API Testing Handshake with Postman | Beginners guide

API (Application Programming Interface) testing has become almost a must to have skill in the modern software testing realm, due to the rise of microservices, cloud-based solutions, and mobile-first applications.

As a software tester, leveraging tools like Postman can simplify and enhance the process of your API testing. in this short article we dive bit deeper on What , Why and how you can use tolls like Postman for your advantage.

What is API Testing?

API testing focuses on verifying that API's function as expected, ensuring the exchange of data between systems is smooth and secure.

It typically involves testing endpoints for reliability, performance, security, and data integrity. Unlike UI testing, which examines the user interface, API testing is closer to the code level.

Why Postman for API Testing?

Postman is one of the most popular tools for API testing. It provides a user-friendly interface, robust features, and the ability to handle complex scenarios. Key reasons why I like to use Postman.

1. Ease of Use: Its intuitive UI allows even non technical testers to create and execute tests.
2. Comprehensive Features: Supports HTTP methods (GET, POST, PUT, DELETE, etc.), environment variables, scripting, and automated testing.
3. Collaboration: Postman’s cloud sync and team workspaces enable seamless collaboration across teams.
4. Cost-Effective: The free version is feature rich, and will have you covered for most of your API testing tasks, while premium tiers cater to advanced needs and large scale collaboration between team members.

Setting Up and Running Your First Test

Download and Install: Postman is available as a desktop application and a browser extension. Download it from Postman’s official site. - I'll would recommend to have the Desktop version

Create a Collection: Collections in Postman organize your API requests. Think of them as folders for storing related endpoints.

Choose testing end points: if you only in the beginning or just want to play around there is plenty of webservices that can provide you with mock endpoints and data so you could test practice or show case your API testing skills.

Few free to use tools that I use:

https://mockbin.io/

https://restful-api.dev/

https://jsonplaceholder.typicode.com/

For the following examples ill be using the https://restful-api.dev Endpoints.

GET Request: Specify the HTTP method and endpoint URL. for the GET request will use https://api.restful-api.dev/objects - that should retrieves list of few objects.

POST Request: Specify the HTTP method and endpoint URL for the POST request we will use https://api.restful-api.dev/objects including this body:

{
   "name": "Apple MacBook Pro 16",
   "data": {
      "year": 2019,
      "price": 1849.99,
      "CPU model": "Intel Core i9",
      "Hard disk size": "1 TB"
   }
}        

Check the Data: Lets check the data we added using the POST request above, we will use the first endpoint with an extension for the specific Object ID that was created (ff808181932badb601943c0d03f66f10)

https://api.restful-api.dev/objects?id=ff808181932badb601943c0d03f66f10

Some Advanced Features for Testers

Once you’re comfortable with the basics, explore Postman’s advanced capabilities.

Also it always a great idea to go to the official documentation or the Postman Learning center for deep

https://learning.postman.com/docs/introduction/overview/

https://learning.postman.com/

Examples for more advanced features:

1. Environment Variables: Define variables for different environments (e.g., development, staging, production) to simplify endpoint management.
2. Assertions with Test Scripts: Use JavaScript to add test scripts for validating API responses. For instance, ensure a 200 status code:
3. Automated Testing: Use the Collection Runner to execute multiple API requests sequentially or in batches.
4. Mock Servers: Test APIs before they’re fully developed by simulating endpoints with mock data.
5. API Documentation: Postman can automatically generate and share API documentation with your team.

Best Practices for API Testing with Postman

To maximize the effectiveness of your testing efforts:

1. Understand the API: Read the API documentation thoroughly to know the expected behavior and constraints.
2. Use Assertions: Validate response status codes, data, and headers to catch errors early.
3. Version Control: Store collections in a version-controlled repository for easier rollback and collaboration.
4. Leverage Automation: Integrate Postman tests into CI/CD pipelines to maintain consistent quality.

Conclusion

As software testers, our role is to ensure the quality and reliability and APIs are not exception. Postman is an indispensable tool that empowers us to test APIs efficiently and thoroughly.

By mastering its features, or even felling conferrable with the basic GET, POST, PUT you can elevate your testing capabilities and contribute significantly more, today there almost no services or developing done without some kind of API involvement - and it's on you to test it.

Whether you’re a beginner or an experienced tester, investing time in learning and diving deeper into Postman will pay off.