Steps to Perform API Performance Testing with LoadRunner

1. Set Up LoadRunner:

• Install LoadRunner and open the Virtual User Generator (VuGen) to create a new script. Select the Web - HTTP/HTML protocol for testing REST APIs.

2. Record API Calls:

• Use the recording feature in VuGen to capture the API calls made by your application. This involves interacting with the application to generate the necessary API requests. For example, if you are testing a to-do application, perform actions like retrieving, adding, and updating tasks.

3. Utilize web_custom_request:

• After recording, you can modify the script to use the web_custom_request function. This function allows you to specify the HTTP method (GET, POST, PUT, DELETE) and the necessary parameters for your API calls. For instance, to add a new to-do item, you would set up a POST request with the appropriate JSON body.

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4. Parameterization and Correlation:

• Implement parameterization to handle dynamic values in your API requests, such as user IDs or session tokens. Use correlation to capture and reuse values from server responses in subsequent requests.

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5. Run Load Tests:

• Configure the LoadRunner Controller to simulate multiple virtual users making API calls simultaneously. This helps assess how the API performs under load, including response times and throughput.

6. Analyze Results:

• After running the tests, use LoadRunner's Analysis tool to review the performance metrics. Look for response times, error rates, and resource utilization to identify any bottlenecks or issues in the API performance.

Additional Resources

• For a more visual approach, you can refer to video sessions on platforms like YouTube that cover REST API performance testing using LoadRunner.

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• Detailed articles and tutorials on testing REST APIs in LoadRunner can also provide further insights and examples.

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  By following these steps, you can effectively conduct performance testing on your APIs using LoadRunner, ensuring they can handle expected loads and perform optimally under various conditions.
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