API Testing Automation
API (Application Programming Interface) testing automation is important because it focuses on the server side of an application, which is a different layer from the user interface (UI) testing. UI tests alone can’t check everything, so API testing is necessary to make sure the backend functions correctly.
API testing can be done using different tools like Postman, RestAssured, and SoapUI. Each tool has its own benefits and features, so before choosing an API testing tool, first understand what your project needs.
As a software tester, having knowledge of API testing is important because it’s used in many projects like e-commerce sites, banking apps, social media platforms, and healthcare systems. It helps ensure the APIs work correctly in these fields.
In this blog, we’ll explain what is API Testing Automation, how it works, and why it’s important for making sure your software runs well.
Let’s first understand what an API is.
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What is API?
In computer programming, an API (Application Programming Interface) is a set of rules and tools that help different software programs communicate with each other. It defines how different software components should interact.
Let’s understand the API with simple example so you will get a clear understanding of an API.
Example –
Imagine you’re at a restaurant. You have a menu that shows all the dishes you can order. You tell the waiter what you want, and then the waiter brings your order to the kitchen and gets your food for you.
In this example, the menu is like the API. It shows you what you can ask for & how to ask for it. The waiter is like the API itself. It takes your request, communicates with the kitchen (the system behind the scenes), and brings back the result.
Also Read – What is Software Testing?
What is API Testing?
API Testing is different from UI (User Interface) testing because it focuses on the core functions of the software rather than how it looks. Instead of checking how the app appears, API Testing involves sending requests to the API using special tools or code, then checking how the system responds.
To test an API, you need to:
- Use a testing tool to interact with the API.
- Write code to test the API.
When you test an API, you’re checking how it deals with requests and what it sends back. Here’s what you might check in the API’s responses:
- Data of any type
- Status messages (like Pass or Fail)
- Calls to other API functions
Also Read – Software Testing Life Cycle (STLC): Ensuring High-Quality Software
Types of bugs that API testing can find
| Type of Bug | Description |
| Error Handling Issues | The API does not handle errors or exceptions correctly, leading to crashes or incorrect error messages. |
| Unused Flags | Flags or options in the API that are not used or needed, indicating unnecessary complexity or bugs. |
| Missing or Duplicate Functionality | Expected functions or features are missing, or there are duplicates, leading to confusion or redundancy. |
| Reliability Issues | Problems with the API’s stability, such as difficulty connecting or getting a response. |
| Security Issues | Vulnerabilities that could be exploited, such as insufficient authentication or data exposure. |
| Multi-Threading Issues | Problems when multiple processes or threads access the API simultaneously, causing conflicts. |
API Testing Tools
Here are some popular API Testing tools –
| Tool | Description |
| Postman | User-friendly tool for sending requests and automating tests. |
| SOAPUI | Comprehensive tool for testing SOAP and REST APIs, with features for functional, security, and load testing. |
| Insomnia | Tool for designing and testing APIs with a clean interface. |
| JMeter | Open-source tool for performance and functional testing of APIs. |
| Rest-Assured | Java library for testing REST APIs, used in automated scripts. |
How many types of API automation testing are there?
There are several types of API automation testing, Here are the main types:
| Type of Testing | Description |
| Functional Testing | Checks if the API does what it’s supposed to do and if its features work correctly according to its instructions. |
| Performance Testing | Look at how well the API performs, including its speed and how it handles different levels of traffic. |
| Security Testing | Checks if the API is safe from attacks, identifies weaknesses, and ensures protection against security threats. |
| Integration Testing | Tests how well the API works with other systems or services to ensure smooth connections and interactions. |
| Load Testing | Measures how the API handles a large number of requests at once to ensure it can manage high traffic. |
| Stress Testing | Pushes the API to its limits to see how it behaves under extreme conditions and to identify breaking points. |
| Reliability Testing | Checks if the API is stable and consistent over time, ensuring it performs reliably without crashing or failing. |
| Regression Testing | Ensures that new changes or updates do not break existing features and that everything still works as expected. |
| Validation Testing | Confirms that the API meets all required standards and follows the specifications outlined in its documentation. |
| Compatibility Testing | Checks how well the API works across different environments, platforms, or software versions to ensure it works correctly everywhere. |
Also Read – Decision Table Testing
Getting Started with API Testing Automation
Here’s a simple step-by-step guide to help you begin API testing Automation
Step 1: Choose an API Testing Tool
- As we discussed earlier there are several tools available for API testing automation.
- For beginners, the Postman tool is a great choice because it is easy to use.
Step 2: Set Up Your Environment
Download and install the API testing tool of your choice. For Postman, you can download it from here.
Step 3: Create a Collection
In Postman, you can organize your API requests into collections. A collection is a group of requests that can be run together.
- Open Postman.
- Click on “Collections” in the left sidebar.
- Click “New Collection” and give it a name.
Step 4: Add Requests to Your Collection
- In your new collection, click “Add Request”.
- Enter the request details:
- URL: The endpoint you want to test.
- Method: GET, POST, PUT, DELETE, etc.
- Headers: Any necessary headers (e.g., Authorization).
- Body: The request payload for methods like POST and PUT.
Step 5: Write Test Scripts
In Postman, you can write test scripts using JavaScript to automate the validation of API responses.
Click on the “Tests” tab in your request.
Write your test script.
For example:
Step 6: Run Your Tests
- Click on the “Runner” button in the Postman app.
- Select your collection.
- Configure the run options (e.g., number of iterations, delay between requests).
- Click “Start Test”.
Step 7: Analyze the Results
After the tests are complete, Postman will display the results, showing which tests passed and which failed. This helps you identify any issues with your API.
Also Read – Testing Comes Under Which Category Of Cost Of Quality
How to Start learning API Testing Automation
Step 1 – Understand the Basics –
Learn what an API is and how it works.
Step 2: Get Familiar with HTTP
- Learn about HTTP methods such as GET, POST, PUT, and DELETE.
- Explore examples of HTTP requests and responses.
Step 3 – Choose a Tool
- Download and install Postman, a user-friendly tool for API testing and if you are freshers then this tool is best for learning API Testing.
- Postman is widely used and has a simple interface, making it great for beginners.
Step 4 – Explore Postman’s basic features and layout
- Open Postman and create a new request.
- Practice sending simple requests to APIs and examine the responses.
Step 5 – Write Test Scripts
- Learn the basics of writing test scripts in Postman using JavaScript.
- Write simple test scripts to check the responses from your API requests.
Step 6 – Automate Tests
- Create collections in Postman to group related API requests.
- Set up automated tests to run your collections regularly.
Step 7 – Explore Advanced Tools
- Once comfortable with Postman, try other tools like SOAPUI, JMeter, or Rest-Assured.
- Experiment with these tools to understand their advanced features.
Step 8 – Learn About Different Types of Testing
- Study different types of API testing such as functional, performance, security, and integration testing.
- Understand the purpose of each type and when to use them.
Also Read – Objectives Of Software Testing
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FAQ’s
Is Selenium used for API automation?
No, Selenium tool is best for web UI testing. Tools like Postman, Rest-Assured, and SOAPUI are better for API automation.
Which is better API testing or automation testing?
Both are important. API testing checks the backend functionality, while automation testing can cover both UI and API tests to improve coverage and efficiency.
Which language is used for API automation?
Here are some common programming languages include:
- Java (Rest-Assured)
- JavaScript (Postman)
- Python (Requests)
- Ruby (HTTParty)
- C# (RestSharp)
What is API testing in QA?
API testing in QA involves testing APIs directly to ensure they work correctly, are reliable, perform well, and are secure. It checks the backend functionality without the UI.
