REST API Automation Testing Tutorial

Load testing stands as an integral component within the realm of software application and REST API development. Its significance lies in providing insights into the functionality of a particular program, ensuring its optimal performance when confronted with real users.

Welcome to our REST API Automation Testing Tutorial, where we embark on a journey to understand load testing RESTful APIs. This comprehensive guide is designed for both beginners and seasoned professionals, providing information on REST APIs, an example test scenario, and much more. Let’s get started and explore the world of automated testing for RESTful APIs!

What is an API?

Wondering what an API is? In simple terms, an API (Application Programming Interface) is a set of rules that helps different programs communicate with each other. Developers create APIs on servers, allowing clients to interact with them. Even if you don’t realize it, APIs are behind many of the everyday services and apps you use. They work behind the scenes to create a seamless, connected, and secure experience. For example, APIs might help you check the weather, log into your social media accounts, or make a payment through PayPal.

Given their vital role in app development and their direct impact on user experience, testing APIs thoroughly is crucial. The performance of an API can make or break the success of an app, so ensuring it works smoothly is key to unlocking opportunities.

Types of APIs

Even though we’re focusing on REST APIs, there are two main types of APIs that you should know about for reference.

 
• RESTful APIs: REST stands for Representational State Transfer, it is an architectural style for designing networked applications. They utilize standard HTTP methods (such as GET, POST, PUT, DELETE) for communication and are designed to be stateless, meaning each request from a client contains all the information needed to understand and fulfill that request. RESTful APIs often use standard data formats like JSON or XML for data exchange. When you’re working with a RESTful API, think of it like having a chat with a server. You ask for data, and the server kindly responds with the information you want. It’s like having a friendly conversation.

 

• SOAP APIs: SOAP stands for Simple Object Access Protocol, is a protocol for exchanging structured information in web services. SOAP APIs (Application Programming Interfaces) use XML as their message format for communication between client and server. SOAP uses HTTP or SMTP as the transport protocol, and they provide a standardized way for diverse systems to communicate with each other over a network. However, the XML-based format can make them more complex compared to the lightweight and flexible nature of RESTful APIs. These APIs are known for their robustness, reliability, and comprehensive security.

What is API Automation Testing?

API Automation Testing is a software testing approach that employs automated tools and scripts to evaluate the functionality, performance, and security of Application Programming Interfaces (APIs). APIs serve as crucial communication links between different software systems, and automated testing ensures that they operate as intended. API Automation Testing allows your teams to sustain rapid development cycles by consistently and systematically validating the expected functionality of their APIs.

This automated approach serves as a safeguard against breaking changes before reaching your production environment, and it is designed to complement, not supplant your manual testing efforts. By automating API tests, teams can swiftly and assuredly introduce new features while preserving developer resources for other critical tasks.

Benefits for REST API Automation Testing

Automation testing of REST APIs has emerged as a crucial practice in the software development lifecycle, allowing teams to efficiently validate the functionality, performance, and security of their APIs. By automating the testing process, teams can achieve faster feedback loops, improve test coverage, and ensure consistent and reliable results across multiple iterations. Here are some stellar benefits for API automation testing:

• Early Detection: Automated REST API tests can be integrated into the continuous integration/continuous deployment (CI/CD) pipeline, enabling the early detection of defects. Identifying and addressing issues at an early stage in development prevents the accumulation of errors and reduces the cost of fixing bugs.
• Cost-Effectiveness: While initial setup may require an investment, automated testing proves cost-effective in the long run. The efficiency gains, reduced testing time, and minimized chances of human error contribute to significant cost savings over the software development lifecycle.
• Scalability: Automated tests are scalable and can handle a large number of concurrent users and requests. This scalability is crucial for testing the performance and reliability of APIs under various load conditions.
• Efficiency and Speed: Automated testing enables the swift execution of test cases, significantly reducing testing time compared to manual methods. This accelerated testing process allows for faster feedback on changes and facilitates quicker software releases.

