15 REST Assured Interview Questions: From Basic and Advanced

Navigating the world of software development, particularly in test automation and software development engineering in test (SDET), demands a comprehensive understanding of various tools and methodologies. “15 REST Assured Interview Questions: From Basic to Advanced” is an essential guide for professionals preparing for interviews in these fields.

REST Assured, a popular Java library for testing RESTful APIs, is a critical skill for automation engineers. This article delves into 15 pivotal rest assured interview questions, ranging from fundamental concepts to advanced applications, providing a thorough overview for candidates aiming to demonstrate their proficiency and stand out in their interviews.

Importance of REST Assured for Automation/SDET Engineer Interviews

In the rapidly evolving landscape of software development, the role of Automation Engineers and Software Development Engineers in Test (SDETs) has become increasingly pivotal. These professionals are tasked with ensuring the reliability and efficiency of software applications, often through the development and implementation of automated testing strategies. One key aspect of this responsibility is the testing of RESTful APIs, which are integral to modern web services and applications. This is where REST Assured, a Java library specifically designed for testing RESTful APIs, becomes crucial.

Understanding REST Assured is vital for Automation Engineers and SDETs for several reasons. Firstly, RESTful APIs are ubiquitous in modern software architecture, making their testing an essential part of the software development lifecycle. REST Assured provides a powerful yet user-friendly framework for sending HTTP requests to REST services, allowing testers to validate and verify the responses efficiently. This capability is critical in ensuring that the APIs function correctly under various conditions and adhere to their specifications.

Moreover, REST Assured supports a range of HTTP methods, including GET, POST, PUT, DELETE, and others, which are fundamental to API testing. Familiarity with these methods and how to test them using REST Assured is often a requirement in Automation/SDET roles. Additionally, REST Assured integrates seamlessly with existing Java-based ecosystems and testing frameworks like JUnit and TestNG. This integration is particularly important for SDETs, who often work within Java environments and need to incorporate API testing into their broader test suites.

In interviews for Automation Engineer and SDET positions, candidates are frequently questioned on their ability to write effective API tests, handle various types of requests and responses, and integrate these tests into larger automated testing frameworks. Proficiency in REST Assured demonstrates a candidate’s expertise in these areas, showcasing their ability to contribute to the development of robust, reliable, and scalable software applications.

Furthermore, advanced knowledge of REST Assured, such as understanding its capabilities for authentication, logging, custom validations, and handling complex JSON and XML payloads, can set a candidate apart. It shows a deeper understanding of API testing challenges and the ability to leverage REST Assured’s features to address these challenges effectively.

Let’s get started with the list of REST Assured automation testing interview questions…

Basic Rest Assured Interview Questions

1. What is REST Assured?

   REST Assured is a Java DSL (Domain Specific Language) that simplifies the process of testing and validating RESTful web services. It provides a convenient way to send HTTP requests to a RESTful web service and verify the response. With REST Assured, testers and developers can write powerful, readable, and maintainable tests for their RESTful APIs, making it an essential tool in the modern testing landscape.

2. Explain the concept of REST.

   REST, or Representational State Transfer, is an architectural style for designing networked applications. It uses a stateless, client-server communication model, where each request from the client contains all the information needed by the server to understand and process that request. RESTful applications use HTTP requests to perform CRUD operations (Create, Read, Update, Delete) on resources, which are identified by URIs (Uniform Resource Identifiers).

3. Define JSON and its significance.

   JSON, which stands for JavaScript Object Notation, is a lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate. Its significance lies in its simplicity and universality. JSON has become the de facto standard for data exchange in web applications, primarily because of its compatibility with most programming languages and its ability to represent complex data structures in a readable format.

4. Which protocol do RESTful Web Services use?

   RESTful Web Services predominantly use the HTTP (Hypertext Transfer Protocol) for communication. HTTP provides a set of methods, such as GET, POST, PUT, DELETE, etc., that correspond to create, read, update, and delete operations, making it a natural choice for implementing RESTful services.

5. Describe the “client-server architecture”.

   The client-server architecture is a computing model where the server hosts, delivers, and manages most of the resources and services to be consumed by the client. In this model: The client is responsible for the user interface and user experience, making requests and displaying the results or functionality. The server stores and retrieves data, processes client requests, and sends appropriate responses back to the client.

6. What is a resource in REST?

   In REST, a resource refers to any object, data, or service that can be accessed by the client over the network. A resource is identified by a unique URI (Uniform Resource Identifier). For instance, in an online book store, each book, author, or category can be considered a resource, and they can be accessed and manipulated using specific URIs.

