Testing using Postman

Postman is a very handy tool for sending requests (which are mock-able) during development and while testing. This “post” will address some common ways Postman can be utilized in a testing effort.

1. Manual Testing

When you need to execute a specific request to a server postman allows you to send that directly. NOTE: If you are jumping back and forward from the browser and Postman (very common), you will want to sync your browser cookies with Postman via the Interceptor to share access to the session — this is a big time saver.

2. Automated BE Smoke Testing

For very common user scenarios, more often than not, you can automateĀ  testing by sending critical requests necessary to mimic a users experience. For example, a user logs in, searches for a product, adds 2 then removes 1, submits their order, confirm their order history. Due to the stable nature of backend tests, this type of testing is recommended to have robust and as the core for Functional testing. Using Postman is faster than creating a custom test framework and it is intuitive to share the Postman collection tests with other members of your team (no documentation necessary šŸ˜‰ ).

3. Performance Testing

If you have built out multiple user workflows in your Postman collection(s), you can utilize them by creating parameterized iterations with your CSV (more on that below). In order to see system thresholds, you can scale up the iterations (delays), or even run multiple collections simultaneously while monitoring your system. Admittedly, there are better tools to suit this purpose.

4. Bootstrapping

Very often there is a need to create data necessary for other services to work properly. Running a collection will allow all the requests to fire in sequence to perform the procedure you need. Often this is used for setting up a system or creating dummy data.

Making the most out of it

In order to fully maximize the effectiveness of Postman, be sure to take advantage of Pre-request script conditions, as well as the post-request Tests. With these you can manipulate variables stored between requests, as well as make assertions on the state of the request. Postman uses Javascript to run.

Next, there may be a set of data you would like to parameterize your requests with — this is done by binding that data to a variable ( {{variable}} ).

Taking variable binding another step further, you can pass in a CSV data set (a “table” with headers of variable names) to allow auto decoupling of the postman collection with the data it will use. This method of using CSV data set, will allow your collection to run N number of times (iterations) for the number of rows of data you have in your data set. When running (Postman Runner), you can specify a delay between iterations if necessary.

Finally, you can execute your postman collection(s) in your CI/CD system by way of Node.js and the Newman package.

Conclusion

Although postman is not as flexible as codifying your own solution for testing (not possible to run BE + FE hybrid tests, 3rd party library integration not supported, varying subscription plan restrictions, etc.) it certainly is a staple in any developing, and testing initiative.

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