API Automation with the RestAssured Framework

API Automation with the RestAssured Framework in Java provides a powerful way to test RESTful web services. Here’s a structured guide to setting up and writing tests using RestAssured:

1. Project Setup

Maven Dependencies

Add the required dependencies to your pom.xml:

<dependencies>
    <!-- RestAssured -->
    <dependency>
        <groupId>io.rest-assured</groupId>
        <artifactId>rest-assured</artifactId>
        <version>5.x.x</version>
        <scope>test</scope>
    </dependency>

    <!-- JSON Path for parsing -->
    <dependency>
        <groupId>io.rest-assured</groupId>
        <artifactId>json-path</artifactId>
        <version>5.x.x</version>
    </dependency>

    <!-- TestNG or JUnit -->
    <dependency>
        <groupId>org.testng</groupId>
        <artifactId>testng</artifactId>
        <version>7.x.x</version>
        <scope>test</scope>
    </dependency>
</dependencies>

2. Key Concepts in RestAssured

BaseURI: The base URL of your API (e.g., https://api.example.com).
Request Specification: Common configurations like headers, auth, etc.
Response Validation: Validate status codes, headers, and response bodies.
JSON Path: Extract data from JSON responses.
Logging: Log requests and responses for debugging.

3. Basic Test Example

Test: Validate a GET Request

import io.restassured.RestAssured;
import io.restassured.response.Response;
import org.testng.Assert;
import org.testng.annotations.Test;

import static io.restassured.RestAssured.*;

public class GetRequestTest {

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

        Response response = given()
            .header("Content-Type", "application/json")
        .when()
            .get("/posts/1")
        .then()
            .statusCode(200)
            .log().all()
            .extract().response();

        // Validate response body
        String title = response.jsonPath().getString("title");
        Assert.assertNotNull(title, "Title should not be null");
    }
}

4. POST Request Test

Test: Create a New Resource

import io.restassured.RestAssured;
import io.restassured.response.Response;
import org.testng.annotations.Test;

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

public class PostRequestTest {

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

        String requestBody = "{\n" +
                "  \"title\": \"foo\",\n" +
                "  \"body\": \"bar\",\n" +
                "  \"userId\": 1\n" +
                "}";

        given()
            .header("Content-Type", "application/json")
            .body(requestBody)
        .when()
            .post("/posts")
        .then()
            .statusCode(201)
            .body("title", equalTo("foo"))
            .log().all();
    }
}

5. PUT Request Test

Test: Update an Existing Resource

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

    String requestBody = "{\n" +
            "  \"title\": \"updatedTitle\",\n" +
            "  \"body\": \"updatedBody\",\n" +
            "  \"userId\": 1\n" +
            "}";

    given()
        .header("Content-Type", "application/json")
        .body(requestBody)
    .when()
        .put("/posts/1")
    .then()
        .statusCode(200)
        .body("title", equalTo("updatedTitle"))
        .log().all();
}

6. DELETE Request Test

Test: Delete a Resource

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

    given()
    .when()
        .delete("/posts/1")
    .then()
        .statusCode(200)
        .log().all();
}

7. Framework Enhancements

Base Test Class

Create a base test class to define standard configurations:

import io.restassured.RestAssured;
import org.testng.annotations.BeforeClass;

public class BaseTest {

    @BeforeClass
    public void setUp() {
        RestAssured.baseURI = "https://jsonplaceholder.typicode.com";
    }
}

Request Specification

Centralize reusable request specifications:

import io.restassured.builder.RequestSpecBuilder;
import io.restassured.specification.RequestSpecification;

public class RequestSpec {

    public static RequestSpecification getRequestSpec() {
        return new RequestSpecBuilder()
            .setBaseUri("https://jsonplaceholder.typicode.com")
            .addHeader("Content-Type", "application/json")
            .build();
    }
}

Use it in tests:

given()
    .spec(RequestSpec.getRequestSpec())
    .when()
    .get("/posts/1")
    .then()
    .statusCode(200);

8. JSON Path for Response Validation

Extract and validate specific data:

Response response = given()
    .when()
    .get("/posts/1")
    .then()
    .extract().response();

String title = response.jsonPath().getString("title");
int userId = response.jsonPath().getInt("userId");
Assert.assertEquals(userId, 1, "User ID should be 1");

9. Parameterized Tests

Use query or path parameters:

@Test
public void validateQueryParams() {
    given()
        .queryParam("userId", 1)
    .when()
        .get("/posts")
    .then()
        .statusCode(200)
        .body("size()", greaterThan(0))
        .log().all();
}

10. Run Tests

Use TestNG or JUnit as your test runner.
Run from an IDE or via Maven command:
```
mvn test
```

This framework setup ensures scalability, modularity, and reusability. Let me know if you need enhancements like integration with reporting tools or CI/CD!