Functional Testing vs Non-Functional Testing: Understand The Difference


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What is functional testing? 

Today we use hundreds, if not thousands, of programming applications without even batting an eye. All that we use, directly from the refrigerator we use, the TV sets we watch, the vehicles we drive, home security frameworks we depend on, the flights we get, our internet shopping binges… and our PCs and cell phones we underestimate every one of these things. We anticipate that they should carry on precisely as we anticipate, without fail! 

At any point thought about how such flawlessness is accomplished? The response to that is the thing that we call Functional Testing. Functional Testing ensures that every one of the applications that drive every one of the treats that we use works precisely as it should. It is typically a type of Black Box Testing, because the testers don’t get into the inward program construction, or how the applications work. They just look at what goes in and what comes out—info and yield. 

Types of Functional Testing

With this tremendous expanse of Functional Testing that assesses a large number of applications consistently, different explicit kinds of testing are intended to meet unmistakable necessities. 

Unit Testing 

The most crucial type of Functional Testing is Unit Testing. It assesses the most essential components or parts of a product program the littlest lumps of code that can be tried. Consequently the name, Unit Testing. Every unit can be a module, capacity, strategy, or subroutine that takes specific info and gives out a specific yield.

Experiments for Unit Testing assess basic viewpoints like line, code, and technique inclusion. These allude to which lines or how much code or what strategies were executed or “covered” during the test. 

Smoke Testing 

Smoke Testing gets its name from an antiquated act of passing smoke in plumbing lines to distinguish cracks. In a product set, Smoke Tests are intended to distinguish whether the code breaks, or fizzles, and under what conditions. It is by and large done after another rendition, or after certain updates, to check if the new forms are steady. 

Sanity Testing

Sanity Testing is a type of testing to guarantee that all the basic/significant functionalities of the application are working accurately. 

Regression Testing 

This type of testing is done after adding new code or making bug fixes to guarantee that the current functionalities are not influenced. Assuming they are, the framework is said to have “relapsed” or fallen back to a lower level of usefulness, consequently the name Regression Testing. 

Integration Testing 

Integration Testing is done when two, or for the most part more than two, modules or segments are incorporated together to build up an application. While the individual modules or parts may work accurately all alone, Integration Testing guarantees that they work together comparably well. 

User Acceptance Testing 

Otherwise called Beta Testing, User Acceptance Testing (UAT) is a type of testing where the application is tried by a little gathering of genuine clients or specialists, delegate of the real end-clients, in actuality, circumstances.

UAT gives significant criticism to designers on whether the functionalities they make truly address clients’ issues and how much, what holes or downsides they face, and what additional highlights they need to add to the application. 

Localization and Globalization Testing 

These sorts of testing are two of a kind. In Localization Testing, the functionalities are checked to discover whether they are appropriate for quite certain nearby societies while, in Globalization Testing, they are checked to determine whether the application is reasonable across all societies all around the world. 

System Testing 

Regarding hierarchy of importance, System Testing, by and large, follow Integration and goes before Beta Testing or UAT. In System Testing, the whole, completely coordinated framework is tried from one finish to another. 

If we take a similarity of a vehicle, Unit Testing will check each nut and fastener, wheels, windows, and so on In Integration Testing, the wheels are gotten together with the pivot and frame and afterwards tried. In System Testing, the entire vehicle is prepared and tried. In UAT or Beta Testing, the client takes the vehicle for a test drive. 

What is non-functional testing? 

While Functional Testing deals with how the projects are executed in an application, Non-Functional Testing takes a gander at how the application acts in a live environment. This kind of testing contemplates perspectives like Speed, Reliability, Scalability, Performance, and Usability. 

Along these lines, Non-Functional Testing is similarly basic with regards to meeting end-client’s prerequisites because in addition to the fact that applications need to “function” however they need to “perform.” 

Types of Non-Functional Testing

This considers factors like execution under high loads, e.g., when thousands or even a large number of clients simultaneously sign into a framework. It thinks about the capacity of the application to deal with different types of pressure, conditions, catastrophes, etc. The most well-known types of Non-Functional Testing include: 

Load Testing 

Load Testing approves that the application reacts as required in any event, when a huge number of simultaneous clients access it at the same time, for example, in actuality, circumstances. It is typically performed on committed workers that mimic genuine utilization conditions. 

Stress Testing 

Stress Testing assesses the exhibition of performance in crunch circumstances, e.g., under low memory/hard plate space conditions. In such conditions, it is possible to identify desserts that would not have been found in typical circumstances. 

Recovery Testing 

This checks whether applications recuperate effortlessly when sources of info are not true to form or when the environment comes up short. For example, when a client types invalid info that causes a data set cycle to cut short, or when systems shut down strangely because of a force failure, etc. 

Security Testing 

This checks whether an application has no defect that can be misused to exploit the framework and lead to loss of information or theft. It centres around testing confirmation, access control, approval, and other such touchy cycles. 

Scalability Testing 

Scalability Testing checks whether the application can deal with an increment in client traffic, number of exchanges, cycles, or volume of information. The application needs proportional up to satisfy such expansions in needs. 

Endurance Testing 

Endurance Testing, otherwise called Soak Testing, checks whether the application can bear a supported burden throughout a long term time. Commonly it is utilized to test for memory spills in a framework. 

Reliability Testing 

This type of testing can be utilized to check whether an application conveys a similar yield reliably over a predefined span. Reliability Testing is incredibly essential in crucial applications like aeroplane frameworks, atomic plant cycles, and medical equipment, among others. 

Baseline Testing 

Baseline Testing alludes to setting a norm for any new application under test. For example, an application might have the option to deal with a heap of 100,000 clients in its initial round of testing, which at that point turns into a benchmark for future testing. 

What is the difference between functional and non-functional testing? 

Functional Testing takes a look at the conduct of an application, though Non-functional Testing takes a look at its exhibition. To make a relationship, assuming you consider an application a child, Functional Testing assesses its habits while Non-functional Testing assesses its evaluations in tests. 

Key differences between functional and non-functional testing 

Below are the key differences:

  1. Functional Testing is perpetually led before the framework goes into the market however Non-Functional Testing should be possible even after go-live.
  2. The extent of Functional Testing is characterized by item determinations while the extent of Non-Functional Testing relies upon the framework design.
  3. Functional Testing assesses “what” though Non-Functional Testing determines “how” an application is to be tried.
  4. Functional Testing is done dependent on end-client necessities through Non-Functional Testing is for the most part determined by the advancement group.
  5. Functional Testing covers the specialized functionalities however Non-Functional Testing incorporates Performance, Reliability, Security, Scalability, and Usability.


Functional and Non-Functional Testing are similarly basic with regards to meeting the end clients’ prerequisites. While Functional Testing takes a look at all the conduct parts of the application, Non-Functional Testing guarantees the right exhibition in the scope of utilization conditions.

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