How do I test asynchronous code in Node.js?

How do I test asynchronous code in Node.js?

You can use testing frameworks like Mocha or Jest. They provide utilities to handle async code.

Can you show me an example using Jest?

Sure! You can use async/await in your tests. Here's a simple example:

test('async test', async () => {
  const data = await fetchData();
  expect(data).toBe('expected value');
});

What if I want to test a promise directly?

You can return the promise from the test function. Jest will wait for it to resolve:

test('promise test', () => {
  return fetchData().then(data => {
    expect(data).toBe('expected value');
  });
});

Are there any best practices for testing async code?

Yes! Always handle errors properly, use async/await for readability, and ensure your tests are isolated.