How do I test asynchronous hooks in React?

How do I test asynchronous hooks in React?

To test asynchronous hooks, you can use libraries like React Testing Library along with Jest. You can mock the asynchronous behavior and assert the expected outcomes.

Can you show me an example of testing a custom hook?

Sure! Here's a simple example:

import { renderHook, act } from '@testing-library/react-hooks';
import useFetch from './useFetch';

test('should fetch data', async () => {
  const { result, waitForNextUpdate } = renderHook(() => useFetch('https://api.example.com/data'));

  await waitForNextUpdate();

  expect(result.current.data).toBeDefined();
});

What if my hook has a loading state?

You can test the loading state by checking the initial state before the data is fetched. For example:

expect(result.current.loading).toBe(true);
await waitForNextUpdate();
expect(result.current.loading).toBe(false);

Are there any best practices for testing hooks?

Yes! Some best practices include isolating your hooks, using mocks for dependencies, and testing both success and error states.