@uifabric/jest-serializer-merge-styles

Provides a Jest serializer for @uifabric/merge-styles which expands class names into css rules.

Overview

When using Jest snapshot testing with components that use @uifabric/merge-styles, class names may be rendered as such in the snapshot (Note the css-2342 generated class name):

<div className='ms-Foo css-2432'>
  Hello world
</div>

Using this serializer, the generated css-2342 class name will be auto expanded to the rules resolved by merge-styles:

<div
  className=
      ms-Foo
      {
        background-color: #f4f4f4;
        box-sizing: border-box;
        color: #333333;
        cursor: pointer;
      }
      &:hover {
        background-color: #f8f8f8;
      }
>
  Hello world
</div>

This means that your tests can pass reliably (no generated class names) and your rules get included in the snapshot. (Snapshots need updates when css is altered.)

Usage

In your jest.config.js (or appropriate config location) include a snapshotSerializers array that references this package:

module.exports = {
  snapshotSerializers: [path.resolve(__dirname, 'jest-serializer-merge-styles')],
};

See Testing for more detailed usage.