Current Date :June 15, 2024

Discover the hidden bugs with Non-Functional Testing

Even when you think you have got it correct, Non-functional testing can reveal hidden flaws.

This is your big vision. Maybe, not necessarily yours, it’s your client’s. But you have spent months pondering over the concept, forming the best team of developers and you are ready to go. Your end purpose is to solve problems and make life easier for the end-user, right? Well, acquiring client satisfaction and holding a positive end-user experience is hinged on one critical factor; Testing.

Quality Assurance(QA) is a key component of your mobile/web application development lifecycle. Whether it be a pre-installed, installed, or browser-based app, strict testing of functionality, compatibility, usability, among others must be accomplished every stage of the way.

Functional testing is an essential and popular step in the app development procedure. Primarily because concentrating on an AUT’s ability and efficiency to serve as needed is second nature to QA practice. However, it is significant to note that non-functional testing is equally necessary as functional testing because it greatly impacts client satisfaction and the complete user experience. In this article, I will attempt to describe what non-functional testing is, distinguish between functional and non-functional testing, and highlight the significance of non-functional testing.

Non-functional Testing

Non-functional testing is a kind of software test for evaluating the non-functional aspects (eg. performance, usability, reliability, etc) of a software application. It is basically aimed at testing the capabilities of a system on such non-functional parameters which are usually not done by functional testing. In other terms, non-functional testing manages the elements of a software application which is not associated with the specified user action or a function.


Security Testing:

This reviews how a system is protected against intentional or spontaneous attacks from known or unknown origins, also known as VAPT (Vulnerability and Penetration Testing). It also catches loopholes within the system and estimates the vulnerability of an AUT to being hacked.

Both Manual and Automated inspection of vulnerabilities via active and passive scans are portions of this testing.

Performance Testing:

Performance testing contains a number of parameters. 

  • Load Testing: Load testing checks the capability of a system/ AUT to deal with various numbers of users provided a performance range. 
  • Stress Testing: Stress Testing evaluates the tenacity of an AUT, calculating what happens to the system when put beneath a valid load in excess of its originally designed ability. For example, how many users functioning on a particular app at a time can cause it to crash?
  • Endurance Testing: This test is necessary to understand the stability of the system over a span of time and to see if small errors that are collected over the said period can impact the efficacy and integrity of the system.
  • Recovery Testing: This reviews that the software system continues to function to the needed standards and recovers fully in the unfortunate case of a system collapse.
  • Reliability Testing: This is done to review the degree to which any software system repeatedly executes a given function without failure. 
  • Scalability Testing: The scalability test is important for the commercialization of a product. It estimates the extent to which a software application can expand its processing capacity to satisfy an increase in demand. 

Portability Testing:

The ease with which a software can be modified or transferred from its existing environment (hardware/software) to another is checked by portability testing.

Usability Testing: 

The ease with which any user can understand, employ, and interact with a system is estimated by the usability test.

Other tests executed during the non-functional testing phase incorporate  Accessibility Testing, Maintainability Testing, Failover Testing, Compatibility Testing, Compliance Testing, Documentation Testing, Volume Testing, Disaster Recovery Testing, Internationalization, and Localization Testing, etc.

Finally, the reason for non-functional testing is to test all elements of an application that would help to create a product that satisfies the expectations of the user. It helps to improve the developer’s understanding of the product behavior, latest trends in technology and supports research development.

 Functional versus Non- Functional Tests: Two Different Concepts

The major difference between the two kinds of testing is this: Functional testing confirms that your product satisfies customer and business requirements and doesn’t have any major bugs. Non-functional testing confirms that the product satisfies the end user’s expectations. 

Functional and Non-Functional tests are technically distinguished from each other based on their objective, focus area, functionality, ease of use, and execution.


Functional testing evaluates the behavior of the software system of the AUT such as login function, valid/ invalid inputs, etc. whereas Non-functional testing deals with the performance or usability of the software.

Focus area:

Functional testing concentrates on consumer requirements, while Non-functional testing concentrates on user expectations.  


Functional tests review that the system functions as expected. Non-functional testing checks how well the system functions. 

Ease of use: 

Functional testing is easy to perform manually, as the black box testing but it is difficult to conduct non-functional testing manually. It is more possible to use automated tools.


Functional testing typically gets executed before non-functional testing, ie. before the compilation of code while Non-Functional testing is mostly conducted after the compilation of code.

Now, imagine completing the masterpiece you have built, and testing its functional requirements completely, leaving out its non-functional requirements. 

Would you like to foretell what would occur when the application is subjected to a massive load when it goes live? Would you be sure of its stress capabilities?

Would you want to guess how slow it may become? What if it crashes on the product launch day? Or an unauthorized party fully takes over the functionality of the system? These techniques depicted create no pleasurable viewing. I wouldn’t want to handle such a product with a ten-foot pole or be associated in any way with it. 

Also Read: AI Is Revolutionizing Software Test Automation

Though testing over the years has been traditionally restricted to functional requirements, the idea of non-functional testing has gradually become an essential part of software processing, without which customer expectations may not be completely met. When a product fails to fulfill these expectations, it impacts the reputation of the developers, company, and even the overall product sale. This is why non-functional testing cannot be neglected.

When you think you have got it correct, non-functional testing will reveal all the hidden flaws!

At TestUnity, we strive for the highest quality in every project, and our professional QA specialists are ready to ensure it. Contact us if you’re looking for a dedicated team to enhance your product’s quality.


Testunity is a SaaS-based technology platform driven by a vast community of testers & QAs spread around the world, powered by technology & testing experts to create the dedicated testing hub. Which is capable of providing almost all kind of testing services for almost all the platforms exists in software word.

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