Jest Async Testing: async/await, Promises & done() Explained

Learn how to properly handle asynchronous JavaScript when writing tests in Jest! Start FREE Testing: https://accounts.lambdatest.com/register?utm_source=YouTube&utm_medium=Organic&utm_campaign=Dec17&utm_term=EAaF1wMcMSw&utm_content=LT_Sign_Up 🎥In this 5th video of the Jest Tutorial Series, join 𝐌𝐚𝐫𝐜𝐨 𝐀 𝐂𝐫𝐮𝐳, founder of automateNow, as he walks you through how to properly test asynchronous JavaScript code in Jest using async, await, Promises, and advanced async matchers. You’ll learn why forgetting await can instantly make your tests flaky, how to handle simulated API calls, and how to validate both success and error responses with full reliability. In this video, Marco covers: ✔️ How async/await works inside Jest tests ✔️ Writing tests for mock GET & POST requests ✔️ Testing API responses, status codes & data ✔️ Handling invalid endpoints (404 responses) ✔️ Using rejects() & toThrow() for rejected Promises ✔️ Preventing flaky tests caused by skipped awaits ✔️ Real-world examples using a custom API Client class By the end of this lesson, you’ll know exactly how to write stable, predictable, and clean async tests in Jest no more random failures or unreliable test behaviour. ⏱️ Video Chapters: 00:00 Introduction 00:42 Async & Await 02:01 Code walk-thru 05:18 GET request using Async/Await 08:56 POST request using Async/Await 08:58 API error handling with Async/Await 13:34 Closing Missed watching the earlier videos? Introduction to Jest (Day 1): https://youtu.be/r4bLSl_j6yw Setting Up Jest (Day 2): https://youtu.be/bm_m0J8L0ko Write Your First Jest Test (Day 3):https://youtu.be/WiwH2VFR6-0 Understanding Jest Matchers (Day 4):https://youtu.be/GrfiZNcK4nw?si=rwkpdbPPzDILBxAk 📘 Learn More: https://www.testmuai.com/jest HOME: https://bit.ly/4uOCPKK BLOG: https://bit.ly/4nlq87I LINKEDIN: https://bit.ly/438HIm2 TWITTER: https://bit.ly/4eOI74s GITHUB: https://bit.ly/4ucseJI NEWSLETTER: https://bit.ly/4dI8Y0S CERTIFICATIONS: https://bit.ly/4tVdw9j