What are Jest snapshots and how do I use them asynchronously?

What are Jest snapshots and how do I use them asynchronously?

Jest snapshots are a feature in Jest that allows you to test the output of your components. They capture the rendered output and save it to a file, which can be compared in future tests. To use them asynchronously, you can wrap your component rendering in an async function.

Can you show me an example of how to create a snapshot test asynchronously?

Sure! Here's a simple example:

import React from 'react';
import renderer from 'react-test-renderer';
import MyComponent from './MyComponent';

test('MyComponent renders correctly', async () => {
  const component = renderer.create(<MyComponent />);
  let tree = component.toJSON();
  expect(tree).toMatchSnapshot();
});

This code creates a snapshot of MyComponent asynchronously.

What should I do if my snapshot test fails?

If your snapshot test fails, it usually means that the output of your component has changed. You can either update the snapshot by running jest --updateSnapshot or investigate the changes to ensure they are expected.

Are there any best practices for using Jest snapshots?

Yes, some best practices include keeping snapshots small and focused, updating them only when necessary, and using them for components that have stable output.