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How to Use JMeter for Backend-Based Functional Testing

Software development and testing has evolved a lot in recent years...


Software once ran without any external connectivity, and functionality testing was done locally. In the mid to late nineties, there was a move to internet-based applications, which meant that testing was done on browsers. Fast forward a couple of decades and mobile devices, wearables, tablets, and the IoT have totally reinvented the way applications are consumed. Nowadays, functionality often lies within an application’s backend, with its frontend mainly tied to how data is presented within the realm of user experience. This has naturally altered how we test the functionality of these modern applications.

Functional Testing with JMeter

JMeter was originally built to provide an open source solution for load and performance testing. However, JMeter can also be used to perform functionality tests on an application’s backend. For example: with JMeter, you can test part of your user registration functionality by testing your system’s APIs and verifying that users are successfully created within your database. Instead of opening a browser and manually entering random data in the provided fields, you can use JMeter to generate an API call with different user names and passwords.


RESTful APIs generally use the GET or POST (with a payload) method of HTTP requests, and either generate properties files from POST requests or JSON files that represent data that you want to move over. Functional testing can be performed with JMeter quite easily, by using a dedicated HTTP or HTTPS sampler. A request sample can be created from data in a tested application - and an external file is then used to provide the different parameters that you’d like to test.


You can also use assertions to configure functional testing in JMeter. Assertions identify if a reply was received from an API, indicating whether the desired data was received or if a process failed. For example: when testing successful user registration, a reply would indicate whether or not a user ID was created.


JMeter can also be used to perform Java unit testing with JUnit. JUnit is natively supported in JMeter, and can be incorporated as part of your overall functional testing strategy. If any JUnit tests were created during software development, they can also be incorporated as part of your testing process. JUnit tests can be used in addition to API calls. Learn how to use JUnit with JMeter.

User Experience Testing

It’s important to verify the backend functionality and the user experience. As the user experience can’t be tested with JMeter, it’s worth looking at solutions that offer frontend testing tools, like SauceLabs and Perfecto Mobile:




Testing the Full Functionality of Your App

Ideally, your testing arsenal should be equipped with a suite of tools to help test your application’s full functionality. Having said that, both back and frontend functionality tests compliment one another and need to be performed in order to cover all of your bases. As an open source tool originally developed for load testing, JMeter really shines as it adapts to changes in software functionality testing. Developers can use the same plugins and samplers that they used to generate loads in order perform these functional tests. This, along with integrating several frontend tools, can truly provide an end-to-end environment that ensures your application’s functionality.


Liked this article? You might also find these useful:


How JMeter can be used to re-run Apache logs to demonstrate real application usage in production

How to use JMeter Assertions in 3 easy steps

3 reasons why open source alone isn’t enough for JMeter experts


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