Testing with Postman

Written by Mensur Kurtagić, Software Developer Softray Solutions

As software developers, we always look for tools that can make our job easier and more efficient. One such tool that has become an essential part of the workflow is Postman. If you’re unfamiliar with it, Postman is an API testing tool that allows you to send requests to a server and receive responses, all within a user-friendly interface.

After playing around with it, we quickly realized how powerful Postman could be. Not only can you send simple GET requests, but you can also test more complex scenarios such as POST, PUT, and DELETE requests. And with the ability to set headers, add query parameters, and more, the possibilities are endless.

One of the things we appreciate most about Postman is the ability to save and organize requests into collections. This makes it easy to group related requests and share them with others on your team. You can also add pre-request scripts and test scripts to your requests, which can be incredibly helpful when testing complex APIs.

But let’s take a closer look at the testing process in Postman. First, here’s an example of how to test an API endpoint that retrieves a list of users from a server:

1. First, we need to create a new request in Postman. We can do this by clicking the “New” button in the top left corner of the interface
2. Next, we need to set the request method to GET and enter the URL of the endpoint we want to test. In this case, the URL might look something like https://example.com/api/users

3. If the endpoint requires any query parameters or headers, we can add those in the appropriate sections of the request. For example, we might need to include an API key in the headers to authenticate our request:

4. Once we’ve set up the request, we can click the “Send” button to send the request to the server. We should see the response from the server displayed in the “Body” section of the interface:

5. We can use Postman’s testing framework to write tests that automatically check the response for specific conditions. For example, we should ensure that the response contains a certain number of users or that each user in the response has a valid email address. We can write these tests in JavaScript and run them within Postman:

6. Finally, we can save the request to our collection and use it to test the endpoint again in the future. This can be especially helpful when working on a project with multiple developers, as it ensures that everyone uses the same test data and conditions.

Another valuable feature of Postman is its ability to perform load testing on APIs. Load testing tests an application’s ability to handle significant traffic or requests. In other words, it’s a way to simulate a real-world scenario where thousands of users are accessing your API at the same time.

To perform a load test in Postman, you can use its built-in feature called “Runner.” The Runner allows you to run multiple requests or a collection of requests in a loop, with configurable delays and several iterations. This means you can send many requests to your API and see how it performs under heavy load.

To set up a load test in Postman, you can follow these steps:

1. Create a new collection of requests that you want to test.
2. Open the Runner tab in Postman and select your collection.
3. Set the number of iterations and the delay between requests.
4. Choose the environment you want to use for your tests.
5. Click “Start Test” and wait for the results.

The load test results will show you the response time of each request, the number of successful and failed requests, and other metrics that can help you identify performance issues. You can also export the results to a CSV or JSON file for further analysis.

Load testing can be a powerful tool for identifying bottlenecks and other performance issues in your API. Using Postman’s Runner feature, you can easily simulate a high-traffic scenario and see how your API performs under pressure.

Of course, like any tool, Postman has its limitations. For example, testing APIs that require authentication or deal with complex data structures can be challenging. But for the most part, Postman has become my go-to tool for API testing and debugging.

If you’re new to Postman, I recommend spending some time playing around with it and getting familiar with the interface. Then, feel free to experiment with different types of requests and try out some of the more advanced features!

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