Types of Software Testing: Functional and Non-Functional

On our testing journeys, each of us has likely encountered a variety of test types. Some of the types of testing may have been mentioned to us or we may have worked on them, but not everyone is familiar with all of them.

A software development company makes certain it has the tools necessary to conduct testing procedures efficiently. In order to do this, they need to have a skilled expert with a thorough understanding of software.

The characteristics, benefits, and drawbacks of each method of testing are unique. However, we have addressed functional and non-functional testing of software in this article as this is what we often do in our day-to-day testing.

Functional Testing

There are four main types of testing that cover the functionality of software.

Unit Testing

Software testing that is done on a single unit or component to test any adjustments is known as unit testing. Unit testing is often carried out by the developer throughout the application development process. Each unit tested during unit testing can be thought of as an object, function, method, or process. For the execution of tests, developers frequently utilise test automation tools like NUnit, XUnit, and JUnit.

Unit testing is essential testing under various types of testing since we could find more bugs in this.


For example, there is a straightforward calculator programme. The unit test may be written by the developer to determine whether the user can enter two numbers and obtain the right total for the additional functionality. A unit test follows (or rather incorporates) –

  • White Box Testing
  • Gorilla Testing


Integration Testing

There is another type of software testing called “integration testing” that involves logically grouping together two or more modules of an application and testing them as a whole. This sort of testing focuses on identifying interface, communication, and data flow flaws between modules. When integrating modules into the overall system, either a top-down or bottom-up strategy is employed.

This kind of testing is carried out while integrating modules into one system or another.

For example, any airline’s website is being used by a user to purchase a ticket. While purchasing a ticket, users can view payment and flight information, although both are handled by separate systems. Integration testing should be carried out when connecting an airline website with a payment processing system.

It incorporates – 

  • Gray box testing


System Testing

System testing is a sort of testing where the entire system is assessed in comparison to the given requirements. It involves – 

  • End to End Testing
  • Black Box Testing
  • Smoke Testing
  • Sanity Testing
  • Happy Path Testing
  • Monkey Testing

Acceptance Testing

In acceptance testing, real-world business scenarios are used to evaluate the software by clients, businesses, or customers.

Only after all the features and capabilities behave as intended does the customer accept the programme. This is the final stage of testing before the programme is put into use. A software development company should be transparent enough to provide their clients a sense of security and genuineness in product delivery.

Another name for this is user acceptance testing (UAT). It involves the following testing – 

  • Alpha Testing
  • Beta Testing
  • Operational acceptance testing (OAT)


Non-Functional Testing

There are four main types of functional testing.

Security Testing

This kind of testing is carried out by a specialised team. Any hacking technique will work to access the system.

Software, applications, and websites are subjected to security testing to determine how well protected they are against internal and/or external dangers. The strength and security of the authorization and authentication processes, as well as the degree of software security against viruses and dangerous programmes, are all subject to testing.

Additionally, it examines how software responds to hacker attacks, malicious software, and how software is maintained for data security following such an assault. It involves – 

Penetration Testing


Performance Testing

Performance testing is one of the various types of non-functional testing that involves adding load to an application to check for stability and reaction time.

The capacity of the application to endure a load is referred to as stability. Response time is the speed at which a user may access an application. Performance testing is carried out using tools. Market-available tools like Loader.IO, JMeter, LoadRunner, etc. are decent ones. It incorporates the following testing – 

  • Load testing
  • Stress Testing
  • Scalability Testing
  • Volume testing (flood testing)
  • Endurance Testing (Soak Testing)


Usability Testing

Usability testing examines an application’s appearance, feel, and user-friendliness from the viewpoint of the user.

For instance, a tester is assessing the usability of a mobile app for stock trading. Testers can look for things like if a mobile app is simple to use with one hand, whether the scroll bar is vertical, whether the app’s backdrop colour is black, and whether the price and stock information are presented in red or green.

The primary concept behind usability testing for this sort of software is that the user should have access to the market as soon as they open the app. It involves – 

  • Exploratory testing
  • Cross browser testing
  • Accessibility Testing


Compatibility testing

This sort of testing verifies how software functions and operates in various environments, including web servers, hardware, and network environments.

Software must pass compatibility testing to verify that it can run on various configurations, databases, and browser versions. Compatibility testing is done by the testing team.


We have discussed thoroughly the different types of testing that a good software development company should conduct before delivering their service. A client should have a crystal-clear understanding of the functionalities of their product. That is why we always assert testing is necessary.

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About the Author

Ronan Healy

Hi everyone. I'm part of the EuroSTAR team. I'm here to help you engage with the EuroSTAR Huddle Community and get the best out of your membership. Together with software testing experts, we have a range of webinars and eBooks for you to enjoy and we have lots of opportunities for you to come together online. If you have any thoughts about the community, please get in contact with me.
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