SDET Interview Preparation - API Testing with REST Assured

Welcome! If you're aiming for an SDET role and need a thorough rundown on API testing with REST Assured, you're in the right place. Let's dive in...

1. Introduction to REST Assured:

REST Assured is a Java library for validating RESTful APIs. It simplifies the process of testing and validating complex responses, making it a popular choice among automation engineers/SDETs. So you need to understand what it is, its benefits, and why it is used for API testing.

2. Basics of RESTful APIs:

REST (Representational State Transfer) is an architectural style for designing networked applications. It uses a stateless, client-server communication model. Understanding the principles of REST and CRUD (Create, Retrieve, Update, Delete) operations is vital for API testing. Learn these principles of REST, the difference between REST and SOAP, and the concepts of CRUD operations.

3. Setting Up REST Assured:

This involves installing the necessary software and libraries, setting up your IDE (Integrated Development Environment), and configuring REST Assured in your project. Understand how to set up and configure REST Assured in your development environment.

4. HTTP Methods and Status Codes:

HTTP methods define actions on resources. Knowing when to use GET (retrieve), POST (create), PUT (update), or DELETE (remove) is crucial. HTTP status codes indicate the server's response, such as 200 (OK), 404 (Not Found), or 500 (Internal Server Error). Understand the different HTTP methods (GET, POST, PUT, DELETE) and status codes, and how they are used in REST Assured.

5. Writing Tests with REST Assured:

Learn to write tests that send requests to APIs and validate responses. This includes writing assertions to check status codes, headers, response time, and body content. Practice how to write and structure tests using REST Assured, including writing assertions to validate responses.

6. Handling Different Response Types:

APIs can return responses in various formats, most commonly JSON and XML. You should know how to parse and validate these with REST Assured. Understand how to use serialization and de-serialization for response body verification with REST Assured.

7. Parameter and Header Handling: Learn how to send query and path parameters, and how to set headers in your requests.

8. Authentication and Authorization:

APIs often require authentication. Learn how to handle different authentication types, such as Basic Auth, API keys, OAuth, and JWT with REST Assured.

9. Error Handling:

Learn how to handle common errors, timeouts, and exceptions in REST Assured. This includes validating error responses from the API. Practice how to handle and troubleshoot common errors.

10. Advanced Topics:

Once you are confident with the basics, explore advanced topics like multi-part file uploads, cookie handling, and handling SSL certificates.

11. Best Practices:

Learn how to write clean, efficient, and maintainable tests. This includes structuring your tests effectively and following coding standards.

12. Integration with Test Frameworks:

REST Assured can be integrated with test frameworks like JUnit and TestNG. Learn how to structure your tests within these frameworks and run them as part of your test suite.

13. Real-world Scenarios: Practice with real-world scenarios to apply your knowledge and prepare for technical interview questions. Apply your knowledge to real-world scenarios like testing a complex API, dealing with a large JSON response, or troubleshooting a tricky error.

14. Mocking and Stubbing: 

In some cases, you may need to mock or stub parts of your system for testing. Learn how to use tools like Mockito or WireMock with REST Assured.

15. Continuous Integration/Continuous Deployment (CI/CD):

In a CI/CD environment, tests are run automatically whenever code is pushed. Learn how to integrate your REST Assured tests into a CI/CD pipeline using tools like Jenkins or Travis CI.

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