Introduction

API testing is crucial in software development, allowing you to validate the functionality, reliability, and performance of your applications. REST Assured is a popular tool that makes it easy to automate testing against RESTful APIs. This post will cover how to set up the REST Assured framework in your Java project, along with examples to get you started on your API testing journey.

Prerequisites

Before diving into the setup, ensure you have the following prerequisites:

1. Java Development Kit (JDK): Version 8 or later. You can download it from Oracle's website.
2. Maven: For dependency management. If you don’t have it installed, refer to the Maven installation guide.
3. IDE: An Integrated Development Environment like IntelliJ IDEA or Eclipse.

Step 1: Create a New Maven Project

To start, create a new Maven project. Here’s how to do it in IntelliJ IDEA:

1. Open IntelliJ IDEA and select File > New > Project.
2. Choose Maven on the left side and click Next.
3. Provide the GroupId (e.g., com.example) and ArtifactId (e.g., RestAssuredDemo), then click Finish.

Alternatively, if you prefer the command line, you can run:

mvn archetype:generate -DgroupId=com.example -DartifactId=RestAssuredDemo -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

Step 2: Add REST Assured Dependency

In your newly created Maven project, open the pom.xml file and add the following dependencies under the <dependencies> section:

<dependencies>
    <dependency>
        <groupId>io.rest-assured</groupId>
        <artifactId>rest-assured</artifactId>
        <version>5.4.0</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.hamcrest</groupId>
        <artifactId>hamcrest</artifactId>
        <version>2.2</version>
    </dependency>
</dependencies>

Make sure to save the file, and Maven will automatically download the required libraries.

Step 3: Configure REST Assured

REST Assured requires configuration for specific settings. In your main Java class or test class, you can set the base URI and other configurations.

import io.restassured.RestAssured;
import org.junit.jupiter.api.BeforeAll;

public class ApiTest {

    @BeforeAll
    public static void setup() {
        RestAssured.baseURI = "https://jsonplaceholder.typicode.com"; // Sample API
    }
}

Important Configuration Options

• Base URI: The root URL for your API.
• Port: Configure if your API runs on a specific port (useful for local testing).

You can also set other configurations like authentication, if required:

RestAssured.authentication = RestAssured.basic("username", "password");

Step 4: Writing Your First API Test

Now that we have set up the environment, let's write a basic test case using JUnit 5. Create a new Java class called ApiTest:

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

import static io.restassured.RestAssured.*;
import static org.hamcrest.Matchers.*;

public class ApiTest {

    @BeforeAll
    public static void setup() {
        RestAssured.baseURI = "https://jsonplaceholder.typicode.com";
    }

    @Test
    public void testGetPosts() {
        given()
            .when()
                .get("/posts")
            .then()
                .statusCode(200)
                .body("[0].title", notNullValue());
    }
}

Breaking Down the Test

• given(): Represents the request specification. Here you can add query parameters, headers, or authentication.
• when(): Represents the request method. You have various options like get(), post(), put(), etc.
• then(): Defines the assertions you want to make, like checking the status code or validating the response body.

Step 5: Running Your Tests

To run your tests, you can use your IDE’s built-in test runner or run the following command in the terminal:

mvn test

You should see output indicating the tests have run and any assertions made.

Additional Features and Best Practices

• Response Validation: Verify not just the status code but also content, headers, and response time.
• Data-Driven Testing: Utilize parameters with JUnit’s @ParameterizedTest.
• Logging: Use REST Assured's logging capability for debugging. Add .log().all() to your request for complete request/response logs.

given()
    .log().all()
    .when()
        .get("/posts")
    .then()
        .log().all();

Conclusion

With this setup, you are now ready to dive deeper into API testing using REST Assured. The framework offers a robust and clean way to validate RESTful services, making your testing processes both efficient and effective. As you progress in your learning journey, explore more functionalities that REST Assured provides, and apply them to your real-world projects for better test coverage and reliability.

References

• REST Assured Documentation
• JUnit 5 User Guide