Common Challenges in REST API Automation Testing

While REST API automation testing offers substantial benefits in enhancing the efficiency and reliability of applications, it is not without its challenges. Navigating these hurdles is essential for ensuring a robust testing strategy. Here are some common challenges encountered in REST API automation testing:

• Dynamic Data Handling: APIs often deal with dynamic data, making it challenging to create stable and reusable test cases. Handling dynamic responses and generating appropriate test data dynamically is a common obstacle. Your teams must take this into account when creating and executing your tests.
• Authentication and Authorization: Testing APIs that require authentication and authorization can be complex. Managing tokens, ensuring secure access, and handling various authentication mechanisms pose challenges in creating comprehensive test scenarios.
• Data Validation and Schema Changes: APIs evolve over time, leading to changes in data structures and schemas. Keeping test scripts adaptable to such changes and ensuring consistent data validation is crucial for maintaining test relevance.

Things You Need to Know Before Performing REST API Testing

HTTP Methods for REST API Automation Testing

REST API uses five HTTP methods to request a command:

• GET: To retrieve the information at a particular URL.
• PUT: To update the previous resource or create new information at a particular URL.
• PATCH: For partial updates.
• POST: It is used to develop a new entity. Moreover, it is also used to send information to servers, such as uploading a file, customer information, etc.
• DELETE: To delete all current representations at a specific URL.

HTTP Status Codes

Status codes are the response given by a server to a client’s request. They are classified into five categories:

• 1xx (100 – 199): The response is informational
• 2xx (200 – 299): Assures successful response
• 3xx (300 – 399): You are required to take further action to fulfill the request
• 4xx (400 – 499): There is a bad syntax, and the request cannot be completed
• 5xx (500 – 599): The server entirely fails to complete the request

These codes act like little messengers telling us how things went. So, if the REST API automation test results show numbers between 200 and 299, it’s like a thumbs up – the application is doing great! For most of us regular internet users, these status codes might not be something we think about, and that is okay. The ones starting with 1, 2, or 3 are more like friendly notes than anything else – they’re just telling us what’s happening, and they won’t mess with our user experience.

But let’s talk about the 4xx and 5xx status codes – those are like our red flags, signaling error messages. If something goes off track, users might encounter these error messages while navigating through APIs. The 4xx status codes usually pop up when there’s a hiccup on the client/browser side, like a little miscommunication. On the flip side, the 5xx status codes point to errors happening at the server’s party. Seeing errors is not exactly a highlight but fixing them up as soon as possible is crucial. They’re like a signal flare for serious issues that can seriously cramp user satisfaction, so a speedy resolution is key.

REST API Automation Testing Tutorial

The following tutorial for REST API Automating Testing will use Postman. Postman is an extremely popular and widely used API client that allows development teams to create, collaborate, share, test, and document their API development process. Postman is a stellar tool that helps to create and save complex APIs as well as simple HTTP/s requests along with their responses.

In the following tutorial, our test scenario will test all five methods on Status Code Weekly to find the status code of the website.

Testing the GET Request

Note: After clicking this link (https://reqres.in/api/users?page=2) you will see the JSON code.

For this test, we’ll be using Postman and the best thing about Postman is that if you have the API URL, you can simply paste it to get the status code, and the same rule applies to all other methods.

1. After launching Postman, select the GET method and copy the GET request link (https://reqres.in/api/users?page=2)

2. Then paste it in the ‘Enter request URL’ field. Once done, click ‘Send’ to see the status.

3. You’ll then be able to see the status display ‘200 OK.’

• • ‘OK’ signifies that the GET request is functioning without errors as the status code is exactly 200.

Benchmark Testing Tool

LoadView stands out as a top-of-the-class cloud-based performance testing solution, enabling users to effortlessly craft diverse test scenarios using the intuitive EveryStep Web Recorder scripting tool. With the LoadView platform, users gain access to authentic browser-based testing, replication of prevalent desktop and mobile devices, and a wide array of geographic locations for creating highly realistic performance testing environments.

Setting up your performance tests for benchmark testing on LoadView is quick and straightforward. You can utilize its load curve features to precisely adjust the load on your website or application according to your specific requirements. Load curves are particularly beneficial for refining benchmark metrics. Once configured, LoadView will execute your tests and provide a comprehensive report containing all the metrics necessary for comparing your results. LoadView’s performance reports offer insightful, easy-to-understand results out of the box. You can save these reports for future reference and define a baseline for repetitive comparisons.