Snapshot Diff Serializer

This is a simple diffing utility for Jest that is inspired by snapshot-diff. The key difference here is that snapshot-diff-serializer only comes as a serializer and is agnostic of other serializers, meaning you get nice diffs with Enzyme, or other serializers applied (something that snapshot-diff doesn't do).

Installation

# npm
npm install --dev snapshot-diff-serializer
# yarn
yarn add -D snapshot-diff-serializer

Configuration

Add the serializer to your snapshotSerializers array in your Jest config (example using package.json)

{
  "jest": {
    "snapshotSerializers": [
      "jest-glamor-react",
      "enzyme-to-json/serializer",
      "<rootDir>/snapshot-diff-serializer"
    ],
  },
}

Usage

Here is an example of using this serializer:

const Component = ({ foo, bar }) => (
  <div>
    {foo != null && foo}
    {bar != null && bar}
  </div>
)

import { shallow } from 'enzyme'
// Test
describe('Component', () => {
  test('variants', () => {
    expect({
      diffA: shallow(<Component foo={3} />),
      diffB: shallow(<Component bar={5} />),
      }).toMatchSnapshot()
  })
})

The produced snapshot would look like this:

exports[`Component variants 1`] = `
- Diff A
+ Diff B

  <div>
-   3
+   5
  </div>
`;