What are the best practices for mocking fetch in tests?

What are the best practices for mocking fetch in tests?

When mocking fetch, it's important to ensure that your tests are isolated and do not rely on actual network calls. Use libraries like Jest or Sinon for effective mocking.

Can you give me an example of how to mock fetch using Jest?

Sure! You can use jest.mock to mock the fetch function. Here's a simple example:

import fetch from 'node-fetch';

jest.mock('node-fetch');

fetch.mockImplementation(() => Promise.resolve({
  json: () => Promise.resolve({ data: 'mocked data' })
}));

What should I do if my fetch call returns an error?

You can simulate an error by modifying the mock implementation. For example:

fetch.mockImplementation(() => Promise.reject(new Error('Network error')));

Are there any libraries specifically for mocking fetch?

Yes, libraries like fetch-mock and msw (Mock Service Worker) are great for mocking fetch requests in tests.