Rest Assured API Testing Interview Questions: Everything You Need to Know

API testing has become an integral part of software development, as it allows developers to ensure that their application programming interfaces (APIs) are functioning correctly and delivering the expected results. One popular tool for API testing is Rest Assured, a Java-based library that simplifies the process of testing RESTful APIs.

If you’re preparing for an interview that includes Rest Assured API testing, it’s crucial to familiarize yourself with common interview questions and be prepared to answer them confidently. In this article, we will cover 15 common interview questions for Rest Assured API testing, along with detailed answers and explanations to help you succeed in your interview.

What is Rest Assured?

Rest Assured is a powerful Java library designed specifically for API testing. It provides a simple and intuitive syntax for writing API tests, making it easier for developers to verify the functionality, reliability, and performance of their RESTful APIs.

With Rest Assured, you can send HTTP requests and validate the responses, allowing you to test various aspects of the API, such as status codes, response headers, response bodies, and more. It also supports authentication and authorization mechanisms, making it a versatile tool for API testing.

15 Common Interview Questions for Rest Assured API Testing

1. What is API testing, and why is it important?

API testing is the process of testing the functionality, reliability, and performance of application programming interfaces (APIs). It involves sending requests to an API and validating the responses to ensure that they meet the expected requirements. API testing is essential because:

• It helps identify bugs and issues in the API
• It ensures that the API functions as intended
• It helps maintain the quality and reliability of the API
• It allows integration between different systems

2. What is the difference between REST and SOAP APIs?

REST (Representational State Transfer) and SOAP (Simple Object Access Protocol) are two different architectural styles used for designing APIs. The main differences between REST and SOAP APIs are:

• REST APIs use lightweight protocols like HTTP, while SOAP APIs use XML-based protocols
• REST APIs are stateless, while SOAP APIs can maintain state between requests
• REST APIs are more flexible and scalable, while SOAP APIs are more standardized and secure
• REST APIs are easier to implement and consume, while SOAP APIs require more overhead

3. How does Rest Assured work?

Rest Assured works by providing a fluent API for writing API tests in Java. It allows you to send HTTP requests and validate the responses using a simple and intuitive syntax. Here’s an example of how Rest Assured works:

1. Import the Rest Assured library in your Java project
2. Create a request specification to specify the base URI, headers, query parameters, etc.
3. Send an HTTP request using the request specification
4. Validate the response using assertions to ensure it meets the expected requirements

4. How do you handle authentication in Rest Assured?

Rest Assured provides built-in support for handling various authentication mechanisms, such as basic authentication, OAuth, and JWT. Here’s an example of how you can handle basic authentication in Rest Assured:

Code:

RestAssured.given().auth().basic("username", "password").when().get("/api/endpoint").then().statusCode(200);

In this example, the given() method sets up the request with basic authentication credentials, and the when() method sends the GET request to the specified endpoint. The then() method validates the response status code to ensure it’s 200 (OK).

5. What are the different HTTP methods supported by Rest Assured?

Rest Assured supports all the standard HTTP methods, including GET, POST, PUT, DELETE, PATCH, HEAD, and OPTIONS. Here’s an example of how you can send a POST request using Rest Assured:

Code:

RestAssured.given().contentType("application/json").body("{ \"name\": \"John Doe\", \"age\": 30 }").when().post("/api/users").then().statusCode(201);

In this example, the given() method sets up the request with the specified content type and request body. The when() method sends the POST request to the “/api/users” endpoint, and the then() method validates the response status code to ensure it’s 201 (Created).

6. How do you validate the response body in Rest Assured?

Rest Assured provides various methods for validating the response body, such as body(), bodyPath(), and body(matchesJsonSchemaInClasspath("schema.json")). Here’s an example of how you can validate the response body using JSONPath:

Code:

RestAssured.given().get("/api/users").then().body("data[0].name", equalTo("John Doe")).body("data[0].age", greaterThan(18));

In this example, the body() method is used to validate the response body using JSONPath expressions. It checks if the name of the first user is “John Doe” and if their age is greater than 18.

7. How do you handle query parameters in Rest Assured?

Rest Assured allows you to specify query parameters using the queryParam() method. Here’s an example of how you can handle query parameters in Rest Assured:

Code:

RestAssured.given().queryParam("page", 1).queryParam("limit", 10).when().get("/api/users").then().statusCode(200);

In this example, the queryParam() method is used to set the page and limit query parameters. The get() method sends the GET request with the specified query parameters to the “/api/users” endpoint.

8. How do you handle path parameters in Rest Assured?

Rest Assured allows you to specify path parameters using the pathParam() method. Here’s an example of how you can handle path parameters in Rest Assured:

Code:

RestAssured.given().pathParam("id", 123).when().get("/api/users/{id}").then().statusCode(200);

In this example, the pathParam() method is used to set the id path parameter. The get() method sends the GET request to the “/api/users/{id}” endpoint, where the {id} placeholder is replaced with the specified value (123).

9. How do you handle headers in Rest Assured?

Rest Assured allows you to specify headers using the header() method. Here’s an example of how you can handle headers in Rest Assured:

Code:

RestAssured.given().header("Content-Type", "application/json").header("Authorization", "Bearer token").when().get("/api/users").then().statusCode(200);

In this example, the header() method is used to set the Content-Type and Authorization headers. The get() method sends the GET request to the “/api/users” endpoint with the specified headers.

10. How do you handle cookies in Rest Assured?

Rest Assured allows you to handle cookies using the cookie() method. Here’s an example of how you can handle cookies in Rest Assured:

Code:

RestAssured.given().cookie("session_id", "1234567890").when().get("/api/users").then().statusCode(200);

In this example, the cookie() method is used to set the session_id cookie. The get() method sends the GET request to the “/api/users” endpoint with the specified cookie.

11. How do you handle timeouts in Rest Assured?

RestAssured.given().timeout(5000) // Set the timeout to 5 seconds.when().get("/api/users").then().statusCode(200);

RestAssured.given().relaxedHTTPSValidation().when().get("/api/users").then().statusCode(200);

Response response = RestAssured.given().get("/api/users");
String name = response.jsonPath().getString("data[0].name");int age = response.jsonPath().getInt("data[0].age");

Response response = RestAssured.given().get("/api/users");
String name = response.xmlPath().getString("data.user[0].name");int age = response.xmlPath().getInt("data.user[0].age");

RestAssured.given().multiPart(new File("path/to/file.txt")).when().post("/api/upload").then().statusCode(200);