I recently found that Postman has a built-in capability to run load (performance) testing. Some use cases to run load testing are identifying bottlenecks, latency, and failures in your API when calling at near-production scale.
One of the advantages of Postman having built-in load testing is that I already have collections/environments for all of my APIs in Postman. So, I do not have to use a different tool for the job or migrate scripts to another platform.
I have used load testing a few times at work:
One of our APIs had slow responses in production. I did a re-implementation and load-tested the API locally as well as in our development and UAT environments with Postman, both pre- and post-implementation.
Another instance occurred after implementing idempotency on another of our APIs. Several scenarios were tested:
- The first call goes through successfully.
- Subsequent calls return an in-flight or in-progress transaction.
- Once the first call finishes, subsequent calls return idempotent responses.
Running Performance Testing
Select the Postman collection to perform the performance testing, click the three dots at the top right, and then click “Run Collection.”
Select the scripts to run the performance testing on.
Select the “Performance” tab on the right. There will be three options:
- Max Virtual Users: How many “users” will run simultaneously calling the collection.
- Test Duration: How long the testing will last.
- Load Profile: If all “users” will start calling the API at the same time (Fixed) or if there will be a Ramp Up time where all “users” will start calling the API after a period of time.
After the test has finished running, you will get a nice graph with detailed results. Some statistics include the total number of requests, requests per second, response times, and errors, if any. If errors are present, you can see detailed responses, status codes, etc.
When you select a particular collection, you can press the “Runs” tab to see past runs, then select a particular run to see details.
I hope you learned something about load/performance testing and start applying this technique to test your APIs.
Have you had any experience with load/performance testing and have you used Postman for this? JMeter maybe?