Supported technologies: Jest, Snapshot Testing

Starting from Jest v24, no configuration is required to start using Wallaby. If you are using a previous version then we recommend updating your Jest package version or refer to our legacy jest docs.

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Starting Wallaby on a project with configured Jest

Overriding Automatic Configuration

Sometimes you may want to add/override some Wallaby configuration settings to the automatically detected settings. For example, 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 or package.json section.

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

module.exports = () => {
  return {
    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 {
    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": {
    "testFramework": {
      "configFile": "./jest.config.walllaby.js"
    }
  }
}

Note that if you are adding/overriding files/tests, then it is required to add the autoDetect: true setting:

module.exports = () => ({
  autoDetect: true,
  files: [...],
  tests: [...],
});

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 continue to have problems, please try manually clearing Jest’s cache and reinstalling Wallaby’s core runtime:

1. Identify the cache location using npx jest --showConfig and identifying the cache location from the config key: cacheDirectory.
2. Delete the folder specified in cacheDirectory.
3. Follow these steps to force a core runtime update.

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.