600+ API Testing Interview Questions Practice Test [2024]

API Testing Interview Questions and Answers Preparation Practice Test | Freshers to Experienced | [Updated 2024]

Welcome to “API Testing Interview Questions Practice Test” the ultimate preparation course designed for aspiring software testers, QA engineers, and developers looking to deepen their understanding of API testing and ace job interviews in this domain. With a meticulously structured curriculum spanning six comprehensive sections and detailed subtopics, this course offers extensive practice tests and interview questions designed to equip you with the knowledge, skills, and confidence needed to succeed in the competitive field of API testing.

Structure:

1. API Testing Basics

   • Understanding of API Testing: Dive into the essentials of API testing, learning what APIs are and why testing them is crucial.

   • Types of APIs: Explore the different types of APIs, including REST, SOAP, and GraphQL, and understand their unique testing requirements.

   • HTTP Methods and Status Codes: Get to grips with the backbone of web communication and how these methods and codes are pivotal in API testing.

   • API Testing vs. Unit Testing: Understand the differences and when to apply each testing methodology.

   • Tools for API Testing: Familiarize yourself with the tools that make API testing efficient, such as Postman and SoapUI.

   • Importance of API Documentation in Testing: Learn why accurate documentation is key to successful API testing.

2. Testing Techniques and Strategies

   • From positive and negative testing scenarios to performance and security testing, this section covers the strategies and techniques essential for thorough API testing.

3. API Testing Automation

   • Automation is a game-changer in API testing. This section delves into tools, scripting, and challenges in automating API tests, ensuring you’re prepared for industry practices.

4. APIs in the Software Development Lifecycle

   • Understand the role of API testing in Agile and DevOps, and learn about version control, collaboration, and monitoring APIs in production environments.

5. Advanced API Testing Concepts

   • This section is dedicated to advanced topics such as microservices, GraphQL, OAuth, and more, preparing you for complex API testing scenarios.

6. Scenario-Based Questions

   • Apply your knowledge to real-world situations, learning to handle rate limiting, third-party integrations, and performance bottlenecks.

Sample practice test questions:

Question 1: What is the primary purpose of API testing?

Options:

A. To verify the user interface and user experience of an application.

B. To ensure that the business logic of an application is functioning as expected.

C. To check the performance and load capacity of a web application.

D. To validate the interaction and communication between different software systems.

Correct Answer: D. To validate the interaction and communication between different software systems.

Explanation: API testing focuses on verifying that the application programming interfaces (APIs) meet expectations for functionality, reliability, performance, and security. Unlike UI testing, which assesses the front-end user experience, API testing is concerned with the back-end logic and the contractual agreement between different software systems. It ensures that APIs respond correctly to a wide range of requests, handle errors gracefully, and deliver consistent performance. This type of testing is critical for systems that rely on external services or components to operate correctly, as it helps identify issues in the integration and communication layers that could lead to data inaccuracies, performance bottlenecks, or security vulnerabilities.

Question 2: Which HTTP status code indicates that a request has been successfully processed, but the server is not returning any content?

Options:

A. 200 OK

B. 204 No Content

C. 301 Moved Permanently

D. 404 Not Found

Correct Answer: B. 204 No Content

Explanation: The 204 No Content status code is used in HTTP responses when the request has been successfully processed, but the server does not have any content to send in the response body. This status code is particularly useful in cases where the client needs to know that the request was successful but doesn’t need to receive any data back, such as when submitting a form or updating data on the server. It’s different from the 200 OK status, which indicates that a request was successful and the response includes the requested data. Understanding the nuances of HTTP status codes is crucial for API testing, as they provide immediate feedback on the outcome of an API request and help testers quickly identify issues with the API’s logic or implementation.

Question 3: In API testing, what is the significance of testing for HTTP method idempotency?

Options:

A. To ensure that the API can handle a high volume of requests.

B. To verify that repeated requests with the same parameters return different outcomes.

C. To check that repeated requests with the same parameters have no additional effects after the first.

D. To validate that the API returns the correct status code for each method.

Correct Answer: C. To check that repeated requests with the same parameters have no additional effects after the first.

Explanation: Idempotency in the context of HTTP methods is a principle ensuring that multiple identical requests have the same effect as making a single request. This concept is critical in API testing, especially for methods like PUT and DELETE, which should not cause additional changes or side effects if called multiple times with the same parameters. For example, if an API endpoint deletes a resource, subsequent DELETE requests should not result in errors or change the system’s state, despite the resource no longer existing. Testing for idempotency is important to ensure the reliability and predictability of an API, particularly in distributed systems where network unreliability might cause clients to retry requests.

Question 4: Which type of API testing focuses on the behavior of the application under test by simulating various usage scenarios?

Options:

A. Load Testing

B. Functional Testing

C. Security Testing

D. Integration Testing

Correct Answer: B. Functional Testing

Explanation: Functional testing of an API involves verifying that the API behaves as expected under various scenarios that mimic real-world use. This type of testing assesses whether the API meets the specified requirements and correctly executes all the tasks it’s designed for, such as retrieving data, handling requests, and interacting with other components or services. Unlike load or security testing, which focus on the API’s performance under stress or its ability to resist attacks, functional testing is concerned with the correctness of the API’s operations and outcomes. It’s a critical aspect of API testing, ensuring that the API functions correctly for all intended use cases and handles inputs, including edge cases, appropriately.

Question 5: Why is contract testing important in microservices architecture?

Options:

A. It ensures that services can handle high traffic loads.

B. It verifies the security measures of each microservice.

C. It validates the interactions between different services based on predefined contracts.

D. It checks the database schema compatibility among services.

Correct Answer: C. It validates the interactions between different services based on predefined contracts.

Explanation: Contract testing is crucial in a microservices architecture because it focuses on validating the interactions between various microservices according to predefined contracts. These contracts specify the expected requests and responses between services, ensuring that changes in one service do not break the integration with others. In a microservices architecture, services are developed, deployed, and scaled independently, which increases the risk of integration issues due to changes in APIs. Contract testing helps mitigate this risk by automatically verifying that any changes to a service still comply with the contracts established with its consumers. This approach promotes a more resilient and reliable system, where developers can make changes with confidence, knowing that they will not inadvertently disrupt the system’s overall functionality.

Enroll Now to: Gain a competitive edge in the job market with comprehensive knowledge and skills in API testing.