Tillitsdone
down Scroll to discover

Mastering Async Tests in Jest with Async/Await

Learn practical techniques for handling asynchronous testing in Jest using async/await.

Discover best practices, common pitfalls, and advanced patterns for reliable test suites.
thumbnail

mdx Copy

Handling Asynchronous Tests in Jest with Async/Await

A futuristic abstract data stream visualization with flowing bright blue and white streams of light against a dark background camera angle: dynamic wide shot with diagonal perspective high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail

Testing asynchronous code can be tricky, but Jest makes it surprisingly straightforward with async/await. Let’s dive into some practical tips and tricks for handling async tests effectively.

Understanding the Basics

When testing async operations, the biggest challenge is ensuring Jest waits for the operation to complete before moving to the next test. Without proper handling, tests can pass even when they shouldn’t.

Abstract minimal geometric shapes floating in space with soft gradients of bright cyan and mint green colors camera angle: top-down view with subtle tilt high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail

Best Practices for Async Testing

1. Always Return Promises

The most common mistake is forgetting to return promises. Jest needs to know it should wait for the promise to resolve:

// ❌ Wrong
test('async operation', async () => {
await someAsyncOperation();
});
// ✅ Correct
test('async operation', async () => {
const result = await someAsyncOperation();
expect(result).toBeDefined();
});
2. Error Handling
When testing error scenarios, combine try/catch with expect statements:
javascript
Copy
test('handles errors', async () => {
expect.assertions(1);
try {
await failingAsyncOperation();
} catch (error) {
expect(error.message).toMatch('Expected error message');
}
});
3. Working with Timeouts
For operations that might take longer, adjust the timeout:
javascript
Copy
test('long running operation', async () => {
const result = await longOperation();
expect(result).toBeTruthy();
}, 10000); // 10 second timeout
![Floating geometric crystal formations in bright emerald and neon green colors against a black backdrop camera angle: low angle shot looking upward high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail](/image_generation/tillitsdone_Jest_Tips-and-tricks_topics_find_Handling-Asynchronous-Tests-in-Jest-with-AsyncAwaitcontent_1732733531420_2.jpeg "Floating geometric crystal formations in bright emerald and neon green colors against a black backdrop camera angle: low angle shot looking upward high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail")
Advanced Techniques
Parallel Testing
Run multiple async operations concurrently:
javascript
Copy
test('parallel operations', async () => {
const results = await Promise.all([
asyncOperation1(),
asyncOperation2(),
asyncOperation3()
]);
expect(results).toHaveLength(3);
});
Clean Up
Always clean up after async tests to prevent memory leaks:
javascript
Copy
afterEach(async () => {
await cleanup();
});
![Ocean waves creating abstract patterns with bright turquoise and white colors during sunset camera angle: aerial view straight down high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail](/image_generation/tillitsdone_Jest_Tips-and-tricks_topics_find_Handling-Asynchronous-Tests-in-Jest-with-AsyncAwaitcontent_1732733531420_3.jpeg "Ocean waves creating abstract patterns with bright turquoise and white colors during sunset camera angle: aerial view straight down high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail")
Copy
icons/code-outline.svg Jest Blogs
Versatile testing framework for JavaScript applications supporting various test types.
icons/logo-tid.svg

Talk with CEO

Ready to bring your web/app to life or boost your team with expert Thai developers?
Contact us today to discuss your needs, and let’s create tailored solutions to achieve your goals. We’re here to help at every step!
🖐️ Contact us
Let's keep in Touch
Thank you for your interest in Tillitsdone! Whether you have a question about our services, want to discuss a potential project, or simply want to say hello, we're here and ready to assist you.
We'll be right here with you every step of the way.
Contact Information
rick@tillitsdone.com+66824564755
Find All the Ways to Get in Touch with Tillitsdone - We're Just a Click, Call, or Message Away. We'll Be Right Here, Ready to Respond and Start a Conversation About Your Needs.
Address
9 Phahonyothin Rd, Khlong Nueng, Khlong Luang District, Pathum Thani, Bangkok Thailand
Visit Tillitsdone at Our Physical Location - We'd Love to Welcome You to Our Creative Space. We'll Be Right Here, Ready to Show You Around and Discuss Your Ideas in Person.
Social media
Connect with Tillitsdone on Various Social Platforms - Stay Updated and Engage with Our Latest Projects and Insights. We'll Be Right Here, Sharing Our Journey and Ready to Interact with You.
We anticipate your communication and look forward to discussing how we can contribute to your business's success.
We'll be here, prepared to commence this promising collaboration.
Frequently Asked Questions
Explore frequently asked questions about our products and services.
Whether you're curious about features, warranties, or shopping policies, we provide comprehensive answers to assist you.