you may use package.json wallaby section:

{
  "wallaby": {
    "autoDetect": true,
    "testFramework": {
      "configFile": "./jest.config.walllaby.js"
    }
  }
}

Snapshot testing

It’s recommended to read the article about Jest snapshot testing workflow with wallaby.js. Amongst other things, the article describes how to update individual test snapshots:

ES modules

Wallaby supports native ECMAScript Modules with Jest in relevant versions of node.js.

Troubleshooting

When configured to run using automatic configuration, Wallaby runs in Jest’s execution pipeline. Wallaby will return the same results and code coverage as you would get when running Jest from the command-line.

The first step of troubleshooting a project configured to use automatic configuration is to identify whether the same results are returned using npx jest. Running Jest from the command-line will usually show/highlight the cause of your problem. You may also try clearing Jest’s cache using: npx jest --clearCache.

If you get stuck or something isn’t working for you, you may find further troubleshooting steps here or else find a similar solved issue in our github issues repository. If you can’t find a solution, create a new issue.