Learn API Testing
You've learned how to read test cases and spot input categories. Now it's time to switch interfaces — from simple form fields to a real API explorer.
This module contains one lesson that explains how the Calculator API (Addition) challenge works — its HTTP method selector, JSON request body, and the three types of results you can expect. Then a hands-on challenge puts you directly in the tester's seat.
What You'll Do in This Module
| # | Activity | Type | Time | XP |
|---|---|---|---|---|
| 1 | How the Calculator API (Addition) Works | Lesson | 10 min | 4 XP |
| 2 | Calculator API (Addition) | Practice | 15 min | 8 XP |
Total: ~25 minutes · 12 XP
Module Goal
Work through the lesson, then complete all 6 test cases of the Calculator API (Addition) challenge. When you finish, you'll earn the "API Adder" badge — proof that you can test a real HTTP endpoint, classify its responses, and recognize when the application itself is at fault.
Why This Matters
Real-world QA work rarely stays at the UI layer. APIs are the backbone of modern software — and testing them means thinking in requests, responses, and data types. The Calculator API challenge introduces this world in a safe, guided way: one endpoint, six test cases, zero guesswork.
API testing theory — REST conventions, HTTP status codes, contract testing, and more — will be covered in depth in future courses. For now, your mission is to build the instinct.