API Automation with REST Assured (Part 1)

REST Assured is a Java library for testing REST APIs: fluent syntax for requests and assertions. This post (Part 1) covers basics: sending GET and POST, asserting status and response body, and structuring your first API tests with JUnit or TestNG.

Why REST Assured?

• Fluent API: Readable request setup and assertions (e.g. given().when().get().then().statusCode(200)).
• Java: Fits Java shops; integrates with JUnit, TestNG, and Maven/Gradle.
• JSON/XML: Easy to assert on response body (path, fields, types).
• Auth, headers, cookies: Built-in support for common needs.

First request and assertion

Conceptually:

• Given: Base URL, headers (e.g. Content-Type, Authorization), body (for POST).
• When: Method and path (e.g. GET /users/1).
• Then: Assert status code, body (e.g. body("id", equalTo(1))), headers.

You write this in Java with REST Assured's given(), when(), then() style.

Structure

• Base URL: Set once (e.g. in @BeforeAll or config) so tests only specify path.
• One test per scenario: e.g. get user positive, get user not found, create user positive.
• Reuse: Extract common given (auth, headers) into a method or filter.

Part 2 covers advanced assertions, JSON path, and organizing tests for CI.

Summary

• REST Assured = fluent Java API for HTTP requests and assertions; integrates with JUnit/TestNG.
• Use given/when/then to set up request and assert status and body.
• Set base URL and auth once; keep one test per scenario; Part 2 adds advanced assertions and structure.