message: Docs: Mention whitelist usecase
diff: @@ -733,8 +733,8 @@ class CustomEnvironment extends NodeEnvironment {
  Default: `{}`
  Test environment options that will be passed to the `testEnvironment`. The
  -relevant options depend on the environment. For example you can override
  -options given to [jsdom](https://github.com/tmpvar/jsdom) such as
  +relevant options depend on the environment. For example you can override options
  +given to [jsdom](https://github.com/tmpvar/jsdom) such as
  `{userAgent: "Agent/007"}`.
  ### `testMatch` [array<string>]
  @@ -916,8 +916,17 @@ will not be transformed.
  These pattern strings match against the full path. Use the `<rootDir>` string
  token to include the path to your project's root directory to prevent it from
  accidentally ignoring all of your files in different environments that may have
  -different root directories. Example:
  -`["<rootDir>/bower_components/", "<rootDir>/node_modules/"]`.
  +different root directories.
  +
  +Example: `["<rootDir>/bower_components/", "<rootDir>/node_modules/"]`.
  +
  +Sometimes it happens (especially in React Native or TypeScript projects) that
  +3rd party modules are published as untranspiled. Since all files inside
  +`node_modules` are not transformed by default, Jest will not understand the code
  +in these modules, resulting in syntax errors. To overcome this, you may use
  +`transformIgnorePatterns` to whitelist such modules. You'll find a good example
  +of this use case in
  +[React Native Guide](http://facebook.github.io/jest/docs/en/tutorial-react-native.html#transformignorepatterns-customization).
  ### `unmockedModulePathPatterns` [array<string>]
  