Mastering API Automation Testing with Rest Assured

Published On: 9 April 2024.By Mohd Bilal.

Mastering API Automation Testing with Rest Assured

Title: A Millennial’s Guide to Mastering API Automation Testing with Rest Assured

Introduction

In today’s fast-paced world of software development, ensuring the reliability and functionality of web applications is paramount. That’s where API automation testing comes in, and Rest Assured is the ultimate weapon in a developer’s arsenal for this task. In this beginner’s guide, we’ll dive into how to harness the power of Rest Assured to streamline API testing, covering everything from its features to best practices.

Understanding Rest Assured and API Automation Testing

Rest Assured isn’t just another library; it’s a game-changer for testing RESTful APIs. It’s like having a supercharged toolkit that lets developers effortlessly validate API endpoints. API automation testing, meanwhile, is all about turbocharging these tests to run automatically, saving time and ensuring consistency.

Getting Started with Rest Assured

Setting up Rest Assured is a breeze. Just add it as a dependency in your project’s build configuration file (think Maven or Gradle), and you’re ready to roll. Then, simply import the library into your Java classes, and you’re off to the races.

java

// Maven dependency
<dependency>
    <groupId>io.rest-assured</groupId>
    <artifactId>rest-assured</artifactId>
    <version>4.3.3</version>
    <scope>test</scope>
</dependency>

// Maven dependency

<groupId>io.rest-assured</groupId>

<artifactId>rest-assured</artifactId>

</dependency>

Writing Your First Rest Assured Test

Now, for the fun part – writing your first Rest Assured test! Fire up a new Java class, sprinkle in some JUnit or TestNG annotations, and let the magic begin. With Rest Assured’s slick API, crafting HTTP requests and validating responses is a breeze. It’s like writing poetry, but for testing.

java

import io.restassured.RestAssured;
import io.restassured.response.Response;
import org.junit.jupiter.api.Test;

import static io.restassured.RestAssured.given;
import static org.hamcrest.Matchers.equalTo;

public class MyFirstRestAssuredTest {

    @Test
    public void testStatusCode() {
        Response response = RestAssured.get("https://api.example.com/users/1");
        response.then().assertThat().statusCode(200);
    }

    @Test
    public void testResponseContent() {
        given().get("https://api.example.com/users/1")
                .then()
                .assertThat()
                .body("id", equalTo(1))
                .body("name", equalTo("John Doe"));
    }
}

import io.restassured.RestAssured;

import io.restassured.response.Response;

import org.junit.jupiter.api.Test;

import static io.restassured.RestAssured.given;

import static org.hamcrest.Matchers.equalTo;

public class MyFirstRestAssuredTest {

@Test

public void testStatusCode() {

Response response = RestAssured.get("https://api.example.com/users/1");

response.then().assertThat().statusCode(200);

}

@Test

public void testResponseContent() {

given().get("https://api.example.com/users/1")

.then()

.assertThat()

.body("id", equalTo(1))

.body("name", equalTo("John Doe"));

}

Handling Authentication and Authorization

Authentication and authorization can be a headache, but Rest Assured has your back. Whether you’re dealing with basic auth, OAuth, or JWT tokens, Rest Assured makes it a cinch to include authentication credentials in your requests and ensure your tests are accessing the right endpoints.

import org.junit.jupiter.api.Test;

import static io.restassured.RestAssured.given;

public class AuthTest {

    @Test
    public void testBasicAuthentication() {
        given()
                .auth().basic("username", "password")
                .when()
                .get("https://api.example.com/secure-endpoint")
                .then()
                .statusCode(200);
    }
}

import org.junit.jupiter.api.Test;

import static io.restassured.RestAssured.given;

public class AuthTest {

@Test

public void testBasicAuthentication() {

given()

.auth().basic("username", "password")

.when()

.get("https://api.example.com/secure-endpoint")

.then()

.statusCode(200);

}

Working with Request and Response Specifications

Nobody likes writing repetitive code, and that’s where request and response specifications come in handy. With Rest Assured, you can define these specifications once and reuse them across multiple tests, making your code cleaner and more maintainable.

import io.restassured.builder.RequestSpecBuilder;
import io.restassured.builder.ResponseSpecBuilder;
import io.restassured.specification.RequestSpecification;
import io.restassured.specification.ResponseSpecification;
import org.junit.jupiter.api.BeforeAll;

import static org.hamcrest.Matchers.lessThan;

public class RequestResponseSpecsTest {

    private static RequestSpecification requestSpec;
    private static ResponseSpecification responseSpec;

    @BeforeAll
    public static void setup() {
        requestSpec = new RequestSpecBuilder()
                .setBaseUri("https://api.example.com")
                .addHeader("Authorization", "Bearer myAccessToken")
                .build();

        responseSpec = new ResponseSpecBuilder()
                .expectStatusCode(200)
                .expectResponseTime(lessThan(5000L))
                .build();
    }
}

import io.restassured.builder.RequestSpecBuilder;

import io.restassured.builder.ResponseSpecBuilder;

import io.restassured.specification.RequestSpecification;

import io.restassured.specification.ResponseSpecification;

import org.junit.jupiter.api.BeforeAll;

import static org.hamcrest.Matchers.lessThan;

public class RequestResponseSpecsTest {

private static RequestSpecification requestSpec;

private static ResponseSpecification responseSpec;

@BeforeAll

public static void setup() {

requestSpec = new RequestSpecBuilder()

.setBaseUri("https://api.example.com")

.addHeader("Authorization", "Bearer myAccessToken")

.build();

responseSpec = new ResponseSpecBuilder()

.expectStatusCode(200)

.expectResponseTime(lessThan(5000L))

.build();

}

Handling Dynamic Data and Test Data Management

In the real world, API testing isn’t always straightforward. Sometimes you need to deal with dynamic data or use different sets of test data for different scenarios. Thankfully, Rest Assured has your back here too. With support for path parameters, query parameters, and more, handling dynamic data is a breeze. Plus, you can easily integrate with external data sources to ensure comprehensive test coverage.