Integration of Rest Assured with JUnit 5

  

Integrating RestAssured with JUnit 5 for API testing is a popular combination for writing clean, structured, and automated API tests in Java. Here's a detailed explanation and sample code:

What is RestAssured?

RestAssured is a Java-based library used to test RESTful APIs. It provides a domain-specific language (DSL) for making requests and validating responses.

What is JUnit 5?

JUnit 5 is the latest version of the popular unit testing framework for Java. It provides annotations, assertions, and other tools to write test cases.

Steps to Integrate RestAssured with JUnit 5

1. Add Maven Dependencies

<dependencies>
    <!-- RestAssured for API testing -->
    <dependency>
        <groupId>io.rest-assured</groupId>
        <artifactId>rest-assured</artifactId>
        <version>5.4.0</version>
        <scope>test</scope>
    </dependency>

    <!-- JUnit 5 -->
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter-api</artifactId>
        <version>5.10.0</version>
        <scope>test</scope>
    </dependency>

    <!-- JUnit 5 Engine -->
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter-engine</artifactId>
        <version>5.10.0</version>
        <scope>test</scope>
    </dependency>
</dependencies>

Sample Test Code

package api;

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

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

public class SampleApiTest {

    @BeforeAll
    public static void setup() {
        // Set the base URI for all tests
        RestAssured.baseURI = "https://jsonplaceholder.typicode.com";
    }

    @Test
    public void testGetPosts() {
        given()
            .when()
            .get("/posts")
            .then()
            .statusCode(200)
            .body("size()", greaterThan(0));
    }

    @Test
    public void testGetPostById() {
        given()
            .when()
            .get("/posts/1")
            .then()
            .statusCode(200)
            .body("id", equalTo(1))
            .body("userId", notNullValue());
    }

    @Test
    public void testCreatePost() {
        String jsonBody = """
            {
                "title": "foo",
                "body": "bar",
                "userId": 1
            }
        """;

        given()
            .contentType(ContentType.JSON)
            .body(jsonBody)
            .when()
            .post("/posts")
            .then()
            .statusCode(201)
            .body("title", equalTo("foo"))
            .body("userId", equalTo(1));
    }
}

Explanation of Annotations

Annotation	Description
@BeforeAll	Runs once before all test methods in the class.
@Test	Marks a method as a test case.

Assertions and Features Used

• statusCode(200): Asserts the HTTP status.

• body("id", equalTo(1)): Asserts the value in response body.

• greaterThan(0): Asserts list size.

• notNullValue(): Ensures the value is present.

How to Run

• In Eclipse/IntelliJ:  Right-click the test class → Run as JUnit Test.

• Using Maven:

mvn test