7. Elaborate on REST Assured method chaining.

   Method chaining in REST Assured allows testers to combine multiple methods in a single line, enhancing code readability and maintainability. This is often seen in the form of given(), when(), and then() constructs. For example:

given().parameters("key", "value").when().get("/endpoint").then().statusCode(200);

This sequence sets up the request with parameters, makes a GET call to the specified endpoint, and then verifies that the response status code is 200.

8. Why choose REST Assured over Postman for automation?

   While Postman is an excellent tool for manual API testing, REST Assured shines in the realm of automation. Here’s why:

• Code Reusability: With REST Assured, common setups, and configurations can be reused across multiple tests.
• Integration with Java: Being a Java library, REST Assured can be seamlessly integrated with Java-based testing frameworks like JUnit or TestNG.
• Customizable Reports: REST Assured allows for generating detailed and customized reports, providing insights into test results.
• Flexibility: REST Assured offers more flexibility in terms of test scripting, data-driven testing, and integrating with other tools in the CI/CD pipeline.

In essence, for those looking to automate their API testing, REST Assured provides a more robust and flexible solution compared to Postman.

Advanced Rest Assured Interview Questions

9. How is method chaining implemented in REST Assured?

   Method chaining in REST Assured is a powerful feature that allows for a more concise and readable way to write tests. It’s implemented using the Fluent API design pattern, which returns the current object after every method call, allowing for the chaining of methods. This design ensures that the code remains clean, organized, and easy to understand. For instance, the sequence given().when().then() is a classic example of method chaining in REST Assured, where each method returns an instance that can call the next method in the chain.

10. Demonstrate a code snippet using REST Assured for testing REST API.

    Certainly! Here’s a simple example that tests a GET request to retrieve a user’s details:

import static io.restassured.RestAssured.*;

public class GetUserDetailsTest {
    public void testGetUser() {
        given()
            .baseUri("https://api.example.com")
            .basePath("/users")
            .param("id", "12345")
        .when()
            .get()
        .then()
            .statusCode(200)
            .body("name", equalTo("John Doe"));
    }
}

In this snippet, we’re using REST Assured to send a GET request to https://api.example.com/users?id=12345 and then verifying that the response status is 200 and the user’s name is “John Doe”.

11. What is JSON path in the context of REST Assured?

    JSON path in REST Assured is a mechanism to navigate and extract data from a JSON document. It’s similar to XPath for XML and provides a simple way to query JSON structures. With JSON path, you can easily extract values, evaluate JSON content, and perform validations. For instance, if you want to extract the name of a user from a JSON response, you can use the expression $.name where $ represents the root of the JSON document.

12. Explain the concept of static import in Java and its use in REST Assured.

    Static import in Java allows for the importing of static members of a class directly, so you don’t need to qualify them with the class name. In the context of REST Assured, static imports simplify the code by importing commonly used methods directly. For example, instead of writing RestAssured.given(), with a static import, you can simply write given(). This makes the code more readable and concise, especially when chaining methods.

13. Define serialization and deserialization in Java.

    Serialization in Java refers to the process of converting an object into a byte stream, which can then be saved to a file or sent over a network. Deserialization is the reverse process, where the byte stream is converted back into an object. This mechanism allows for the persistent storage and transmission of Java objects. In the context of REST APIs, serialization might be used to convert Java objects into JSON or XML format before sending them in a request, while deserialization would convert received JSON or XML data back into Java objects.

14. Discuss the difference between path parameters and query parameters.

    Path parameters are part of the URL path and are used to identify a specific resource or resources. For example, in /users/123, 123 is a path parameter representing a user’s ID. On the other hand, query parameters are appended to the URL after a ? and are typically used to filter, sort, or provide additional information about a resource. For instance, in /users?type=admin, type=admin is a query parameter filtering users by type.

15. Describe the request specification and response in Rest Assured.

    In REST Assured, the request specification allows you to define various aspects of an HTTP request, such as headers, parameters, body, and authentication details. It’s created using the given() method. The response, on the other hand, represents the HTTP response received after making a request. It provides methods to extract data, verify status codes, and validate response content. The response can be obtained using methods like get(), post(), and put(), and its content can be validated using the then() method.

In today’s digital age, proficiency in tools like REST Assured is invaluable. As web services become integral to businesses, ensuring their reliability is paramount. With the right knowledge and preparation, especially around pivotal REST Assured interview questions, professionals can not only enhance their skill set but also become indispensable assets to their organizations. Stay informed, stay ahead, and harness the power of REST Assured to its fullest.