What are some tips for testing asynchronous code in Jest?

What are some tips for testing asynchronous code in Jest?

When testing async code in Jest, you can use async/await syntax or return a promise. This helps ensure your tests wait for the async operations to complete.

Can you give me an example of using async/await in a Jest test?

Sure! Here's a simple example:

test('fetches data', async () => {
  const data = await fetchData();
  expect(data).toEqual(expectedData);
});

What about testing promises directly?

You can return the promise directly in your test:

test('fetches data', () => {
  return fetchData().then(data => {
    expect(data).toEqual(expectedData);
  });
});

Are there any specific Jest matchers for async tests?

Yes! You can use matchers like resolves and rejects for promises:

await expect(fetchData()).resolves.toEqual(expectedData);
await expect(fetchData()).rejects.toThrow();