Testing AWS UI components with Jest
Developers who have recently installed AWS’s new UI component library may quickly run into trouble with their unit tests. AWS UI is written in ECMAScript, and Jest cannot import it by default.
The full error will look something like this:
Test suite failed to runJest encountered an unexpected tokenThis usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".Here's what you can do:
* If you are trying to use ECMAScript Modules, see ... for how to enable it.
* To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
* If you need a custom transformation specify a "transform" option in your config.
* If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.You'll find more details and examples of these config options in the docs:
...Details:.../node_modules/@awsui/components-react/.../....js
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){export ...
^^^^^^SyntaxError: Unexpected token 'export' at Runtime.createScriptFromCode (...)
at Object.<anonymous> (...)
There are a few configurations you need to make to force the transpilation of AWS UI from ECMAScript to CommonJS in order for Jest to adequately test it.
Regenerator runtime 🤖
If you are attempting to support IE11 and are not already providing regeneratorRuntime, check out the documentation on the regenerator-runtime NPM package to get it installed and setup.
If you are not supporting IE11, you do not need to do this step.
Babel 🦜
You will need to install and configure Babel, if you are not already, in order to transpile AWS UI. If you are already using TypeScript, this may sound…
