Section 1 Review
You've finished API Testing Foundations, the first section of API Testing. This page is a dedicated recap — bookmark it as a fast reference, separate from the modules themselves.
Section Summary
✔ What Is API Testing? — why testing at the request/response layer catches defects a UI-only pass structurally cannot, and how API testing complements (rather than replaces) UI and unit testing ✔ HTTP Fundamentals — reading a response with a tester's precision: status code, headers, and body together, not the body alone ✔ REST Architecture and API Design Principles — the conventions a RESTful API is expected to follow, and why a convention violation is often a lead pointing at a real behavioral defect
How they build on each other: Module 1 established why this path exists at all — what API testing catches that UI testing can't. Module 2 gave you the literacy to read a request and response precisely. Module 3 closed the section by giving that literacy a design model — the conventions a well-built API is expected to follow, so a deviation from them reads as a specific, testable finding rather than a vague feeling that something's off.
API Design and Testing Focus Matrix
A quick reference for what to check depending on what you're looking at:
| What You're Looking At | Focus | Why |
|---|---|---|
| A response that looks successful | Status code first, then headers, then body | A correct-looking body can still sit behind the wrong status code |
| An error path | Whether the 4xx/5xx range matches the actual cause | A wrong range misleads anything reacting differently to client vs. server errors |
| A set of related routes | Naming and method consistency across them | Cross-route inconsistency is invisible when testing one route at a time |
| A route whose name implies reversibility or a lesser action | Whether its actual behavior matches what the name promises | A misleading name is often a symptom of a real behavioral defect |
Section 1 Knowledge Check
Five realistic scenarios. For each, identify what a tester should check and why. No answers are provided here. Solutions: Section 1 Solutions.
Scenario 1: AtlasBank's GET /accounts/{id}/balance endpoint returns a 200 OK with what looks like correct balance data, every time it's tested.
Scenario 2: A POST /transfers request returns 200 OK with a body indicating the transfer was accepted, but the UI built on top of it shows a generic "Success!" message regardless of the response body's actual content.
Scenario 3: AtlasBank's GET /transactions?accountId={id}&from={date}&to={date} returns 200 OK with {"transactions": []} both for an account with genuinely zero transactions in range, and for an account ID that doesn't exist.
Scenario 4: A new route, POST /beneficiaries/{id}/suspend, appears alongside the existing DELETE /beneficiaries/{id}.
Scenario 5: AtlasBank's KYC-verification API is documented as always returning Content-Type: application/json, including on error responses.
Continue to Section 2
Data, Contracts, and Test Cases, starting with API Requests and Responses — where this section's HTTP and REST literacy gets applied to reading and validating full request/response payloads.