How can I use Sinon for mocking fetch requests in my tests?

How can I use Sinon for mocking fetch requests in my tests?

You can use Sinon to create a fake server that intercepts fetch requests. This allows you to simulate responses.

Can you show me a code example of how to set this up?

Sure! Here's a simple example:

import sinon from 'sinon';

const server = sinon.createFakeServer();

server.respondWith('GET', '/api/data', [200, { 'Content-Type': 'application/json' }, JSON.stringify({ key: 'value' })]);

// Now, when you call fetch, it will return the mocked response.
fetch('/api/data')
  .then(response => response.json())
  .then(data => console.log(data));

server.respond(); // This will trigger the response

What if I want to test error responses?

You can simulate error responses by using a different status code. For example:

server.respondWith('GET', '/api/data', [500, { 'Content-Type': 'application/json' }, JSON.stringify({ error: 'Internal Server Error' })]);