What is Functional Testing?

Logix Guru

Those involved in software development know that testing is a time-consuming yet absolutely vital aspect of the process. Installation testing ensures that your software accomplishes the goals it is programmed to do, is fully installed, and has a user-friendly interface that actually makes the lives of the target market easier. One of the key parts of installation testing is function testing: the type of testing that ensures precise operations from the software. Logix Guru - the leaders in functional and installation testing in Pittsburgh - is here to break down what you need to know and understand about functional testing for your software.

What is Functional Testing?

Software Installation Testing that Ensures Proper Operation


Functional testing is a form of software testing that checks how a product operates. While this sounds vague, the operation of the software is much different than its individual facts. Focusing on how all functions of a program are used, functional testing is the type of installation testing focused on everything from APIs to security to the user interface. This type of installation testing sets out to achieve a few main functions: 

  • Check basic usage
  • Check accessibility of the system
  • Check the functions that display error messages

How all these parts operate together and function is the basis for functional testing.

What sets functional testing apart from other testing is that functional testing typically doesn’t require the tester to look at the software code, meaning it is classified as ‘black box’ testing. This means that the testing looks at how the code operates without looking at the code itself. Placing all testing from the perspective of the user, functional testing ensures that T’s are crossed and I’s are dotted in terms of how the software functions.

Functional testers check different functions, mapping out a cause and effect graph that tracks whether or not the software is in accordance with the specified input and output. This information helps the tested relay where troubles may be arising in the coding.

We know this sounds a lot like quality testing. To some degree, it is! The difference is that functional testing is asking the very baseline question, “does it work?” During QA, you are often looking for proper speeds and responsiveness across browsers. Kinks like speed and appearance will often be sorted out down the road.

How is Functional Testing Performed?

The Four Main Steps in Functional Installation Testing

Check Marks

When new software rolls out, functional testing is completed in the early stages of installation testing. There are 4 main steps in functional testing, including:

  1. Define the input. Choosing your testing data - what will be clicked, hovered, or processed?
  2. Define the output expected. When the input is performed, what is supposed to happen? Be specific in order to iron out kinks early, but be sure to focus on the baseline functionality.
  3. Execute test cases. Test your input multiple times, keeping record the the real output.
  4. Compare real vs. expected output. Compare the frequency of each real output with the expected output. Did your software function as it is supposed to?

Using this process, you’ll learn whether or not your software functions process, making it possible to iron out functional issues early on in the installation testing process.

How are Functional and Non-functional Testing Different?



Functional testing is significantly more specific than non-functional testing. Non-functional testing is focused on more general metrics like scalability, reliability, readability, and performance of the software. Functional testing, however, focuses on specifications that need to be verified against the system. Functional testers operate exclusively against these parameters rather than the impressions of non-functional testing.


Functional testing is almost always performed before non-functional testing. This is logical given that testing the overall performance of a system is extremely difficult when vital functions are not working. Functional testing essentially lays out the baseline functions before other types of installation testing can occur.


Functional testing uses both manual and automated testing tools. This is because functional testing is more specific and can be easily spotted during both manual and automated testing. Because of this ease, manual testing from Logix Guru is nearly ideal for functional testing.

However, on-functional testing generally benefits from automated testing tools because it is much faster at sensing general impressions without bias or comparison.

Sources of Input

Functional testing checks to make sure software conforms to design and business specifications set forth by the operator. However, as mentioned before, non-functional testing checks more general metrics. The results you’ll receive from functional versus non-functional testing, for this reason, and vastly different.


While it’s easy to confuse functional testing with QA, the truth of the matter is that QA is closer aligned to non-functional testing. Non-functional testing focused on the general quality and less specific performance aspects while functional testing ensures the software coding is doing exactly what it is supposed to do.

It’s clear that functional testing is a vital aspect of software installation testing. Ready to utilize functional testing in your software development process? Get in touch with Logix Guru today for all your installation testing needs.