How can I use Jest for testing asynchronous code?

How can I use Jest for testing asynchronous code?

You can use Jest's built-in support for promises and async/await to test asynchronous code. Would you like an example?

Yes, please provide an example of testing a function that returns a promise.

Sure! Here's a simple example:

test('async test example', async () => {
  const data = await fetchData(); // fetchData returns a promise
  expect(data).toBe('expected data');
});

What if I want to test a function that uses callbacks instead?

In that case, you can use Jest's done callback to signal that your test is complete. Here's an example:

test('callback test example', done => {
  fetchDataWithCallback((data) => {
    expect(data).toBe('expected data');
    done();
  });
});