API Testing
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🔗 API Testing

REST API fundamentals, Postman, RestAssured (given/when/then), JSON validation, and status codes.

What is API Testing?

API testing evaluates Application Programming Interfaces (APIs) directly for functionality, reliability, performance, and security without relying on a graphical user interface (GUI).

HTTP Methods & Status Codes

Understanding standard REST API requests and HTTP response codes.

Method Purpose Common Success Code Common Error Code
GET Retrieve data from server 200 OK 404 Not Found
POST Create new resource 201 Created 400 Bad Request
PUT Update / Replace resource 200 OK 401 Unauthorized
DELETE Remove resource from server 204 No Content 403 Forbidden

Automating REST APIs with RestAssured

RestAssured provides a BDD syntax (`given()`, `when()`, `then()`) for testing REST services in Java.

ApiTest.java Java 
import io.restassured.RestAssured;
import static io.restassured.RestAssured.*;
import static org.hamcrest.Matchers.*;
import org.testng.annotations.Test;

public class ApiTest {
  @Test
  public void testGetUser() {
    RestAssured.baseURI = "https://jsonplaceholder.typicode.com";

    given()
      .header("Content-Type", "application/json")
    .when()
      .get("/users/1")
    .then()
      .statusCode(200)
      .body("name", equalTo("Leanne Graham"))
      .body("address.city", notNullValue());
  }
}